AC can exceed 50% of summer energy

Wausau Pilot & Review reported on August 5 that air conditioning can account for more than 50% of a home’s energy use during summer months in many households. The article said the familiar 78-degree thermostat target is widely cited but does not work equally well in every home. It pointed to differences in age, health, humidity, home design and cooling equipment as reasons a single number can fall short. Federal guidance on energy savings and heat safety supports that narrower point: higher settings can reduce energy use, but health and local conditions still matter. ### Why does one thermostat number show up everywhere? ENERGY STAR has long used 78 degrees Fahrenheit as an example cooling setting in its thermostat guidance, including pre-programmed schedules that pair 78 degrees when people are home with warmer settings when they are away or asleep. The Department of Energy also says households can save as much as 10% a year on heating and cooling by turning the thermostat back 7 to 10 degrees for eight hours a day from its normal setting. (wausaupilotandreview.com) The Wausau Pilot & Review article said that shorthand can be useful for controlling costs, but it is not a safety threshold and not a universal comfort standard. That framing matches a broader body of public guidance that treats thermostat settings as an efficiency tool rather than a one-size-fits-all health rule. (energystar.gov) ### Why can air conditioning take more than half of summer energy use? Wausau Pilot & Review said cooling can exceed 50% of a household’s summer energy use, especially during heat waves and in homes that run air conditioning for long stretches. That share rises when outdoor temperatures stay high overnight, when homes leak conditioned air, or when older systems run less efficiently. (wausaupilotandreview.com) The Department of Energy says home energy use depends heavily on system efficiency and the building itself, including insulation levels and window characteristics. Its Home Energy Score program likewise bases expected energy use on inputs such as insulation and windows, underscoring why two homes set to the same temperature can have very different bills and comfort levels. (wausaupilotandreview.com) ### Why might 78 degrees feel fine in one house and miserable in another? The Wausau Pilot & Review article said humidity, equipment condition, floor plan and home age all affect how a thermostat setting feels. A well-sealed house with lower indoor humidity can feel comfortable at a higher setting than an older or poorly insulated home. (energy.gov) CDC heat guidance says humidity can contribute to heat stress, alongside air temperature and underlying health issues. That means the same thermostat reading may not deliver the same level of relief for people in different climates or in homes where moisture control is weak. ### Who may need cooler indoor conditions? CDC says adults 65 and older are more prone to heat-related health problems. (wausaupilotandreview.com) The agency advises older adults and caregivers to stay cool and hydrated during hot weather and to use air conditioning or find a location that has it if needed. The CDC also lists people with chronic medical conditions among those who should be checked on during extreme heat. (stacks.cdc.gov) That is why a cost-saving setting that works for one household may not be appropriate for a home with an older resident, a young child or someone with health risks. ### What should people do instead of treating 78 as a rule? The Department of Energy says the thermostat should be set as high as is comfortable in cooling season, while using setbacks when people are away or asleep to save energy. (cdc.gov) ENERGY STAR-certified smart thermostats are designed to automate those adjustments and can help reduce heating and cooling use over time. CDC guidance adds a separate test during heat waves: if indoor conditions are no longer safe or tolerable, use air conditioning, find a cooling location, or contact local health or emergency agencies for help locating one. (cdc.gov) For households trying to balance comfort and cost, the next reference points are the ENERGY STAR thermostat schedules, Department of Energy setback guidance and CDC heat-health advice for older adults and other higher-risk groups. (energy.gov)