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

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

4 tons central AC or heat pump, about 51,500 BTU/hr of load

The 20 BTU per square foot chart would put in 3.5 tons, which falls short here. On a design day the unit runs flat out and the house still drifts above 75°F by late afternoon.

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 466 square feet in this climate. For a single room, size by the room: 25.7 BTU/hr per square foot.

The climate it is sized for

Climate from NOAA's 1991 to 2020 normals at Laredo International Airport (2.3 mi away). Aug is the hottest month, averaging a high of 100.9°F and a low of 76.8°F, with about 185 days a year at 90°F or more. That gives a design temperature of 109°F against 75°F inside.

What it costs to run

About 6,819 kWh a year at SEER2 14.3, or roughly $1,093 at Texas's average residential rate of 16.03¢ per kWh. Cooling runs 10 months of the year here.

What drives the load in Laredo

Of the 51,500 BTU/hr, 24,480 comes through walls, roof and windows on a 109°F afternoon (48%), 13,000 is sun on the house (25%), 2,120 is four people and their appliances, and 11,900 is moisture the coil has to wring out of Laredo'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 39,600 BTU/hr before the moisture allowance.

Other house sizes in Laredo

Single rooms with a window or mini-split unit: a 150 sq ft bedroom needs about 3,900 BTU/hr; a 350 sq ft living room needs about 9,000 BTU/hr; a 600 sq ft open plan kitchen and family room needs about 15,400 BTU/hr.

Month by month in Laredo

Aug alone uses 17% of the year's cooling energy. The unit runs the equivalent of 1,894 hours a year at full output.

Laredo against nearby cities

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

Where Laredo's weather numbers come from

The nearest NOAA station with full 1991 to 2020 normals is Laredo International Airport, 2.3 miles from the center of Laredo at 494 ft above sea level. That is close enough that the station's summers are Laredo's summers.

No other city in this set uses Laredo International Airport, so this sizing is Laredo's alone.

The sun over Laredo in late July

At 27.56°N, the noon sun on 21 July stands 82.8° above the horizon over Laredo and the day runs 13 h 30 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.

261,260 people live in Laredo, the 11th largest of the 252 Texas cities sized on this site. Coordinates used: 27.5604, -99.4892.

Laredo AC sizing questions