Track airflow, temperatures, humidity, effectiveness, and recovered energy. See loads, savings, payback, and supply conditions. Use practical inputs for fast engineering checks and reports.
| Scenario | Airflow | Indoor Condition | Outdoor Condition | Sensible Eff. | Latent Eff. | Total Recovery | Annual Savings |
|---|---|---|---|---|---|---|---|
| Office Summer | 1200 CFM | 75 °F / 50% | 95 °F / 65% | 70% | 55% | 23520 BTU/h | $1106.00 |
| School Wing | 2200 CFM | 72 °F / 45% | 25 °F / 40% | 75% | 50% | 83853 BTU/h | $3621.00 |
| Clinic Retrofit | 1800 CFM | 74 °F / 50% | 88 °F / 72% | 68% | 62% | 34910 BTU/h | $1925.00 |
1. Sensible supply temperature:
Supply Temperature = Outdoor Temperature + Sensible Effectiveness × (Indoor Temperature − Outdoor Temperature)
2. Supply humidity ratio:
Supply Humidity Ratio = Outdoor Humidity Ratio + Latent Effectiveness × (Indoor Humidity Ratio − Outdoor Humidity Ratio)
3. Sensible recovery:
Sensible Recovery = 1.08 × Airflow in CFM × |Outdoor Temperature − Supply Temperature|
4. Latent recovery:
Latent Recovery = 4840 × Airflow in CFM × |Outdoor Humidity Ratio − Supply Humidity Ratio|
5. Total recovery:
Total Recovery = Sensible Recovery + Latent Recovery
6. Annual savings:
Annual Recovered Energy = Total Recovery ÷ 3412.142 × Hours per Day × Days per Year
Net Annual Savings = Gross Annual Savings − ERV Power Cost
An energy recovery ventilator helps reduce the cost of conditioning outdoor air. It transfers heat and moisture between exhaust air and incoming fresh air. That lowers HVAC load. It can also improve indoor air quality while controlling energy use. This calculator gives fast design checks for engineers, estimators, and facility teams.
The tool estimates sensible recovery, latent recovery, and total recovery. It also predicts the leaving supply air condition after the recovery core. That includes supply temperature, supply humidity ratio, and supply relative humidity. These values help you understand how much work the downstream coil must still handle.
Airflow drives the total load transfer. Indoor and outdoor temperature define the sensible difference. Indoor and outdoor humidity define the latent difference. Sensible effectiveness shows how well the core transfers dry heat. Latent effectiveness shows how well it transfers moisture. Pressure matters because humidity ratio depends on psychrometric relationships.
The calculator converts recovered thermal energy into equivalent kilowatt-hours. It then compares that value with the ERV electrical input. This gives gross savings, fan cost, and net savings. When installation cost is entered, the tool estimates simple payback. That quick check helps during early budgeting and retrofit screening.
Use the results with mechanical schedules, ventilation calculations, and energy studies. Compare different effectiveness values during equipment selection. Test summer and winter conditions. Review supply air conditions before final coil sizing. Always verify manufacturer data, climate assumptions, frost control strategy, and operating schedule before making final design decisions.
It estimates heat recovery, moisture transfer, supply air condition, annual recovered energy, operating savings, and simple payback from your airflow and indoor-outdoor air conditions.
Sensible effectiveness measures dry heat transfer. Latent effectiveness measures moisture transfer. Many wheels and plates perform differently for heat and humidity, so separate inputs improve realism.
Yes. The formulas work for both hot and cold outdoor air. The calculator labels the operating profile based on whether the outdoor temperature is above or below the indoor condition.
Humidity ratio depends on vapor pressure and total atmospheric pressure. Higher elevations change psychrometric values, so pressure improves moisture and enthalpy calculations.
No. It is a screening estimate. Real savings depend on climate bins, part-load performance, frost control, fan operation, maintenance, and actual schedules.
Total recovery is the sum of sensible recovery and latent recovery. It represents the full thermal benefit transferred by the ventilator before the supply air reaches the coil.
If net annual savings are zero or negative, the simple payback cannot be computed. That can happen with low runtime, poor effectiveness, or high electric cost for the unit.
No. Use it for fast engineering checks and comparison studies. Final design should still include manufacturer certified data, code review, detailed load analysis, and project-specific controls.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.