What size AC for Madison, IN? 3 tons for 2,000 sq ft

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

3 tons central AC or heat pump, about 32,300 BTU/hr of load

The 20 BTU per square foot chart would put in 3.5 tons, about 30% 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 3 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 743 square feet in this climate. For a single room, size by the room: 16.1 BTU/hr per square foot.

The climate it is sized for

Climate from NOAA's 1991 to 2020 normals at Madison Sewage Plt (1.5 mi away). Jul is the hottest month, averaging a high of 88°F and a low of 66.1°F, with about 25 days a year at 90°F or more. That gives a design temperature of 93°F against 75°F inside.

What it costs to run

About 1,789 kWh a year at SEER2 14.3, or roughly $305 at Indiana's average residential rate of 17.04¢ per kWh. Cooling runs 5 months of the year here.

What drives the load in Madison

Of the 32,300 BTU/hr, 12,960 comes through walls, roof and windows on a 93°F afternoon (40%), 13,000 is sun on the house (40%), 2,120 is four people and their appliances, and 4,200 is moisture the coil has to wring out of Madison's summer air (13%).

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 28,080 BTU/hr before the moisture allowance.

Other house sizes in Madison

Single rooms with a window or mini-split unit: a 150 sq ft bedroom needs about 2,400 BTU/hr; a 350 sq ft living room needs about 5,600 BTU/hr; a 600 sq ft open plan kitchen and family room needs about 9,700 BTU/hr.

Month by month in Madison

Jul alone uses 29% of the year's cooling energy. The unit runs the equivalent of 792 hours a year at full output.

Madison against nearby cities

Of 88 Indiana cities here, Madison has the 8th highest cooling load. The range runs from Auburn at 24,100 BTU/hr to Jasper at 36,400.

Where Madison's weather numbers come from

The nearest NOAA station with full 1991 to 2020 normals is Madison Sewage Plt, 1.5 miles from the center of Madison at 460 ft above sea level. That is close enough that the station's summers are Madison's summers.

No other city in this set uses Madison Sewage Plt, so this sizing is Madison's alone.

The sun over Madison in late July

At 38.76°N, the noon sun on 21 July stands 71.6° above the horizon over Madison and the day runs 14 h 19 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.

12,108 people live in Madison, the 73rd largest of the 88 Indiana cities sized on this site. Coordinates used: 38.7588, -85.3971.

Madison AC sizing questions