What size AC for Truckee, CA? 2 tons for 2,000 sq ft

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

2 tons central AC or heat pump, about 25,500 BTU/hr of load

The 20 BTU per square foot chart would put in 3.5 tons, about 65% 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 943 square feet in this climate. For a single room, size by the room: 12.7 BTU/hr per square foot.

The climate it is sized for

Climate from NOAA's 1991 to 2020 normals at Truckee Rs (1.6 mi away). Jul is the hottest month, averaging a high of 83.8°F and a low of 41.4°F, with about 10 days a year at 90°F or more. That gives a design temperature of 88°F against 75°F inside.

What it costs to run

About 79 kWh a year at SEER2 14.3, or roughly $26 at California's average residential rate of 32.58¢ per kWh. Cooling runs 0 months of the year here.

What drives the load in Truckee

Of the 25,500 BTU/hr, 9,360 comes through walls, roof and windows on a 88°F afternoon (37%), 13,000 is sun on the house (51%), 2,120 is four people and their appliances, and 1,000 is moisture the coil has to wring out of Truckee'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 24,480 BTU/hr before the moisture allowance.

Other house sizes in Truckee

Single rooms with a window or mini-split unit: a 150 sq ft bedroom needs about 1,900 BTU/hr; a 350 sq ft living room needs about 4,400 BTU/hr; a 600 sq ft open plan kitchen and family room needs about 7,600 BTU/hr.

Month by month in Truckee

Jul alone uses 54% of the year's cooling energy. The unit runs the equivalent of 45 hours a year at full output.

Truckee against nearby cities

Of 376 California cities here, Truckee has the 257th highest cooling load. The range runs from Corte Madera at 15,700 BTU/hr to Palm Desert at 59,000.

Where Truckee's weather numbers come from

The nearest NOAA station with full 1991 to 2020 normals is Truckee Rs, 1.6 miles from the center of Truckee at 5,823 ft above sea level. That is close enough that the station's summers are Truckee's summers.

No other city in this set uses Truckee Rs, so this sizing is Truckee's alone.

The sun over Truckee in late July

At 39.35°N, the noon sun on 21 July stands 71.0° above the horizon over Truckee and the day runs 14 h 22 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.

17,240 people live in Truckee, the 315th largest of the 376 California cities sized on this site. Coordinates used: 39.3505, -120.1939.

Truckee AC sizing questions