Skip to main content
Calcimator

HRV Sizing Calculator

Size heat recovery ventilators based on building volume, air change requirements, and climate conditions.

Inputs

cu ft
ACH

ASHRAE 62.2: residential 0.35 ACH target; commercial per 62.1 Table 6.2.2.1; new tight homes 0.1–0.3 ACH natural

°F
°F
%

Results

Required Ventilation

93 CFM

Recommended HRV Size

100 CFM

Heat Recovered4,536 BTU/hr
Est. Annual Savings$272.00
Defrost Cycles/Day2
How to Use This Calculator
  1. Enter Building Volume, Air Changes per Hour, and Occupants.
  2. Set Design Outdoor Temp, Indoor Temperature, and Sensible Efficiency.
  3. Review Required Ventilation (CFM) and Recommended HRV Size (CFM).
  4. Use Heat Recovered (BTU/hr) and Est. Annual Savings ($) to inform your decision.

How the result changes with Building Volume

Building VolumeRequired VentilationRecommended HRV Size
50,900297 CFM300 CFM
175,6501,025 CFM400 CFM
325,3501,898 CFM400 CFM
450,1002,626 CFM400 CFM

What each input means

Building Volume
Total interior volume of the building (floor area × ceiling height).
Air Changes per Hour
Target air changes per hour per ASHRAE 62.2-2022 (residential). ASHRAE 62.2 requires max(0.01×CFA + 7.5×(Nbr+1), ~15 CFM/person); typical houses 0.35 ACH. Also: minimum 7.5 CFM/person per ASHRAE 62.1 for commercial.
Occupants
Number of occupants for per-person ventilation requirement.
Design Outdoor Temp
Winter design outdoor temperature for your location. Used for heat recovery calculation.
Indoor Temperature
Target indoor air temperature.
Sensible Efficiency
Sensible heat recovery efficiency of the HRV unit. Typical range: 65–85%.

How this is calculated

Worked example, using the default values

  1. Identify Input Parameters
    4 parameters
    Building Volume = 16000, Air Changes per Hour = 0.35, Occupants = 4, Design Outdoor Temp = 10 = 6 input(s) provided
  2. Calculate Required Ventilation
    Required Ventilation
    93 = 93
  3. Calculate Recommended HRV Size
    Recommended HRV Size
    100 = 100
  4. Calculate Heat Recovered
    Heat Recovered
    4536 = 4536
  5. Calculate Est. Annual Savings
    Est. Annual Savings
    272 = $272

Engine last updated . Checked against 2 independently-derived tests — how we verify calculators.

Related Calculators

The questions that sit next to this one — chosen by subject, including calculators filed under a different category.

HVAC

Ventilation Rate Calculator

Calculate required outdoor air ventilation rates per ASHRAE Standard 62.1 based on occupancy and space type.

HVAC

Manual J Heat Load Calculator

Estimate heating and cooling loads using a simplified Manual J method based on building envelope, windows, and occupancy.

Biomedical Engineering

Ventilator Settings Calculator

Calculate initial ventilator parameters including ideal body weight, tidal volume, respiratory rate, minute ventilation, PEEP, and FiO₂.

Wearables

Health Metric Dashboard Calculator

Compute a composite readiness score from wearable health metrics: resting HR, HRV, sleep duration, daily steps, SpO2, and stress level.

Air Quality

Air Change Rate Calculator

Calculate air changes per hour (ACH) from airflow rate and room volume with recommendations by room type.

More in Construction & Building Trades.