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Ventilation heat loss Calculator
Estimate air-change heating losses and heat-recovery benefit. This free ventilation heat loss calculator shows the calculation and its assumptions so you can compare your own figures.
Your results
Estimate air-change heating losses and heat-recovery benefit.
Calculated outcomes
- Heat Loss Watts Per Kelvin
- 49.5 W/K
- Recovered KWh
- 0 kWh
- Residual Heat Loss KWh
- 2,613.6 kWh
Assumptions and estimates
- Method: Loss coefficient = 0.33 × air changes/hour × volume. Annual heat = coefficient × degree-days × 24 ÷ 1,000.
- Air changes and recovery are editable estimates. Excludes fan electricity, bypass and defrost effects, demand control and infiltration interactions.
Useful next steps
- Use Compare options to test an alternative side by side.
- Copy, print or download a record of this calculation when you need one.
Reports open your email app addressed to s@s1.ie with the public page address only. Your inputs are never added.
How the ventilation heat loss calculation works
Loss coefficient = 0.33 × air changes/hour × volume. Annual heat = coefficient × degree-days × 24 ÷ 1,000.
Air changes and recovery are editable estimates. Excludes fan electricity, bypass and defrost effects, demand control and infiltration interactions.
Using this calculator
- Enter your own figures in the labelled inputs. Keep the currencies, units and time periods consistent.
- Choose any applicable rate profile, pattern or assumption shown for this tool. Open additional inputs when relevant.
- Review annual heat loss kwh and residual heating cost, then read the stated assumptions and eligibility conditions before using the result.
Worked example
This is a static example using illustrative inputs, not facts about you or today’s date. The displayed eligibility selections and assumptions apply only to this example.
See example inputs
- Heated building volume (m³)
- 300
- Average air changes per hour
- 0.5
- Annual heating degree-days (K·days)
- 2200
- Effective heat recovery (%)
- 0
- Heating efficiency (%)
- 90
- Input energy price (€/kWh)
- 0.1
- Annual Heat Loss KWh
- 2,613.6 kWh
- Residual Heating Cost
- €290.40