The thermal performance of a building refers to the process of modelling the energy transfer between a building and its surroundings. For a conditioned building, it estimates the heating and cooling load and hence, the sizing and selection of HVAC equipment can be correctly made. For a non-conditioned building, it calculates temperature variation inside the building over a specified time and helps one to estimate the duration of uncomfortable periods. These quantifications enable one to determine the effectiveness of the design of a building and help in evolving improved designs for realising energy efficient buildings with comfortable indoor conditions. The lack of proper quantification is one of the reasons why passive solar architecture is not popular among architects. Clients would like to know how much energy might be saved, or the temperature reduced to justify any additional expense or design change. Architects too need to know the relative performance of buildings to choose a suitable alternative. Thus, knowledge of the methods of estimating the performance of buildings is essential to the design of passive solar buildings.

1. Heat Exchange Analysis Of
G+3 Residential Building
Presented by
Aswin Baby
Itihas Dhareppagol
Shyam Anandjiwala
Swosti Sunder Sen
Vineeth M S
INDIAN INSTITUTE OFTECHNOLOGY DELHI

2. INTRODUCTION
Heat exchange mechanisms in a building:
• Conduction
• Convection
• Radiation

3. Case study:
Heat exchange analysis of a G+3 residential building situated in
New Delhi with aspect ratio>1
Aim:
To develop a computer program in excel spread sheet to obtain the
24 hourly internal temperature for a naturally conditioned building
with variable ventilation condition and comparing the results with
the results obtained by computer software.

4. Data collection
Temperature Data obtained from: INDIAN SOCIETY OF HEATING,
REFRIGERATING AND AIR CONDITIONING ENGINEERS (ISHRAE)

5. Radiation data from the journal: “Estimation of hourly solar radiation on horizontal and inclined
surfaces in western Himalayas” by Shyam S Chandal and Rajeev K Agarwal-Scientific research
journal smart grid and renewable energy-2011
Data collection (contd.)

6. Hourly variation of number of air exchange: assumed arbitrarily
Data collection (contd.)
Latitude :28.380N (New Delhi)

7. Building Selection:

8. Wall Details

11. Cosi = Cosϒ Cosβ

12. Incident Radiation on walls
I = Ib cosi

14. Ventilation heat transfer coefficient ( Cv )values
Cv=NV/3
volume of room
V=8.7x6x3m3

15. ∑UjAj+Cv calculations

16. ∑AY+Cv calculations

17. RHS matrix calculations
∑UjAjαjImj/hoj +∑AjImjθmj + Cv (i)Tfo(i) + ∑µjUjAj[Toa(i-φj)-Tmo] + ∑µjUjAjαjIfj(i-φj)/hoj +∑AjIfj(i)θj

18. ∑UjAj + Cmv
Coefficient ofTfi for
ith hour = Cvi/24

19. 25x25 Matrix
This matrix will give the hourly temperature fluctuations along with ΔTm

20. Inverse of the matrix

21. Calculation of ΔTm and 24 hourly variationTfi
[A] X [T]=[B]
[A]=25X25 matrix
[T]=25x1 matrix containing variables ΔTm &Tfi(i), where i=1,2,3,....n
[B]= 25x1 matrix containing RHS values
[T]= [A]-1X [B]
Thus we can obtain the fluctuating component of internal temperature for every hour
and from that total internal temperature is found out.The above matrix calculation is for
3rd floor. Similarly we can do for all other floors.

22. INTERNAL TEMPERATURE FOR THE BUILDING

23. GRAPHICAL REPRESENTATION OF HOURLY VARIATION OF INTERNAL
TEMPERATURE FOR EVRY MONTH FOR 3RD FLOOR

24. SOFTWARE ANALYSIS FOR INTERNAL TEMPERATURE AND
THERMAL LOADS
3D IMAGE OF BUILDING IN EQUEST

25. Heating and cooling loads by EQuest & Excel

26. Graphical plot for hourly variation of internal temperature from EXCEL
Graphical plot for hourly variation of heating/cooling load from EQUEST

27. Graphical plot for hourly variation of internal temperature in the month of January by Autodesk Ecotect & Excel

28. Graphical plot for hourly variation of internal temperature in the month of June by Autodesk Ecotect & Excel