What are the main differences between low energy and passive houses?

The concept 'low energy house' is not as strictly defined. For meeting the requirements of the passive house standard, energy use for space heating needs to be less than 15 kWh/m2 per year.

In a passive house, the investment that is normally used for a heating system is used for more isolation, better insulating windows and better ventilation. As a result, the total energy use in a passive house is a factor 2.5 lower than for a low energy design. A passive house does not require a central heating system for space heating.

In addition, a passive house always uses a mechanical ventilation system with heat recovery, which is not always the case in low energy houses. A passive house meets a predefined air tightness level (n50≤0,6/h) and that guarantees a correct working of the mechanical ventilation system with heat recovery.

Source: Passiefhuis - Platform