# load calculation

### The 7 Biggest Opportunities for HVAC Contractors

Heating and air conditioning contractors have a lot of opportunities to make homes better and to be profitable. The surprising thing is just how few HVAC companies take advantage of all the opportunities that are available to them.

### We Are the 99% — AND the 1%

We're making progress! With the all the emphasis on energy codes and energy efficiency programs like Energy Star New Homes, more homes are getting Manual J heating and cooling load calculations these days. The intent is for the heating and cooling systems to be sized properly because oversized systems have problems (poor dehumidification, short cycling...).

### When Do I Need to Perform a Load Calculation?

In my last three blogs, I discussed the basics of heat-loss and cooling load calculations. The unfortunate truth about these calculations is that fast methods aren’t particularly accurate, and accurate methods require making measurements, checking specifications, and entering data into a computer program — in other words, a significant investment of time. So how should builders go about making these calculations?

### Calculating Cooling Loads

A few decades ago, residential air conditioning was very rare in colder areas of the U.S., and cooling load calculations were usually unnecessary. These days, however, new U.S. homes routinely include air conditioning equipment, even in Minnesota, so most U.S. builders are faced with the need to calculate cooling loads.

### How to Perform a Heat-Loss Calculation — Part 2

To continue last week’s discussion of heat-loss calculation methods, let’s consider a simple rectangular building, 20 feet by 30 feet, with 8-foot ceilings. Let’s assume it has an 8-foot-high basement with uninsulated concrete walls; the below-grade portion of the basement is 7 feet high, with 1 foot above grade. To keep things simple, we’ll assume that the house has a flat roof, and that each side of the house has two windows (each 3 ft. by 4 ft.) and one door (3 ft. by 7 ft.). The house doesn’t have a chimney.