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

What size AC a 2,000 sq ft house in Humble 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 Intercontinental Airport (5.8 mi away). Aug is the hottest month, averaging a high of 94.9°F and a low of 75.4°F, with about 111 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 5,165 kWh a year at SEER2 14.3, or roughly $828 at Texas's average residential rate of 16.03¢ per kWh. Cooling runs 9 months of the year here.

What drives the load in Humble

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 Humble'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 Humble

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 Humble

Aug alone uses 19% of the year's cooling energy. The unit runs the equivalent of 1,610 hours a year at full output.

Humble against nearby cities

Of 252 Texas cities here, Humble has the 156th highest cooling load. The range runs from Levelland at 37,300 BTU/hr to Laredo at 51,500.

Where Humble's weather numbers come from

The nearest NOAA station with full 1991 to 2020 normals is Houston Intercontinental Airport, 5.8 miles from the center of Humble at 90 ft above sea level. That is close enough that the station's summers are Humble's summers.

No other city in this set uses Houston Intercontinental Airport, so this sizing is Humble's alone.

The sun over Humble in late July

At 29.99°N, the noon sun on 21 July stands 80.4° above the horizon over Humble and the day runs 13 h 39 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.

16,561 people live in Humble, the 180th largest of the 252 Texas cities sized on this site. Coordinates used: 29.9882, -95.2644.

Humble AC sizing questions