Most Heat Recovery Ventilation (HRV) systems including the aircycle range, are air-to-air types. These recover heat from the exhaust air stream and use it to pre-condition the incoming air from outside. The effectiveness of these units is given by its heat recovery efficiency i.e. the proportion of waste heat that is usefully recovered by the process (this figure is typically expressed as a percentage).
A heat recovery unit will reduce the amount of energy needed to heat up the incoming air to room temperature. This benefit must always be balanced against the electrical power requirements needed to drive the process. HRV systems are most efficient in more airtight homes, where almost all ventilation takes place via the heat exchange core. The concept is simple, the less heat that is lost through the leaks in the building envelope then the more heat there is to recover.
The Energy Savings Trust Best Practice recommendation for heat recovery efficiency is 85% or higher. The aircycle 3.1 Heat Recovery Ventilation unit currently achieves up to 93% heat recovery efficiency which makes it one of the market leaders in the industry.