Some flats are more attractive than other ones...
This is enabled by the energy performance certificate. Since the last energy saving ordinance came into force, existing flats have been able and obliged to be assessed energetically too. This allows flats to be compared in the same way as the fuel consumption of different motor vehicles can be compared on a daily basis and low consumption levels are regarded as a quality feature. Flats with high energy efficiency and low heating costs are more attractive and easier to rent out than flats which have not been remediated.
The actual heating costs saved by installing a convenience ventilation system depend on numerous influencing factors, primarily on the behaviour of the owner or tenant. However, approximate values are possible, as illustrated by the calculation example:
Flat of 90 m², room height: 2.50 m, heated room volume Ve = 225 m³
According to the energy saving ordinance (EnEV), the infiltration heat loss is calculated as follows:
Qv = 66 x Hv
with Hv = 0.19 x Ve
Qv = 66 x 0.19 x 225 m³ = 2,822 kWh
The EnEV is based on "standardised" people with standardised airing behaviour and therefore on an air exchange rate of 0.7 h-1.
Infiltration heat losses in reality:
In practice, the air exchange rate may by all means be 2.0 h-1 due to incorrect user behaviour (leaving windows ajar), in which case the actual infiltration heat losses are, for example, 8,000 kWh per year (corresponding to costs of, for example, 800 € per year, depending on the current energy price and energy price increase rate).
Our calculation example is based on the assumption that up to 70% of the infiltration heat requirement can be saved with a Pluggit ventilation system. This already takes into account temporary opening of windows and doors.
