Sizing Window & Portable Room Air Conditioners
To obtain optimum cooling at the lowest energy costs the sizing of a room air conditioner (Figure 1) is critical. An air conditioner that is larger than needed will turn on and off frequently which increases energy costs and wear and tear on the air conditioner.
Figure 1 - Window air conditioner
Selection of window
The factors that are important are:
- The square foot area of the room (length X width).
- The amount of sunlight in the room.
- The number of people normally in the room.
- Is the room a kitchen?
Table 1 is based on 1 or 2 people occupying the room with normal sunlight (neither shaded or in direct sun).
Table 1 - Room Air Conditioner Sizing |
|||
Room Size in Feet |
Square Footage |
Basic Room BTU's |
Kitchen BTU's |
10 X 10 |
100 |
4,500 |
9,000 |
10 X 15 |
150 |
5,400 |
10,000 |
10 X 20 |
200 |
6,000 |
12,000 |
17 X 20 |
340 |
8,000 |
16,000 |
20 X 20 |
400 |
9,000 |
18,000 |
18 X 25 |
450 |
10,000 |
20,000 |
22 X 25 |
550 |
12,000 |
24,000 |
25 X 30 |
750 |
14,500 |
29,000 |
25 X 34 |
850 |
16,000 |
32,000 |
25 X 40 |
1,000 |
18,000 |
|
35 X 40 |
1,400 |
24,000 |
|
38 X 40 |
1,520 |
28,500 |
|
40 X 40 |
1,600 |
32,000 |
|
Adjustments to the size of the air conditioner must be made based on the additional factors shown in Table 2
Table 2 - Adjustments |
|
Factor |
Add To BTU's |
Sunny Rooms |
+ 10% |
Shaded Rooms |
- 10% |
More Than 2 People Occupying Room |
+10% per person |