♻️ Energy Recovery Ventilators: How ERVs and HRVs Work, When to Use Them, and How to Size Them

The Energy Cost of Ventilation

Outdoor air ventilation is essential for indoor air quality, but it comes with an energy cost. Every cubic foot of outdoor air brought into a building must be conditioned — heated in winter, cooled and dehumidified in summer — before it reaches occupants. In a cold climate, a 50,000 ft² office building following ASHRAE 62.1 might require 15,000–20,000 CFM of outdoor air, which must be heated from -10°F to 70°F on the coldest days. The energy required to do this is substantial — often 30–40% of total HVAC energy consumption.