Calculator Inputs
Formula Used
Envelope heat flow: Qc = U × A × ΔT
Ventilation heat flow: Qv = 0.33 × ACH × Volume × ΔT
Heating load: Qh = max(Qc + Qv - Internal gains, 0)
Cooling load: Qcool = max(Qc + Qv + Internal gains, 0)
Delivered energy: kWh = Load kW × Hours per day × Days × Saving factor
Purchased electric energy: Electric kWh = Delivered kWh ÷ COP
Fuel units: Units = Delivered kWh ÷ Fuel heat value ÷ Efficiency
Total cost: Energy cost + demand charge + fixed fee + tax
How to Use This Calculator
Enter the building size, height, U-value, and air change rate.
Add indoor and outdoor temperatures for each season.
Choose the heating system and enter its performance value.
Enter energy rates, losses, savings, demand charges, and tax.
Press the calculate button to show results above the form.
Use CSV or PDF buttons after calculation to save the report.
Example Data Table
| Scenario | Area | U-value | ACH | Heating COP | Cooling COP | Electric Rate |
|---|---|---|---|---|---|---|
| Efficient small home | 95 m² | 0.38 | 0.35 | 3.8 | 3.6 | 0.15 |
| Average family home | 150 m² | 0.65 | 0.60 | 3.2 | 3.1 | 0.18 |
| Older leaky home | 210 m² | 1.10 | 1.20 | 2.7 | 2.6 | 0.22 |
Heating and Cooling Cost Guide
Understanding Heating and Cooling Cost
Heating and cooling cost depends on heat flow. Heat moves through walls, roofs, windows, floors, and outside air leaks. A larger temperature difference causes a larger load. A weak envelope also raises the load. This calculator uses those physics ideas and converts the estimated load into seasonal expense.
Why Physics Helps
A simple bill estimate can miss important details. Physics based inputs show where the money goes. The U value represents envelope conductance. The envelope area factor expands floor area into an estimated heat transfer surface. Air changes per hour estimate ventilation and leakage. Internal gains represent people, lights, appliances, and sun. These gains reduce heating demand, yet they increase cooling demand.
The calculator separates delivered energy from purchased energy. Delivered energy is the useful heat removed or supplied indoors. Purchased energy is what the equipment must buy from fuel or electricity. A heat pump uses a coefficient of performance. A furnace uses seasonal efficiency. Cooling uses its cooling performance value. Duct loss, thermostat setbacks, demand charges, fixed fees, and tax refine the final cost.
Practical Energy Planning
Use average seasonal conditions for budget planning. Use design conditions for sizing checks. For old buildings, choose a higher U value and higher air changes. For tight modern buildings, lower both values. Compare two runs to test upgrades. For example, reduce U value after insulation. Then compare total cost and peak load. You can also test a better heat pump, lower tariffs, or fewer daily runtime hours.
Interpreting Results
The peak load helps show equipment stress. Seasonal energy shows total work over time. The cost per square meter supports building comparisons. A high ventilation load may suggest sealing gaps. A high conduction load may suggest insulation, better windows, or roof work. A high demand charge may suggest load shifting or staged operation.
The result is an estimate, not a contractor design. Real bills also depend on weather swings, zoning, humidity, maintenance, occupancy, and thermostat behavior. Still, the method gives a structured starting point. It helps users explore choices before spending money. Always verify major equipment decisions with local energy data and a qualified professional. Save each report before changing inputs, so comparisons stay clear and traceable later.
FAQs
1. What does this heating cooling cost calculator estimate?
It estimates seasonal heating and cooling expense using heat transfer, ventilation, equipment efficiency, energy rates, demand charges, fixed fees, and tax.
2. What is the U-value input?
U-value measures heat flow through the building envelope. A lower value means better insulation and usually lower heating or cooling load.
3. Why does air change rate matter?
Air changes bring outdoor air indoors. That air must be heated or cooled, so higher leakage can raise energy use significantly.
4. How should I enter heat pump efficiency?
Enter the seasonal coefficient of performance. For example, use 3.2 when the heat pump provides 3.2 units of heat per electric unit.
5. How should I enter furnace efficiency?
Select fuel furnace and enter the seasonal efficiency as a percent. For example, enter 90 for a furnace rated near ninety percent.
6. Does the calculator include cooling gains?
Yes. Internal gains are added to cooling load. They are subtracted from heating load because they help warm the space.
7. Why is the result different from my bill?
Actual bills include changing weather, humidity, behavior, zoning, maintenance, and utility rules. Use this result as a planning estimate.
8. Can I compare insulation upgrades?
Yes. Run one calculation with the current U-value. Then lower the U-value and compare peak load, seasonal energy, and total cost.