What size AC for Gautier, MS? 3.5 tons for 2,000 sq ft

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

3.5 tons central AC or heat pump, about 41,200 BTU/hr of load

Here the 20 BTU per square foot chart lands close: 3.5 tons against a load of 3.4 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 583 square feet in this climate. For a single room, size by the room: 20.6 BTU/hr per square foot.

The climate it is sized for

Climate from NOAA's 1991 to 2020 normals at Pascagoula Lott International Airport (8.6 mi away). Jul is the hottest month, averaging a high of 90.9°F and a low of 73.4°F, with about 80 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 4,107 kWh a year at SEER2 14.3, or roughly $619 at Mississippi's average residential rate of 15.06¢ per kWh. Cooling runs 7 months of the year here.

What drives the load in Gautier

Of the 41,200 BTU/hr, 16,560 comes through walls, roof and windows on a 98°F afternoon (40%), 13,000 is sun on the house (32%), 2,120 is four people and their appliances, and 9,500 is moisture the coil has to wring out of Gautier'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 31,680 BTU/hr before the moisture allowance.

Other house sizes in Gautier

Single rooms with a window or mini-split unit: a 150 sq ft bedroom needs about 3,100 BTU/hr; a 350 sq ft living room needs about 7,200 BTU/hr; a 600 sq ft open plan kitchen and family room needs about 12,400 BTU/hr.

Month by month in Gautier

Jul alone uses 20% of the year's cooling energy. The unit runs the equivalent of 1,426 hours a year at full output.

Gautier against nearby cities

Of 41 Mississippi cities here, Gautier has the 16th highest cooling load. The range runs from Brookhaven at 36,900 BTU/hr to Columbus at 44,000.

Where Gautier's weather numbers come from

The nearest NOAA station with full 1991 to 2020 normals is Pascagoula Lott International Airport, 8.6 miles from the center of Gautier at 9 ft above sea level. That is close enough that the station's summers are Gautier's summers.

3 other cities use the same station and get the same climate inputs. The closest to Gautier: Pascagoula (7 mi away, 7.3 mi from the station), Moss Point (8 mi away, 2.6 mi from the station), Ocean Springs (8 mi away, 15.9 mi from the station). Gautier is farther from the station than 2 of them.

The sun over Gautier in late July

At 30.41°N, the noon sun on 21 July stands 80.0° above the horizon over Gautier and the day runs 13 h 41 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.

19,055 people live in Gautier, the 21st largest of the 41 Mississippi cities sized on this site. Coordinates used: 30.4062, -88.6593.

Gautier AC sizing questions