ERV is apparently the term used for HRVs that also exchange humidity and keep it in/out as required, though I'm not sure that makes much logical sense since E is for Energy and H is for Heat, no mention of humidity.
Possibly just different terms used in different countries where the humidity is a bigger problem (very hot and/or very cold outside air).
This current OpenERV product appears to use dessicants for this purpose but might be an optional add-on?
A perfect ERV will recover the heat (occurs naturally by a temperature difference) and the latent heat (associated with condensation/evaporation).
i.e. water vapour in the outbound flow should be transferred the inbound flow.
This is to avoid energy loss that would occur when moisture condenses (i.e. the latent heat) by using an adsorbant material to capture moisture before it escapes, or a membrane that allows moisture in the outbound flow to pass to the inbound flow.
