A modern house (Class A) well insulated and sealed allows you to recover, thanks to an ERV, up 45% of the consumed energy.
But I would like to proceed with caution since many parameters can influence the effective recovery of energy , like the micro-climatic conditions, and the conduct of people due to the habits and perceptions of comfort.
To an underestimation of the Pay Back period (PB), we can assume a minimum of 33% energy recovery, on the annual consumption for heating and cooling (air conditioning in summer), as the annual energy savings.
PB [year] = ERV Cost (including installation and maintenance) [€] / annual energy savings [€/year]
In the case of a central facility for an apartment of 120sqm we can approximate calculation using the following values:
PB = 3.000 [€] / 600 [€/year] = 5 [years]
Since the 5-year warranty for certain products, we can conclude that the investment fruits, from an economic standpoint, only from 5 years onwards (limited only in cases of extraordinary maintenance).
The result is commendable considering that the main objective of an ERV is to ensure the quality of the air (healthy air – no SBS) and the comfort, including noise reduction thanks to a ventilation with closed windows.
But the hope is that in the near future the technological and market evolution could offer solutions with high efficiency and durability and with a PB less than one year.