As concern about indoor air quality increases, many homeowners and building professionals are seeking energy-efficient solutions. Proper ventilation that brings fresh air into the home while exhausting stale or contaminated air can significantly boost indoor air quality. Energy recovery ventilators are an important feature of many effective ventilation strategies, but their features vary widely between units.
Energy Transfer Rate
Heat recovery ventilators transfer energy from the exhaust air to the intake air, reducing utility costs. This means that a certain percentage of heat is transferred to the intake air instead of being wasted when air is exhausted from the home. This feature makes this type of ventilation system more efficient than supply or exhaust ventilation systems that bring unconditioned air into the home or exhaust conditioned air. Some units, however, have higher energy transfer rates than others.
To determine the energy transfer rate of a heat recovery ventilator, read the product specification sheet. Zehnder makes the most efficient heat recovery ventilator on the market, with an efficiency rating of 93% from the Passive House Institute.
Effectiveness of Filters in Removing Airborne Particles
This is especially important when outdoor air quality is a concern or occupants suffer from allergies, asthma, and other respiratory ailments. The Minimum Efficiency Reporting Value (MERV) of filters can ranges from 1 to 16. The higher the number, the more efficient the filter in removing airborne particles.
Zehnder manufactures both MERV 7 and MERV 13 filters. The MERV 13 filters block 90% of the particles and are effective at removing dust, pollen, mold spores, and pet dander.
Cost of Ownership
It is helpful to consider the cost per year of operating an energy recovery ventilator. How much electricity does it require to operate? How frequently do the filters need to be changed? What is the cost of the replacement filters?
Zehnder systems use energy-efficient ECM motors with specific electrical power from 0.0082 to 0.0118 Wh/cf, but energy consumption rates vary by model and manufacturer. Zehnder America recommends inspecting filters every four to six months. The filters can be vacuumed as needed to remove debris and should be replaced every six to twelve months.
Ease of Service
It is important to have a heat recovery ventilator that is designed to be serviced easily. The filters require periodic maintenance, so it is ideal that these are simple to access. Ease of service is impacted by where the unit is located. For example, if the heat recovery ventilator is installed in an attic that is hard to access, it will be harder to make repairs or perform maintenance.