Table of Contents
- 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.
- 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.
- 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.
- 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.
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.
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.
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.
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.