Passivhaus buildings are often marketed as requiring no heating at all, but this is misleading. While it is true that Passivhaus buildings achieve an impressive 70% reduction in space heating demand compared to conventional buildings, they still require a small heating system to maintain comfort during the coldest days of the year.

One of the core requirements of Passivhaus certification is to ensure thermal comfort in all occupied spaces throughout the year. This means that even with high-performance insulation, airtight construction, and a mechanical ventilation system with heat recovery (MVHR), some form of supplementary heating is needed. This is particularly critical in spaces such as bathrooms, where occupants are most vulnerable to cold immediately after showering, when they are wet and not wearing clothes. A small heating element in these spaces ensures comfort and compliance with certification standards.

In warm climates, the idea that Passivhaus buildings do not require active cooling is equally misleading. Overheating can still occur, and certification explicitly requires mechanical cooling when the overheating frequency—defined as the percentage of time when indoor operative temperatures exceed 25ºC—exceeds 10% according to the PHPP calculations. Even in buildings where overheating frequency is between 5% and 10%, Praxis, as qualified Passivhaus certifiers, strongly recommends incorporating a small cooling system.