Heating and Cooling Loads: Do You Know the 3 Different Types?

The HVAC industry uses the heating and cooling loads of homes to determine the size the HVAC system needs to be to ensure comfort and energy efficiency. HVAC engineers have designed software tools that take into account the three different loads every structure has to find the best fit.

In the HVAC field, a load is the amount of conditioning a home requires, and it takes into account the building’s ability to resist heat transfer. Homes with lower loads don’t require systems with as much capacity or size for heating and cooling.

Design Load

This load is driven by the physical characteristics of the home, like the number of levels it has, insulation, air infiltration, orientation to the sun, along with the quality of exterior doors and windows. The HVAC professional uses the average outdoor summer and winter temperatures to estimate the capacity the HVAC system needs to maintain comfortable indoor air temperatures.

Extreme Load

The second type of load is the extreme load, which takes into account the extreme outdoor temperatures the home experiences. Unless the home lacks insulation or has high rates of air infiltration, the extreme load isn’t normally an important consideration when considering the heating and cooling loads.

If the extreme load were given more credence in the load analysis, many homes would have oversized systems that drive up energy costs, reduce comfort and wear out faster.

Part Load

The last load to consider is the part load, or the normal seasonal temperatures. This load plays a major role in the load calculation HVAC contractors conduct, along with the design load. Manual J software largely determines the design load, and its sister software, Manual S, helps the HVAC contractor fine tune the equipment choice for the specific climate. Humidity in this region increases the cooling load, and with Manual S software, the HVAC pro can find the optimally sized system for your home.

To learn more about heating and cooling loads and how they affect HVAC sizing and performance, contact Stack Heating & Cooling. We’ve provided trusted HVAC services for greater Cleveland homeowners since 1976.

Our goal is to help educate our customers in Cleveland, Ohio about energy and home comfort issues (specific to HVAC systems).  For more information about heating and cooling loads and other HVAC topics, download our free Home Comfort Resource guide.

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