Whole-House Ventilation Upgrade ROI Calculator
Enter your home and energy details to see ventilation savings and comfort metrics.
| Metric | Value |
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Balanced Ventilation Delivers Healthy Air without Energy Waste
Airtight homes require mechanical ventilation to maintain healthy indoor air quality. Energy recovery ventilators (ERVs) and heat recovery ventilators (HRVs) supply fresh air while capturing heat and, in the case of ERVs, moisture from exhaust air. Instead of exhausting conditioned air and pulling in unconditioned air through leaks, these systems balance airflows and transfer energy through a heat exchanger. Homeowners considering an upgrade often ask whether the comfort and health benefits justify the cost. This calculator quantifies energy savings, maintenance benefits, and the monetary value of improved indoor air quality so you can make an informed decision.
As building codes push for tighter envelopes, passive air exchange through cracks diminishes. Without mechanical ventilation, indoor pollutants—from cooking, cleaning products, and building materials—can accumulate. Balanced ventilation with recovery devices maintains fresh air without large heating or cooling penalties. ERVs also manage humidity in humid climates, protecting wood finishes and reducing mold risk. This calculator evaluates how energy recovery offsets fan energy and installation cost, incorporating both tangible savings and the value of cleaner air.
Understanding the Inputs
Conditioned floor area and ceiling height determine home volume. Current natural ACH (air changes per hour) represents background leakage. Blower-door tests or energy models can estimate this. Target ventilation rate is typically derived from ASHRAE Standard 62.2 (roughly 0.01 × floor area + 7.5 × occupants). Device efficiencies describe how much heat and moisture the unit recovers; consult manufacturer specs.
Heating and cooling degree days describe climate severity. Energy prices translate recovered energy into dollars. Fan power quantifies electricity used to move air through the core. Equipment and installation costs should include ducting, controls, and commissioning. Incentives from efficiency programs can significantly reduce net cost. Filter and maintenance savings capture reduced HVAC filter replacements or avoided moisture damage. The health value is a user-supplied estimate representing fewer sick days or improved sleep—set to zero if you prefer a strict financial analysis.
Calculations Behind the Scenes
The calculator first determines baseline infiltration ventilation: natural ACH multiplied by volume yields cubic feet per hour. Comparing this to the target ventilation rate reveals whether the ERV adds fresh air or simply replaces uncontrolled leakage. The recovered energy is estimated using degree days, recovery efficiencies, and airflow. We approximate heating savings with:
where V̇ is airflow, ρ is air density, cp is specific heat, ΔT represents seasonal temperature difference, and η is recovery efficiency. Cooling savings use a similar formula with latent efficiency contributing to moisture control. Fan energy is subtracted to get net energy savings. The tool adds maintenance and health values to compute annual benefit. Net upfront cost is equipment plus labor minus incentives. Discounted cash flow analysis yields net present value and payback.
Example: Airtight Retrofit in a Mixed Climate
A renovated home in Portland, Oregon (2,200 sq ft, 8.5-ft ceilings) tests at 0.2 ACH. The owners plan to install an ERV delivering 120 cfm with 82 percent sensible and 55 percent latent recovery efficiency. Heating degree days are 4,200, cooling degree days 600. Heating is via a heat pump costing $0.13 per kWh; cooling is $0.16 per kWh. The ERV consumes 110 watts at design flow. Installed cost is $6,200, offset by a $900 incentive. Maintenance savings of $70 per year reflect cleaner HVAC coils, and the family values improved health at $150 per year due to reduced allergy symptoms.
The calculator estimates annual heating savings of $272 and cooling savings of $46, totaling $318. Fan energy costs about $106 per year, resulting in net energy savings of $212. Adding maintenance and health value raises total annual benefit to $432. Net cost after incentives is $5,300. Simple payback is 12.3 years, but net present value over fifteen years at 3 percent is $1,030. The results show that while the ERV may not pay back quickly on energy alone, health and maintenance benefits tip the scales.
Scenario Comparison
| Scenario | Annual Benefit | Simple Payback | NPV (15 yrs) |
|---|---|---|---|
| Base Case | $432 | 12.3 years | $1,030 |
| No Health Value | $282 | 18.8 years | -$620 |
| Higher Efficiency (90%/65%) | $516 | 10.3 years | $2,350 |
| Electricity Price +30% | $495 | 10.7 years | $2,020 |
The table illustrates how recovery efficiency and energy prices drive economics. Removing health valuation extends payback but still provides comfort justification. In regions with rising electricity costs, energy savings grow substantially.
Interpreting Your Results
A positive net present value suggests the ERV delivers more value than your chosen discount rate. Compare simple and discounted payback to your expected tenure in the home. Use the CSV export to document assumptions for incentive applications or green building certifications. If the payback feels long, explore reduced installation costs by combining the ERV with other mechanical upgrades or leveraging DIY duct routing.
Beyond finances, ERVs improve sleep quality by maintaining CO₂ levels below 1,000 ppm and humidity within 40–60 percent. Consider pairing this calculator with indoor air quality monitors to validate results. Balanced ventilation can also support electrification by enabling smaller heating and cooling systems due to controlled ventilation loads.
Limitations and Assumptions
The model uses degree-day approximations and assumes constant airflow. Actual energy savings depend on ventilation schedules, defrost cycles, and control strategies. Fan power may vary at different speeds; enter an average value. Health valuation is subjective—set it to zero if unsure. The calculator does not account for duct leakage or installation quality, both of which affect performance. Despite these simplifications, the tool offers a comprehensive starting point for evaluating whole-house ventilation upgrades.