Compare heating and cooling energy from delivered thermal loads
The electricity used for space heating and cooling depends on the amount of heat that must be moved and the efficiency of the equipment doing that work. A house can need more thermal energy in winter than in summer, so comparing one heating COP with a cooling SEER2 rating without specifying seasonal demand would give a misleading picture. Enter two separate delivered thermal energy assumptions in kilowatt-hours of heat: one for winter heating demand and the other for cooling removed from the building over the season.
The heating side assumes an electrically driven heat pump with a seasonal coefficient of performance (COP). The cooling side uses SEER2, expressed as seasonal cooling output in Btu per watt-hour of electrical energy. These efficiencies are not on the same numeric scale. The calculator converts them separately, then applies the same electricity price to each resulting kWh figure. It does not estimate the building's underlying thermal demand; that should come from appropriate load or consumption information.
Seasonal electric-energy formulas
Cooling electricity (kWh) = delivered cooling (kWh thermal) × 3.41214 ÷ cooling SEER2
Heating energy charge = heating electricity × electricity price
Cooling energy charge = cooling electricity × electricity price
Example: different seasonal loads
Assume a building needs 18,000 kWh of delivered space heating with a seasonal heating COP of 3.2. The modeled heating electricity is 5,625 kWh. If it also needs 12,000 kWh of delivered cooling and the cooling system has SEER2 15, cooling electricity is approximately 2,729.7 kWh. At $0.18 per kWh, those uses correspond to about $1,012.50 for heating and $491.35 for cooling, or $1,503.85 combined.
The larger heating charge follows the different seasonal loads and entered efficiencies. It does not establish that all heat pumps or homes are more expensive to heat than cool. In another climate, the cooling season may dominate or the real seasonal efficiencies may differ considerably.
Choose realistic demand and efficiency assumptions
Delivered heating and cooling requirements can be estimated from professional energy modeling, historical operating data or sufficiently detailed equipment monitoring. Electricity meter readings alone may include lighting, water heating and appliances, which makes them unsuitable as direct heating load inputs. If a house uses gas heat, this particular comparison is not the right model: gas consumption, fuel heating value and the furnace's AFUE would need a separate calculation.
SEER2 is a seasonal equipment efficiency rating, not a fixed instantaneous power draw. Likewise, real heat-pump COP varies with outdoor temperature, supply temperature, defrost behavior and equipment staging. The totals omit fixed utility charges, demand charges and future rate changes. When using the result to consider new equipment, compare it with an actual bill or meter history rather than treating the modeled amount as a guaranteed saving.
Heating and cooling comparison questions
Why are COP and SEER2 entered as different kinds of numbers?
COP compares delivered heating energy with electric input in matching energy units, while SEER2 measures cooling output in Btu per watt-hour of electrical use. Cooling requires a unit conversion before it can be compared with heating electricity in kWh.
Can I compare an electric heat pump with a gas furnace here?
No. The heating calculation assumes electricity and a seasonal heating COP. Gas systems require a fuel-based model using AFUE and the applicable fuel rate, rather than assigning a COP to a gas furnace.
Does a higher SEER2 guarantee lower total cooling bills?
Not by itself. For the same delivered seasonal cooling load, a higher SEER2 reduces modeled electricity use. Actual bills also depend on weather, thermostat settings, system sizing, ducts, auxiliary equipment and changes in the amount of cooling demanded.