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

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

2 tons central AC or heat pump, about 20,700 BTU/hr of load

The 20 BTU per square foot chart would put in 3.5 tons, about 103% 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 1,159 square feet in this climate. For a single room, size by the room: 10.4 BTU/hr per square foot.

The climate it is sized for

Climate from NOAA's 1991 to 2020 normals at Imperial Beach Ream Field NAS (0.2 mi away). Aug is the hottest month, averaging a high of 75.2°F and a low of 65°F, with about 2 days a year at 90°F or more. That gives a design temperature of 79°F against 75°F inside.

What it costs to run

About 723 kWh a year at SEER2 14.3, or roughly $235 at California's average residential rate of 32.58¢ per kWh. Cooling runs 3 months of the year here.

What drives the load in Imperial Beach

Of the 20,700 BTU/hr, 2,880 comes through walls, roof and windows on a 79°F afternoon (14%), 13,000 is sun on the house (63%), 2,120 is four people and their appliances, and 2,700 is moisture the coil has to wring out of Imperial Beach's summer air (13%).

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 18,000 BTU/hr before the moisture allowance.

Other house sizes in Imperial Beach

Single rooms with a window or mini-split unit: a 150 sq ft bedroom needs about 1,600 BTU/hr; a 350 sq ft living room needs about 3,600 BTU/hr; a 600 sq ft open plan kitchen and family room needs about 6,200 BTU/hr.

Month by month in Imperial Beach

Aug alone uses 31% of the year's cooling energy. The unit runs the equivalent of 499 hours a year at full output.

Imperial Beach against nearby cities

Of 376 California cities here, Imperial Beach has the 322nd highest cooling load. The range runs from Corte Madera at 15,700 BTU/hr to Palm Desert at 59,000.

Where Imperial Beach's weather numbers come from

The nearest NOAA station with full 1991 to 2020 normals is Imperial Beach Ream Field NAS, 0.2 miles from the center of Imperial Beach at 24 ft above sea level. That is close enough that the station's summers are Imperial Beach's summers.

No other city in this set uses Imperial Beach Ream Field NAS, so this sizing is Imperial Beach's alone.

The sun over Imperial Beach in late July

At 32.57°N, the noon sun on 21 July stands 77.8° above the horizon over Imperial Beach and the day runs 13 h 50 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.

25,568 people live in Imperial Beach, the 270th largest of the 376 California cities sized on this site. Coordinates used: 32.5654, -117.1146.

Imperial Beach AC sizing questions