Air-to-Air Energy Recovery Ventilators (ERVs)

Today’s building owners are more concerned about saving money through energy efficiency than ever before. Fortunately, air-to-air energy recovery ventilators (ERVs) help them save energy and money by recapturing 40–80 percent of the energy of the exhausted building air and using it to pre-condition incoming ventilation air. (Specific values can be found in the AHRI Directory of Certified Product Performance.) This process decreases system load and thus the amount of energy used by the system, thereby decreasing costs. This technology allows users to downsize their entire system. In most applications, costs are recouped in payback periods ranging from less than one year to three years. Read on to learn how ERVs work.

ERVs can be used effectively in any reasonably tightly constructed building with the return/exhaust air duct(s) located near the fresh make-up air intake(s). ERVs are available in three different types of the technology: rotary wheels, heat pipe exchangers, and plate exchangers.

In addition to cost savings, ERVs help buildings achieve LEED certification. This technology is certified by AHRI’s renowned certification program and governed by specific standards and guidelines.

To better understand ERVs, please see the glossary below.

The term “Energy Recovery Ventilator,” or ERV, is used here as a generic term for all air-to-air heat recovery ventilation technologies. This includes products that are typically called “Heat Recovery Ventilator” (HRV), which transfer sensible energy (temperature difference) only, and those that transfer water vapor and latent energy.

What are the advantages of ERVs?

• ERVs have the ability to transfer humidity. They can dehumidify the outside air in hot/humid climates, and keep the humidity inside the building in cold/dry climates, which improves the comfort of the building space.
• ERVs can enable the size of an air conditioner to be downsized because it reduces the latent load on the system.
• In certain operating conditions there is no need for a drain or drain pan because the ERV doesn’t produce any condensation.
• ERVs can go to lower temperatures before defrost is required, which results in energy savings.

What are the advantages of HRVs?

• In applications like pools, spas and gyms, it is preferable to not recover the humidity from the exhaust air stream. An HRV is better suited for this goal.