Temperature effectiveness (sensible)
Temperature effectiveness compares supply temperature change to the maximum possible:
epsilon_T = (T_supply_out - T_supply_in) / (T_exhaust_in - T_supply_in)
This is the number a sensible plate reports, and it is what most generic “efficiency” labels mean.
Dew-point effectiveness (total / enthalpy)
For an enthalpy wheel or membrane, moisture matters, so effectiveness is referenced to the exhaust humidity (dew point):
epsilon_DP = (W_supply_out - W_supply_in) / (W_exhaust_in - W_supply_in)
where W is the humidity ratio. This captures both the temperature and the latent recovery of an enthalpy wheel or membrane ERV.
Which to quote
For sensible-only units, temperature effectiveness is the honest figure. For total-energy recovery, dew-point (or enthalpy) effectiveness is the right one – quoting only temperature understates the latent saving. Always check which basis a supplier uses when comparing devices.
Frequently asked questions
Can dew-point effectiveness exceed temperature effectiveness? They measure different things; a wheel can have high dew-point effectiveness even when temperature effectiveness is modest.
Which matters for cooling load? Both – but latent (dew-point) recovery is what relieves the cooling coil in humid climates.
Need help specifying the right air-to-air heat recovery for your project? Contact the QIYU engineering team – WhatsApp +86 157 5335 5505, or email kuns913@gmail.com.
Frequently Asked Questions
What is temperature effectiveness?
It is the ratio of actual to maximum supply-temperature change using dry-bulb temperatures; the common sensible-effectiveness figure.
What is dew-point effectiveness and when does it differ?
Dew-point effectiveness uses the enthalpy or humidity potential instead of dry-bulb; for enthalpy wheels recovering moisture it can be quite different from temperature effectiveness, so both numbers are reported.
Frequently Asked Questions
What is temperature effectiveness?
It is the ratio of actual to maximum supply-temperature change using dry-bulb temperatures; the common sensible-effectiveness figure.
What is dew-point effectiveness and when does it differ?
Dew-point effectiveness uses the enthalpy or humidity potential instead of dry-bulb; for enthalpy wheels recovering moisture it can be quite different from temperature effectiveness, so both numbers are reported.
Specify the right heat exchanger
Our engineers size the core to your airflow, temperature and pressure-drop budget, and select plate, rotary or heat-pipe recovery by application. Read the heat exchanger guide or contact us for a specification.
Related products
Plate, wheel or pipe recovery for HVAC and ventilation.
Stationary, high-surface-area cores for air and liquid.
High-effectiveness energy recovery for large airflows.
Passive, fully separated streams for clean applications.