Energy Savings
How to Read Your HVAC Energy Bill and Cut It by 30%
Heating and cooling is typically 45 to 55% of a Puget Sound home's annual energy spend, and it is the single line most homeowners have never actually looked at closely. Your bill will not break it out for you, but you can get very close in ten minutes.
Start with the shoulder months. Take your lowest bill of the year, usually May or September, when almost nothing is heating or cooling. That is your baseline household load - lighting, appliances, hot water. Everything above that baseline in January or August is your HVAC system. Subtract it across twelve months and you have your real annual HVAC cost.
Then look at the shape of the curve. A steep January spike relative to your neighbors usually means envelope loss, not equipment: attic insulation below R-38, uninsulated ducts in a crawlspace, or leaky duct joints. Duct sealing alone recovers 10 to 20% on most Seattle houses built before 1990, and it is the cheapest efficiency work available.
Next, thermostat behavior. A setback of 7 to 10 degrees for eight hours a day saves about 10% annually on a furnace. Important caveat for heat pumps: deep setbacks can trigger the electric resistance strip on recovery, which wipes out the savings. On a heat pump, use a smart thermostat with a heat pump mode and keep the setback to 3 or 4 degrees.
Finally, the equipment itself. If your system is 15 years or older you are likely at SEER 10 or below. Moving to SEER2 16 to 18 typically cuts cooling energy by 30 to 40%. Beyond SEER2 18 in our mild summers you are buying efficiency you will not recoup. Stack that against PSE rebates and the federal credit before you assume replacement is out of reach.
