We’d like to thank Ken Nelson at Panasonic for his terrific video explanation of how ERVs work. Have you been wondering what an ERV is and how it really works, as in, how this techology adds fresh air to built spaces while preserving energy and leveraging heat, and how exactly air and water vapor move around in that enthalpic (or magic) core? Do you want ideas on how to explain this technology to clients in terms everyone can understand? Read below for a fairly detailed summary of this presentation, and then plan to sit down to watch Ken's video presentation and conversation to learn more.
How we get clean air into our homes is especially important given a range of issues brought to the forefront recently, including wildfires and other pollution. In addition, we’re spending even more time indoors and at home, and good indoor air quality is essential to our health as well as for maintaining our furnishings.
An Energy Recovery Ventilator, or ERV is part of a complex HVAC system that manages air temperature, humidity and particulates in our built environment. An ERV is energy-efficient ventilation equipment that brings fresh air into the home while exhausting some of that “bad” or stale air out, in equal measure. The supply and exhaust airstreams pass each other divided by a specially designed capillary plate that enhances the enthalpic heat transfer process. This transfer lets us keep humidity inside when it’s drier out, or shunt excess moisture back to the exhaust airstream when the outside air is more humid. We also recapture heat, or expel unwanted heat. And finally, the ERV provides cleaner air as a part of this process as it also filters the supplied air. We must realize that our HVAC systems can’t keep up when humidity and temperature differences are too extreme, and the ERV helps us moderate these extremes.
As Ken explains, an ERV helps keep the air flows in our systems “predictable” and “uneventful.” That is a primary ventilation goal. Bringing in this fresh air through a supply fan dilutes toxins and improves indoor air quality, while keeping the system in balance by expelling the existing air through an exhaust fan. This idea of balanced air pressure within the home is essential and beneficial. It’s a key objective across the building industry to educate more builders and occupants about this technology as it moves from a leading-edge building practice to a code and healthy home requirement.
Moderating or tempering the air helps prevent our HVAC systems from working too hard. Think about it this way - would we want to carelessly expel humid air in the winter, only to bring in colder, drier air we that now needs to be heated and humidified? Re-claiming heat energy and moisture saves us a good deal of energy. The best practice for builders and occupants is to balance supply and exhaust air flows to recapture or expel the heat and humidity that is not optimal.
Ken walks us though how and why this technology works, and he also reviews:
Ken points out that he loves talking about the best strategy for a particular situation. We agree with him that we can all learn together and that our goal is "to create a better living environment for the occupant, for the earth.” Ken’s closing question is powerful: "How do we raise the bar?”
What are your thoughts and recommendations on ERVs and Indoor Air quality generally? What are your top questions? We’d love to hear, and we bet Ken will be happy to reply.
Additional Information:
Demystifying Ventilation and Energy Recovery Ventilators (ERVs)
A Look at How ERVs Work with Panasonic: How 80% Efficiency Might Work in Practice
The Benefits of an ERV + How it Works | Panasonic FV-04VE1+FV-WC04VE1
Spot Energy Recovery Ventilation (ERV) - Designed for One Location (vs Whole House)
Humidity Control Master Class from Therma-Stor
Humidity, Hardwoods and Homes - The Building Science Approach to Protecting your Investment
Whole House Humidity Control - Dehumidification and Humidification, with Aprilaire
Green Building Myth Busting: Natural Ventilation - Do Your Walls Need to "Breathe?" (Video)
Your House May be Making You Sick!
What is the ideal humidity needed to help maintain hardwood flooring?
Indoor Air Quality (IAQ) 101 - An Introduction, and Starting a Wider Conversation
Date: December 30, 2025
Author: Rate It Green Team
Energy Recovery and Heat Recovery Ventilation
