It is often assumed that the Passivhaus Standard only applies to individual houses, or perhaps semi-detached or terraced houses. It is true that the Passivhaus Standard was originally developed for houses. And the translation of the German word “Passivhaus” into English as “Passive House” reinforces this assumption. However, once established, the Passivhaus Standard rapidly expanded to include many other building types as people realised the benefits it consistently delivers. And as other types of buildings have been delivered to the Passivhaus Standard, the Passive House Planning Package used in the design and certification process has evolved and developed also. Now it is possible for almost any type of building to achieve certification to the Passivhaus Standard.
Quality assured design and construction, reliable indoor comfort and radical reductions in energy consumption – who wouldn’t want these outcomes for any kind of building?
I often read and hear people, including passivhaus experts, state that once a building is airtight it requires mechanical ventilation. This is not strictly true. And there are many examples of passivhaus buildings that operate using ‘natural ventilation’ during the summer months. An airtight building significantly reduces air movement through the building fabric: walls, floor, roof, window frames and junctions etc.. And we should never rely on this kind of air movement to provide the air that we breath inside a building, for ventilation, that is. (Fancy drinking the water that seeps through a leaking roof? It’s kind of similar.) A ventilation strategy and system that genuinely does work, and is used properly all year round, is needed in any building, airtight or not. Once you add comfort and energy efficiency into the equation, this almost always means mechanical ventilation with heat recovery will be required for some of the year. The comfort and energy efficiency benchmarks of the Passivhaus Standard certainly mean this is the case.
And this is where airtightness and mechanical ventilation converge – both are needed for comfort and energy efficiency.