What size AC for D'Iberville, MS? 3.5 tons for 2,000 sq ft

What size AC a 2,000 sq ft house in D'Iberville needs

3.5 tons central AC or heat pump, about 40,200 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 596 square feet in this climate. For a single room, size by the room: 20.1 BTU/hr per square foot.

The climate it is sized for

Climate from NOAA's 1991 to 2020 normals at Gulfport - Biloxi Airport (11.3 mi away). Aug is the hottest month, averaging a high of 90.7°F and a low of 74.6°F, with about 69 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 4,318 kWh a year at SEER2 14.3, or roughly $650 at Mississippi's average residential rate of 15.06¢ per kWh. Cooling runs 7 months of the year here.

What drives the load in D'Iberville

Of the 40,200 BTU/hr, 15,840 comes through walls, roof and windows on a 97°F afternoon (39%), 13,000 is sun on the house (32%), 2,120 is four people and their appliances, and 9,300 is moisture the coil has to wring out of D'Iberville'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 30,960 BTU/hr before the moisture allowance.

Other house sizes in D'Iberville

Single rooms with a window or mini-split unit: a 150 sq ft bedroom needs about 3,000 BTU/hr; a 350 sq ft living room needs about 7,000 BTU/hr; a 600 sq ft open plan kitchen and family room needs about 12,100 BTU/hr.

Month by month in D'Iberville

Jul alone uses 20% of the year's cooling energy. The unit runs the equivalent of 1,534 hours a year at full output.

D'Iberville against nearby cities

Of 41 Mississippi cities here, D'Iberville has the 26th highest cooling load. The range runs from Brookhaven at 36,900 BTU/hr to Columbus at 44,000.

Where D'Iberville's weather numbers come from

The nearest NOAA station with full 1991 to 2020 normals is Gulfport - Biloxi Airport, 11.3 miles from the center of D'Iberville at 16 ft above sea level. That is close enough that the station's summers are D'Iberville's summers.

3 other cities use the same station and get the same climate inputs. The closest to D'Iberville: Biloxi (3 mi away, 8.7 mi from the station), Gulfport (10 mi away, 0.9 mi from the station), Long Beach (17 mi away, 6.3 mi from the station). D'Iberville is farther from the station than 3 of them.

The sun over D'Iberville in late July

At 30.44°N, the noon sun on 21 July stands 80.0° above the horizon over D'Iberville 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.

13,399 people live in D'Iberville, the 30th largest of the 41 Mississippi cities sized on this site. Coordinates used: 30.4435, -88.8954.

D'Iberville AC sizing questions