What size AC for University Place, WA? 1.5 tons for 2,000 sq ft

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

1.5 tons central AC or heat pump, about 19,500 BTU/hr of load

The 20 BTU per square foot chart would put in 3.5 tons, about 116% 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 1.5 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 1,233 square feet in this climate. For a single room, size by the room: 9.7 BTU/hr per square foot.

The climate it is sized for

Climate from NOAA's 1991 to 2020 normals at Tacoma Narrows Airport (3.8 mi away). Aug is the hottest month, averaging a high of 75.6°F and a low of 54.3°F, with about 2 days a year at 90°F or more. That gives a design temperature of 80°F against 75°F inside.

What it costs to run

About 166 kWh a year at SEER2 14.3, or roughly $24 at Washington's average residential rate of 14.42¢ per kWh. Cooling runs 1 month of the year here.

What drives the load in University Place

Of the 19,500 BTU/hr, 3,600 comes through walls, roof and windows on a 80°F afternoon (18%), 13,000 is sun on the house (67%), 2,120 is four people and their appliances, and 700 is moisture the coil has to wring out of University Place's summer air (4%).

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 18,720 BTU/hr before the moisture allowance.

Other house sizes in University Place

Single rooms with a window or mini-split unit: a 150 sq ft bedroom needs about 1,500 BTU/hr; a 350 sq ft living room needs about 3,400 BTU/hr; a 600 sq ft open plan kitchen and family room needs about 5,800 BTU/hr.

Month by month in University Place

Jul alone uses 39% of the year's cooling energy. The unit runs the equivalent of 122 hours a year at full output.

University Place against nearby cities

Of 91 Washington cities here, University Place has the 68th highest cooling load. The range runs from Burlington at 15,700 BTU/hr to Kennewick at 32,900.

Where University Place's weather numbers come from

The nearest NOAA station with full 1991 to 2020 normals is Tacoma Narrows Airport, 3.8 miles from the center of University Place at 290 ft above sea level. That is close enough that the station's summers are University Place's summers.

6 other cities use the same station and get the same climate inputs. The closest to University Place: Lakewood (4 mi away, 7.5 mi from the station), Tacoma (5 mi away, 5.6 mi from the station), Gig Harbor (9 mi away, 5 mi from the station), Fife (9 mi away, 10.9 mi from the station), Puyallup (12 mi away, 14.7 mi from the station). University Place sits closer to the station than any of them, so its numbers are the best measured of the group.

The sun over University Place in late July

At 47.22°N, the noon sun on 21 July stands 63.2° above the horizon over University Place and the day runs 15 h 10 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. Long days mean the house keeps gaining heat into the evening, well after the outdoor peak.

35,160 people live in University Place, the 36th largest of the 91 Washington cities sized on this site. Coordinates used: 47.2154, -122.5473.

University Place AC sizing questions