What size AC for Shelbyville, KY? 2.5 tons for 2,000 sq ft

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

2.5 tons central AC or heat pump, about 30,300 BTU/hr of load

The 20 BTU per square foot chart would put in 3.5 tons, about 38% 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 791 square feet in this climate. For a single room, size by the room: 15.2 BTU/hr per square foot.

The climate it is sized for

Climate from NOAA's 1991 to 2020 normals at Shelbyville 1 E (1.9 mi away). Jul is the hottest month, averaging a high of 87.6°F and a low of 62.3°F, with about 34 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 1,273 kWh a year at SEER2 14.3, or roughly $181 at Kentucky's average residential rate of 14.2¢ per kWh. Cooling runs 5 months of the year here.

What drives the load in Shelbyville

Of the 30,300 BTU/hr, 12,960 comes through walls, roof and windows on a 93°F afternoon (43%), 13,000 is sun on the house (43%), 2,120 is four people and their appliances, and 2,200 is moisture the coil has to wring out of Shelbyville's summer air (7%).

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 Shelbyville

Single rooms with a window or mini-split unit: a 150 sq ft bedroom needs about 2,300 BTU/hr; a 350 sq ft living room needs about 5,300 BTU/hr; a 600 sq ft open plan kitchen and family room needs about 9,100 BTU/hr.

Month by month in Shelbyville

Jul alone uses 32% of the year's cooling energy. The unit runs the equivalent of 601 hours a year at full output.

Shelbyville against nearby cities

Of 42 Kentucky cities here, Shelbyville has the 40th highest cooling load. The range runs from Versailles at 29,000 BTU/hr to Paducah at 36,900.

Where Shelbyville's weather numbers come from

The nearest NOAA station with full 1991 to 2020 normals is Shelbyville 1 E, 1.9 miles from the center of Shelbyville at 730 ft above sea level. That is close enough that the station's summers are Shelbyville's summers.

No other city in this set uses Shelbyville 1 E, so this sizing is Shelbyville's alone.

The sun over Shelbyville in late July

At 38.21°N, the noon sun on 21 July stands 72.2° above the horizon over Shelbyville and the day runs 14 h 16 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.

18,048 people live in Shelbyville, the 24th largest of the 42 Kentucky cities sized on this site. Coordinates used: 38.2063, -85.2336.

Shelbyville AC sizing questions