What size AC for Ithaca, NY? 2 tons for 2,000 sq ft

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

2 tons central AC or heat pump, about 21,700 BTU/hr of load

The 20 BTU per square foot chart would put in 3.5 tons, about 93% 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 1,105 square feet in this climate. For a single room, size by the room: 10.9 BTU/hr per square foot.

The climate it is sized for

Climate from NOAA's 1991 to 2020 normals at Ithaca 13 E (13.1 mi away). Jul is the hottest month, averaging a high of 78.7°F and a low of 55.8°F, with about 2 days a year at 90°F or more. That gives a design temperature of 83°F against 75°F inside.

What it costs to run

About 361 kWh a year at SEER2 14.3, or roughly $106 at New York's average residential rate of 29.26¢ per kWh. Cooling runs 3 months of the year here.

What drives the load in Ithaca

Of the 21,700 BTU/hr, 5,760 comes through walls, roof and windows on a 83°F afternoon (27%), 13,000 is sun on the house (60%), 2,120 is four people and their appliances, and 800 is moisture the coil has to wring out of Ithaca's summer air (4%).

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 20,880 BTU/hr before the moisture allowance.

Other house sizes in Ithaca

Single rooms with a window or mini-split unit: a 150 sq ft bedroom needs about 1,600 BTU/hr; a 350 sq ft living room needs about 3,800 BTU/hr; a 600 sq ft open plan kitchen and family room needs about 6,500 BTU/hr.

Month by month in Ithaca

Jul alone uses 37% of the year's cooling energy. The unit runs the equivalent of 238 hours a year at full output.

Ithaca against nearby cities

Of 90 New York cities here, Ithaca has the 87th highest cooling load. The range runs from Gloversville at 20,200 BTU/hr to Spring Valley at 33,400.

Where Ithaca's weather numbers come from

The nearest NOAA station with full 1991 to 2020 normals is Ithaca 13 E, 13.1 miles from the center of Ithaca at 1,228 ft above sea level. That is close enough that the station's summers are Ithaca's summers.

1 other city uses the same station and get the same climate inputs. The closest to Ithaca: Cortland (20 mi away, 11.6 mi from the station). Ithaca is farther from the station than 1 of them.

The sun over Ithaca in late July

At 42.44°N, the noon sun on 21 July stands 68.0° above the horizon over Ithaca and the day runs 14 h 39 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.

33,768 people live in Ithaca, the 20th largest of the 90 New York cities sized on this site. Coordinates used: 42.4439, -76.5031.

Ithaca AC sizing questions