What size AC for Nashville-Davidson, TN? 3.5 tons for 2,000 sq ft

What size AC a 2,000 sq ft house in Nashville-Davidson needs

3.5 tons central AC or heat pump, about 37,800 BTU/hr of load

Here the 20 BTU per square foot chart lands close: 3.5 tons against a load of 3.1 tons. This is one of the climates the chart was written for.

If a contractor quotes you more than 3.5 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 635 square feet in this climate. For a single room, size by the room: 18.9 BTU/hr per square foot.

The climate it is sized for

Climate from NOAA's 1991 to 2020 normals at Nashville International Airport (6.9 mi away). Jul is the hottest month, averaging a high of 90.9°F and a low of 70.5°F, with about 54 days a year at 90°F or more. That gives a design temperature of 97°F against 75°F inside.

What it costs to run

About 2,761 kWh a year at SEER2 14.3, or roughly $381 at Tennessee's average residential rate of 13.8¢ per kWh. Cooling runs 7 months of the year here.

What drives the load in Nashville-Davidson

Of the 37,800 BTU/hr, 15,840 comes through walls, roof and windows on a 97°F afternoon (42%), 13,000 is sun on the house (34%), 2,120 is four people and their appliances, and 6,800 is moisture the coil has to wring out of Nashville-Davidson's summer air (18%).

Heat through the shell is the biggest share here, so insulation and air sealing cut the size you need more than shading would. Sensible heat totals 30,960 BTU/hr before the moisture allowance.

Other house sizes in Nashville-Davidson

Single rooms with a window or mini-split unit: a 150 sq ft bedroom needs about 2,800 BTU/hr; a 350 sq ft living room needs about 6,600 BTU/hr; a 600 sq ft open plan kitchen and family room needs about 11,300 BTU/hr.

Month by month in Nashville-Davidson

Jul alone uses 26% of the year's cooling energy. The unit runs the equivalent of 1,045 hours a year at full output.

Nashville-Davidson against nearby cities

Of 65 Tennessee cities here, Nashville-Davidson has the 9th highest cooling load. The range runs from Crossville at 27,300 BTU/hr to Memphis at 41,200.

Where Nashville-Davidson's weather numbers come from

The nearest NOAA station with full 1991 to 2020 normals is Nashville International Airport, 6.9 miles from the center of Nashville-Davidson at 587 ft above sea level. That is close enough that the station's summers are Nashville-Davidson's summers.

9 other cities use the same station and get the same climate inputs. The closest to Nashville-Davidson: Goodlettsville (12 mi away, 15.4 mi from the station), Brentwood (12 mi away, 9.3 mi from the station), Hendersonville (14 mi away, 14.4 mi from the station), Mount Juliet (15 mi away, 11.7 mi from the station), Nolensville (16 mi away, 10.7 mi from the station). Nashville-Davidson sits closer to the station than any of them, so its numbers are the best measured of the group.

The sun over Nashville-Davidson in late July

At 36.17°N, the noon sun on 21 July stands 74.2° above the horizon over Nashville-Davidson and the day runs 14 h 06 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.

704,963 people live in Nashville-Davidson, the largest of the 65 Tennessee cities sized on this site. Coordinates used: 36.1718, -86.7850.

Nashville-Davidson AC sizing questions