목차
- Annual energy saved (kWh) = 1.2 x airflow (m3/h) x eta x dT (C) x hours/year / 1000 Where 1.2 is the approximate volumetric heat capacity of air (Wh/m3.K), eta is effectiveness, and dT is the temperature difference between exhaust and supply.
- Airflow: 10,000 m3/h Effectiveness: 75 % (0.75) dT (winter average): 20 C Operating hours: 6,000 / year Energy price: $0.12 / kWh Saved = 1.2 x 10,000 x 0.75 x 20 x 6,000 / 1000 = 1,080,000 Wh = 1,080 kWh/year. Value = 1,080 x $0.12 = $129.6 / year. If the unit (installed) costs $1,500, payback is about 11.6 years - but add fan-energy savings and incentives, and real projects in cold climates often land at 2-4 years.
- Higher dT (colder climate, hotter exhaust) More operating hours (continuous processes) Higher energy price Rebates or carbon credits Combined heating + cooling savings (enthalpy)
- Should I include fan energy? Yes - subtract the extra fan electricity from the saved heating value for a true net payback. Is this accurate enough to buy on? It is a good screening estimate; confirm with the manufacturer's performance curve and a detailed energy model before purchase.
비efore buying a recovery unit, a quick payback calculation shows whether it makes sense. You only need a few field numbers and the local energy price.
Annual energy saved (kWh) = 1.2 x airflow (m3/h) x eta x dT (C) x hours/year / 1000
Where 1.2 is the approximate volumetric heat capacity of air (Wh/m3.K), eta is effectiveness, and dT is the temperature difference between exhaust and supply.
- Airflow: 10,000 m3/h
- Effectiveness: 75 % (0.75)
- dT (winter average): 20 C
- Operating hours: 6,000 / year
- Energy price: $0.12 / kWh
Saved = 1.2 x 10,000 x 0.75 x 20 x 6,000 / 1000 = 1,080,000 Wh = 1,080 kWh/year.
Value = 1,080 x $0.12 = $129.6 / year.
If the unit (installed) costs $1,500, payback is about 11.6 years - but add fan-energy savings and incentives, and real projects in cold climates often land at 2-4 years.
- Higher dT (colder climate, hotter exhaust)
- More operating hours (continuous processes)
- Higher energy price
- Rebates or carbon credits
- Combined heating + cooling savings (enthalpy)
Should I include fan energy?
Yes - subtract the extra fan electricity from the saved heating value for a true net payback.
Is this accurate enough to buy on?
It is a good screening estimate; confirm with the manufacturer's performance curve and a detailed energy model before purchase.