What size AC for Fayetteville, NC? 3.5 tons for 2,000 sq ft

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

3.5 tons central AC or heat pump, about 38,700 BTU/hr of load

Here the 20 BTU per square foot chart lands close: 3.5 tons against a load of 3.2 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 621 square feet in this climate. For a single room, size by the room: 19.3 BTU/hr per square foot.

The climate it is sized for

Climate from NOAA's 1991 to 2020 normals at Fayetteville Regional Airport Grannis F (8.3 mi away). Jul is the hottest month, averaging a high of 91.4°F and a low of 71.9°F, with about 71 days a year at 90°F or more. That gives a design temperature of 98°F against 75°F inside.

What it costs to run

About 3,023 kWh a year at SEER2 14.3, or roughly $452 at North Carolina's average residential rate of 14.94¢ per kWh. Cooling runs 7 months of the year here.

What drives the load in Fayetteville

Of the 38,700 BTU/hr, 16,560 comes through walls, roof and windows on a 98°F afternoon (43%), 13,000 is sun on the house (34%), 2,120 is four people and their appliances, and 7,000 is moisture the coil has to wring out of Fayetteville'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 31,680 BTU/hr before the moisture allowance.

Other house sizes in Fayetteville

Single rooms with a window or mini-split unit: a 150 sq ft bedroom needs about 2,900 BTU/hr; a 350 sq ft living room needs about 6,800 BTU/hr; a 600 sq ft open plan kitchen and family room needs about 11,600 BTU/hr.

Month by month in Fayetteville

Jul alone uses 25% of the year's cooling energy. The unit runs the equivalent of 1,118 hours a year at full output.

Fayetteville against nearby cities

Of 91 North Carolina cities here, Fayetteville has the 2nd highest cooling load. The range runs from Boone at 21,700 BTU/hr to Lumberton at 40,200.

Where Fayetteville's weather numbers come from

The nearest NOAA station with full 1991 to 2020 normals is Fayetteville Regional Airport Grannis F, 8.3 miles from the center of Fayetteville at 186 ft above sea level. That is close enough that the station's summers are Fayetteville's summers.

2 other cities use the same station and get the same climate inputs. The closest to Fayetteville: Spring Lake (7 mi away, 15 mi from the station), Hope Mills (8 mi away, 4.7 mi from the station). Fayetteville is farther from the station than 1 of them.

The sun over Fayetteville in late July

At 35.08°N, the noon sun on 21 July stands 75.3° above the horizon over Fayetteville and the day runs 14 h 01 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.

209,496 people live in Fayetteville, the 6th largest of the 91 North Carolina cities sized on this site. Coordinates used: 35.0828, -78.9735.

Fayetteville AC sizing questions