Calculate the heat gained (conduction) through the outside wall for the two foll

Question

Calculate the heat gained (conduction) through the outside wall for the two following scenarios

a) Scenario 1: The outside wall of the office is 10 m wide by 4 m high, and is made of two layers. The outside layer is concrete [k=1.73 W/(m . K)] and 15-cm thick. The inside layer is gypsum board [k=0.48 W/(m . K)] and 1-cm thick. The outdoor and indoor wall temperature surfaces are assumed to be 35C and 24C.

b) Scenario 2: We have added two windows in the middle of the wall of the type: Low-e double glazing, clear. Each window is 2 m wide by 1 m high. The specifications of this glazing type are :

1/U= 0.53(m2.k/w) , 3.0 (h.ft2.Fo/Btu)

e(emissivity)=0.15

SC(shading coefficient)=0.66

Tv(Transmissivity for visible radiation)=0.72

ke=Tv/SC = 1.1

The non-window part of the wall is similar to that of Scenario 1. The outdoor and indoor wall temperature surfaces are also assumed to be 35C and 24C.

c) Compare the results of questions (a) and (b). Are the results different and why?

Assumptions: steady-state conduction, one-dimensional (from one wall exposed to the outdoor environment) , and with constant k values.

Working with the building dimensions of scenario 2 above,

a) Calculate the solar gain through the windows, knowing that the Solar Heat Gain Coefficient (SHGC) is 0.8 and the solar radiation is 500 W/m2.

b) Repeat the calculation for SHGC values of 0, 0.5, and 1, and plot the results.

c) Which one of the scenarios of Question (b) will lead to the highest energy efficiency for the cooling system? Is the SHGC the only glass property that is important or is there another characteristic that should also be considered? If you answer yes, explain why it is important.

Explanation / Answer

ANSWER:

Heat gain refers to the transfer of heat into your home through a variety of sources. The primary source ofheat is the sun, and the absorption of heat by your structure increases dramatically during the summer months as solar radiation intensifies.

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