What size AC for Rosenberg, TX? 4 tons for 2,000 sq ft

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

4 tons central AC or heat pump, about 45,900 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 523 square feet in this climate. For a single room, size by the room: 22.9 BTU/hr per square foot.

The climate it is sized for

Climate from NOAA's 1991 to 2020 normals at Houston Sugarland Mem (11 mi away). Jul is the hottest month, averaging a high of 95°F and a low of 75.7°F, with about 112 days a year at 90°F or more. That gives a design temperature of 103°F against 75°F inside.

What it costs to run

About 5,318 kWh a year at SEER2 14.3, or roughly $852 at Texas's average residential rate of 16.03¢ per kWh. Cooling runs 9 months of the year here.

What drives the load in Rosenberg

Of the 45,900 BTU/hr, 20,160 comes through walls, roof and windows on a 103°F afternoon (44%), 13,000 is sun on the house (28%), 2,120 is four people and their appliances, and 10,600 is moisture the coil has to wring out of Rosenberg's summer air (23%).

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 35,280 BTU/hr before the moisture allowance.

Other house sizes in Rosenberg

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 Rosenberg

Jul alone uses 19% of the year's cooling energy. The unit runs the equivalent of 1,658 hours a year at full output.

Rosenberg against nearby cities

Of 252 Texas cities here, Rosenberg has the 138th highest cooling load. The range runs from Levelland at 37,300 BTU/hr to Laredo at 51,500.

Where Rosenberg's weather numbers come from

The nearest NOAA station with full 1991 to 2020 normals is Houston Sugarland Mem, 11 miles from the center of Rosenberg at 77 ft above sea level. That is close enough that the station's summers are Rosenberg's summers.

6 other cities use the same station and get the same climate inputs. The closest to Rosenberg: Richmond (4 mi away, 6.7 mi from the station), Fulshear (11 mi away, 14.6 mi from the station), Sugar Land (12 mi away, 2.3 mi from the station), Stafford (16 mi away, 5.5 mi from the station), Katy (17 mi away, 16.2 mi from the station). Rosenberg is farther from the station than 4 of them.

The sun over Rosenberg in late July

At 29.55°N, the noon sun on 21 July stands 80.8° above the horizon over Rosenberg and the day runs 13 h 37 min from sunrise to sunset. With the sun that close to overhead, the roof takes most of the heat at midday and the west wall takes the rest after 3 pm. Shorter days give the house a longer night to shed the day's heat.

42,571 people live in Rosenberg, the 88th largest of the 252 Texas cities sized on this site. Coordinates used: 29.5500, -95.8214.

Rosenberg AC sizing questions