What size AC for Barstow, CA? 5 tons for 2,000 sq ft

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

5 tons central AC or heat pump, about 55,200 BTU/hr of load

The 20 BTU per square foot chart would put in 3.5 tons, which falls short here. On a design day the unit runs flat out and the house still drifts above 75°F by late afternoon.

If a contractor quotes you more than 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 435 square feet in this climate. For a single room, size by the room: 27.6 BTU/hr per square foot.

The climate it is sized for

Climate from NOAA's 1991 to 2020 normals at Barstow-Daggett Airport (14.6 mi away). Jul is the hottest month, averaging a high of 105°F and a low of 74.2°F, with about 145 days a year at 90°F or more. That gives a design temperature of 113°F against 75°F inside.

What it costs to run

About 4,916 kWh a year at SEER2 14.3, or roughly $1,602 at California's average residential rate of 32.58¢ per kWh. Cooling runs 7 months of the year here.

What drives the load in Barstow

Of the 55,200 BTU/hr, 27,360 comes through walls, roof and windows on a 113°F afternoon (50%), 13,000 is sun on the house (24%), 2,120 is four people and their appliances, and 12,700 is moisture the coil has to wring out of Barstow's summer air (23%).

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 42,480 BTU/hr before the moisture allowance.

Other house sizes in Barstow

Single rooms with a window or mini-split unit: a 150 sq ft bedroom needs about 4,100 BTU/hr; a 350 sq ft living room needs about 9,700 BTU/hr; a 600 sq ft open plan kitchen and family room needs about 16,600 BTU/hr.

Month by month in Barstow

Jul alone uses 24% of the year's cooling energy. The unit runs the equivalent of 1,273 hours a year at full output.

Barstow against nearby cities

Of 376 California cities here, Barstow has the 14th highest cooling load. The range runs from Corte Madera at 15,700 BTU/hr to Palm Desert at 59,000.

Where Barstow's weather numbers come from

The nearest NOAA station with full 1991 to 2020 normals is Barstow-Daggett Airport, 14.6 miles from the center of Barstow at 1,919 ft above sea level. That is close enough that the station's summers are Barstow's summers.

No other city in this set uses Barstow-Daggett Airport, so this sizing is Barstow's alone.

The sun over Barstow in late July

At 34.87°N, the noon sun on 21 July stands 75.5° above the horizon over Barstow and the day runs 14 h 00 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.

24,897 people live in Barstow, the 276th largest of the 376 California cities sized on this site. Coordinates used: 34.8670, -117.0430.

Barstow AC sizing questions