What size AC for Columbus, MS? 4 tons for 2,000 sq ft

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

4 tons central AC or heat pump, about 44,000 BTU/hr of load

Here the 20 BTU per square foot chart lands close: 3.5 tons against a load of 3.7 tons. This is one of the climates the chart was written for.

If a contractor quotes you more than 4 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 546 square feet in this climate. For a single room, size by the room: 22 BTU/hr per square foot.

The climate it is sized for

Climate from NOAA's 1991 to 2020 normals at Columbus (3.1 mi away). Jul is the hottest month, averaging a high of 93.8°F and a low of 72.7°F, with about 83 days a year at 90°F or more. That gives a design temperature of 101°F against 75°F inside.

What it costs to run

About 3,918 kWh a year at SEER2 14.3, or roughly $590 at Mississippi's average residential rate of 15.06¢ per kWh. Cooling runs 7 months of the year here.

What drives the load in Columbus

Of the 44,000 BTU/hr, 18,720 comes through walls, roof and windows on a 101°F afternoon (43%), 13,000 is sun on the house (30%), 2,120 is four people and their appliances, and 10,200 is moisture the coil has to wring out of Columbus's summer air (23%).

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 33,840 BTU/hr before the moisture allowance.

Other house sizes in Columbus

Single rooms with a window or mini-split unit: a 150 sq ft bedroom needs about 3,300 BTU/hr; a 350 sq ft living room needs about 7,700 BTU/hr; a 600 sq ft open plan kitchen and family room needs about 13,200 BTU/hr.

Month by month in Columbus

Jul alone uses 23% of the year's cooling energy. The unit runs the equivalent of 1,274 hours a year at full output.

Columbus against nearby cities

Of 41 Mississippi cities here, Columbus has the highest cooling load. The range runs from Brookhaven at 36,900 BTU/hr to Columbus at 44,000.

Where Columbus's weather numbers come from

The nearest NOAA station with full 1991 to 2020 normals is Columbus, 3.1 miles from the center of Columbus at 145 ft above sea level. That is close enough that the station's summers are Columbus's summers.

No other city in this set uses Columbus, so this sizing is Columbus's alone.

The sun over Columbus in late July

At 33.51°N, the noon sun on 21 July stands 76.9° above the horizon over Columbus and the day runs 13 h 54 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.

22,820 people live in Columbus, the 18th largest of the 41 Mississippi cities sized on this site. Coordinates used: 33.5082, -88.4071.

Columbus AC sizing questions