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1. 4 Aas Wheater Print Figure 43 Trnsys scheme for the case with two external orientations The type 56 Room in the middle of the images contains all the parameters of the room These values have been entered using the part of the program called Trnsys Build This component models the thermal behavior of a building divided into different thermal zones The TRNBUILD program reads in and processes a file containing the building description and generates two files that is used by the TYPE 56 component during a TRNSYS simulation The file containing the building description processed by TRNBUILD it was generated with the interactive program TRNBUILD It generates an information file describing the outputs and required inputs of TYPE 56 The level of detail of TRNSYS building model is compliant with the requirements of ANSI ASHRAE Standard 140 2001 In this part of program it is possible to include all the features of the room and then recalled in the Type 56 The latter has been linked to the types with the external 63 conditions Four txt file were created with the same setting values in SST then imported into the TRNSYS Studio and finally connected to the type that contains Room parameters with the Type 9a These files are e Tempext It contains 24 values of the external temperature one for each hour e Sun Irrad It contains 24 values of the solar irradiation depending which external orientation is needed one for each
2. 1 Jan 12 Dec Slab See image below Layer the pipes from the top Material Carpet Thickness m 0 01 i Thermal conductivity W m k 0 07 1 2 pal Specific Heat L kg k 1000 1000 1000 Density kg m 3000 2000 2400 Layer the pipes Material Concrete 2400density Concrete Screed Thickness m 0 06 0 01 Thermal conductivity W m K 2i ales Specific Heat U kg k 1000 1000 Density kg m 2400 2000 Slab Model Carpet Above the pipes Concrete Screed 0 17m conjete 2400 di sali Pipes level Concrete 2400 density Concrete Screed Below the pipes 0 07m Room Next Step Insert Wall Thickness Density Lambda External Wall m kg m W mk Lime cement plaster 0 01 1800 0 9 Brick 0 3 1400 0 52 Lime cement plaster 0 01 1800 0 9 TOT 0 32m TOT 1 669 Internal Wall Lime cement plaster Perforated Brick Lime cement plaster TOT Im kg m 0 01 1800 0 1 750 0 01 1800 0 12m TOT W mK 0 9 0 35 0 9 3 247 East 3 m Windows Shading 20 External Walls Color Bright Type of glass Double 4 16 4 Coated Glass Argon U value 1 50 W m k External Infiltration Mechanical 0 3 Volumes per hour 0 Volumes per hour Show Values Room Floor Area WallArea hAirToFloor hAirToCeiling hAirToWalls Total View Factor Add Floor Resistance Add Ceiling Resistance Wall Resistance Cwalls Location External Orientation
3. 76 6 Limitation The simplified model based on finite difference method FDM consists in detailed dynamic simulations which predict the heat transfers in the slab and in the room It requires the knowledge of the values of the variable cooling loads of the room during each hour of the day In comparison with the Rough sizing method which is based on standard calculations of cooling loads and suggests an error of about 20 30 the FDM exhibits a small estimated error of about 10 15 In the SST the thermodynamic properties outside the considered room are unknown hence it assumes that the internal conditions the internal loads and the trend of temperature loads of the other rooms around are the same This means that the heat exchange between the considered room and the other ones is neglected that is the internal walls are adiabatic Moreover there is no air exchange between the different internal rooms i e there are no open doors Whichever environments without people lightings or equipment covered or not by the cooling system e g a hallway is not considered Therefore the heat that could be transferred to the different areas remains inside the considered room leading to possible errors In order to get a more realistic simulation if areas with different conditions border the room it is recommended to simulate a bigger room with the same absolute internal loads If the bordering areas are uncooled e g an uncooled corrid
4. e Circuit heat is the value of the used cooling power hour per hour during the period It is in specific or absolute power depending on the option selected e Floor Ceiling and Internal wall surface heats are the values of the heat transfer between the pipes and the thermal node Floor Ceiling and Internal Wall respectively e Total radiant and convective gains are the fractions of room radiant and convective loads acting on the pipes As last available option is also possible to see only the report file by clicking on Create Report it will open only the output file of the simulation as excel file Obviously the software folders contain all the project parameters divided in Input files Output files and Project Files These files can be opened with Notepad or a similar program 59 60 5 Validation 5 1 About Trnsys The good performance of the SST program depends on the quality of its results To verify this it was compared with the program Trnsys an acronym for TRaNsient SYstem Simulation Program version 16 for the dynamic simulation The code of Trnsys has been developed by the Solar Energy Laboratory at the University of Wisconsin Madison and is currently one of the most reliable scientific programs for the study of dynamical systems in the energy field Its use ranges from the study of heating and electrical systems fed with traditional sources and or renewable energy analysis of HVAC systems hydraulic systems hy
5. One of the most important parts for the functionality of the program is its protection We must avoid that the user can delete important parts of the program such as formulas or spreadsheets The user can see only some sheets because many of them are hidden In this way it is not possible to modify the core of the calculation of the program rendering it unusable In fact the available sheets are New project Loads Load WE Overview Projects These are the main sheets and they are sufficient to create a new project or view the results There are some usable sheets more Boundary Circ Pipe Room and Slab They contain all the parameters of the different projects and it is not recommended to modify data except for advanced users To avoid the problems with an incorrect user utilization of the software some precautions had to be implemented Two different types of protections are used in this tool The first is visual and the user can recognize which parameters the tool needs by inserting data only in the white cells The second is the protection of the sheets and it is indispensable to not permit voluntary or accidentally attempts to delete formulas Therefore all the white cells were let unblocked and later all the sheets were protected 39 40 4 Interface In this chapter all the parts that compose the interface of the program are explained creating the user manual that will be attached to the program This chapter contains all the
6. Uponor Europe Business Group Indoor climate Engineering amp Special Projects Coaloulations for selected day Based on ASHAAE Dear Sky Modes Location Latitude Longitude Time Zone Daylight Savings Time Month Day Clearness Number Ground Reflectance Window Area Direction Tilt Window SHGC Shading Results Hour Window Transmitted Heat Gains w 1 0 0 2 0 0 3 0 0 4 0 0 5 79 0 Hamburg 6 270 6 53 55 7 367 6 350 0 8 3931 27 3 364 0 T 10 294 2 7 11 187 6 8 12 841 1 13 65 3 02 14 60 6 1m 15 56 4 a 16 50 2 st 7 42 3 0 65 18 325 25 13 20 0 Window transmitted heat gains oi23 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Figure 27 Solar Tool sheet the right shows the sheet with the case of east orientation 37 3 8 Inserting wrong data protection To prevent at the user to enter data that are not realistic negative values or poorly written the presence of letters in the cells that require a numeric value and the forgetfulness of some values leaving the empty cell it was necessary to implement an automatic control via the VBA code Do not implement this control would lead to the malfunctioning of the program by creating errors in the calculation of the parameters and subsequently the simulation The figure is a screenshot of the If shI Range C8 0 Then MsgBox Insert a city vbExclamation
7. View Factor Floor To Ceiling View Factor Slab To ExtWall View Factor Slab To IntWall Yes Unit KELIG m 25 m 15 W m K 15 W m K 5 5 W m k 25 Cl 0 354 Hl 0 161 i 0 484 i 1 00 m k W o m K W 0 m k W 0 5991 U m K 49500 Venice i E Figure 29 New Project sheet L The geographic conditions are completely different from North Europe to Arabian countries where the maximal temperature for the hottest day in the year goes from 20 7 C in Dublin Ireland to 42 3 in Doha Qatar Furthermore depending on the location the solar radiation for the north and south orientations might be very different due to the different sun height between the tropic and the polar circle Obviously for this reasons the behavior of a room with a glass fa ade or a little windows might be completely different because of the solar irradiance entering from the external and consequently might change the operative temperature and the needed cooling power In the New Project sheet there are five arrows for inserting the parameters in the database in order to help the users to have a user friendly connection with the program All the parts must be added for the functioning of the simulation if some parameter is missing simulation will be interrupted Location it is the city where we want to simulate the project The user can choose a city from the library or insert a new location manually With t
8. needed information to use the program from creating a new project to viewing the results The Simple Simulation Tool is composed by two parts v the Excel worksheet v the program file compiled in C The two parts can be used together to size Thermally Activated Building Systems and the required maximum chiller capacity considering different operation modes Moreover the program permits to simulate the trend of the temperature in different part of the room such the internal temperature inside the wall temperature or the outlet water temperature It is possible to test the impact of different pipe circuit and slab configurations on room temperature In combination with adjustments of the cooling period it is possible to see if the internal heat capacity of the structure is sufficient to limit cooling to night time where the required electrical energy might be cheaper of even free low outside temperatures during night SST can simulate an internal space principally an office surrounded by similar other areas divided by the internal walls and the areas above and below Therefore it is not possible to simulate the conditions the last floor of a building because it is not programmed to consider the heat transfer through the ceiling and the solar radiation acting upon it There are three steps connected with several main sheets and they are called New project Loads and Overview In the following chapters we will focus on these thre
9. in the red curve to 100 75 and 100 curves are coincident The chart shows the inside temperature trends using the results of the simulation For the 100 simulation the temperature range is between 18 C and 22 C down to 17 C during the weekend but the absolute values of the temperatures are 26 not similar to the values used in reality in an office during the hottest day in summer This chart shows that inside the room there will be a daily excursion temperature of 4 degrees Moreover in the 0 cooling simulation the value of the internal temperature reaches over 40 C after 10 days This is due to the problem of the load calculation Formulas are based on an internal design temperature only manually modifiable fixed in a variable range of values between 22 and 24 degrees depending on the hour In this way when the values of the internal gains are entered in the program for a number of days all the thermal loads per hour for one day are calculated based on a fixed internal temperature and if this value comes out of the comfort range this difference of the internal loads is not taken into consideration Hence all the internal load calculation could be correct only in the comfort range Temperature U p o n o r 39 l jy Alo A 19 Y l N j E NS 14 w o x 0 D N q wo z a 72 192 216 240 Office Office_0 Office_25 Office_50 Office_75 Figure 18 Simulation of 25 m
10. 06 0 1 m Thermal conductivity 0 07 1 2 2 1 W m K Specific Heat 1000 1000 1000 J kg K Density 3000 2000 2400 kg m Layer below the pipes A B Material Concrete Concrete Screed Thickness 0 06 0 01 m Thermal conductivity 2 1 1 2 W m K Specific Heat 1000 1000 J kg K Density 2400 2000 kg m Pipe Values Circuit Values Type of Pipes Contec Pipe 20 Pipe Spacing 0 15m Diameter external 0 02 m Area Fraction 1 Wall thickness 0 0023 m Mass flow mm 16 kg h m Thermal conductivity 0 35 W m K Fluid Water Fluid Density 1000 kg m Fluid Specific Heat 4186 8 J kg K 66 The parameters of the internal gains are Hour n People Activity n Equipment Type Equipment 8 2 Seated light work typing 2 PC with monitor 9 2 Seated light work typing 2 PC with monitor 10 2 Seated light work typing 2 PC with monitor 11 2 Seated light work typing 2 PC with monitor 12 2 Seated light work typing 2 PC with monitor 13 2 Seated light work typing 2 PC with monitor 14 2 Seated light work typing 2 PC with monitor 15 2 Seated light work typing 2 PC with monitor 16 2 Seated light work typing 2 PC with monitor 17 2 Seated light work typing 2 PC with monitor Second simulation In the second simulation the thickness of the external wall has been changed from 32 mm to 12 mm Such a thin wall is not used in buildings but it has been necessary to test a wall wit
11. 11 12 13 14 15 16 17 18 19 20 21 22 23 24 parameters and setting 1 409 Day Hours Convective Radiative for the specific values or 0 for the absolute values Figure 36 Chart with the calculated Convective and Radiative Loads Curves By setting Yes it is possible to change the parameters of the simulation regarding the type of iteration The requested values are e Number of Time Step number of hours of calculation and it has to be equal at the sum of all the hours inserted below e TimeStep the number of division in second for one hour calculation e nSubTimeStep maximal number of iteration if the program reach this number of iterations without a stable solution a negative response will be appear It is possible to increase the number of iteration for contrast however the calculation time will be longer e tolDayMax is the tolerance of the simulation for one day step calculation e tolHourMax is the tolerance of the simulation for one hour step calculation For both tolerances it is possible to decrease the value of the calculation accuracy to decrease the calculation time however the results will be less accurate 51 4 3 Overview Once all the necessary data are inserted in the previous sheets get to the summary screen regarding the data of boundaries circuit pipe room and slab by clicking the arrow From this sheet the user can browse all the projects inserted and choose the diffe
12. In the present work the greatest errors have been found in the latter simulation considering the limitations of the program uponor N lt w D OperativeTemperature C R fh 23 120 144 168 a 8 R amp SssT Trnsys Figure 46 Differences between Trnsys and SST for the first simulation results with 12 h functioning and the Comfort range option set to Top min 23 C Top offset 1 C Top Range 2 C Pcootinc 40W Second simulation The simulation results in the case of thin external wall are similar to those one carried out with the thick wall The results of the operative temperature of Trnsys are slightly higher than those of the Figure 45 because the thinner wall has a lower thermal conductivity 4 66 W mK instead of 1 67 W mK with respect to the external wall Also in this case the results of the two programs are similar and the shape of the curves corresponds at several points The difference in the values of the maximum temperatures in the first days of the week is little ie about 0 4 C but the minimum temperatures are almost similar The results are not exactly alike at the weekend but the error is negligible See Figures 47 and 48 70 uponor 27 Operative Temperature C N uw 168 ssT Trnsys Figure 47 Differences between Trnsys and SST for the first simulation results with 24 h functioning and the Comfort range option set to Top min 23 C Top o
13. With this data the program can calculate the quantity of heat that the ceiling can store for each layer Even in this case it is possible to add manually a new material by inserting the values in the cells showed in the Figure 26 at the v Internal loads library right There are three different libraries for the internal loads e Library for the people For each different human activity there are different values of sensible and latent heat These values are in according with the standard UNI 7730 in W Degree of Activity Av Metabolic rate Sensible Heat Latent Heat Seated at rest 100 60 40 Seated very light writing 120 65 55 Seated eating 170 75 95 Seated light work typing 150 75 75 Standing light work 185 90 95 Light bench work 230 100 130 Walking 1 3 m s light machine work 305 100 205 Moderate dancing 375 120 255 Heavy work Heavy machine work 465 165 300 Heavy work athletics 525 185 340 e Library for the lighting There are some different values for the Irradiance due to the artificial lights in W m2 The user can select between 5 10 13 17 19 and 55 W m2 e Library for the equipment For each Equipment there are a value of heat load in W Copy Machine Type of Equipment Power W Flat Monitor 20 30 Laptop 40 Laser Printer Small 70 Terminal 80 Laser Printer Medium 130 PC with monitor 140 550 35 v W
14. a temperature range in which the maximum cooling power is gradually reduced from 100 to 0 tOpRange always has to be greater than zero The principle is similar as the other case the maximum power available is multiplied for a load factor fc which varies between 0 and 1 according to the operative temperature inside 31 the analyzed room When the temperature is below the minimal operative temperature including the addition of the offset value the load factor is equal to 0 When it surpasses this value the cooling factor begins to be different from zero up to one when the minimal operative temperature including the addition of the offset and the range values is reached The formula is Por Puax fe The Figure 22 shows the meaning of the three temperatures and the factor fc 26 Temp 255 4 Top Off Range 245 4 24 4 235 4 Top Offset 225 Top 215 21 0 8 0 6 0 4 0 2 Figure 22 Functioning of Comfort Range option In this case has been set a minimal operative temperature of 22 C an offset of 1 C and a range of 2 C 32 The Figure 23 illustrates the differences of the two cases uponor 26 Operative Temperature C 8 16 ba 2 R 8 120 144 168 Option activated Option deactivated Figure 23 Differences between Comfort Range option activated blue line or deactivated red line Obviously to control the correct functioning of these implemented opti
15. all the improvement I implemented the user manual of the program an explanation of the functions created the verifications carried out by the program with the comparison of the results with the program Trnsys the limitations observed and the conclusions that have been reached Contents Preface Contents 1 Introduction 2 Simplified model based on FDM 2 1 Cooling system 2 2 Hydraulic circuit and slab 2 3 Room 2 4 Limits of the method 3 Implementation 3 1 From the beginning 3 2 First Steps 3 3 Excel code 3 4 VBA code 3 5 Implemented Options 3 6 Library creation 3 7 Solar Tool 3 8 Inserting wrong data protection 3 9 Program protection 4 Interface 4 1 New Project 4 2 Loads and Loads WE 4 2 1 Commodity 4 2 2 Manual insertion 4 3 Overview 4 4 Manual 4 5 Other sheets 4 6 Results 5 Validation 5 1 About Trnsys 5 2 Trnsys model 5 3 Simulations parameters O O W 10 11 12 15 15 18 23 24 26 33 37 38 39 41 41 46 49 50 52 55 55 56 61 61 62 65 5 4 Simulation Results 5 4 1 Results of the simulations 5 4 2 Option Results 6 Limitation 7 Conclusion Appendix A 8 References Acknowledgements 69 69 73 77 79 81 83 85 1 Introduction The calculation formulas of this tool are based on the simplified model based on finite difference method in the standard ISO 11855 mainly on part 4 It allows the calculation of the trend of different internal temperatures in the room under consideration as
16. contains the library of different materials with their characteristics see chapter 3 6 When a material is selected from a data list the function searches the values needed in the library contained on this sheet Data contains all the names and values for the lists of data validation and the tables Results After running the simulation results can be viewed by pressing the button Show Chart on the Overview sheet A macro will open a new file containing the results and charts that show the evolution of the operating temperature within the room and the power used for the entire period simulated 56 Suleyman_0 IV Suleyman_25 I Suleyman_50 Iv Suleyman 75 uponor The power chart shows s co the results in specific power or absolute depending on the option _ selected earlier in the Overview sheet Operative Temperature C The Figures 39 and 40 show an example of a results file In the first a a g R 8 g g B a chart is possible to Suleyman Suleyman 0 Suleyman25 Suleyman 50 Suleyman_75 Figure 39 Example ofa results chart It is possible to see the curves visualize the trends of the with the different cooling power available Operative air temperature based on the selected options In the x axis are represented the hours and in the y axis the operative temperature of the analyzed case If the Run with no Cooling option is enabled in the upper part of t
17. could be solved by introducing a sort of control into the calculation However the suggested low internal temperatures are of cause not those the user would like to see in a real building This could be helped by introducing a sort of control into the calculation Hence as the Load Limitation case a function was implemented to fix this problem This function is called Comfort Range can be enabled or disabled according with what the user wants The program needs a parameter 0 or 1 in case the user wants to activate this function or not The user only needs to tick a box in the options available in the Overview sheet and the tool will automatically assign the value of 0 or 1 e ComfortRangeLowerEnd 0 Simulations will be executed without consideration of the lower end of the comfort range Cooling power is only limited through the set point temperature and the available cooling power e ComfortRangeLowerEnd 1 Simulations will be executed with a lower comfort temperature in place The cooling power is gradually reduced if the room temperature falls below the defined threshold The function has three parameters that are described below and need to be provided via the boundary input file tOpMin lower limit for the operative temperature tOpOffset can be used to start the reduction of cooling at higher operative temperatures If set to zero cooling will only be reduced if the operative temperature reaches tOpMin tOpRange defines
18. for ceiling cooling system e Air to Walls fixed at 2 5 W mK v Three values of View Factor the sum has to be equal to 1 e Floor to Ceiling between parallel equal rectangular plates of size W1 W2 separated a distance H where et y x vVl x yE h y H H 1 x Ve x y F _c ln 2 y arctan arctan x 2y x arctan arctan y my x y 1 y X e Slab to External Walls from a horizontal rectangle of W L to adjacent vertical rectangle of H L where fe TEA L L a flew w ltw h Pltw h I Iph w Siswi a Urwin v 45 l Le E 1 1 a F _ h arctan w arctan Vh w art tan Inlab c h Ih w 4 TW w e Slab to Internal Walls the same for External Walls v Possible presence of additional floor or ceiling resistance layers with no values inserted it has zero as default value v Wall surface thermal resistance in m K W calculated for every layer by Wall Res thickness where A thermal conductivity v Average specific thermal capacity of the internal walls in J m K calculated for every layer by C p thickness cp where p density cp specific heat capacity In the right part of this screen and in all the others are present the arrows to switch from one sheet to another These arrows are Next Step Previous Step with an obvious significance Loads and New Project to return in the previous sheets This
19. heat capacity of the fluid utilized In most of Figure 12 Circuit sheet the cases the fluid is water hence the parameters were every times the same Vv Pipe The sheet contained the three main parameters regarding the pipes that are the external diameter and the thickness of the pipe and the thermal conductivity of the material that pipes are made Usually these are standard values and are established by materials A B C Pipe Data Unit D E 11855 4 Luca_pipe available in the market For a normal project the most used type of pipe is the one with a aA nf wN e diameter of 20 mm 16 diameter_ext m wall_thickness m thermal_cond W m K 0 02 0 01 0 0023 0 0023 0 35 0 35 Figure 13 Pipe sheet v Slab The last sheet enclosed the data referred to the ceiling that contains the pipes It is very important to set correctly these values because the efficacy of the plant is strictly connected with disposition of the layers The list is in order from the top to the bottom and is divided for the layer above and bottom the pipe level The program needed the following parameters e Number of Layers number of layers of which the ceiling is composed and it has to be equal at the sum of all the layers inserted below e ActiveLayerDepth the depth in which there are the pipes of the circuit calculated from above Afterwards for each layer it was necessary to fill in t
20. hour e Mass flow It contains 24 values of the mass flow in kg h depending which case is simulated one for each hour Hence 24 equal values for the continuous mode operation or 12 values when the system is turned on and 12 null values when it is turned off e TempSky It contains 24 values of the sky temperature one for each hour According to the ASHRAE code hourly temperatures given the hour 1 24 are depending by the peak temperature the daily range and multiplied by the coefficient p t With regard to other necessary meteorological parameters in Trnsys the type TempSky is connected to the Type 15 3 where the weather data of Venice are implemented in it as in the case analyzed in SST The type required to view the results is the Type 65c in which is possible to select the parameters to be displayed and the position in order to save the results in txt file Finally the simulation was run and the Figure 44 shows an example of results Temperatures Heat transfer rates Ti Conv TAIR_INT Rad Twater Tot Toper TOFL_S6 35 00 2000 31 00 1600 3 1200 Temperatures N D 2 S q J 0 S S Heat transfer ra 19 00 400 15 00 0 1 0 15 0 29 0 43 0 57 0 71 0 85 0 99 0 113 0 127 0 141 0 155 0 169 0 Simulation Time 169 00 hr Figure 44 Trnsys results with the trends of the internal operative external and return water temperature 64 o g 2 5 3 Simulations param
21. inlet temperature of the water 15 and the maximum cooling power available The problem was that the user hardly knew which the loads were hour by hour so the calculation resulted difficult Room B E D E F i 1 In this part the program needed all the parameters Ts int ssa ioc oom 2 A 3 FloorArea m2 30 100 about the room therefore the dimensions of the Wailes m2 PA re i i 5 hAirToFloor W m2 K 15 15 room under consideration such the floor and the 5 hAirToCeiling Bon 5 5 5 5 x hAirToWalls W m2 2 5 2 5 internal wall area three convective heat transfer s FvFloorToCeiling 0o21 0 21 9 FvSlabToExtWall 0 35 0 35 coefficients between air and floor ceiling and 10 FloorResistance zng oi 01 11 CeilingResistance m2 K 0 0 internal walls the view factor between floor and wallResistance m2 K 4 0 05 0 05 13 CWalls m2 K 25600 25600 ceiling or external walls three values of resistances of the floor ceiling and walls and the Figure 11 Room sheet average specific thermal capacity of the internal walls v Circuit In this sheet the user had to insert all A B c D al the data connected with the type of 2 Circuit Data Unit 11855 4 Luca_circuit 3 pipe_spacing m 0 1 0 1 the circuit such the pipe spacing the 4 area_pere Cl 2 1 5 mass_flow_mm kg h m2 36 36 fraction of area covered by the pipes fluid_char_rho kg m3 ann a F fluid_c_w kg K 4187 4187 R the mass flow the density and the
22. loads is mandatory in order to keep also the daily temperature range comparable with the results of Trnsys A first attempt could be to differentiate the decrease between radiant and convective loads and make them dependent on the external temperature 79 80 Appendix A Operative temperature is defined as a uniform temperature of a radiantly black enclosure in which an occupant would exchange the same amount of heat by radiation plus convection as in the actual nonuniform environment Is a simplified measure of human thermal comfort derived from air temperature mean radiant temperature and air speed It can be useful in assessing the likely thermal comfort of the occupants of a building Actual thermal comfort is dependent on environmental factors such as air temperature air velocity relative humidity and the uniformity of conditions as well as personal factors such as clothing metabolic heat acclimatisation state of health expectations and even access to food and drink However as empirical fits to these variables are very complex a simpler measure can be more useful in practice The mean radiant temperature can be calculated from the temperatures the areas and the view factors of the surfaces bounding the room through the relation Tur 2 hpa i Operative temperature is defined as T he Ty hp h h C R Topera TIVE Where Hc convective heat transfer coefficient Hr radiative heat tran
23. measured meteorological phenomena and vicinity to genuine data sites using a correlated model For this reason the values can be very different between one day and another as regards both the external temperature and the solar radiation of each orientation hence it is not possible to compare the results using these 61 parameters from data TRNSYS Appropriate provisions should therefore manually insert using two input types type 9a the values of external temperature and solar radiation taken directly from ASHRAE data and the Solar Tool 5 2 Trnsys model The Trnsys model used for the simulations is composed by different types see Figure 42 below The main Type is the Type 56 it contains all the parameters regarding the room under consideration It is created by the program part called Trnsys Build that is an interface for creating and editing all of the non geometry information required by the TRNSYS Building Model this is included in the software package TRNBuild allows the user extensive flexibility in editing wall and layer material properties creating ventilation and infiltration profiles adding gains defining radiant ceilings and floors and positioning occupants for comfort calculations It consists of a graphical front end TRNSYS Simulation Studio to intuitively create a simulation it is an interface for the detailed TRNSYS multi zone building where it is possible to add different zones with the related parameters In this c
24. method makes of the program but of course it is possible to change the sheet in the traditional method by clicking on the name of the sheets at the bottom 4 2 Loads and Loads WE The conditions within a room can be highly variable in relation to the type of building its destination and the geographic location The thermal loads change depending on the hours of the day especially for an office having the maximum internal load often coinciding with the warmer hours of the day where there is the maximum heat load from outside and also the internal conditions varies on weekdays or weekend Furthermore according to the type of cooling system it is possible to set the number of hours of functioning Longest is 46 the period of daily use and smaller will be the chiller size conversely utilizing the cooling system only during the night it permits to save on the cost of electricity The sheet is concerning the internal gains and the maximal cooling power insertion User can define for every hours of the day which are the cooling capacity available and the type of activities participating inside the analysed room A screenshot of the Loads sheet is showed in Figure 32 Name Project persone Change Operative Temp Insert Days Values Temp Op Min 22 GC Number of repeated days 5 Can
25. parameters 7 tolHourMax 0 00001 0 00001 8 gg cHoures E z e Number of Time Step number of hours of 10 convHeatFlux W 30 30 ee adHeatFlux W a8 2 calculation and it has to be equal at the sum of all the 12 runningMode 1 1 13 tWater ic 20 20 hours inserted below 14 maxCoolPower W 1000 1000 15 e TimeStep the number of division in second 16 nHoures 11 6 17 convHeatFlux W 400 400 for one hour calculation 18 radHeatFlux w 300 300 19 runningMode 0 0 e nSubTimeStep maximal number of iteration 20 tWater C 20 20 21 maxCoolPower W 0 0 if the program reach this number of iterations 22 23 nHoures Hl 5 2 without a stable solution a negative response will be 24 convHeatFlux Ww 150 300 25 radHeatFlux W 100 200 appear It is possible to increase the number of 26 runningMode 1 0 97 tWater Ic 20 20 iteration for contrast however the calculation time 28 maxCoolPower W 1000 0 Figure 10 Boundary sheet will be longer e tolDayMax is the tolerance of the simulation for one day step calculation e tolHourMax is the tolerance of the simulation for one hour step calculation For both tolerances it is possible to decrease the value of the calculation accuracy to decrease the calculation time however the results will be less accurate Afterwards for each interval with the same characteristics it was necessary to enter the number of hours the convective and radiant heat loads the
26. program code that shows an Exit Sub End If example of the controls a eee a mates A MsgBox Insert windows shading value vbExclamation inserted Exit Sub End If If shiI Range I56 Then Most of the controls in the MsgBox Insert Esternal Wall Color vbExclamation Exit Sub program have been written r 7 If shiI Range H60 Then using the functions If and Elself MsgBox Insert Type of Glass vbExclamation Exit Sub When the user tries to enter the ElseIf shI Range H60 lt gt Single Then If shI Range H61 Or shI Range H62 Then data b clickin on the MsgBox Insert Type of Glass vbExclamation y 8 Exit Sub El corresponding arrow and there ae eae End If are mistakes then a message If shiI Range I66 lt 0 Or shI Range I66 gt 10 Then box will appears which explains MsgBox Insert realistic value of air change rate vbExclamation Exit Sub Else which parameter is missing or sna 3 inserted incorrectly When this message appears the macro Figure 28 Example of VBA code for the Data Protection data entry is interrupted and thereby avoiding the presence of errors Without these controls eg the biggest problem might be the lack of some values when entering data of the boundary This absence would create different spaces between the values entered and the relationship between the required parameters and values entered would be lose 38 3 9 Program protection
27. room temperature exceeds a defined threshold The function has three parameters that are described below and need to be provided in the boundary input file tMax is the value of the maximum operative temperature in the room Above this value the loads start to be reduced tMaxOffset can be used to start the reduction of loads at lower operative temperatures If set to zero loads will only be reduced if the operative temperature reaches tMax tMaxRange defines a temperature range in which the maximum loads are gradually reduced from 100 to 0 tMaxRange always has to be greater than zero The principle underlying this method is to multiply the cooling factor f for the sum of the convective and radiative loads The cooling factor varies between 0 and 1 according with the operative temperature in the analyzed room When the temperature in the room is below the maximal operative temperature including the addition of the offset value the cooling factor is equal to 1 In the case of reaching this value the factor starts to decrease down to 0 when the maximal operative temperature with the addition of the offset value is reached 28 The formula used by the program is Q oan Qeonv Qrav fi The Figure 19 shows the meaning of the three temperatures and the factor fi 36 Temp 34 Top Off Range 32 30 Top Offset Top max se 08 0 6 0 4 0 2 Figure 19 Functioning of Load Limitation opt
28. the internal air temperature of the room and the outlet water temperature in the pipes and the peak cooling capacity in a structure using Thermo Active Building System TABS The Simple Simulation Tool calculates automatically the heat gains such solar internal heat and ventilation gains from the input parameters and afterwards it uses those values in the FDM The input parameters are position and size of the room components of the walls and the slab type of windows and circuit The FDM aimed the calculation of cooling capacity in non steady state conditions The ISO 11855 is applicable to water bases embedded surface cooling system in residential commercial and industrial buildings The concept of Thermally Active Surfaces TAS A Thermally Active Surface TAS is an embedded water based surface cooling system there the pipe is embedded in the central concrete core of building construction see Figure 1 C Concrete P Pipes Rl Reinforcement F Floor R Room W Window Figure 1 Example of position of pipes in TAS The building constructions embedding the pipe are usually the horizontal ones As a consequence in the following sections floors and ceilings are usually referred to as active surfaces but in the tool only the ceiling is considered as active surface because most of edifices built by Uponor have a ceiling cooling system Looking at a typical structure of a TAS heat is removed by a cooling system for instance a ch
29. the external walls would increase with rising indoor temperature To avoid this problem see the option Load Limitation below N Splitting Cooling Capacity if Run with no Cooling option is enabled then this option is available It is the number of divisions of the cooling capacity up to 10 For example if number 4 is selected the cooling power is split in 0 25 50 75 and of course 100 Total resistance calculation there are currently 4 rTModes available to provide the total resistance coefficient option 0 is manually insertion option 1 is with the formula B1 of the standard 11855 part 4 with limitations option 2 is with the formula B2 of the standard 11855 part 2 with no limitations 53 option 3 is only printing results of the two above For further details see Chapter 3 2 e Load Limitation In order to have realistic values of the temperatures if Run with no Cooling option is enabled the heat loads are gradually reduced with rising internal temperatures If this option is enabled the loads are gradually reduced if the room temperature exceeds a defined threshold The function has three hided parameters that are described in chapter 3 5 If the option is disabled the simulations will be executed without considerations of a maximum operative temperature and the loads will not be reduced e Comfort range If the option is enabled the simulations will be executed with a lower comfort temperature in place The
30. 34 Saved parameters in Boundary sheet 48 how the data are saved in the sheet Boundary Once inserted the values necessary to choose the number of days that have the same conditions and click on Insert Day Values button The program support up to 10 days simulation and below the cell with the number of the days is showed how many days and boundaries up to 240 the user has already inserted 4 2 1 Commodity It is possible to delete all the data entered by clicking the button cancel boundaries and to switch from Loads to Loads WE with the arrow Weekend and vice versa In addition it is possible to copy data from one sheet to another by using two buttons ii Copy data it allows copying all the values contained in the 24 hours table regarding Cooling Loads Lighting People and Equipment B Paste data with this button is possible to paste the copied data in both Loads sheets It is possible to memorize only one table of data In the bottom part of the sheet 15 Loads there are two charts see Figures 35 and 36 The first is 8 regarding the loads for each hours of the day These are split in convective and radiative heat iss as the program needs Each curve 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 Mean External Temperature pee ee RO ee Figure 35 Suggestion of Inlet Water Temperature convective and radiative all the loads that participate in the analyzed room therefore it m
31. 4 6 2 Sydney 34 000 209 000 30 65 13 22 9 2 based on the geographical location Bae 48 233 343 667 23 8 81 23 22 7 i pect 3 53 9 332 43334 26 8 33 21 18 2 i Belgium selected Furthermore the library contains tus soss 355633 ao s o a w 7 3 7 z ona 16 450 68 367 16 8 10 7 4 3 2 the maximal external temperature during Bam Aas 4 489 xe a ea Rio de Janeiro 22 950 43 200 33 2 6 1 2 27 8 2 Salvador I 38 450 32 5 8 ai 28 1 2 the summer the thermal excursion p Zam eo a a2 gee 2 Sofia 42 667 336 667 30 12 22 20 8 ti Canada between day and night the time zone the 2e EST et as m1 soa 7 Chile Santiago 33 467 70 750 30 7 17 2 a 20 8 2 monthly mean temperature for the hottest x eR ee 50 a ee IT Chongqing 29 767 253 433 35 5 7 4 6 28 7 T7 Hong Kons 22 333 245 817 33 47 6 23 5 t mo nth an d its numb er of mo nth o f the Neee Nanking 32 050 241 117 33 3 66 6 28 2 7 Shanghai 31 167 238 533 33 6 55 16 28 6 fi Cyprus hottest one for ex 7 July for 137 ccn an ee a ES p arat Bogot 4 533 74 250 20 8 3 4 5 14 2 5 different locations ho 4 300 344 717 33 1 3 23 27 4 4 g Jape 45 8 344 034 30 10 6 23 24 1 7 s faa 23 133 82 383 32 3 8 9 S 275 8 Czech Republic These values come from the ASHRAE fe S088 ESA m ap as ee i Copenhagen 55 667 347 433 24 8 23 7 3 a Handbook Fundamental 2009 edition Figure 24 Screenshot of Location Library ASHRAE is the American Society of Heating Refrigerating and Air Condition
32. 8 22 867 23 3082 23 9724 23 0336 23 0925 23 0631 8 36263 2 08031 5 33905 0 554298 6 81429 0 272486 9 22 3348 18 22 8188 24 2743 22 8361 23 5076 24 9384 24 0277 25 8869 24 1327 25 0098 9 00581 10 3776 26 0764 0 760044 19 9822 16 9278 10 21 5161 18 22 8059 24 9023 22 8519 23 8484 25 6606 24 1211 26 3993 24 6719 25 5356 24 13 0559 31 7562 1 28476 28 199 17 3839 Figure 41 Example of results for the first ten hours of simulation The sheet contains all the results of the different nodes temperatures and the powers It is divided in 18 columns and respectively e Hours number of hours of the simulation e Pipe Inlet and Set Point Pipe Inlet Temperature the first is the actual value of the inlet water temperature hour per hour depending on the selected options the second is the inlet temperature the user set For a given hour if the cooling power is set to zero the inlet temperature is equal to the outlet one e Pipe Outlet Temperature is the value of the return water temperature from the pipes e Nodes temperature the program gives the results of the temperature in different points as the Floor surface Pipe layer Ceiling surface Wall surface Internal wall surface and the Air temperature See chapter 2 for further details 58 e Mean radiant temperature and Operative Temperature the first temperature is combined with the Air temperature in order to have the Operative temperature in the analyzed room See Appendix A for further details
33. BQ UNIVERSITA DEGLI STUDI DI PADOVA Laurea Magistrale in Ingegneria Energetica Development of a simplified method for sizing Thermo Active Building Systems TABS Supervisor Michele De Carli Co Supervisor Holmer Deckee Student Luca Catalano Academic Year 2013 2014 Preface I did this work from 4t November 2013 to 30 March 2014 during my internship in Uponor GmbH located in Hamburg I worked together with a German PhD student called Benjamin Behrendt and we developed this software to evaluate the possibility of using TAB System or Thermally Active Building see the appendix for more details in a new project of a building The purpose of this edifice could be various from a house to an office We can use this program for a simple calculation of the thermal loads the trend of the temperature and a rough dimension of the chiller size This program is composed from two main parts the interface and the calculation program I worked mainly in the first and Benjamin in the second one We worked together to connect the interface with the computer program and looked for the solution to the problems that gradually were In order to understand which is the purpose of this software what is its effective range its features the qualities and the limitations I have written this thesis that which will include also part of the manual as it will be an extrapolation of this paper and will be attached in the program It contains
34. CH The MATCH function searches for a specified item in a range range Two or more cells on a sheet The cells in a range can be adjacent or nonadjacent of cells and then returns the relative position of that item in the range INDIRECT The INDIRECT function returns a reference specified by a text string evaluates that reference and displays its contents ROUND The ROUND function rounds a number to a specified number of digits Obviously it is possible to use more formulas together and combine the conditions and controls to achieve the desired result See an example in the Figure 16 below fe TEXT I2 MOD INDIRECT T7 amp R 1 C amp MATCH D1 INDIRECT T7 amp R2 FALSE 0 FALSE 24 24 INT INDIRECT T7 amp R 1 C amp MATCH D1 INDIRECT T7 amp R2 FALSE 0 FALSE 24 h mm amp h amp INT INDIRECT T7 amp R 1 C amp MATCH D1 INDIRECT T7 amp R2 FALSE 0 FALSE 24 8dF INT INDIRECT T7 amp R 1 C amp MATCH D1 INDIRECT T7 amp R2 FALSE 0 FALSE 24 gt 1 days day Figure 16 Example of an Excel formula 3 4 VBA code In order to have a user friendly interface and an easy way to work with data VBA programming is required Visual Basic for Applications VBA is an implementation of Microsoft s event driven programming language Visual Basic and its associated integrated development environment IDE Visual Basic For Applications allows user a level of customization beyond what is avail
35. K W Thickness 0 1 m tOpRange 3 0 O m k W ThCond 2 1 W m K tMax 27 0 0 599 m K W SpecHeat 1000 J kg K tMaxOffset 2 0 49500 J m K Density 2400 kg m tMaxRange 8 0 Above the Slub 2 MaxCoolPower 40 W m i Venice External Orientation E nDivisions 34 nHours 1 h Thickness 0 1 m ConvHeatFlux 0 196 W m7 Macro Report last macro executed ThCond 2 1 W m K RadHeatFlux 0 782 W m Project Data has been exported SpecHeat 1000 J kg K RunningMode if Project has been simulated Density 2400 kg m tWater 18 0 Timestampe 2014 04 08 12 29 48 Above the Slub 0 tOpMin 22 C tOpOffset 1 0 nDivisions 1 tOpRange 3 0 Thickness 0 02 m tMax 27 0 ThCond 0 9 W m K tMaxOffset 210 SpecHeat 1000 J kg K tMaxRange 8 0 Density 1800 kg m MaxCoolPower 40 W m Above the Slub 0 Figure 37 Overview sheet From a list it is possible to choose the project we want to simulate and check that the inputs have been entered correctly The options of the simulation are e Save results as Excel File the results will be saved in an out format file text file and it could be opened with Excel e Save results as Latex File the results will be saved in a dat format file and it could be opened with Latex 52 Specific values the SST can either use specific or absolute values input values for the heat flux and the cooling power If specific inputs are selected results will appear in specific values a
36. W gt 0 3 and da W lt 0 2 1 May sp Cw Ry Rp Ry gt The equation for Rz is valid only if 2 To utilize the Rr formula both conditions have to be respected For further details see the standard ISO 11855 4 For the normal parameters used in Uponor pipes the second condition has encountered problems because often the value of mass flow typically used in a normal project was too little especially if it was less than 12 kg m2h In this case the results might be incorrect and the method cannot be used To overcome this problem it is possible to use a different method of calculation of the resistance using the formula for the steady state condition in the standard 11855 2 where Rr is determined by R T U U 1 1 Ry R R myc W P X Hsp My sp C 1 exp 22 where 4s is the specific design cooling fluid mass flow in kg s related to the pipe covered area Ui is the heat transfer coefficient between the conductive layer and the space side i 1 or i 2 Therefore for the total resistance of the active layer within the slab construction were implemented three different ways in the tool e rTMode 0 The total resistance should be provided via the circuit data bypassing the internal calculation of Rr by providing a value with the circuit data As Rr is depending on the combination of slab circuit and pipe this option should be used with care e rTMode 1 The total resistance is calcul
37. able in Microsoft Office products such as Excel A user types commands into an editing module to create a macro Macros can allow the user to automatically generate customized reports charts and perform other data processing functions In SST the VBA code is divided in 12 modules containing all the macro that the program needs The division was needed to organize the macros in order to have an easier access to and understanding even in the event of a change Each part of the code is commented to make possible easier future developments An example is showed in Figure 17 24 iE File Edit View Insert Format Debug Run Tools Add Ins Window Help Typea uestion for help pna Say tn1 col1 NE d i aa Project VBAProject x General asf p EB Sheet16 Project proj a E Sheet17 ProjectRun EB Sheet18 SSTe configuratic EB Sheet 19 SSTe start EB Sheet2 Carrier E Sheet20 Version History EB Sheet21 Loads EB Sheet22 Loads WE E Sheet23 Solar tool W EB Sheet24 Slab EB Sheet25 ProjectDataExpor EB Sheet26 Solar tool S E Sheet27 SSTe_Files EB Sheet28 Sorting EB Sheet29 Circ Pipe Room Sheet3 Materials EB Sheet30 Solar tool E EB Sheet Data EB Sheet Location EB Sheet51 New Project EB Sheets Boundary EB Sheet7 Sheet 1 EB Sheet8 Overview EB Sheet9 Solar tool N Dim temp As Integer open file Project shO Range C3 spec
38. addition to the two charts in the generated file are present the sheets containing the numerical results of the simulation one for each case An example can be seen in the Figure 41 Hour Pipe Inlet Set Point Pipe Outlet Node 0 Node9 Node1l4 Node15 Node16 Node17 meanradT operative T circuit heat floor surf heat ceiling surf heat int wall surf tot rad gain tot conv gain Floor surface Pipe layer Ceiling surf Wall surf Wallint Air 0 24 24 24 24 24 24 24 24 24 24 24 0 0 0 0 0 0 1 22 194 18 22 8213 23 3019 22 8437 23 0187 23 3476 24 3748 23 2314 23 2035 23 2175 11 6658 0 559099 3 69271 0 857248 2 84761 0 88985 2 22 2207 18 22 7912 23 216 22 8116 22 9634 23 2579 24 3109 23 1406 23 1285 23 1346 10 617 0 413677 3 15913 0 878731 2 35982 0 685748 3 22 2378 18 22 7619 23 1459 22 7806 22 9159 23 1876 24 2466 23 0634 23 0671 23 0677 9 752 0 350937 2 8156 0 883792 2 09217 0 544096 4 22 2451 18 22 7317 23 0751 22 7491 22 8688 23 1132 24 1818 22 996 23 0046 23 0003 9 05475 0 235924 2 40807 0 891705 1 70417 0 404811 5 22 254 18 22 7031 23 0124 22 7191 22 8257 23 0489 24 1169 22 9346 22 949 22 9418 8 35067 0 163975 2 10524 0 891261 1 42335 0 311115 6 22 2726 18 22 6886 23 0685 22 7034 22 834 23 1442 24 0613 22 9687 22 9958 22 9823 7 74084 0 98135 3 41034 0 765274 3 60466 0 327864 7 22 2309 18 22 6696 23 1178 22 6853 22 8427 23 2124 24 0127 22 969 23 0338 23 0014 8 16285 1 49427 4 21775 0 667791 5 20436 0 106988 8 22 2113 18 22 6607 23 1885 22 676
39. aking it more intuitive Results confirm the accuracy of the program when the Comfort Range option is activated and the parameters are well set otherwise the program simulates operative conditions with the cooling system close to the maximum capacity Moreover the program can be used for the chiller sizing The ease of changing a few parameters for a new simulation is a key point Unfortunately some problems limit the use of the program as explained in the previous section However the software has been designed for a pre design of a system using TABS and it fully plays its role The program could be improved and the first future developments should be e Fix the problem of the Passive Loads at present the limitations regarding the size of the windows arise if the user wants to design a room with a full glass facade or with two external sides and many windows By implementing a tool that calculates the amount of the additional load due to the passive solar gains it will be possible to increase the capability of the software e Improve the Load limitation option the total amount of loads is reduced when the temperature exceeds some threshold At present with increasing the internal temperature the range between the maximum and minimal temperature is lost but the results tend to an asymptotic value hence the user can only have a reference on what will be the average temperature The implementation of a more complex method of decreasing
40. anually the values of the new fluid Pipe The only parameter is requested is the type of pipes from a little library of the available products in Uponor There is the possibility to insert a different type from the library clicking in Other in the list Slab in this section the user can enter the layers by which the floor or the ceiling it is composed It is possible to enter up to 10 different layers 5 above and 5 below the pipes level The requested data are the type of material selected from the library and the thickness of the layer with the eventual possibility of adding a new material in the library using the Add Material button When a material is selected the program automatically searches for the requested parameters in the library and they are inserted underneath There is a scheme below the field of data entry that displays the structure of the inserted slab with the total dimensions as the Figure 31 shows Slab Model Fibreglass Above the pipes Concrete Screed 0 2m Congete 2400 oeny o Concrete 2400 density Below the pipes 0 12 m Pipes level Figure 31 Slab model Room It is the part regarding the parameters of the internal and external walls and the windows For the walls the user can insert up to 5 layers for each wall The requested values are the material of the layer from the same library of the Slab and the thickness of the layer Moreover there is the possibility to choose the color of the external
41. ase only one zone was sufficient to simulate an environment similar to that created with SST It was built a single room of 25 m with an external south wall with a surface of 15 m2 three interior walls for a total surface of 45 m2 and an active surface that represents the TABS system of 25 m2 In the south exposed wall has been a window of 3 m placed with identical parameters to those chosen in SST as U value and g value The same values of infiltration have been set equal to 0 3 volumes per hour and the same parameters for internal gains i e two people with a activity degree of seated light work 75 W as Sensible Heat and 75 W as Latent Heat and two computers with monitors 140 W each during office hours from 8 to 18 All the other Regime Data have been deactivated The initial values for Trnsys have been set equal to the values calculated with the SST in order to have the same operating conditions as much as possible All the Types are connected with lines where the user can select the connection between two different types Figures 42 and 43 62 i USER Mass flow Y h s USER 4 USER Room Sunlrrad TempSky USER Tempext r C a GA gt Ia Wheater ty Ey Figure 42 Trnsys scheme for the first and second simulation A s gt USER USER Mass flow Sun Irrad South a USER Room USER TempSky user Sun Irrad East Tempext Y
42. ated internally and the original calculation method is used see equation B1 in ISO 11855 4 This method is to be preferred over the approach in the next point However it cannot be used for all cases depending on the limitations e rTMode 2 Using the calculation method for steady state conditions see equation B2 in ISO 11855 2 This method is originally intended for other conditions but can also be used here if the previous method fails e rTMode 3 Will print the results for the two previous modes for on screen comparison The simulation will quit after the total resistances have been displayed 3 3 Excel code For the interface many different excel functions were used to connect different sheets find values for tables depending of a choice of the user or different conditions The main functions used were IF The IF function returns one value if a condition you specify evaluates to TRUE and another value if that condition evaluates to FALSE VLOOKUP The VLOOKUP function performs a vertical lookup by searching for a value in the left most column of table_array and returning the value in the same row in the index_number position Where 23 e value is the value to search for in the first column of the table_array e table_array is two or more columns of data that is sorted in ascending order e index number is the column number in table_array from which the matching value must be returned The first column is 1 MAT
43. atly a folder with the name of the simulated 55 project is created and it is possible to save all the simulation results in this folder The new folder will be SSTe O_Files Name Project Output options it contains different parts and are all connected with the information showed when the simulation is run The second type of hides sheets is regarding all the data for the internal calculations for the excel interface and the input data for the calculations tool Also changes of these sheets can lead to malfunctioning of the program or the wrong calculation of the parameters The names of those sheets are 4 6 Solar Tool there are four different sheets for every orientation N S E W Each sheet contains the solar tool and is activated when the corresponding external orientation is selected Location contains the library of the different cities with the weather data see chapter 3 6 When a city is selected from the New Project sheet the function searches the values needed in the library contained on this sheet Carrier it is the core of the calculation for the internal and external loads The sheet contains all the parameters entered by the user mainly in the New Project sheet and calculated according to the Carrier method the necessary values which are used to create the necessary input for the simulation In the sheet there are two equal parts one connected with the sheet Loads and the other with Loads W Materials
44. cel Inlet Temperature Water 18 s4 Temp Op Offset 1 C EndDayTime 0 00 h 7 days B sindariee Change Inlet Temp Temp Op Range 2 e N of Inserted Boundaries 168 240 Internal Gains Legend Lighting 7 Specific Values Total Total 5 W m Hour maxCoolPower n Lighting Lighting n People People Sens Heat Lat Heat Jne Equipment Equipment Sens Heat Lat Heat 10 W m W m W m w Iw w w 13 W m EVG Direkt 0 40 0 9 17 W m EVG Direkt Indirekt 1 40 inl o 0 19 W m KVG Direkt pi 40 55 W m Halogen Lamp 3 a o 0 4 40 0 0 5 40 oO 0 oo gt 7 40 jil o 0 8 2 Seated eating 2 PC with monitor 140 430 190 9 2 Seated eating 75 95 2 PC with monitor 140 430 190 ib 2 Seated eating 75 95 2 PC with monitor 140 430 190 ay 2 Seated eatin 2 PC with monitor B 12 2 Seated eating 75 95 2 PC with monitor 140 430 190 B i 2 Seated eating 75 35 2 PC with monitor 140 430 190 ED 14 2 Seated eating 75 95 2 PC with monitor 140 430 190 Ehi 2 Seated eating 75 95 rd PC with monitor 140 430 190 16 2 Seated eatin 2 PC with monitor 430 190 17 2 Seated eating 2 PC with monitor 430 190 18 40 o oO 19 40 0 0 20 40 oO 0 2 40 I o 0 22 40 0 0 23 40 0 0 CE Copy Equipment i uponor Figure 32 Loads sheet The section is composed by two sheets called Loads and Loads WE Both are similar and allow the user to insert the internal loads for every hours of the day for each days of desired simulation The reasons of tw
45. cooling power is gradually reduced if the room temperature falls below the defined threshold Is it is disabled the simulations will be executed without consideration of the lower end of the comfort range The function has the three parameters selected in the Loads and Loads WE sheets For further information see chapter 3 5 After choosing the desired options it is possible to proceed the simulation using the button Export and Run Project The program starts by exporting the inserted data and saving them in the I_files folder it can be seen from the changed sheet and at a later stage launches the simulation that iteratively find a solution If the program reaches a solution the DOS box disappears and the results are saved in the O_files folder Use the button Show Chart to display the results as explained in chapter Results In case the program does not immediately find a solution using to the entered data the screen will remain visible until it arrives at a solution or otherwise it will show the explanation of the reason for the error In the Figure 38 is showed the DOS box Gas C Windows system32 cmd exe el mC Users Caia Documents gt cd C Users Caia Desktop STFinal iC Users Caia Desktop SSTFinal gt SSTe exe This is STe Version 1 6 6 Now simulating project settsottparz Figure 38 Screenshot of DOS box of the calculation program 54 4 4 Manual The sheet contains a manual explaining the operation of the
46. drogen systems and the study of the management and optimization of the plant to the characterization of the behavior performance of buildings The code also allows interfacing with other software such as Excel in this case and others The heart of the program is the Simulation Study a virtual work environment that allows managing the elements called Type which describe the physical problem technical object of the simulation The general model to be simulated will therefore be composed of a set of Type interconnected via the GUI IISIBAT3 so as to form a block diagram that summarizes the physico mathematical relationships of the various functional elements of the system Simulation study is carried out through the management of the operation of the code choosing the control parameters such as the simulation time the type of numerical solver the step time discretization etc It has been simulated the same room with the same thermal loads and weather conditions and it has been verified that the results of the simplified tool were in an acceptance tolerance In order to have comparable results the input data have to be the same for both programs The weather database contains values for each hour of the year and they are an average of realistic measurements in fact the TMY data of Trnsys was derived from 30 years of measured solar radiation and temperatures for 26 locations The remaining locations were generated based on other
47. e parts 4 1 New Project In the first sheet the user can start with a new simulation by inserting all data that the program needs This sheet is divided in many parts regarding the position the dimension the characteristics and the type of TABS system installed in the room under analysis See the Figure 29 41 Name Project Existing project Venice T max 32 1 C AT 8 8 C Timezone Insert Dimensions Length North or South side Length East or West side 5 Height 3 m m I External South Side I External West Side I External North Side Int uponor Circuit Unit KELTO Pipe Spacing m 0 15 Area Fraction tl 1 Mass flow mm kg h m 16 Fluid Water Fluid Density kg m 1000 Fluid Specific Heat U kg K 4186 8 Pipe Unit Value Type of Pipes Contec Pipe 20 Diameter external m 0 02 Wall thickness m 0 0023 Thermal conductivity Ww m K 0 35 uponor Insert Circuit Values N B New Material and Location are in last position of the lists Name Material Thermal conductivity W m k Specific Heat U kg k Densi g m Latitude Longitude Degree Time Zone Max External Temperature c Temp range Day Night c Mean T Hottest Month c Hottest Month Not obligatory Longitude From 0 Greenwich to left Ex Lisbon 9 15 Oslo 349 3 TimeZone 23 Germany 0 England 21 Russia Moscow
48. each slab surface is connected to the wall surface node see Figure 9 Moreover hourly heat gains are distributed on air and surfaces depending on their characteristics see again Figure 9 11 Figure 9 Scheme of the thermal network representing the room where A thermal node representing the air in the room C thermal node representing the ceiling surface CHT convective heat transfer F thermal node representing the floor surface IW thermal node representing the internal walls IWS thermal node representing the internal wall surface RHT radiant heat transfer Qconv total convective heat gains Qran total radiant heat gains 2 4 Limits of the method The following limitations shall be met pipe spacing from 0 15 m to 0 3 m usual concrete slab structures have to be considered A 1 15 2 00 W mkK with upward additional materials which might be acoustic insulation or raised floor No discontinuous light fillings can be considered in the structures of the lower and upper slabs Under the above mentioned conditions a cooling load calculation or a simulation for a convective system can be carried out for an entire 24 h period and with an internal 12 temperature equal to the average room operative temperature during the occupancy hours The results of this calculation to be taken into account as input for the present simplified model are the solar heat gains and the heat flows into
49. eans the sum of the solar gain heat through the wall and windows and the internal gains due to people lighting and equipment The charts show the results calculated with the Carrier method These data might be used to have a first idea regarding the cooling power requested for the project The sum of the two curves gives the value of the maximum thermal load that weighs in the room in the case in the figure it has an approximate value of 45 W m around 17 pm A strong point of the TABS is that it allows to reduce the peak value required hence a good point to start is to set a value lower than that illustrated by the graph 49 The second chart is regarding the inlet temperature suggested based on the average monthly temperature of the warmest month for the selected city in the cooling case This chart has been taken from the book TABS Control Steuerung und Regelung von thermoaktiven Bauteilsystemen In order to have a faster tool for different similar simulations there are two buttons connected with the inlet water temperature and the operative temperature needed for the Comfort option and they permit to change only these values without reinserting all the parameters for each day It is only needed to change one of those temperature and click at the corrisponding button Changing the values using these two buttons the temperatures will change for all the inserted days in the simulation in the case there is the need for changing the temperat
50. egards the design of TABS the planner needs to know if the capacity at a given water temperature is sufficient to keep the room temperature within a given comfort range Moreover the planner needs also to know the heat flow on the water side to be able to dimension the heat distribution system and the chiller boiler When using TABS the indoor temperature changes moderately during the day and the aim of a good TABS design is to maintain internal conditions within the range of comfort i e 0 5 lt PMV lt 0 5 during the day according to ISO 7730 see Figure 4 30 29 PMV 2 wW a lt a Ww a w Figure 4 Example of temperature profiles and PMV values vs time where Axis X time h Axis Y temperature C PMV Predicted Mean Vote Tair air temperature Tmr mean radiant temperature PREDICTED MEAN VOTE y Coolin Day Night Methods 0000000 O OF Groundwater 0 oo0o00o000000 eC Chiller Figure 5 Conception on operation of thermo active building system Some detailed building system calculation models have been developed to determine the heat exchanges under unsteady state conditions in a single room the thermal and hygrometric balance of the room air prediction of comfort conditions check of condensation on surfaces availability of control strategies and calculation of the incoming solar radiation The use of such detailed calculation models is howe
51. erified in operative conditions of continuous load or only during the night Finally in the last simulation the orientation from South to East has been changed to verify the difference in calculation between the two programs v First simulation The first simulation is divided in two parts one with the cooling system working continuously and the other with the cooling system working only during the night for 12 hours For both cases it was considered a normal office with one external and three internal walls and the room has been simulated for two operative conditions Five working days and two days of weekend with two person and two personal computers has been considered as standard week Only the lighting is absent 65 The parameters of the room are Location Venice Length North or South side 5 m Length East or West side 5 m Area of the room 25 m Orientation of the external walls South Area windows for external side 3 m Type of glass Double U value 1 5 W m K G value 0 62 External Wall m kg m W mK Lime cement plaster 0 01 1800 0 9 Brick 0 30 1400 0 52 Lime and gypsum plaster 0 01 1500 0 54 Internal Wall m kg m W mK Lime cement plaster 0 01 1800 0 9 Perforated Brick 0 1 750 0 35 Lime and gypsum plaster 0 01 1500 0 54 Layer above the pipes 1 2 3 Material Carpet Concrete Screed Concrete Thickness 0 01 0
52. eters Different cases were simulated in order to verify the results of SST each one for a period of one week and compared with the results of Trnsys With Trnsys the results of each parameters can be saved hour per hour as txt file from the options Afterward these results were opened in the same excel file of the results of SST The comparison was made by modifying the charts in order to have the two curves in the same chart the Figure 45 shows an example of such a comparison In addition there is the possibility to compare not only the operative temperature but also all the other parameters In this way it was possible to verify the reliability of the results and at the same time to understand which the limit of validity of the program is The parameters of the simulations are illustrated below The selected office working hours are from 8 to 18 that is 10 hour presence of internal loads In the case of intermittent functioning of the cooling system it is switched on from 20 to 8 thus it runs for 12 night hours and it remains off during the day Three simulations obtained by modifying the heat load in the room in several ways are related as follows by changing the thickness of the external wall in order to change the thermal losses or by increasing the number of people and equipment inside the room and consequently increasing the internal gains In the first two simulations the performances in two different operation methods have been v
53. f living in Hamburg in an exciting experience working on many interesting topics and for been always present even out of working time I would also like to thank Holmer Deckee that has been an excellent boss with my work giving me a lot of tips and been helpful in many occasions and all my colleagues in Uponor Thanks to all the people that helped and sustained me with the thesis they made a really good work Last but not least I would like to thank all my friends that have supported and guided me during these many years for the study and especially for the entertainment 85
54. f the room m s Qsx k th internal source of sensible heat W fax thermal storage factor for the k th internal source of sensible heat AGeq is the equivalent temperature difference for the generic wall C As regards the ventilation part have hypothesized two cases ie ventilation caused by infiltration or mechanical ventilation In the first case are kept into account only the infiltration and eventual manual opening of the windows A typical value assumed for the Air Change Ratio is 0 3 vol h and from this value is calculated the renewal air flow rate by the formula G nVp where V is the volume of the room and p is the density of the air 20 The same formula is also used for mechanical ventilation and the ACR value is selected based on to the choice of the ventilation system In the first case the temperature of the air is the value of the external temperature hour per hour in the second case the value is chose from the user by inserting a value of the inlet air temperature In both parameters are selected the total amount of renewable air is the sum of the values Then to calculate the heat gain due to infiltration Ga is multiplied for the specific heat and the difference between the internal and external temperature for the considered hour To calculate the external temperatures during the day referring to the ASHRAE code hourly temperatures given the hour 1 24 are depending by the peak temperature the da
55. ffset 1 C Top Range 2 C Pcootinc 30W As in the intermittent functioning of the first simulation this case also presents more problems than the one with continuous functioning However in this simulation the differences are minor in the comparison between the two programs During the week the shape of the curves presents the same trend and the daily maximum values are similar The value of the daily temperature range is slightly different In fact in Trnsys simulation the minimum values of operative temperature during the week are greater of 0 8 C and the maximum values during the weekend are lower of 0 6 C 71 uponor Operative Temperature C i Figure 48 Differences between Trnsys and SST for the first simulation results with 12 h functioning and the Comfort range option set to Top min 22 C Top offset 1 C Top Range 2 C Pcootinc 50W Third simulation The third simulation has been performed on a slightly larger office with four people and four computers during office hours specified above The Figure 49 shows that the two programs use a different method for the calculation of the effects of solar loads The exposure of the external wall in this case is to the east and it is possible to see from the chart that the SST reaches a higher temperature early in the day and then drops slightly when the solar radiation on the east side decreases Rather in the simulation with Trnsys the operative temperature increases g
56. gains due to persons lighting and equipment e Solar gains The biggest problem to solve was to implement a method for the calculation of the thermal loads in a room for each hours of the day Now the program can calculate automatically these two values thanks to the implementation of the Carrier method with the standard ISO 11855 2012 19 As first step the Carrier method permits to evaluate the sensible heat due with the follow formula N N N N N Q z Qwan Owind ag Osotar vent It is the sum of the heat throw the wall and the windows due to the difference of internal and external temperature Qwai Qwin the solar gain due to sun irradiance throw the windows Qs and the ventilation gain Qy The program calculates the values N for each hour in a day 24 values Orn S US Ab Oii US 0 a 0 j v Os is Fas OF Gc 0 6 where U transmittance of the j th external opaque wall W m K Sj area of the j th external opaque wall m7 Oi internal temperature C Ixv maximum daily solar radiation on the v th glazed surface it is automatically calculated see the chapter Solar Tool W m2 Oe external hour temperature C Sv area of the glazed surface m7 Uv transmittance of the j th glazed surface W m K fav thermal storage factor for the v th window fsv shielding factor of the generic v th window n number of volumes per Hours of air change in the room V internal volume o
57. h low thermal inertia and to verify the functionality of the program under various conditions The Carrier method utilizes the calculation of the equivalent AT and consequently the values of thermal loads depend on the thermal mass of the building By varying the thickness of the wall the values used in the calculation of the heat loss change Also this simulation is divided in two parts one with the case with the cooling system in continuous functioning and the other is functioning only during the night for 12 hours The following are the changed parameters External Wall m kg m W mK Lime cement plaster 0 01 1800 0 9 Brick 0 10 1400 0 52 Lime and gypsum plaster 0 01 1500 0 54 v Third simulation In the latter simulation a larger room and a different external orientation but the same windows area and city have been chosen The aim is to test the accuracy of the calculation of the internal gains when the number of people and computers in the room is doubled hence from 2 to 4 during the working hours This simulation is tested only for the continuous functioning in order to avoid too high values of the operative temperature in the room The following are the changed parameters as regards the room 67 Location Venice Length North or South side 6 m Length East or West side 6 m Area of the room 36 m Orientation of the external walls East Area windows for external side 3 m Ex
58. he chart there are n checkboxes where n is the number of the split cases which allow to show or hide the lines of the various cases and facilitate the visualization of the results Hours Power Nm 0 Circuit Heat Wim Lat mee mee med meaotiname SSAMARETHPRRAEBSRRSBBREEHSBS 121 125 129 133 137 141 145 149 153 157 161 165 Figure 40 Chart of the used cooling power hour per hour The second chart allows the user to see the results of the utilized power during the analyzed period In the x axis are represented the hours and in the y axis the cooling power needed of the specific case 57 By using the two charts the user can dimension the size of the chiller For example the first figure is the result of a simulation with the number of split set to four The file lines represent the cases of 0 25 50 75 and 100 of the selected cooling power It is possible to see that the cases with 50 75 and 100 are similar hence half of the selected power for the simulation might be sufficient for the analyzed case Another way to get an idea of how to decrease the power required can be had from the second graph In this case it refers to a normal simulation with the Run with no Cooling option disabled and it is possible see the percentage of power used hour by hour The purpose is to have the orange area as large as possible by reducing the size and increasing the utilization factor of the chiller In
59. he values for the number of divisions of the layer for the calculation the thickness and three parameters of the material as the thermal conductivity specific heat and density The Overview was the last sheet and it showed all the inserted parameters A B E D E 1 2 Slab Data Unit 11855 4 Luca_slab 3 nLayers 4 4 4 ActiveLayer_depth m 0 19 0 22 5 6 nDivisions 1 1 7 Thickness m 0 02 0 05 8 ThCond W m K 0 17 0 17 9 SpecHeat U kg K 2300 2300 10 Density kg m3 700 700 11 12 nDivisions 2 2 13 Thickness m 0 07 0 07 14 ThCond W m K 1 1 1 1 15 SpecHeat D kg K 850 850 16 Density kg m3 1900 1900 a Ff 18 nDivisions 3 3 19 Thickness m 0 1 0 1 20 ThCond W m k 1 9 1 9 21 SpecHeat U kg K 8380 880 22 Density kg m3 2000 2000 23 24 nDivisions 3 3 25 Thickness m 0 1 0 1 26 ThCond W m k 1 9 1 9 27 SpecHeat U kg K 880 880 28 Density kg m3 2000 2000 Figure 14 Slab sheet There was the possibility to select a project from the list and to run it With the Create Report button the program displayed the results in a table See a screenshot in the Figure 15 17 Project Boundary Circuit Pipe Room Slab Boundary Data 11855 4 11855 4 11855 4 11855 4 11855 4 Unit Create Report Exportand Run Project Circuit Data Unit 11855 4 Unit nTimeSteps ITimeStep nSubTimestep tolDayMax tolHourMax nHoures convHeatFlux radHeatFlux runningM
60. his choice the program takes the coordinate data from the internal database and it uses these values with the Solar Tool It supplies the radiation data for every part of the world for different slopes as horizontal and vertical and for the four main orientations North East South and West Therefore this parameter influences the weather data for the hottest day in summer used as design project condition Dimension There are three cells where the requested parameters are regarding the dimension of the room taken into consideration as length North or South side length East or West side and height The room is supposed rectangular and the dimensions are in meters Orientation The user has to insert the orientation is 4 of the external and internal walls Those are Ext R connected mainly with the solar radiation and with nah the thermal inertia of the room It is possible to change the orientations by clicking on the red Ext arrows See the screenshot in Figure 30 Int Figure 30 External Orientation Circuit The needed values in this section are the parameters regarding of the circuit hence the pipe spacing the fraction area covered by the cooling system the mass flow in kg m2h in the pipes and which fluid is used in the plant Normally the used fluid is water and the program contains the values of the density 43 and the specific heat If the fluid is different select to Other in the list and insert m
61. ific shO Range C15 look if is in the folder with the project name or not Dim mFile As Application Dim mFolder As String strFile As String stFi2 As String relativePath ThisWorkbook Path nume shD cells 36 16 Value Pro name shO Range C3 amp _ amp nume mFolder relativePath amp O Files strFile Dir mFolder amp Project amp out stFi2 Dir mFolder amp Pro_name amp out to avoid the problem 0 and _n condition when n split 1 If Range H13 1 Then If strFile Project amp out Then ThisWorkbook E Else E E Modules f mFolder relativePath amp O Files amp Project amp A Module1 stxrFile Project amp out 3 Module 10 End If 8 Module 11 A Module 12 Else 3 Module 13 A Module2 look if both condition are good if not look in the folder 8 Module3 If strFile Project amp out And stFi2 Pro_name amp out Then 2 Module4 Else 3 ModuleS mFolder relativePath amp O Files amp Project amp 48 Module6 strFile Project amp out A Module7 End If 3 Modules 8 Moduled End If i r j 4 Figure 17 Screenshot of VBA code Modules have been organized as Module 1 and 2 contain the macros for the Overview sheet as Export and Run the Project or Open Report File They also contain other functions necessary for the functioning of the program Module 3 and 4 contain all the macro connected at the Solar tool Module 5 con
62. ification of a future developer were inserted several comments for each part of the code and are visible with the green color preceded by The last part of the work was to avoid displaying the error and debugging box in the event that a macro does not work properly In this case the macro is interrupted and several problems could appear The main problem emerge when in the macro is contained the function Application Calculation xlManual This function is used in order to increase the speed of the macro deactivating the automatic updating of the formulas in the whole file If the macro containing this function is interrupted the updates of the formulas remain deactivated making the program unusable it is needed to re activate this option from the setting of excel The method used was to insert an error control using the function On error goto this allows to automatically exit from the macro restore the initial conditions and make it appear an alert box of the error without losing the functionality of the program 3 5 Implemented Options Once written all the code calculation the results of the simulation do not correspond to realistic values that are expected to have as operative temperatures normally used in the summer In the Figure 18 is showed the results of a simulation of ten days in an office i e with five working days and is easily possible to recognize the weekend These curves are for different available cooling power from 0
63. iller connected to pipes embedded in the slab The system can be divided into the elements shown in Figure 2 Figure 2 Simple scheme of a TAS where 1 heating cooling equipment 2 hydraulic circuit 3 slab including core layer with pipes 4 possible additional resistances floor covering or suspended ceiling 5 room below and room above PL pipe level Thermally active surfaces exploit the high thermal inertia of the slab in order to perform the peak shaving The peak shaving consists in reducing the peak in the required cooling power see Figure 3 so that it is possible to cool the structures of the building during a period in which the occupants are absent during night time in office premises This way the energy consumption can be reduced and a lower night time electricity rate can be used At the same time a reduction in the size of heating cooling system components including the chiller is possible 9 SJ S F FF FF FF SF S oS Ss s FF FoF FFF oF 08 98 oP 0 oh Figure 3 Example of peak shaving effect TABS may be used both with natural and mechanical ventilation depending on weather conditions Mechanical ventilation with dehumidifying may be required depending on external climate and indoor humidity production In the example in Figure 3 the required peak cooling power needed for dehumidifying the air during day time is sufficient to cool the slab during night time As r
64. ily range and multiplied by the coefficient p t Taye f Hour Peak p T Range 1 0 87 13 0 11 2 0 92 14 0 03 3 0 96 15 0 4 0 99 16 0 03 5 1 17 0 1 6 0 98 18 0 21 7 0 93 19 0 34 8 0 84 20 0 47 9 0 71 21 0 58 10 0 56 22 0 68 11 0 39 23 0 76 12 0 23 24 0 82 The internal gains are calculated by the sum of the number of the people lighting and equipment and are divided in sensible internal gain Qs n and latent internal gain Qumt To split these internal gains in the radiative and convective parts itis possible to assume N _ QO s m O tmi Qin 2 From the standard ISO 11855 2012 part 4 the formulas for the calculation of the total heat loads acting toward the room are N _ N N N Qcon 0 15 Qwan vent za Qni N N N N N Q kaad 0 85 Qwan OQwind Qsotar i Q mi 21 Another problem using the standard formulas with the parameters mainly used with TABS especially for the mass flow was to remain within the conditions imposed in the Resistance method The finite resistances method can be used within certain limits Rr is the total thermal resistance in m2K W between the water supply temperature and the pipe level temperature and it can be calculated by Rr R R Rp Ry where peA s m rn rf pe 3 eee Ryn a2 xd 2 tity Cy 8 tity L ee NET a R Two conditions shall be fulfilled for the application of these equations The equation for Rx is valid only if s
65. indows library There are multiple ways of treating glass to enhance its strength energy efficiency or appearance High thermal resistance can be obtained by evacuating or filling the insulating units with gases such as Argon which reduces conductive heat transfer due to their low thermal conductivity The important parameters for the program are the type of window type of insulating gas the transmittance value and the SHGC factor Solar Heat Gain Coefficient based on the standard UNI EN 1279 The value for a single glass is 0 85 between 0 62 and 0 72 for the double glass and between 0 62 and 0 48 for the triple glass depending on the thickness and the gas of the insulating layer The list of the available types of glasses is Type of glass U value W m K G value Air Argon Air Argon Single Glass 5 7 0 85 4 6 4 Uncoated Glass 3 3 3 0 72 0 7 4 8 4 Uncoated Glass 3 1 2 9 0 72 0 7 4 12 4 Uncoated Glass 2 8 2 7 0 72 0 7 4 16 4 Uncoated Glass 27 2 6 0 72 0 7 4 6 4 Coated Glass 2 6 2 3 0 65 0 62 4 8 4 Coated Glass 2 3 2 0 65 0 62 4 12 4 Coated Glass 1 9 1 6 0 65 0 62 4 16 4 Coated Glass 1 7 S 0 65 0 62 4 6 4 6 4 Uncoated Glass 2 3 2 1 0 62 0 6 4 8 4 8 4 Uncoated Glass Bel 1 9 0 62 0 6 4 12 4 12 4 Uncoated Glass 1 9 1 8 0 62 0 6 4 6 4 6 4 Coated Glass 1 6 1 2 0 55 0 5 4 8 4 8 4 Coated Glass 1 3 1 0 55 0 5 4 12 4 12 4 Coated Glass 1 0 8 0 52 0 48 v Pipes Library Uponor mainly
66. ing Engineers and the Handbook Fundamental is one of the four volume ASHRAE Handbook resource for HVAC amp R technology These values are utilized in the Carrier method in order to calculate the heat loads for the analyzed Add Location in Library room Name Location Latitude Degree Longitude Degree Therefore it is possible to add manually a TimeZone H Max External Temperature c new location by inserting the values in the Temp range Day Night c Mean T Hottest Month c cells like shown in the Figure 25 at the right Hottest month a v Material library Figure 25 Screenshot of the Add Location option For the most common construction material a library was included with all the parameters the program needs for the internal calculations according with the standard UNI EN ISO 13786 The library is used for the insertion of the materials of building structures regarding the external and internal walls and the structure of the ceiling the floor is supposed identical For these Add Material in Library different structures different parameters are Name Material N Thermal conductivity W m k required Regarding to the internal and specificheat U kg K Density kg m7 external walls are necessary only values of the density in kg m3 and the thermal Figure 26 Screenshot of the Add Material option 34 conductivity in W mK For the slab another parameter is requested and it is the specific heat
67. ion 73 uponor 26 25 24 Operative Temperature C i 21 ssT Trnsys Figure 50 Simulation results of Trnsys red curve and SST blue curve without the Comfort Range option The trends are similar but SST temperature are lower The trend of the operative temperature when the air conditioning system is absent and consequently what it would be the natural evolution of the temperature inside the room are shown in Figure 51 with Run with no Cooling option activated To get realistic results it is necessary that the Load Reduction option is enabled in order to have the thermal loads decreased according to the internal temperature The figure shows the chart of the results in the normal case The trend of the red curve refers to the case with no cooling system and it grows without control reaching values up to 35 C after three days This problem is not restricted only to the case without the cooling system but also in other cases of follow up simulation 74 ra treeeeww_0 ra treeeeww_25 ira treeeeww_50 ira treeeeww_75 uponor LJ B JM Air Temperature C ies B AX AWAY INEN 2 R amp 5 B 144 168 treeseww treeeeww_lO0 treeeeww_25 treeeeww_50 treeeeww_75 Figure 51 Simulation results with the Load Limitation option disabled With the Load Limitation option enabled the program reduces the loads selected in the interface and the curve
68. ion In this case has been set a maximal operative temperature of 26 C an offset of 2 C and a range of 5 C 29 The Figures 20 and 21 illustrate the differences of the two cases Gates en isoa Bows UPONOF NIALL iY 2 e 21 19 R 2 R a 8 8 settsottparz settsottparzO settsottparz_25 settsottparz50 settsottparz_75 Figure 20 Simulation with the Load Limitation disabled z settsottparz_0 ira settsottparz_25 ira settsottparz_50 ira settsottparz_75 uponor 35 33 SS Operative Temperature C N R a x 2 R 2 g Fl 168 settsottparz settsottparzO settsottparz_25 settsottparz 50 settsottparz_75 Figure 21 Simulation with the Load Limitation activated 30 y Low room temperature problem Another problem with SST was the values of the results of the operative temperature too low during the simulation In the first configurations the program always cooled the building as much as possible Depending on the input values this could cause significant undercooling or at least operative temperatures notable below the desired values This is not surprising as the tool should answer the question if the current system configuration is able to provide sufficient cooling or not And this question is of cause answered However the suggested low internal temperatures are of cause not those the user would like to see in a real building This
69. kg K 1900 kg m3 Unit 30 m2 48 m2 1 5 W m2 k 5 5 W m2 K 2 5 W m2 K FvFloorToCeiling 0 21 FvSlabToExtWall 0 35 FloorResistance 0 1 m2 K W CeilingResistance 0 m2 k W WallResistance 0 05 m2 K W CWalls 25600 J m2 K Macro Report last macro executed Project Data has been exported Project has been simulated Timestamne 2014 01 07 14 40 39 Circuit lt Pipe Room lt Slb lt SSTe Files I I 4 M 3 Thickness 0 1 m ThCond 1 9 W m K SpecHeat 880 J kg K 2000 kg m3 3 Thickness 0 1 m ThCond 1 9 W m k SpecHeat 880 J kg K 2000 kg m3 Figure 15 Overview sheet difficult to know such as the hourly value of thermal loads Initially the program was able to simulate a room situated at the center of a building therefore without a connection to the external environment and it performed the calculations in accordance with the load input set by the user One purpose of the interface was to move this room toward outside with minimum one external wall in order to make the program connected with the external conditions without requiring the user to enter them manually anymore 18 During the implementation of the tool were spotted numerous problems e Number of boundaries one of the biggest problems was to create a tool with the possibility of simulation during one week in non steady state conditions At the beginning it was allo
70. m In the latter case the ratio between the floor area and the windows is less than 5 The figure also shows that the minimum temperatures calculated by the program and that ones calculated by Trnsys are similar On the other hand the difference between the maximum and minimum temperature is lower In particular in the considered case the values of the maximum temperature are about 1 5 degrees lower A possible solution to overcome this limitation could be to set the value of the area of the windows larger than the area of the project uponor 32 Operative Temperature C R B ho gt SST Trnsys Figure 54 Differences between SST blue curve and Trnsys red curve in the simulation with 6 m2 windows area Obviously this solution cannot be applied to simulate a full glass fa ade This issue is included in future developments see chapter Conclusion for further information 78 7 Conclusion In the present work the following improvements of the SST have been made in comparison to the first version i the program is now automated ii the user has far fewer parameters to insert iii the interface is user friendly and projects can be simulated in shorter time and more easily The program has also been verified by users with experience in the TABS field of work in order to test its quality user friendliness and usability Some more changes have been made to improve the usage of the program m
71. nd vice versa The interface recognizes the selected option and shows the power chart with the correct unit of measurement In general it is recommended to use specific values only as this makes it possible to compare cases where for instance the room dimensions have been changed Run with no cooling option the program can simulate the same case without the cooling system therefore the tool shows the trend of the internal temperature Then the follow up simulations are used to study the temperature development under unchanged environmental conditions if the maximum cooling capacity is reduced This is the number of divisions of the cooling capacity up to 10 in which case the maximum cooling power would be reduced by 10 for each case This function can be used to determine the minimal cooling power needed to maintain acceptable operative temperatures throughout the day As for the nature of the tool the temperature fluctuation during the day is more important than the actual absolute values With reduced maximum cooling power the temperatures in the room will eventually rise during the simulation period At this point the available cooling would be insufficient to keep the internal temperatures within acceptable ranges if the load conditions would remain as they are If for instance cooling would be turned off completely the temperature in the room would rise indefinitely This is obviously not the case of a real building as the heat loss through
72. o different sheets are e Possibility of insert different values for a working days and weekend e Easy and fast insertion the user can insert easily the input for a working day and choose the number of days where the conditions are the same Then it is possible to insert the inputs during the weekend by coping and modify the values for the WE case and return to the Load sheet to insert more working days for example a simulation from Wednesday to Tuesday 47 Obviously the insertion of data in two sheets is not closely related to the type of examined day but it is possible to use the two sheets simply to insert different conditions for different types of working days The first parameter to set is the inlet temperature of the water this must be between 10 and 25 C in order to be accepted by the program Once is entered a value this remains constant for the entire defined interval therefore it is not possible to change the water temperature by hour of day It is possible only to change it for the 24 hours by entering one day at a time a different value of temperature or manually in the sheet Boundary even if this second option is not recommended In the table below we need the values of cooling power and internal loads for the 24 hours of the day in detail e maxcoolpower it is possible to insert the value of the maximum cooling power available for each hour of the day In the case of a blank cell is considered equal to
73. ode tWater maxCoolPower nHoures convHeatFlux radHeatFlux runningMode tWater maxCoolPower nHoures convHeatFlux radHeatFlux runningMode tWater maxCoolPower Lama Overview Comparison 3 2 The primary objective at the beginning was to create a user friendly program decreasing the complexity in entering data and the number of parameters to be entered After the initial stage of understanding of the functioning and the potential of the program has been created a sheet for inputting of all the data regarding the room to be analyzed and the type of cooling system the user needs to avoid him having to insert the data in several different sheets Some parameters do not change during the various simulations and then have been eliminated among those must be inserted It has been searched for an automated method of calculation with hided formulas in order to avert entering other parameters First Steps IDA Input 24 3600 s 500 0 0001 0 00001 8 30 Ww 10 wW 1 20 C 1000 W 11 400 w 300 Ww ot 20 C o w SC 150 W 100 w 15 20 C 1000 w Project pipe_spacing 0 1 m 4 10 0 19 m 36 kg h m2 1000 kg m3 ivisi 1 4187 J kg K i 0 02 m 0 17 W m k SpecHeat 2300 J kg K 700 kg m3 Unit 0 02 m wall_thickness 0 0023 m 0 35 W m K 20 Thickness 0 07 m ThCond 1 1 W m k SpecHeat 850 J
74. office in Madrid for two persons south external orientation The red line show the unnatural trend of temperature in 10 days simulation with no cooling power 27 Y Unrealistic room temperature problem To resolve this issue has been dealt a first approach which provided an automatic iteration of the program using a macro whom did start the simulation taking the results of the internal calculated temperature and with these 24 day values recalculated thermal loads by the carrier method and use them for a new simulation The problem was that only one iteration was not sufficient to ensure the results and the code implementation for iterating a greater number of times was not a real solution because the components that could make stop the simulation were clearly noticeable Finally another method has been chosen it was easier to implement a function that automatically diminishes the thermal loads in the calculation formulas of the exe file This function is called Load Limitation can be enabled or disabled according with what the user wants The program needs a parameter 0 or 1 in case the user wants to activate this function or not The user only needs to tick a box in the Overview sheet and the tool will automatically assign the value of 0 or 1 e LoadLimitation 0 Simulations will be executed without considerations of a maximum operative temperature Loads will not be reduced e LoadLimitation 1 Loads are gradually reduced if the
75. ons it was necessary to verify the results with the real data found in other cases and with some other programs 3 6 Library creation To improve the potential of this software and to get it faster and easier entering the data there are two different libraries about different types of construction material and weather data All these libraries are hidden to reduce the complex of the program but the values are automatically called when a parameter is selected Y Location library Every city in the world has different weather conditions In the New Project sheet there is the possibility to select a city in which we want to execute the simulation Therefore it was necessary to create a library with all the required parameters for each city By selecting a location on the New Project sheet the program will automatically search the values needed in the library The program can calculate the loads that have influence on the room 33 temperature under consideration starting reallat reallong Tmax deltaT Timezone MeanT Hot month s i z Algeria with the coordinates Using that in the s se est a E Buenos Aires 34 583 58 367 30 67 3 24 4 1 C rdoba 31 467 64 167 3 n 2 3 23 6 i solar tool the software evaluates the solar i PEREN ie e es ae Bikane 27 483 206 867 30 78 4 25 1 Darwin 12 467 229 150 33 3 is 45 29 n heat load with a time profile over 24 hours etoue S 216033 2 33 Bo ms 2 Perth 31 950 244 133 35 13 1 6 2
76. oo high and the solution has not reached the given accuracy That would require a higher value of nmax or Cmax in case a lower degree in accuracy can be accepted 2 1 Cooling system As regards the cooling equipment it is simulated via the following magnitudes OWATER nS water inlet set point temperature in the h th hour C ParcurrMa 4 maximum cooling power reserved to the circuit under consideration in the h th hour W The limited power of the cooling system shall be taken into account since the chiller is able to keep a constant supply water temperature only when the heat flow extracted by the circuit is lower than the maximum cooling power expressed by the chiller 2 2 Hydraulic circuit and slab The Resistance Method for further details see ISO 11855 2 is applied It sets up a straightforward relation expressed in terms of resistances between the water supply temperature and the average temperature at the pipe plane Op so that the slab can be split into two smaller slabs In this way the upper slab which is above the pipe plane and the lower slab which is below the pipe plane are considered separately see Figures 14 and 15 Their thermal behavior is analyzed through an implicit FDM o R Ro R o o o Water n EE y CUNE e R R R oe x eed 6 8 f 8 PL Waler n esp Av eae ig Figure 7 Concept of the Resistance Method where LS lower part of
77. or the percentage of the area covered by the cooling system will be smaller otherwise it will be the same Another observed limitation is caused by the presence of the passive loads Solar gain refers to the increase in temperature in a space an object or a structure that results from solar radiation The amount of solar gain increases with the strength of the sun and with the ability of any intervening material to transmit or resist the radiation The hourly solar gains are calculated by means of the Solar Tool In the program they are simulated by increasing the internal air temperature that is as if the heat warmed the air Instead the stored heat on the floor due to the sun is considered negligible When the ratio between the floor area divided by the windows area is above a certain value the latter hypotheses can be unacceptable Numerous cases have been evaluated in order to clarify this issue leading to the following finding the ratio should not be lower than 5 otherwise the results are unrealistic 77 The Figure 54 shows the trend of the internal operative temperature in the case of a 25 m2 room with two external orientations East and South and 3 m windows for each side 6 m in total See the following table for further details Location Venice Length North or South side 5 m Length East or West side 5m Area of the room 25 m Orientation of the external walls East South Area windows for external side 6
78. ours because some additional and not economically acceptable costs of system are needed to cover the extra part of the heat loads For both these reasons then it is no wonder if temperature results are greater than the comfort zone 68 5 4 Simulation Results 5 4 1 Results of the simulations Following there are the results and charts of the three simulations y First simulation In the case of continuous functioning simulation the results are tolerably similar with the Trnsys results the shape of the two curves coincides in several points and the maximum difference is about 0 2 C This case is the one with better results Those are showed in Figures 45 and 46 uponor Operative Temperature C fh 21 ssT Trnsys Figure 45 Differences between Trnsys and SST for the first simulation results with 24 h functioning In the case of partial functioning the Trnsys results of the simulation are different from that one of the SST In fact the daily maximum values are similar there is an error about 0 3 C in the days during the week but the minimum values are different The daily temperature range of Trnsys is lower than that one of SST with an error of 1 2 C for the minimum value during the week The different trend of the temperatures also can be seen 69 during the weekend the difference between the maximum and the minimum for Trnsys is approximately 2 C while it is around 3 C for SST
79. power tabs W m2 floor area 2 Simplified model based on FDM The finite difference method FDM is based on the calculation of the heat balance for each thermal node defined within the slab and the room The slab and the room are divided into thermal nodes used to calculate the main heat flows taking place during the day The temperature of each thermal node during the hour under consideration depends on the temperatures of the other thermal nodes during the same hour As a consequence the heat balances of all the thermal nodes would require the solution via a system of equations or an iterative solution The last I option is the one chosen in this part of ISO 11885 As a consequence most of the equations regarding this method apply for each iteration executed in order to approach the final solution The use of an iterative method requires the definition of four quantities n actual number of the current iteration Nmax maximum number of iterations allowed actual tolerance at the current iteration K max maximum tolerance allowed K The actual number of the current iteration and the actual tolerance at the current iteration are calculated at each iteration and compared with the maximum number of iterations and tolerance allowed respectively In particular if lt Gmax and n lt nmax then the solution has been found within the given conditions Instead if n nmax then the number of iterations performed has been t
80. program with the main functions the limits of the program and recommendations taken from this paper It is a synthetic manual but it contains the link for the complete manual 4 5 Other sheets There are some editing sheets where the user can see all the data he inserted for all the projects and he can manually modify the parameters For the proper functioning and the user friendly of the software most of the sheets are hidden and protected There are two types of hidden sheets the first type are the sheets necessary for the connection between the excel part and the calculation program Any change of these sheets can lead to malfunctioning of the entire software and then all manual adjustments should be done carefully It is suggested to make a safety copy of the file before making any changes The names of those sheets are e SSTe configuration e 6SSTe start e Project proj e Boundary inp e Circuit inp e Pipe inp e Room inp e Slab inp All these sheets contain the data project for the SST exe format only the SSTe configuration includes all the different options for the simulation Some options are showed in the Overview sheet but there are some others that are hided because are less relevant and are e Save in folder option this function is available only in the hidden SSTe config sheet Normally the results of the simulations are saved in the folder SSTe O_Files In order to handle files saved more ne
81. radually up to a temperature greater than 0 5 C with respect of the daily maximum values with SST 72 uponor 32 Pots Operative Temperature C X B ho gt 0 24 8 96 120 144 168 ssT Trnsys Figure 49 Differences between Trnsys and SST for the third simulation results with 12 h functioning and the Comfort range option set to Top min 23 C Top offset 1 C Top Range 4 C Pcooinc 25W 5 4 2 Option Results In order to have comparable results the Comfort Range option needs to be activated It is possible to see the difference between the two cases in the Figure 50 below This picture shows the different temperature range of the results This is due to the fact that SST is using the whole amount of cooling power to cool the inlet water temperature as much as possible until it reaches the inlet water set point temperature This means that the room temperature goes down to the minimum values reached with the available power selected In practice the results are the minimum values reached from the cooling system with no temperature control in the room These temperature values are generally too low for the practice usage but it does not mean that the values of the operative temperature in the room can be set higher The two curves in the Figure 50 have a similar trend and shape with Comfort Range option it is possible to adjust the curve of the results by moving it up or down to get the optimal solut
82. re area in according with the standard UNI 7730 82 References UNI EN ISO 13786 2007 Thermal performance of building components Dynamic thermal characteristics Calculation methods EN 15377 2007 Heating system in buildings Design of embedded water based surface heating and cooling system Part 3 Optimizing for use of renewable energy sources ISO 11855 2 2012 Building environment design Design dimensioning installation and control of embedded radiant heating and cooling systems Part 2 Determination of the design heating and cooling capacity ISO 11855 2 2012 Building environment design Design dimensioning installation and control of embedded radiant heating and cooling systems Part 4 Dimensioning and calculation of the dynamic heating and cooling capacity of Thermo Active Building Systems TABS ASHRAE Handbook 2009 Fundamentals UNI EN 1279 Glass in building Insulating glass units 2010 Todtli Gwerder Lehmann Renggli Dorer TABS Control Steuerung und Regelung von thermoaktiven Bauteilsystemen Zurich Facktor Verlag 2009 UNI EN ISO 7730 Moderate Thermal Environments Determination of the PMV and PPD indices and specification of the condition for thermal comfort 83 84 Acknowledgements First of all I want to thank my parents they gave me the possibility to study and spend my time in different parts of Europe A special thanks to my Professor Michele De Carli Supervisor for giving me the chance o
83. rent options for the calculation of the results see Figure 37 Projects E Saveresults as Excel files O Saveresults esLatex files 5 e Boundary Hamburg Z Use Spaciic Values Remena Show Charts Circ Pipe Room Hamburg Slab Hamburg Project Cancel Charts Boundary Data Hamburg Unit nTimeSteps 168 h ITimeStep 3600 nSubTimeStep 500 TolDayMax 0 0001 TolHourMax 0 00001 SpecificHeatFiux 1 Hamburg Unit Thickness 0 01 m 0 15 m ThCond 0 07 W m K nHours 1 h 14 SpecHeat 1000 J kg K ConvHeatFiux 0 433 W m 16 kg h m Density 3000 kg m RadHeatFiux 1 733 W m i 1000 kg m Above the Slub a RunningMode 1f i j 4186 8 J kg K tWater 18 C 0 m k W nDivisions 1 tOpMin 22 C Thickness 0 03 m tOpOffset 1 0 Hamburg Unit ThCond 0 037 W m K tOpRange 3 0 DiameterExt 0 02 m SpecHeat 1030 J kg K tMax 27 0 WallThickness 0 0023 m Density 20 kg m tMaxOffset 2 0 ThermaiCond 0 35 W m K Above the Slub a tMaxRange 8 0 MaxCoolPower 40 000 W m7 Room Data Hamburg Unit nDivisions 2 25 m7 Thickness 0 06 m nHours 1 h 15 m7 ThCond 1 2 W m k ConvHeatFlux 0 301 W m i 1 5 W mK SpecHeat 1000 J kg K RadHeatFlux 1 205 W m i ili 5 5 W m kK Density 2000 kg m RunningMode 1 i 2 5 W m K Above the Slub 1 tWater 18 C ili 0 354 tOpMin 22 0 0 161 nDivisions 30 tOpOffset 1 0 i O m
84. s are no longer a linear upward trend but a logarithmic trend until reaching an asymptotic value The Figure 52 below shows the case with the option enabled where differences between the two models can be seen 4 treeeeww_0 ira treeeeww_25 ira treeeeww_50 r treeeeww_75 upon 0 35 N Air Temperature C hh R 8 R a f Ss 144 168 treeeeww treeseww_O treeseww_25 treeeeww_50 treeeeww_75 Figure 52 Simulation results with the Load Limitations enabled As mentioned before it has been necessary to set the three parameters for this option in order to obtain results similar to reality This has been done by comparing the results of 75 SST with the Trnsys results By changing these three parameters the obtained trend is the one depicted in the Figure 53 It can be clearly seen in this case that the thermal loads in SST sensible and latent are decreased indiscriminately in contrast with Trnsys therefore for the last days of the simulation is lost the range between maximum and minimum temperature but the user can evaluate the value of the mean temperature in the analyzed room to which it tends uponor 32 Operative Temperature C b 8 w a 24 a 2 R 96 120 144 168 ssT Trnsys Figure 53 Trends of internal temperature with no cooling system Is lost the range between maximum and minimum temperature during the last days of the simulation
85. sfer coefficient Or z _ Typ T V10 v OPERATIVE 1 v10 v Where Ta air temperature 81 Twr mean radiant temperature v air speed m s Where the air speed is less than 0 1m s as is typical in buildings radiative and convective heat transfers may be similar and so the equation can be simplified to T Tyr 2 operative In many spaces with low air velocity and where air temperature and mean radiant temperature may be similar air temperature alone can be a reasonable indicator of thermal comfort However in spaces where surfaces may be heated or cooled where there is significant thermal mass or where solar radiation is present air and radiant temperatures may be very different and so it is necessary to take account of radiant temperatures in assessing thermal comfort The Figure 55 shows the comfort temperature area depending on the mean surface temperature and the air temperature It is possible to see the winter case top part of the figure and the summer case bottom part of the figure Using a radiant cooling system For example the Operative point in the extreme case of internal air temperature of 30 C and a mean radiative temperature of 12 C is inside the green area therefore the people are living in the comfort zone Mean surface temperature C Thermal comfort according to P O Fanger 12 14 16 18 20 22 24 26 28 30 Air temperature C Figure 55 Comfort temperatu
86. tains the macros used in Loads and Loads WE sheets for copying the values related with cooling power people lighting and equipment in the row below Module 6 contains all the macro for cancelling data such values in the sheets or Project data These macros work also on the hided sheets In addiction it contains the macros regarding the functioning of the arrows Module 7 contains the macro needed for the creation of charts from the results of the calculation program It recognizes the different selected options and creates the chart type based on these Module 8 contains the macros to add values in the different libraries as Materials Locations and Equipment Module 9 contains the macros connected with Loads and Loads WE sheets to change the temperature of the inlet water temperature of the project and to copy the values from one sheet to another 25 e Module 10 is one of the most important modules it contains the macros to insert the data from the New Project sheet to the database where the calculation program gets the data to run the simulation as the circuit room and pipe values It contains also the macros to change sheets or position in a page with the arrows e Module 11 contains all the macros concerning data insertion in the normal or manual way and the macro for cancelling the inserted boundary of Loads sheet e Module 12 contains the macro concerning data insertion of Loads WE sheet To make easier a possible the mod
87. ternal Wall m kg m W mK Lime cement plaster 0 01 1800 0 9 Brick 0 30 1400 0 52 Lime and gypsum plaster 0 01 1500 0 54 The parameters for the internal gains are Hour n People Activity n Equipment Type Equipment 8 4 Seated light work typing 4 PC with monitor 9 4 Seated light work typing 4 PC with monitor 10 4 Seated light work typing 4 PC with monitor 11 4 Seated light work typing 4 PC with monitor 12 4 Seated light work typing 4 PC with monitor 13 4 Seated light work typing 4 PC with monitor 14 4 Seated light work typing 4 PC with monitor 15 4 Seated light work typing 4 PC with monitor 16 4 Seated light work typing 4 PC with monitor 17 4 Seated light work typing 4 PC with monitor The results show that in certain cases the operative temperature exceeds 26 C for a few hours and consequently it falls off the comfort range This is due to the fact that the Simple Simulation Tool simulates the worst weather conditions for each day of the simulation values according with the selected city This is due to the size of peak power demand from the cooling system which is necessary to use the values of design more burdensome Furthermore in a normal project the value of the operative temperature is considered acceptable if in some period it exceeds the threshold limit of 26 C for a few hours in a year a limit could be 1 or approximately 100 h
88. the room from the external surface The Simple Simulation Tool has the following purposes e Verify in a simplified method the possibility of installation of TABS for a particular system installed in a room with various parameters in a hypothetical location that means for a different position of the room in a building and for a different position of the building in the world e To have quickly results of the trend of the temperatures for the room focal points as the operative and the walls temperature and inlet and outlet temperatures of the fluid in the pipe e To havea simple program results and chart to show eventually at the customers to demonstrate that the use of the TABS system might be a good design decision 13 14 3 Implementation 3 1 From the beginning This project was started by Benjamin Behrendt who created a simple interface to insert manually the data in five different sheets Boundary Room Circuit Pipe and Slab The interface required to enter all data manually on each sheet and the last there was the opportunity to view all the entered values and launch the simulation The five sheets are illustrated below A z 5 z vY Boundary 1 Boundary Exported f f 2 Boundary Data Unit 11855 4 Luca_boundar iintimesteps lE a The first sheet that the user had to complete was 4 ITimeStep s 3600 3600 i B nsubtimestep IE a regarding the boundaries data The program needed ponam 0 0001 0 0001 the following
89. the slab Rr pipe thickness thermal resistance Rw convection thermal resistance at the pipe inner side Rx pipe level thermal resistance Rz water flow thermal resistance S slab S1 thickness of the upper part of the slab S2 thickness of the lower part of the slab US upper part of the slab OEsp av average temperature at the outer side of the pipe Op_ average temperature at the pipe level Owater m Water inlet temperature 10 On Ss E a vate Out o L Prvaterin Circuit length Figure 8 General scheme of the Resistance Method where L length of installed pipes LS lower part of the slab Rr pipe thickness thermal resistance Rw convection thermal resistance at the pipe inner side Rx pipe level thermal resistance Rz water flow thermal resistance T pipe spacing US upper part of the slab OEsp av average temperature at the outer side of the pipe Oisp av average temperature at the inner side of the pipe I ri average temperature at the pipe level Owater av Water average temperature Owater m Water inlet temperature Owater out Water outlet temperature 2 3 Room An air node is taken into account and connected with the upward and downward surface of the slab and with a fictitious thermal node at the wall surface Two surfaces of the slab are connected to each other to take into account the radiation exchange between them and finally
90. ures only for some days it is necessary to re enter all the data in Loads and Loads WE sheets 4 2 2 Manual insertion Only the sheet Loads gives the possibility to insert manually the parameters by clicking the Manual Insertion button in the right part of the screen This button lead up to a different part of the sheet where the user can insert manually the convective and radiative heat and the cooling power available for the room for different number of hours The requested values are e nHours in this mode is possible to insert the same condition for a different number of hours in one time here the program needs the number of hours e ConvHeatFlux and RadHeatFlux the values of convective and radiative heat loads for each hour set before in W or W m depending on the selected option e Running Mode it is possible to set 0 or 1 if the cooling system is disabled or enabled e Temperature Water is the value of set point of the inlet temperature of the water for every hour if the cooling system is deactivated or not sufficient this temperature will be larger e maxCoolPower the value of the maximum cooling power available for each hour as ConvHeatFlux and RadHeatFlux 50 The values of Convective 409 Radiative and Cooling Power can be inserted in T gt Z absolute or specific values E amp wn by selecting Yes in cell V17 00 1 Li ioi i T e oe at the question Change 1 2 3 4 5 6 7 8 9 10
91. uses three different types of pipes AECE Diameter Wall thickness Thermal conductivity external m m W mK Contec Pipe 20 0 02 0 0023 0 35 Contec Pipe 17 0 017 0 002 0 35 MLC 0 02 0 00225 0 4 Hence it is possible to insert manually a new type of pipes by selecting Other in the list and by inserting the values in the empty cells 36 3 7 Solar Tool The SST program permits to create a simulation of a room in different geographic conditions This means it needs different solar irradiances for every coordinates The solar tool allows the calculation of the solar irradiance for four principal external orientations The inputs that the tool needs are the coordinates the time zone the number of the hottest month the SHGC factor depending of the types of windows and the shading coefficient of the city that is simulated see Location Library There are some like predefined parameters the ground reflectance fixed on 0 2 and the windows area fixed on 1 to have the specific solar irradiance in W per square meters of windows There are four different sheets each one for a different orientation and a different number of direction 0 North 90 East 180 South 270 West Each sheet gives 24 values of solar irradiations for the hottest day of the year These values are used to calculate the solar gain due to sun irradiance throw the windows QS by the Carrier Method The Figure 27 at uponor
92. ver limited due to the high amount of time needed for the simulations The diagrams in Figure 5 show an example of the relation between internal heat gains water supply temperature heat transfer on the room side hours of operation and heat transfer on the water side The diagrams refer to a concrete slab with raised floor R 0 45 m2 K W and an allowed room temperature range of 21 C to 26 C The upper diagram shows on the Y axis the maximum permissible total heat gain in space internal heat gains plus solar gains W m2 and on the X axis the required water supply temperature The lines in the diagram correspond to different operation periods 8 h 12 h 16h and 24 h and different maximum amounts of energy supplied per day Wh m2 d The lower diagram shows the cooling power W m2 required on the water side to dimension the chiller for TAS as a function of supply water temperature and operation time Further the amount of energy rejected per day is indicated Wh m2 d overall heat gain 460 Whim 50 E o 40 c a 30 E 20 o 0 15 16 17 18 19 20 21 22 23 24 25 Supply water temperature C 15 16 17 18 19 20 21 22 23 24 25 0 m 10 E 20 5 5 30 o 5 40 8 V 50 60 Figure 6 Working principle of TABS where Axis X upper diagram inlet temperature tabs C Axis Y upper diagram maximum total heat gain in space W m floor area Axis Y lower diagram mean cooling
93. walls between bright normal and dark This affects the amount of energy absorbed by the wall for different external colors For the windows the program needs the area of the windows for each external orientation the type of glass single double or triple and the eventual material in the interspace and the windows shading The U value and the SHGC factor are different for the different type of glass see paragraph Windows Library in Chapter 3 6 for further details As regards the ventilation is possible to choose between the case of infiltration from outside or the case of mechanical ventilation by inserting the value of the Air Change Ratio 44 in volumes per hour Obviously in the case of infiltration from outside inlet air temperature is equal to the outside temperature calculated hour by hour as previously described When a value of ACR for mechanical ventilation is inserted another cell will appear where is needed to insert the temperature value for the air inlet This temperature will be unique and constant for the duration of the simulation The parameters that the program needs are automatically calculated and they are v Floor area calculated from the dimensions in m2 v Wall area it is the area of the internal walls only depending on the height of the room in m2 v Three values of convective heat transfer coefficient between e Airto Floor fixed at 1 5 W m2K for ceiling cooling system e Air to Ceiling fixed at 5 5 W m2K
94. wed to insert parameters for only one day so the usefulness of the program was limited Both part of the tool had to be modified to permit at the user the possibility to create a simulation of multiple days Now the program can make a simulation up to 10 days by entering different values of load for each hour Obviously simulation can be extended to a longer period of time by manually entering the values of the loads up to 240 intervals of times This however is not recommended by the fact that the accuracy of the results is lower if the simulation period becomes larger and the computation time could make a substantial increase e Automatic loads calculation one of the main purposes of the tool was to create a calculation method that utilizes the inserted parameter as input to calculate all the values the program needs The purpose was to minimize as much as possible the number of parameters that the user has to insert in order to decrease the needed time to simulate the project and to get a user friendly software Therefore it was necessary to implement a list of formulas tables and libraries in order to automatically calculate the requested parameters As mentioned earlier at the beginning the software needed the values of convective and radiative gains as input parameters but it was complicated for a user to insert a realistic values These two parameters are influenced by e External conditions e Walls and windows materials e Internal
95. zero It is possible to insert the values of cooling power as absolute W or relative W m by selecting the check box e lighting it is composed by 2 columns to introduce the values regarding lighting ie the number of lights in the room and the specific power of each light To the right of the table you can find the legend of the selectable values e people it is composed by 2 columns to insert the values concerning the internal gains due to people ie the number of people inside the room and the type of activities they perform Add equipment e equipment it is composed by 2 columns to enter the iame values on the equipment that is the number of fixtures in Value w the room and the type of device It is possible to inserta Figure 33 Screenshot of the Add Equipment option new device in the library in the box below see Figure 33 Below each column there are buttons that allow nHours h 6 5 F copying the data entered in a cell in the cell of the medians bwin RadHeatFlux W m 50 next hour or delete the all the data inserted in the RunningMode 1 table with the X buttons eae cl tOpMin c 22 tOpOffset c 1 The program also needs the three values for the tOpRange c 2 operative temperature as discuss in chapter tMax c 24 inei d t h h b tMaxOffset el 1 mplemented Options these parameters have to be taaxRange ec 3 set in the normal way In the Figure 34 is showed MaxCoolPower w m 70 Figure

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