To determine the Air Change per Hour (ACH) for the house, we need to follow a series of steps:
1. Determine the volume of the house:
- The house area is given as 3600 square feet.
- The ceiling height is given as 9 feet.
- The volume of the house, [tex]\( V \)[/tex], can be calculated using the formula:
[tex]\[
V = \text{house area} \times \text{ceiling height}
\][/tex]
Substituting the given values:
[tex]\[
V = 3600 \, \text{sq ft} \times 9 \, \text{ft} = 32400 \, \text{cubic feet}
\][/tex]
2. Calculate the Air Changes per Hour at 50 pascals (ACH 50):
- The airflow rate, given in cubic feet per minute (cfm), is 2100 cfm.
- The formula to find ACH 50 is:
[tex]\[
\text{ACH 50} = \frac{\text{cfm} \times 60}{\text{volume}}
\][/tex]
This formula is derived from the fact that there are 60 minutes in an hour, and it converts the cfm to cubic feet per hour.
Substituting the given values:
[tex]\[
\text{ACH 50} = \frac{2100 \, \text{cfm} \times 60}{32400 \, \text{cubic feet}}
\][/tex]
3. Perform the calculation:
- First, calculate [tex]\( 2100 \times 60 \)[/tex]:
[tex]\[
2100 \times 60 = 126000 \, \text{cubic feet per hour}
\][/tex]
- Next, divide by the volume of the house:
[tex]\[
\text{ACH 50} = \frac{126000}{32400} \approx 3.888888888888889
\][/tex]
Therefore, the Air Change per Hour (ACH) for this house is approximately 3.888888888888889, which is closest to option c.
Answer:
c. 3.88 ACH 50
