What size AC for El Paso de Robles (Paso Robles), CA? 3 tons for 2,000 sq ft

What size AC a 2,000 sq ft house in El Paso de Robles (Paso Robles) needs

3 tons central AC or heat pump, about 35,200 BTU/hr of load

The 20 BTU per square foot chart would put in 3.5 tons, about 19% 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 682 square feet in this climate. For a single room, size by the room: 17.6 BTU/hr per square foot.

The climate it is sized for

Climate from NOAA's 1991 to 2020 normals at Paso Robles Municipal Airport (3.1 mi away). Aug is the hottest month, averaging a high of 94°F and a low of 53.2°F, with about 92 days a year at 90°F or more. That gives a design temperature of 101°F against 75°F inside.

What it costs to run

About 1,205 kWh a year at SEER2 14.3, or roughly $392 at California's average residential rate of 32.58¢ per kWh. Cooling runs 5 months of the year here.

What drives the load in El Paso de Robles (Paso Robles)

Of the 35,200 BTU/hr, 18,720 comes through walls, roof and windows on a 101°F afternoon (53%), 13,000 is sun on the house (37%), 2,120 is four people and their appliances, and 1,400 is moisture the coil has to wring out of El Paso de Robles (Paso Robles)'s summer air (4%).

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 33,840 BTU/hr before the moisture allowance.

Other house sizes in El Paso de Robles (Paso Robles)

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 6,200 BTU/hr; a 600 sq ft open plan kitchen and family room needs about 10,600 BTU/hr.

Month by month in El Paso de Robles (Paso Robles)

Aug alone uses 28% of the year's cooling energy. The unit runs the equivalent of 489 hours a year at full output.

El Paso de Robles (Paso Robles) against nearby cities

Of 376 California cities here, El Paso de Robles (Paso Robles) has the 136th highest cooling load. The range runs from Corte Madera at 15,700 BTU/hr to Palm Desert at 59,000.

Where El Paso de Robles (Paso Robles)'s weather numbers come from

The nearest NOAA station with full 1991 to 2020 normals is Paso Robles Municipal Airport, 3.1 miles from the center of El Paso de Robles (Paso Robles) at 820 ft above sea level. That is close enough that the station's summers are El Paso de Robles (Paso Robles)'s summers.

1 other city uses the same station and get the same climate inputs. The closest to El Paso de Robles (Paso Robles): Atascadero (10 mi away, 13.1 mi from the station). El Paso de Robles (Paso Robles) sits closer to the station than any of them, so its numbers are the best measured of the group.

The sun over El Paso de Robles (Paso Robles) in late July

At 35.63°N, the noon sun on 21 July stands 74.8° above the horizon over El Paso de Robles (Paso Robles) and the day runs 14 h 04 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.

31,568 people live in El Paso de Robles (Paso Robles), the 236th largest of the 376 California cities sized on this site. Coordinates used: 35.6285, -120.6504.

El Paso de Robles (Paso Robles) AC sizing questions