What does passive house (or Passivhaus) mean?

The design and construction principle of passive house or ‘Passivhaus’, is a rigorous German method of measuring the energy performance of a building in its design and construction to ensure it performs as efficiently as it possibly could.

Passive house insulation 

In very simple terms, passivhaus is about designing high levels of insulation into the walls, roof and floor, and to install highly efficient triple glazing to form the external envelope of the building. Typically, the buildings should be orientated as southerly as possible, with larger areas of glazing are located to the south for solar gain (but not too much) and smaller areas of glazing to the north.

Air tight construction 

Passive house construction also needs to be airtight, which is normally achieved from the inside of the building fabric, with specialist membranes, boards and tapes, so the detailing around the junctions is critical to achieving this.

Finally, the house needs to be installed with MVHR (mechanical ventilation and heat recovery), where a ventilation system typically extracts air out of bathrooms and kitchens, captures up to 90% of the heat in the heat recovery unit, and distributes warm fresh air back into the other living areas around the house.

Energy efficiency 

The energy efficiency works at its best when the windows are shut during the winter to avoid heat loss, but fresh air is constantly circulating around the building at the desired temperature (normally about 20 deg c). In the summer, when you are not looking to use energy to heat the house, you can open the windows and doors as much as you like.

However, the key is to achieve a stable and balanced temperature all year round using very little energy.

Alongside our ongoing work for clients, Andrew Kirby, built his own house to these standards (although not yet certified), with construction costs comparable to mainstream construction methods.

This has been achieved using an optimum construction method, with an established supply chain for the frame, windows and MVHR, which helps maintain consistent pricing. Building to passivhaus standards, does not need to be expensive, but to achieve the best results balanced with the best value, careful and knowledgeable site analysis and early thermal modelling is required to achieve the best balance of cost and thermal efficiency. Read more about our approach in our next blog.

Want to know more?

If you’d like to talk to us about how passive house design might work for you please do get in touch or take a look at one of our passive house projects

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