What is a Passivhaus?

The north elevation of this Passivhaus manages to look traditional without pretending to be something it is not. Architect Adrian Cook.

We use the German spelling rather than Passive House so that it is clear what we are claiming and to avoid confusion with passive solar or passive ventilation. You can find more details elsewhere and the Passivhaus Trust website is a good starting point to lean more:

“Passivhaus buildings provide a high level of occupant comfort while using very little energy for heating and cooling. They are built with meticulous attention to detail and rigorous design and construction according to principles developed by the Passivhaus Institute in Germany, and can be certified through an exacting quality assurance process.”

winter comfort

Passivhaus buildings set the standard for summer and winter comfort and excellent air quality. Old Holloway Passivhaus by Juraj Mikurcik

Claiming the passivhaus standardPassivhaus is not a trademark. However, if someone claims that a building is a Passivhaus then
they are claiming that it actually meets the strict energy and comfort requirements of the standard. Unlike the meaningless ‘eco-home’ or ‘sustainable building’ this is a strong and verifiable claim under Trading Standards. The Passivhaus Trust document, Claiming the Passivhaus Standard clarifies this. The document has been translated into Spanish and also adapted for North America.

If you want to really understand Passivhaus then we would strongly recommend visiting some buildings and talking to the occupants. Some home owners open their houses for the International Passivhaus Open Days.

What does a Passivhaus Look Like?

Like all buildings, some look great, some don’t, and beauty is always in the eye of the beholder. But why do some people say they don’t like the look of Passivhaus buildings?

Asking what a Passivhaus looks like is a bit like asking what a bird looks like. A small brown wren does not look anything like an eagle or a bird of paradise and yet all birds are instantly recognisable as birds. This is because birds evolved within constraints, very different to those for fish or mammals.

There are an infinite number of ways of designing a genuinely low energy building that is cool in summer and warm in winter but, as with flying birds, there are a number of clear constraints imposed by the laws of nature (physics mostly). These constraints include the building form and the size and orientation of windows and glazed doors.

straw passivhaus

Straw, clay, modest single storey home with cheap agricultural roofing and home-charred timber cladding. Award winning certified Passivhaus. Architect, self-builder Juraj Mikurcik.

A building with lots of glass that faces the setting sun will almost certainly overheat. This is due to the low afternoon sun which cannot be shaded by simple overhangs. Such a building will fail to meet the Passivhaus Standard unless it is fitted with expensive external blinds that then block out the view. Designers who want to make buildings that feel as good as they look embrace these constraints. Those focussed on external appearance  see constraints as limiting free expression.

Do you ever look at a wild bird and think it looks too functional?

Lancaster co housing passivhaus development

Lancaster Co-Housing. Certified Passivhaus development. Architect Andrew Yeats

Passivhaus as a Design Constraint

The designers Charles and Ray Eames saw constraints as a valuable part of the creative process that should not be confused with compromise. Charles Eames said:

“Here is one of the few effective keys to the Design problem: the ability of the Designer to recognise as many of the constraints as possible; his willingness and enthusiasm for working within these constraints. Constraints of price, of size, of strength, of balance, of surface, of time, and so forth. Each problem has its own peculiar list.”

Very glazed passivhaus facing south

Deep overhangs shade the fully glazed south elevation of this RIBA award-winning certified Passivhaus. Architect Dean Benbow.

Many of the things we love about traditional buildings were the result of constraints. When glass was hand-made, panes were small. The limited availability of suitable local materials led to roofs clad in slate, thatch, clay tiles or shingles. These constraints are mostly redundant and yet we still copy the look with fake glazing bars, artificial slate, asphalt shingles and even plastic thatch.

mineral painted timber

Thick insulated walls mean deep reveals that protect windows from sun and rain making even a timber house feel very substantial. Architect Charles Grylls.

Passivhaus and Elemental Solutions

Nick Grant attended his first Passivhaus Conference in 2007 with his friend and colleague Chris Herring. Some of the more technical details took time to sink in. However what struck them both was that here was an approach to sustainable building that actually works.

One of the presentations from a fellow Brit explained that all new buildings in the UK would be zero carbon by 2016; we cringed. Nick and Chris returned home inspired and have been working on Passivhaus projects ever since. They are both founding Directors of the Passivhaus Trust.

Passivhaus is a proven approach but it is our nature to remain sceptical. We regularly challenge the details as you can see from the papers presented at the International conference.