Answer: the rate of heat flow through the wall when the inside air temperature is 68 °F and the outside temperature is 5 °F is 257.42 BTU per hour.
Step-by-step explanation: The rate of heat flow through the wall can be found using the formula:
Rate of heat flow = (Temperature difference) / (Effective R-value)
The temperature difference is the difference between the inside and outside temperatures, which is:
Temperature difference = (68°F) - (5°F) = 63°F
The effective R-value of the wall is given as 15.5.
To calculate the total area of the wall, we first need to find the area of the window, which is:
Area of window = (width) x (height) = (5 ft) x (3.5 ft) = 17.5 square feet
The area of the wall without the window is:
Area of wall = (length) x (height) - Area of window
Area of wall = (14 ft) x (8 ft) - 17.5 square feet
Area of wall = 105.5 square feet
So, the rate of heat flow through the wall is:
Rate of heat flow = (Temperature difference) / (Effective R-value) x (Total area of the wall)
Rate of heat flow = (63°F) / (15.5) x (105.5 square feet)
Rate of heat flow = 257.42 BTU per hour