What size AC for Holmen, WI? 2.5 tons for 2,000 sq ft

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

2.5 tons central AC or heat pump, about 29,800 BTU/hr of load

The 20 BTU per square foot chart would put in 3.5 tons, about 41% 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 805 square feet in this climate. For a single room, size by the room: 14.9 BTU/hr per square foot.

The climate it is sized for

Climate from NOAA's 1991 to 2020 normals at La Crosse Municipal Airport (6.4 mi away). Jul is the hottest month, averaging a high of 85.4°F and a low of 64.5°F, with about 18 days a year at 90°F or more. That gives a design temperature of 90°F against 75°F inside.

What it costs to run

About 1,309 kWh a year at SEER2 14.3, or roughly $249 at Wisconsin's average residential rate of 19.05¢ per kWh. Cooling runs 5 months of the year here.

What drives the load in Holmen

Of the 29,800 BTU/hr, 10,800 comes through walls, roof and windows on a 90°F afternoon (36%), 13,000 is sun on the house (44%), 2,120 is four people and their appliances, and 3,900 is moisture the coil has to wring out of Holmen'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 25,920 BTU/hr before the moisture allowance.

Other house sizes in Holmen

Single rooms with a window or mini-split unit: a 150 sq ft bedroom needs about 2,200 BTU/hr; a 350 sq ft living room needs about 5,200 BTU/hr; a 600 sq ft open plan kitchen and family room needs about 8,900 BTU/hr.

Month by month in Holmen

Jul alone uses 33% of the year's cooling energy. The unit runs the equivalent of 628 hours a year at full output.

Holmen against nearby cities

Of 98 Wisconsin cities here, Holmen has the 3rd highest cooling load. The range runs from Two Rivers at 20,200 BTU/hr to La Crosse at 29,800.

Where Holmen's weather numbers come from

The nearest NOAA station with full 1991 to 2020 normals is La Crosse Municipal Airport, 6.4 miles from the center of Holmen at 650 ft above sea level. That is close enough that the station's summers are Holmen's summers.

2 other cities use the same station and get the same climate inputs. The closest to Holmen: Onalaska (6 mi away, 2.5 mi from the station), La Crosse (10 mi away, 4 mi from the station). Holmen is farther from the station than 2 of them.

The sun over Holmen in late July

At 43.97°N, the noon sun on 21 July stands 66.4° above the horizon over Holmen and the day runs 14 h 48 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. Long days mean the house keeps gaining heat into the evening, well after the outdoor peak.

11,866 people live in Holmen, the 83rd largest of the 98 Wisconsin cities sized on this site. Coordinates used: 43.9710, -91.2663.

Holmen AC sizing questions