What You Need to Know About the 3 Heating and Cooling Loads

What You Need to Know About the 3 Heating and Cooling LoadsHeating and cooling loads refer to the amount of heat energy required to keep your house warm in winter or cool in summer. These figures vary according to the local climate, as well as the thermal characteristics of the house and its overall efficiency. To achieve the manufacturer’s promised energy and performance specifications for a new furnace or air conditioner, installation must always be preceded by a formal load calculation performed by a qualified HVAC technician using standardized industry software.

There are three kinds of heating and cooling loads that impact your indoor comfort and operating costs. Let’s take a look at each.

Design Load

Expressed in British thermal units (BTUs), the amount of heat that must be generated in winter or removed during summer to maintain a comfortable indoor temperature in the mid-70 degree range is called the home’s design load. The amount of heat the furnace can generate or the air conditioner can remove is known as the unit’s capacity. The goal of proper HVAC sizing is to match the home’s design load with a furnace or air conditioner with the appropriate capacity.

Extreme Load

While the design load represents the average scenario, extreme load applies to the volume of heating or cooling capacity needed to sustain a comfortable temperature during periods of exceptionally hot or cold weather. Generally, these statistically less-likely conditions are predicted to prevail only 1 percent of the time during a given year. The BTU capacity under extreme load is usually estimated to be 15 to 20 percent above that of the design load.

Part Load

A large portion of an average day is spent in neither design load nor extreme load temperatures. Part load conditions are those hours such as the cool morning of a hot summer’s day or a warmed up winter afternoon before the chill returns at night. Under these temperate conditions, household comfort can be sustained without having to meet design load heating or cooling specifications.

For more about calculating heating and cooling loads, ask the experts at Paitson Bros., your year-round source of indoor comfort and efficiency.

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

Credit/Copyright Attribution: “Rafael Croonen/Shutterstock”

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    Jeff Paitson Jeff Paitson is a third generation business owner who continues to run the business with the same values that have been passed down from previous generations since 1922.

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