What size AC for Artesia, NM? 3.5 tons for 2,000 sq ft

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

3.5 tons central AC or heat pump, about 38,100 BTU/hr of load

Here the 20 BTU per square foot chart lands close: 3.5 tons against a load of 3.2 tons. This is one of the climates the chart was written for.

If a contractor quotes you more than 3.5 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 630 square feet in this climate. For a single room, size by the room: 19.1 BTU/hr per square foot.

The climate it is sized for

Climate from NOAA's 1991 to 2020 normals at Artesia 6s (7.1 mi away). Jun is the hottest month, averaging a high of 95.2°F and a low of 61.9°F, with about 109 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 2,336 kWh a year at SEER2 14.3, or roughly $358 at New Mexico's average residential rate of 15.34¢ per kWh. Cooling runs 5 months of the year here.

What drives the load in Artesia

Of the 38,100 BTU/hr, 20,160 comes through walls, roof and windows on a 103°F afternoon (53%), 13,000 is sun on the house (34%), 2,120 is four people and their appliances, and 2,800 is moisture the coil has to wring out of Artesia's summer air (7%).

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 Artesia

Single rooms with a window or mini-split unit: a 150 sq ft bedroom needs about 2,900 BTU/hr; a 350 sq ft living room needs about 6,700 BTU/hr; a 600 sq ft open plan kitchen and family room needs about 11,500 BTU/hr.

Month by month in Artesia

Jul alone uses 27% of the year's cooling energy. The unit runs the equivalent of 877 hours a year at full output.

Artesia against nearby cities

Of 19 New Mexico cities here, Artesia has the 9th highest cooling load. The range runs from Las Vegas at 25,500 BTU/hr to Sunland Park at 44,800.

Where Artesia's weather numbers come from

The nearest NOAA station with full 1991 to 2020 normals is Artesia 6s, 7.1 miles from the center of Artesia at 3,366 ft above sea level. That is close enough that the station's summers are Artesia's summers.

No other city in this set uses Artesia 6s, so this sizing is Artesia's alone.

The sun over Artesia in late July

At 32.85°N, the noon sun on 21 July stands 77.5° above the horizon over Artesia and the day runs 13 h 51 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.

12,550 people live in Artesia, the 16th largest of the 19 New Mexico cities sized on this site. Coordinates used: 32.8522, -104.4246.

Artesia AC sizing questions