What size AC for West Lafayette, IN? 2.5 tons for 2,000 sq ft

What size AC a 2,000 sq ft house in West Lafayette needs

2.5 tons central AC or heat pump, about 26,400 BTU/hr of load

The 20 BTU per square foot chart would put in 3.5 tons, about 59% more than this climate needs. An oversized unit cools the air fast, shuts off before it pulls moisture out, and leaves the house cold and clammy.

If a contractor quotes you more than 2.5 tons for an average 2,000 sq ft house here, ask to see the Manual J load calculation behind it before you sign. That works out to one ton per 908 square feet in this climate. For a single room, size by the room: 13.2 BTU/hr per square foot.

The climate it is sized for

Climate from NOAA's 1991 to 2020 normals at Lafayette Purdue University Airport (2.5 mi away). Jul is the hottest month, averaging a high of 83.8°F and a low of 63.4°F, with about 21 days a year at 90°F or more. That gives a design temperature of 88°F against 75°F inside.

What it costs to run

About 1,153 kWh a year at SEER2 14.3, or roughly $196 at Indiana's average residential rate of 17.04¢ per kWh. Cooling runs 5 months of the year here.

What drives the load in West Lafayette

Of the 26,400 BTU/hr, 9,360 comes through walls, roof and windows on a 88°F afternoon (35%), 13,000 is sun on the house (49%), 2,120 is four people and their appliances, and 2,000 is moisture the coil has to wring out of West Lafayette's summer air (8%).

Sun is the biggest share here, more than heat through the walls, so shading west windows and a light roof cut the size you need more than extra insulation would. Sensible heat totals 24,480 BTU/hr before the moisture allowance.

Other house sizes in West Lafayette

Single rooms with a window or mini-split unit: a 150 sq ft bedroom needs about 2,000 BTU/hr; a 350 sq ft living room needs about 4,600 BTU/hr; a 600 sq ft open plan kitchen and family room needs about 7,900 BTU/hr.

Month by month in West Lafayette

Jul alone uses 31% of the year's cooling energy. The unit runs the equivalent of 624 hours a year at full output.

West Lafayette against nearby cities

Of 88 Indiana cities here, West Lafayette has the 71st highest cooling load. The range runs from Auburn at 24,100 BTU/hr to Jasper at 36,400.

Where West Lafayette's weather numbers come from

The nearest NOAA station with full 1991 to 2020 normals is Lafayette Purdue University Airport, 2.5 miles from the center of West Lafayette at 596 ft above sea level. That is close enough that the station's summers are West Lafayette's summers.

1 other city uses the same station and get the same climate inputs. The closest to West Lafayette: Lafayette (4 mi away, 4.5 mi from the station). West Lafayette sits closer to the station than any of them, so its numbers are the best measured of the group.

The sun over West Lafayette in late July

At 40.44°N, the noon sun on 21 July stands 70.0° above the horizon over West Lafayette and the day runs 14 h 28 min from sunrise to sunset. A lower noon sun puts more of the day's heat on east and west walls than on the roof, which is why shading west glass pays off here. Shorter days give the house a longer night to shed the day's heat.

46,338 people live in West Lafayette, the 23rd largest of the 88 Indiana cities sized on this site. Coordinates used: 40.4437, -86.9236.

West Lafayette AC sizing questions