What size AC for Shafter, CA? 4 tons for 2,000 sq ft

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

4 tons central AC or heat pump, about 45,700 BTU/hr of load

Here the 20 BTU per square foot chart lands close: 3.5 tons against a load of 3.8 tons. This is one of the climates the chart was written for.

If a contractor quotes you more than 4 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 525 square feet in this climate. For a single room, size by the room: 22.8 BTU/hr per square foot.

The climate it is sized for

Climate from NOAA's 1991 to 2020 normals at Bakersfield Airport (8.8 mi away). Jul is the hottest month, averaging a high of 98.3°F and a low of 71.3°F, with about 112 days a year at 90°F or more. That gives a design temperature of 106°F against 75°F inside.

What it costs to run

About 3,574 kWh a year at SEER2 14.3, or roughly $1,165 at California's average residential rate of 32.58¢ per kWh. Cooling runs 7 months of the year here.

What drives the load in Shafter

Of the 45,700 BTU/hr, 22,320 comes through walls, roof and windows on a 106°F afternoon (49%), 13,000 is sun on the house (28%), 2,120 is four people and their appliances, and 8,200 is moisture the coil has to wring out of Shafter's summer air (18%).

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 37,440 BTU/hr before the moisture allowance.

Other house sizes in Shafter

Single rooms with a window or mini-split unit: a 150 sq ft bedroom needs about 3,400 BTU/hr; a 350 sq ft living room needs about 8,000 BTU/hr; a 600 sq ft open plan kitchen and family room needs about 13,700 BTU/hr.

Month by month in Shafter

Jul alone uses 25% of the year's cooling energy. The unit runs the equivalent of 1,119 hours a year at full output.

Shafter against nearby cities

Of 376 California cities here, Shafter has the 21st highest cooling load. The range runs from Corte Madera at 15,700 BTU/hr to Palm Desert at 59,000.

Where Shafter's weather numbers come from

The nearest NOAA station with full 1991 to 2020 normals is Bakersfield Airport, 8.8 miles from the center of Shafter at 490 ft above sea level. That is close enough that the station's summers are Shafter's summers.

3 other cities use the same station and get the same climate inputs. The closest to Shafter: Bakersfield (13 mi away, 5.7 mi from the station), McFarland (13 mi away, 18.9 mi from the station), Arvin (29 mi away, 20.9 mi from the station). Shafter is farther from the station than 1 of them.

The sun over Shafter in late July

At 35.48°N, the noon sun on 21 July stands 74.9° above the horizon over Shafter and the day runs 14 h 03 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.

22,754 people live in Shafter, the 285th largest of the 376 California cities sized on this site. Coordinates used: 35.4794, -119.2013.

Shafter AC sizing questions