Walk into any ventilation specification meeting and you will hear the letters HRV and ERV used almost interchangeably. They should not be. A heat recovery ventilator (HRV) and an energy recovery ventilator (ERV) solve the same problem\u2014bringing fresh outdoor air in while throwing away as little conditioning energy as possible\u2014but they handle moisture very differently, and that difference decides comfort, humidity control and even first cost in a given climate. Choose wrong and you either bake the building with reheat in summer or over-dry it in winter. This article sets out exactly what each technology recovers, where each one belongs, and how the choice ripples through the rest of the HVAC system. For background on the recovery hardware itself, start with our air-to-air heat recovery overview<\/a>.<\/p>\n The distinction comes down to what “energy” means in the airstream. Air carries two forms of thermal energy: sensible heat (the dry-bulb temperature you feel) and latent heat (the energy bound up in water vapour). An HRV transfers only sensible heat through a plate or wheel that keeps the supply and exhaust streams physically separated or only thermally coupled. An ERV, by contrast, uses a desiccant-coated wheel or a selective membrane that also moves moisture, transferring total energy\u2014heat and humidity together.<\/p>\n That single difference has large consequences. In a humid climate, an HRV will recover the temperature but dump a stream of muggy exhaust moisture-laden outdoor air that the cooling coil must then remove, often requiring reheat to control space humidity. An ERV pre-conditions the incoming air’s humidity as well, slashing both the cooling load and the reheat energy. In a dry, cold climate the calculus flips: an ERV can remove needed indoor humidity in winter, while a simple HRV leaves it alone. Our rotary energy wheel guide<\/a> explains how desiccant coatings make the moisture transfer possible.<\/p>\nSensible versus total energy recovery<\/h2>\n
HRV vs ERV at a glance<\/h2>\n