Heat Recovery Efficiency Calculator
Enter measured outdoor, supply, and extract air temperatures plus supply airflow. Sensible efficiency uses the outdoor-to-supply temperature rise divided by the outdoor-to-extract temperature difference.
A QUICK WALKTHROUGH
How to use this tool
- Enter measured outdoor, supply, and extract temperatures in °C.
- Enter supply airflow in m³/s and your assumed air density and specific heat capacity.
- Review sensible temperature effectiveness and recovered heat; this is not a certified rating.
Formula and assumptions
Sensible temperature effectiveness η = (T_supply − T_outdoor) / (T_extract − T_outdoor). Recovered sensible heat Q = ρ × cp × airflow × (T_supply − T_outdoor), in watts when SI inputs are used. Density and specific heat capacity are user-supplied; no properties are looked up.
Scope
Uses one set of measured temperatures and supply airflow, assumes the supplied air properties apply, and does not account for latent heat, leakage, fan power, transient operation, or measurement uncertainty. This is not a certified performance rating.
GOOD TO KNOW
Common questions
Does this provide a certified HRV/ERV rating?
No. It calculates an indicative sensible result from your measurements and assumptions; it is not a certification or test procedure.
Where do density and specific heat come from?
Provide values appropriate to your conditions and units. The calculator does not assume or retrieve them.