The cheapest Btu is the one the house does not need
Reducing unnecessary heat gain in summer and heat loss in winter can reduce HVAC runtime regardless of which equipment is installed.
Understand what actually drives heating and cooling costsβand where efficiency improvements are most likely to produce useful savings.
HVAC operating cost is a system problem: weather, building load, equipment efficiency, airflow, controls and utility rates all interact.
A practical hierarchy for reducing heating and cooling energy use.
Read guide βEnergy SavingsHow setpoints, setbacks and schedules affect runtime and comfort.
Read guide βEnergy SavingsHow to think about higher cooling efficiency and realistic payback.
Read guide βEnergy SavingsWhat drives heat-pump electricity use in heating and cooling.
Read guide βEnergy SavingsHow AFUE, weather, load and fuel price affect heating cost.
Read guide βEnergy SavingsWhy lost supply air and return leakage can increase HVAC consumption.
Read guide βEnergy SavingsHow the building envelope changes the load your HVAC system must handle.
Read guide βEnergy SavingsWhy both dirty filters and overly restrictive filtration can affect airflow.
Read guide βEnergy SavingsHow air movement can improve comfort without actually lowering room temperature.
Read guide βEnergy SavingsWhy moisture control affects comfort, thermostat choices and cooling operation.
Read guide βEnergy SavingsHow to compare replacement cost with realistic energy savings.
Read guide βEnergy SavingsSeparate weather, rate changes, runtime and equipment issues when bills increase.
Read guide βReducing unnecessary heat gain in summer and heat loss in winter can reduce HVAC runtime regardless of which equipment is installed.
SEER2, HSPF2 and AFUE are useful comparison metrics, but actual utility savings depend on the home, climate, usage, rates and installation.
Compare the added installed price of higher-efficiency equipment against realistic operating savings and the period you expect to own the system.
Start with the factors that usually matter most.
Understand SEER2, EER2, HSPF2 and AFUE.
Apply energy information to a replacement decision.