Why Is the Total Area for Calculating Heat Loss 320 Square Feet?

[tweety1234]

Homework Statement

Calculate wall loss rate in BTUs per hour. For a 10 ft by 10 ft room with an 8 ft ceiling, with all surfaces insulated to R19 as recommended by the U.S. Department of Energy, with inside temperature 68°F and outside temperature 28°F:

heat loss = $$\frac{Q}{t} = \frac{(Area) \times (T1-T2)}{R}$$

I don't get the working out,

can someone please explain why the area is 320ft^{2}?

$$\frac{Q}{t} = \frac{(320 ft^{2}) \times (68-28)}{19}$$ surely its just 10 x 8 = 80 ft?

 

[gneill]

Homework Statement

Calculate wall loss rate in BTUs per hour. For a 10 ft by 10 ft room with an 8 ft ceiling, with all surfaces insulated to R19 as recommended by the U.S. Department of Energy, with inside temperature 68°F and outside temperature 28°F:

heat loss = $$\frac{Q}{t} = \frac{(Area) \times (T1-T2)}{R}$$

I don't get the working out,

can someone please explain why the area is 320ft^{2}?

$$\frac{Q}{t} = \frac{(320 ft^{2}) \times (68-28)}{19}$$


surely its just 10 x 8 = 80 ft?

How many walls are there in a square room?

 

[tweety1234]

How many walls are there in a square room?

4? But how does that make 320?

 

[tweety1234]

Dont worry, I got it,

thanks for your help.

 

[rwisz]

I can explain the calculation for the area in this context. The area in this case refers to the surface area of the walls, ceiling, and floor of the room that are exposed to the outside temperature. In this case, the room is a cube with dimensions of 10 ft by 10 ft by 8 ft, so the total surface area would be 320 square feet. This is because each wall has an area of 10 ft by 8 ft (80 square feet), and there are four walls in the room. Additionally, the ceiling and floor also have areas of 10 ft by 10 ft (100 square feet each), adding another 200 square feet to the total surface area. This is why the area in the calculation is 320 ft^2.