What size AC for Brighton, CO? 3 tons for 2,000 sq ft

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

3 tons central AC or heat pump, about 31,900 BTU/hr of load

The 20 BTU per square foot chart would put in 3.5 tons, about 32% 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 753 square feet in this climate. For a single room, size by the room: 15.9 BTU/hr per square foot.

The climate it is sized for

Climate from NOAA's 1991 to 2020 normals at Denver International Airport (11 mi away). Jul is the hottest month, averaging a high of 89.9°F and a low of 60.2°F, with about 46 days a year at 90°F or more. That gives a design temperature of 95°F against 75°F inside.

What it costs to run

About 1,109 kWh a year at SEER2 14.3, or roughly $186 at Colorado's average residential rate of 16.8¢ per kWh. Cooling runs 4 months of the year here.

What drives the load in Brighton

Of the 31,900 BTU/hr, 14,400 comes through walls, roof and windows on a 95°F afternoon (45%), 13,000 is sun on the house (41%), 2,120 is four people and their appliances, and 2,400 is moisture the coil has to wring out of Brighton's summer air (8%).

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 29,520 BTU/hr before the moisture allowance.

Other house sizes in Brighton

Single rooms with a window or mini-split unit: a 150 sq ft bedroom needs about 2,400 BTU/hr; a 350 sq ft living room needs about 5,600 BTU/hr; a 600 sq ft open plan kitchen and family room needs about 9,500 BTU/hr.

Month by month in Brighton

Jul alone uses 37% of the year's cooling energy. The unit runs the equivalent of 497 hours a year at full output.

Brighton against nearby cities

Of 53 Colorado cities here, Brighton has the 25th highest cooling load. The range runs from Boulder at 15,700 BTU/hr to Grand Junction at 36,500.

Where Brighton's weather numbers come from

The nearest NOAA station with full 1991 to 2020 normals is Denver International Airport, 11 miles from the center of Brighton at 5,404 ft above sea level. That is close enough that the station's summers are Brighton's summers.

1 other city uses the same station and get the same climate inputs. The closest to Brighton: Commerce City (6 mi away, 7.8 mi from the station). Brighton is farther from the station than 1 of them.

The sun over Brighton in late July

At 39.97°N, the noon sun on 21 July stands 70.4° above the horizon over Brighton and the day runs 14 h 25 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.

43,473 people live in Brighton, the 21st largest of the 53 Colorado cities sized on this site. Coordinates used: 39.9657, -104.7941.

Brighton AC sizing questions