Heat Recovery Ventilation (HRV) vs. Energy Recovery Ventilation (ERV)

HRVs and ERVs – What’s the Difference?

In newly constructed homes over the past five years, you likely have an HRV (Heat Recovery Ventilator) or ERV (Energy Recovery Ventilator) installed in your mechanical room. Improved insulation and air-tightness in these new-builds lead to less natural airflow, impacting indoor air quality. HRVs and ERVs are designed to enhance indoor air quality and reduce heating costs. While both systems facilitate the transfer of fresh air into the home and the exhaustion of stale air outside, the main difference is that an HRV transfers heat, while an ERV transfers both heat and moisture.

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What is the difference between an HRV and an ERV?

HRVs and ERVs both facilitate the transfer of fresh air into the home and the exhausting of stale air outside, recovering energy from the exhausted air in the process. The primary difference between the two systems is that an HRV transfers only heat, while an ERV transfers both heat and moisture. HRVs are typically preferred in areas where humidity is not a year-round concern, making them more common in places like Edmonton and surrounding areas. ERVs, on the other hand, are better suited for climates with year-round humidity extremes.

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Which one is right for my home?

The choice between an HRV and an ERV depends on your local climate and specific indoor air quality needs. HRVs are ideal for regions with significant seasonal humidity variation but not constant year-round humidity. ERVs are more effective in climates that face extreme humidity throughout the year, as they help manage both heat and moisture levels.

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Choosing Between an HRV and an ERV

When deciding between an HRV and an ERV, consider the climate and humidity levels in your area. HRVs are better for colder climates where the primary concern is heat retention. They transfer the heat from the stale exhaust air to the incoming fresh air, helping to reduce the energy required to heat the incoming air. ERVs, however, are more suitable for humid climates as they transfer both heat and moisture. This helps maintain a balanced indoor humidity level, reducing the load on your air conditioning system during summer and keeping the indoor air from becoming too dry during winter.

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How HRVs Work

HRVs use the heat from stale exhaust air to preheat incoming fresh air. The two air currents do not mix; they pass through separate channels in the HRV core, allowing heat exchange through conduction. This process reduces the energy required to bring the outside air up to room temperature, saving money on heating costs. HRVs typically have efficiency rates ranging from 55% to 75%, with some high-efficiency models achieving up to 93%.

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How ERVs Work

ERVs go a step further by transferring both heat and moisture. In winter, an ERV transfers humidity from the outgoing air to the incoming dry air, helping to maintain indoor humidity levels. In summer, the ERV removes humidity from the incoming air before it enters the home. This reduces the load on the air conditioning system and helps control indoor humidity. ERVs tend to have higher efficiency than HRVs, although this depends on the humidity levels on either side of the thermal envelope.

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Factors to Consider

When choosing between an HRV and an ERV, consider the specific climate and indoor air quality needs of your home. If your home tends to be too humid in winter, an HRV is the better choice. If your home is too dry in winter, an ERV would be more suitable as it helps retain moisture. During summer, HRVs may increase indoor humidity, making ERVs a better choice for hot and humid climates. Additionally, ensure that whichever system you choose, it operates quietly and is installed correctly to avoid the temptation of turning it off due to noise, which would compromise both your financial and health investment.

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Conclusion

In conclusion, both HRVs and ERVs are essential for maintaining healthy indoor air quality in airtight, energy-efficient homes. The best choice between the two depends on your climate and specific indoor air quality needs. HRVs are ideal for colder climates focused on heat recovery, while ERVs are better suited for humid climates requiring both heat and moisture control. Regardless of which system you choose, an airtight home with an HRV or ERV represents a significant improvement over the leaky houses of the past century. If building or renovating an airtight home, especially for Passive House or LEED certification, ensure you install either an HRV or ERV to maintain optimal indoor air quality and energy efficiency.

Don't hesitate to contact us at Whyte Plumbing & Heating for a free, no-pressure consultation and quote. 

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