What size AC for Auburn, CA? 3 tons for 2,000 sq ft

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

3 tons central AC or heat pump, about 35,000 BTU/hr of load

The 20 BTU per square foot chart would put in 3.5 tons, about 20% 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 3 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 686 square feet in this climate. For a single room, size by the room: 17.5 BTU/hr per square foot.

The climate it is sized for

Climate from NOAA's 1991 to 2020 normals at Auburn (0.9 mi away). Jul is the hottest month, averaging a high of 92.7°F and a low of 63.4°F, with about 63 days a year at 90°F or more. That gives a design temperature of 99°F against 75°F inside.

What it costs to run

About 1,897 kWh a year at SEER2 14.3, or roughly $618 at California's average residential rate of 32.58¢ per kWh. Cooling runs 6 months of the year here.

What drives the load in Auburn

Of the 35,000 BTU/hr, 17,280 comes through walls, roof and windows on a 99°F afternoon (49%), 13,000 is sun on the house (37%), 2,120 is four people and their appliances, and 2,600 is moisture the coil has to wring out of Auburn's summer air (7%).

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 32,400 BTU/hr before the moisture allowance.

Other house sizes in Auburn

Single rooms with a window or mini-split unit: a 150 sq ft bedroom needs about 2,600 BTU/hr; a 350 sq ft living room needs about 6,100 BTU/hr; a 600 sq ft open plan kitchen and family room needs about 10,500 BTU/hr.

Month by month in Auburn

Jul alone uses 28% of the year's cooling energy. The unit runs the equivalent of 775 hours a year at full output.

Auburn against nearby cities

Of 376 California cities here, Auburn has the 143rd highest cooling load. The range runs from Corte Madera at 15,700 BTU/hr to Palm Desert at 59,000.

Where Auburn's weather numbers come from

The nearest NOAA station with full 1991 to 2020 normals is Auburn, 0.9 miles from the center of Auburn at 1,292 ft above sea level. That is close enough that the station's summers are Auburn's summers.

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

The sun over Auburn in late July

At 38.90°N, the noon sun on 21 July stands 71.5° above the horizon over Auburn and the day runs 14 h 20 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.

13,780 people live in Auburn, the 336th largest of the 376 California cities sized on this site. Coordinates used: 38.8951, -121.0767.

Auburn AC sizing questions