A major impact on the energy consumption and CO2 emissions is related to the efficiency of the heating and/or cooling system, its efficiency on production, emission, control and distribution. Conventional systems used in Passivhaus buildings must have a high performance level, should have low levels of emissions and primary energy consumption.

The energy consumption of a building can be expressed in terms of equivalent consumption in primary energy — Tons of Oil Equivalent — or in terms of CO2 emissions. However, the conversion factors are country dependent on the energy mix and the way the energy is generated. Renewable energy is favourably a good choice.

3.7 Appliances and lighting

The adoption of high-efficiency appliances can significantly reduce the total energy consumption. Whenever possible the design should rely on daylight and minimize the use of artificial light. Although inefficient appliances can help reduce heating loads in winter, this is a very inefficient way to heat a house. Also, internal gains from inefficient appliances increase summer cooling loads and the overall net energy balance is usually negative.

There are simple and effective passive strategies that minimize or reduce the energy consumed. Adopting them depends mainly on the occupants’ behaviour. Using the washing machines during night when the energy demand is reduced and cheaper, drying the linen in the sun instead of in a tumble dryer, switching off appliances instead of relying on standby mode are just a few examples.