How to precool your home
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Stay cool and comfortable and save on your energy bills this summer by precooling your home. It's the #1 tip to save on EZ-3 since air conditioning alone can account for 50% or more of summer energy bills. Install a programmable or smart thermostat and set it to automatically precool.
- Set the thermostat temperature three degrees below your preferred setting three hours before your higher-cost hours begin (either 2–5 p.m.*, 3–6 p.m. or 4–7 p.m. Monday through Friday.) For example, if you are on the EZ-3 3-6 p.m. plan and usually set the temperature to 78 degrees, precool your home to 75 degrees from noon until 3 p.m. while prices are lower.
- At the start of the higher-cost period, set the thermostat temperature three degrees above your preferred setting so that the air conditioner doesn't run much, if at all, during your three higher-cost hours. For example, if you are on the EZ-3 3–6 p.m. plan and usually set the temperature to 78 degrees, after precooling your home, increase your thermostat setpoint to 81 degrees from 3–6 p.m. while prices are higher.
- Set the thermostat to return to your preferred setting when higher-cost hours end.**
- Some homes may require more time to precool and return to preferred settings when higher-cost hours end. You may need to vary temperature and time settings based on your home's size, age and building materials and your preferred comfort level.***
* The 2–5 p.m. EZ-3 experimental plan is frozen from new participation and will be eliminated on April 30, 2021. The 3–6 p.m. and 4–7 p.m. options remain.
** Some thermostats offer advanced features that will achieve your set temperature by the time programmed instead of starting to cool at the time programmed. Check the instruction manual or manufacturer's website to verify advanced features.
*** Precooling guidelines are based on optimum results from "Modeling and Testing Multiple Precooling Strategies in Three Residential Building Types in the Phoenix Climate," an SRP research project in partnership with Arizona State University.