Question

The walls of your bedroom have an R value of 13 F sq.ft. hr/BTU. Your bedroom is 13 feet long and 12 feet wide with walls that are 8 ft high. On a particular day the average outside temperature is 25 degrees F. How much heat is lost through the walls by conduction on that day (in BTUs)?

Answer 1

To solve this problem we will apply the concept of heat transfer and conduction depending on the Area, the temperature change and the thermal resistance, this can be expressed as

`Q = (A(HDD))/(R)`

Where,

A = Surface Area

HDD=Heating Degree Day

R = Thermal Resistance

According to the information the Area of the wall can be calculated with the given dimensions

`A = 2 ((13*8) + (12*8))`

`A= 400 ft^2`

Heating Degree Day would be

`HDD = 65-25 = 40 \°F`

Finally the heat transferred is

`Q = ((400ft^2)(40 \°F)((24 hours)/(1 day)))/(13(\° F \cdot ft^2 hr)/(BTU))`

`Q = 29538.46BTU/day`

Therefore the heat that is lost through the walls by conduction on that day is 29538.46BTUs