Simply put, a heat recovery ventilation (HRV) system is a method of ventilating a property. Today’s buildings are highly insulated and air-tight and with this high level of insulation and air-tightness comes new problems. You still need ventilation in the property. You can either drill a series of 100mm holes in each room to ventilate the building with outdoor air. With this method, the air can be cold, hot, stale, smelly, pollen filled, humid. Sometimes there lots of air coming in through these, say on windy days. Other calm days, your home is not being ventilated at all. The other option is to use controlled mechanical ventilation or HRV.