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

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

4 tons central AC or heat pump, about 43,100 BTU/hr of load

Here the 20 BTU per square foot chart lands close: 3.5 tons against a load of 3.6 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 557 square feet in this climate. For a single room, size by the room: 21.5 BTU/hr per square foot.

The climate it is sized for

Climate from NOAA's 1991 to 2020 normals at Rockport Aransas County Airport (2.5 mi away). Aug is the hottest month, averaging a high of 92.4°F and a low of 79.2°F, with about 105 days a year at 90°F or more. That gives a design temperature of 100°F against 75°F inside.

What it costs to run

About 5,928 kWh a year at SEER2 14.3, or roughly $950 at Texas's average residential rate of 16.03¢ per kWh. Cooling runs 9 months of the year here.

What drives the load in Rockport

Of the 43,100 BTU/hr, 18,000 comes through walls, roof and windows on a 100°F afternoon (42%), 13,000 is sun on the house (30%), 2,120 is four people and their appliances, and 9,900 is moisture the coil has to wring out of Rockport'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 33,120 BTU/hr before the moisture allowance.

Other house sizes in Rockport

Single rooms with a window or mini-split unit: a 150 sq ft bedroom needs about 3,200 BTU/hr; a 350 sq ft living room needs about 7,500 BTU/hr; a 600 sq ft open plan kitchen and family room needs about 12,900 BTU/hr.

Month by month in Rockport

Aug alone uses 17% of the year's cooling energy. The unit runs the equivalent of 1,969 hours a year at full output.

Rockport against nearby cities

Of 252 Texas cities here, Rockport has the 215th highest cooling load. The range runs from Levelland at 37,300 BTU/hr to Laredo at 51,500.

Where Rockport's weather numbers come from

The nearest NOAA station with full 1991 to 2020 normals is Rockport Aransas County Airport, 2.5 miles from the center of Rockport at 24 ft above sea level. That is close enough that the station's summers are Rockport's summers.

No other city in this set uses Rockport Aransas County Airport, so this sizing is Rockport's alone.

The sun over Rockport in late July

At 28.05°N, the noon sun on 21 July stands 82.4° above the horizon over Rockport and the day runs 13 h 31 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.

11,069 people live in Rockport, the 232nd largest of the 252 Texas cities sized on this site. Coordinates used: 28.0476, -97.0500.

Rockport AC sizing questions