Now that you know how to calculate hourly heat loss, how would you calculate daily heat loss?

Since there are 24 hours in a day, you would simply multiply the hourly heat loss by 24.

$$Heat\text{\hspace{0.17em}}Loss\left(\frac{BTUs}{h}\right)=\frac{Area(f{t}^{2})\times Temperature\text{\hspace{0.17em}}Difference{(}^{o}F)}{R\text{\hspace{0.17em}}value\left(\frac{f{t}^{2}{}^{\text{\hspace{0.17em}}o}F\text{\hspace{0.17em}}h}{BTUs}\right)}\text{\hspace{0.17em}}\times \text{\hspace{0.17em}}24hr/day$$

### Example

**What is the hourly and daily heat loss of a 15-ft by 15-ft room with an 8-ft ceiling, with all surfaces insulated to R13, with inside temperature 65°F and outside temperature 25°F?**

Once we know the heat loss rate per hour, we can determine the heat loss per day by multiplying by 24 (hours in a day).

In a 24-hour period or one day, the heat loss would be:

$$Daily\text{\hspace{0.17em}}Heat\text{\hspace{0.17em}}Loss\text{\hspace{0.17em}}per\text{\hspace{0.17em}}day=\frac{1477\text{\hspace{0.17em}}BTUs}{h}\text{\hspace{0.17em}}x\frac{24\text{\hspace{0.17em}}h}{day}=35,448\text{\hspace{0.17em}}\frac{BTUs}{day}$$Area (ft^{2}) is the sum of the area of all four walls. Each wall is 8' x 15', or 120 sq. feet, so take 4 x 120 sq ft to get 480 ft^{2} in the equation.