Passiv - what is it and why it is the future of housing?

Passivhaus, or ‘passive house’, a voluntary approach to building design, is probably the highest building energy efficiency standard in the world. According to United Nations, we have a climate emergency, and that buildings of all types, but especially people’s homes, need to use less energy. Designing new buildings, and retrofitting many existing ones, to this ‘Passiv’ standard , or — at the very least — using its principles, should be one component of addressing the world’s climate problems.

A ‘Passiv’ design approach can be applied to both residential and commercial buildings to dramatically reduce the energy needs of both space heating and cooling, whilst simultaneously creating excellent indoor comfort levels. It has been used to design and build not just energy efficient homes, but schools, hospitals, offices and various other types of building.

What does ‘passive’ mean?

A Passivhaus building is so-called because it has minimal requirements for active heating and cooling; rather, it relies on both the passive use of the sun and a reduced loss of the heat created by people and equipment inside buildings. This ensures thermal comfort in cold weather and, with shading and ventilation techniques as well the insulation keeping external heat out, coolness in hot weather. (Both effects are enhanced by high levels of airtightness and high-performance glazing.)

We’ve described the Passivhaus principles elsewhere and they are applicable to new buildings and to ‘retrofitting’ many existing ones. The key Passivhaus features are:

• much higher levels of insulation than in a standard construction

  — the outer, pink line in the diagram at the top of the page shows the thickness of wall and roof insulation in a standard-build new house;

• as far as possible, the avoidance of ‘thermal bridges’ that is, anything in the structural design that breaks the insulation layer and can thus transmit heat through it;

• very high-performance windows and doors to optimise heat from the sun to keep the house warm in colder months;

• very high levels of airtightness to create a draught-free internal environment and to minimise heat losses through the fabric of the building

  — the inner, red line in the diagram at the top of the page shows the airtightness layer (note that it extends underneath the building); and

• a mechanical ventilation heat recovery system to provide a continuous supply of 100% fresh air and to avoid condensation on surfaces and within the fabric of the building.

According to the Passive House Trust, ‘Passivhaus buildings are optimised for Net Zero and meet the predicted capacity of our future decarbonised grid’. Certainly, it makes sense that all new buildings should be designed to minimise energy use for both heating and cooling. And it is noteworthy that the Scottish government is apparently considering mandating that all new buildings are built to the Passivhaus standard (or a Scottish equivalent).

In the video on the right, Dave Borlace, talks about the principles of Passivhaus and why, in his view, all future buildings should be built to this standard.

However, new homes are expected to last for at least 60 years and many have much longer lifespans. So, even if all new buildings from now met the Passivhaus standard, this would not solve the climate emergency. We also need to improve the energy efficiency of as much of our current housing stock and other buildings as possible.

In this second video, Dave Borlace talks about retrofitting existing buildings to the special Passivhaus retrofit standard, EnerPHit, to improve sustainability. We have also looked at applying Passivhaus principles to retrofitting in another post.

Is it worth doing?

In terms of quality of your home living environment, coupled with tiny heating and cooling bills, we certainly think so! Passivhaus offices have a much improved internal working environment and have been claimed to have improved levels of productivity and less absenteeism. And in Passivhaus schools, the classrooms never get stuffy, there are no uncomfortable draughts or cold spots and CO2 levels were dramatically improved.

And in this final video, the children of Wilkinson Primary School explain the Passivhaus principles as applied to their school and why it’s a better learning environment as a consequence.

Not only can making our buildings more ‘passiv’ substantially reduce our energy needs and therby contribute to dealing with our climate emergency, it will also make them much more pleasant to be in all of the time.

Experience the passive house difference yourself

Discover what it’s like to live in a Passivhaus staying at Malvern B&B where we’ll be pleased to talk with you about our experiences of self-building and living in a Passivhaus.