Not all HRVs work in exactly the same way. An alternative system called energy recovery ventilation (ERV) works in a similar way but transfers some of the moisture from the outgoing airstream into the incoming air, so it keeps the humidity in your home at a constant level. That’s important if you don’t want your home too dry. As a general rule, ERV is a better option if you have air conditioning and live in a humid climate, because it will help to keep moisture outside, reducing the load on your air conditioner and saving on the air-con bills. HRV is often better if you don’t have air conditioning, or live in a less humid climate, since it will help keep the humidity down by transferring excess indoor moisture outside.