What Does an HVAC Load Calculation Involve?
Selecting a new heating and air conditioning system in a home is much more complicated than simply pointing to a unit and saying, “That ought to do it!” It’s vital that a new HVAC system is sized to match a house. Sizing doesn’t mean finding a unit that will fit (although that’s certainly a requirement). It means finding a unit that has the heating power/cooling capacity necessary to provide comfort without wasting energy or malfunctioning. To find the right sweet spot between “too big” and “too small” requires HVAC professionals to perform a heat load calculation.
The parts of a heat load calculation
The short description of a heat load calculation is that it’s a formula that takes different factors about a home and uses this data to find out how much heat a system must either output (a heater) or remove (an air conditioner) to create sufficient indoor comfort. This heat load or cooling capacity is expressed in BTUs, British Thermal Units.
An accurate heat load calculation requires trained professionals, and it uses the follow criteria about a home:
- The area in square feet of space to be cooled or heated.
- Heat gain through the windows. This also takes into account how much light exposure the windows receive and if they have shading.
- Heat generated by the home’s regular occupants. Each person accounts for an extra 600 BTUs.
- Heat from appliances. This includes computers, refrigerators, ovens, laundry machines, etc.
- Heat from lighting.
- Levels of insulation. The better insulated the home, the easier to heat and cool it.
Once the professionals have gathered this data, they will use it to come up with the total heat load and cooling capacity.