What size AC for Southbridge Town, MA? 2 tons for 2,000 sq ft

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

2 tons central AC or heat pump, about 23,300 BTU/hr of load

The 20 BTU per square foot chart would put in 3.5 tons, about 80% more than this climate needs. An oversized unit cools the air fast, shuts off before it pulls moisture out, and leaves the house cold and clammy.

If a contractor quotes you more than 2 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 1,029 square feet in this climate. For a single room, size by the room: 11.7 BTU/hr per square foot.

The climate it is sized for

Climate from NOAA's 1991 to 2020 normals at Worcester (16.7 mi away). Jul is the hottest month, averaging a high of 79.8°F and a low of 61.7°F, with about 3 days a year at 90°F or more. That gives a design temperature of 84°F against 75°F inside.

What it costs to run

About 656 kWh a year at SEER2 14.3, or roughly $198 at Massachusetts's average residential rate of 30.19¢ per kWh. Cooling runs 3 months of the year here.

What drives the load in Southbridge Town

Of the 23,300 BTU/hr, 6,480 comes through walls, roof and windows on a 84°F afternoon (28%), 13,000 is sun on the house (56%), 2,120 is four people and their appliances, and 1,700 is moisture the coil has to wring out of Southbridge Town's summer air (7%).

Sun is the biggest share here, more than heat through the walls, so shading west windows and a light roof cut the size you need more than extra insulation would. Sensible heat totals 21,600 BTU/hr before the moisture allowance.

Other house sizes in Southbridge Town

Single rooms with a window or mini-split unit: a 150 sq ft bedroom needs about 1,800 BTU/hr; a 350 sq ft living room needs about 4,100 BTU/hr; a 600 sq ft open plan kitchen and family room needs about 7,000 BTU/hr.

Month by month in Southbridge Town

Jul alone uses 38% of the year's cooling energy. The unit runs the equivalent of 402 hours a year at full output.

Southbridge Town against nearby cities

Of 58 Massachusetts cities here, Southbridge Town has the 56th highest cooling load. The range runs from Pittsfield at 22,600 BTU/hr to Framingham at 28,000.

Where Southbridge Town's weather numbers come from

The nearest NOAA station with full 1991 to 2020 normals is Worcester, 16.7 miles from the center of Southbridge Town at 1,002 ft above sea level. That is close enough that the station's summers are Southbridge Town's summers.

1 other city uses the same station and get the same climate inputs. The closest to Southbridge Town: Worcester (19 mi away, 3.3 mi from the station). Southbridge Town is farther from the station than 1 of them.

The sun over Southbridge Town in late July

At 42.06°N, the noon sun on 21 July stands 68.3° above the horizon over Southbridge Town and the day runs 14 h 37 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. Long days mean the house keeps gaining heat into the evening, well after the outdoor peak.

18,106 people live in Southbridge Town, the 53rd largest of the 58 Massachusetts cities sized on this site. Coordinates used: 42.0597, -72.0339.

Southbridge Town AC sizing questions