What size AC for Alachua, FL? 3.5 tons for 2,000 sq ft

What size AC a 2,000 sq ft house in Alachua 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 Gainesville Regional Airport (13.9 mi away). Jul is the hottest month, averaging a high of 91.1°F and a low of 71.6°F, with about 90 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 4,041 kWh a year at SEER2 14.3, or roughly $619 at Florida's average residential rate of 15.32¢ per kWh. Cooling runs 9 months of the year here.

What drives the load in Alachua

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 Alachua'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 Alachua

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 Alachua

Jul alone uses 18% of the year's cooling energy. The unit runs the equivalent of 1,495 hours a year at full output.

Alachua against nearby cities

Of 173 Florida cities here, Alachua has the 158th highest cooling load. The range runs from Miami Shores at 36,500 BTU/hr to Plant City at 44,900.

Where Alachua's weather numbers come from

The nearest NOAA station with full 1991 to 2020 normals is Gainesville Regional Airport, 13.9 miles from the center of Alachua at 133 ft above sea level. That is close enough that the station's summers are Alachua's summers.

1 other city uses the same station and get the same climate inputs. The closest to Alachua: Gainesville (11 mi away, 4.3 mi from the station). Alachua is farther from the station than 1 of them.

The sun over Alachua in late July

At 29.78°N, the noon sun on 21 July stands 80.6° above the horizon over Alachua and the day runs 13 h 38 min from sunrise to sunset. With the sun that close to overhead, the roof takes most of the heat at midday and the west wall takes the rest after 3 pm. Shorter days give the house a longer night to shed the day's heat.

10,856 people live in Alachua, the 169th largest of the 173 Florida cities sized on this site. Coordinates used: 29.7793, -82.4848.

Alachua AC sizing questions