Heating Degree-Day Cost Calculator
Season heating energy and cost from your design heat loss and local degree-days.
Degree-days compress a whole winter into one number. A heat pump at COP 3 enters as 300% efficiency — and cuts this bill to a third.
Formula
Disclaimer: This tool is for general informational and estimation purposes only and is not professional financial, tax, accounting or legal advice. All figures are estimates — verify with a qualified professional before making decisions. Read the full disclaimer.
Heating Degree-Day Cost Calculator is a free degree days heating for HVAC designers, technicians and energy auditors — instant, accurate and 100% client-side, with the governing formula and reference shown next to the result so the number can be defended, not just quoted.
About Heating Degree-Day Cost Calculator
Season heating energy and cost from your design heat loss and local degree-days. The calculation implements E = (UA × HDD × 24)/η, UA = Q_design/ΔT_design (ASHRAE Fundamentals ch. 19; degreedays.net data). Degree-days compress a whole winter into one number. A heat pump at COP 3 enters as 300% efficiency — and cuts this bill to a third.
How to use Heating Degree-Day Cost Calculator
- 1Enter Design heat loss in kW.
- 2Enter Design ΔT in °C.
- 3Enter Annual heating degree-days (base 18 °C) in °C·day.
- 4Enter System efficiency / COP×100 in %.
- 5Read Season energy, Season cost instantly — no submit button needed.
- 6Need US units? Flip the SI/Imperial toggle and every field converts.
Why use Heating Degree-Day Cost Calculator?
- ✓Implements the standard formula — E = (UA × HDD × 24)/η, UA = Q_design/ΔT_design
- ✓Reference cited on-page: ASHRAE Fundamentals ch. 19; degreedays.net data
- ✓One-click SI ⇄ Imperial toggle — values convert in place, physics stays in SI
- ✓Runs entirely in your browser — nothing uploaded, free forever
Frequently asked questions
What formula does the Heating Degree-Day Cost Calculator use?+
It computes E = (UA × HDD × 24)/η, UA = Q_design/ΔT_design, per ASHRAE Fundamentals ch. 19; degreedays.net data. The formula is displayed under the result.
What should I keep in mind when using this calculator?+
Degree-days compress a whole winter into one number. A heat pump at COP 3 enters as 300% efficiency — and cuts this bill to a third.
Is this based on ASHRAE methods?+
The calculations follow the standard ASHRAE/ISHRAE formulations cited under the result, simplified where industry practice does the same. For permit-grade design, confirm with the full code procedure.
Is the Heating Degree-Day Cost Calculator free to use?+
Yes — completely free, no sign-up, no limits. It runs client-side in your browser, so inputs stay private and results are instant even on slow connections.
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