# Heat loss through a wall

## 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 dont 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
Mentor

## 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 dont 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?

How many walls are there in a square room?

4? But how does that make 320?

Dont worry, I got it,

thanks for your help.