Ventilators are a key part of maintaining great air quality in many modern homes. As insulation improves, it becomes more difficult for your home to passively exchange stale indoor air for fresh outdoor air—ventilators fix that by mechanically exchanging air.
Here in Ontario, simple ventilation just doesn’t cut it in the winter—the incoming air is too cold. Heat recovery ventilators (HRVs) and energy recovery ventilators (ERVs) are elegant solutions to this problem. In this article, we’re going to examine what they both do, the differences between them, and which one you should consider installing in your home.
Heat recovery ventilators are ventilators that use passive heat transfer principles to heat cold outdoor air as it enters your home. Using a simple heat exchange core, warm, stale exhaust air heats cold outdoor air as it enters the ventilator. By pre-heating the air, your furnace or boiler has to work that much less to maintain the temperature in your home.
The indoor and outdoor air streams never cross—“don’t cross the streams” is an important rule in ventilation. By isolating the streams but allowing heat to transfer between them, it’s possible to preheat incoming air without passing contaminants from stale air.
Energy recovery ventilators work on a very similar principle to HRVs; they employ heat exchange cores to heat incoming air. The main difference is what these heat exchange cores are made of. While HRVs typically use aluminum or polymer cores, ERV cores are made of membranes that allow water vapour to pass between air streams. These membranes don’t allow contaminants to pass, so you’re still getting clean, fresh air from your ERV.
There’s one key difference between ERVs and HRVs—how they handle humidity. HRVs may reduce the overall humidity in your home, while ERVs may increase the amount of humidity. This makes ERVs a fairly attractive choice for Ontario, where our winters can be quite dry—but things are a little more complicated than that, as we’ll explore in the section “Choosing The Right System For Your Home”.
Both heat recovery ventilation and energy recovery ventilation come with advantages and disadvantages. Here’s a quick comparison table that highlights the pros and cons of each:
| Feature | ERV | HRV |
| Best Suited For | Dry climates | Humid climates |
| Moisture Recovery | Yes | No |
| Indoor Humidity Levels | Balanced/increased humidity | Reduced humidity |
| Energy efficiency | High | High |
| Installation cost | Higher | Lower |
| Maintenance cost | Higher | Lower |
ERVs tend to be slightly more expensive to purchase, install, and maintain, but those costs can be well worth it in dry environments. While this table should help you understand which ventilator is right for you, things are more complex than they might seem at first—let’s delve deeply into which system is best for different scenarios.
There are several different factors that can influence whether you should buy a heat recovery ventilator or an energy recovery ventilator; we’re going to cover four of the most important:
As a rule of thumb, dry, cold climates are better served by ERVs, while hot and dry climates are better served by HRVs. That’s a bit counterintuitive, but it helps to understand that ERVs mediate moisture—they can transfer moisture from incoming air to outgoing air or vice versa. This means that an ERV can actually reduce moisture levels.
For homeowners in Ontario, this means that ERVs are useful both in our cold, dry winters and on hot, humid summer days. They actually lower the amount of work that your air conditioner has to do by reducing indoor air humidity, so they’re helping you improve energy efficiency on two fronts.
We generate a lot of moisture from daily activities—showering, washing dishes, boiling water, and more. In a small home, this can lead to a lot of moisture buildup—and that can make an HRV the best choice. HRVs reduce humidity, so if you find that your air is always humid, they can be the best option.
ERVs, on the other hand, keep humidity mostly constant, so they’re well suited to larger homes, where moisture from daily activities builds up less quickly.
Another factor to consider is the system you use to heat your home. Boilers tend to generate a lot of humidity, so if your home has a boiler, you might want to go for an HRV. Gas and electric furnaces, on the other hand, tend to dry out the air; if that’s what you’re using to heat your house, an ERV might be better suited.
Air conditioners and ERVs play nicely together—the ERV will eliminate some of the moisture in the air, reducing the amount of work that your air conditioner has to do. Less moisture also means less chance for bacterial and mould growth in your air condition system, and that leads to healthier air quality.
Humidifiers are another appliance to consider. Humidifiers and HRVs literally work against each other; HRVs are removing humidity from the air, and humidifiers add it right back in. ERVs might reduce how often you have to use your humidifier, which can be an advantage.
Now that you know about energy recovery ventilation benefits, heat recovery ventilation benefits, and where they should both typically be used, we hope you have a better idea of which system is right for you. Need more advice? Contact us today—we’d be happy to help you determine whether an HRV or ERV is best for your needs. We can even recommend different products, and install them for you. We also offer ERV and HRV maintenance and repairs.
