What is Passivhaus?
Passivhaus, also spelt Passive House, is an international standard for reducing the ecological footprint of a building by building them to be ultra-low in energy consumption. This performance-based energy standard has been around for decades, although it’s been thrust into the zeitgeist more recently as a result of global commitments to the environment.
Back in 1991, a physicist in Austria, Dr Feist, was pondering the typical building methods of homes and how they were subsequently heated. Mulling over the process, he could see that vast amounts of energy were being wasted and had a hunch that he could design a better process. So he did just that.
Approaching his project, he had four major focal points. The home needed:
- Proper insulation
- No air leaks
- No thermal bridges
- Smarter design
Proper insulation is obvious, and the construction industry caught up to that one shortly after the first Passivhaus was built, but the other three points are still often overlooked.
Air leaks are a huge energy zapper, a tiny annoyance that sucks out all the glorious warm air you want to keep inside. These suckers have to be covered. In Passivhaus design, that’s achieved by using products like Passive Purple, which is an airtight vapour membrane that covers all leaks throughout the house.
Cutting out thermal bridges can also be achieved with airtightness and improving insulation. And smarter design is really the crux of the whole Passivhaus approach.
Why build in a way that you will then have to build more to counter against? Passivhaus solutions to design are as simple as:
Installing proper windows
Installing triple-pane glass keeps the heat from escaping and the cold from getting in. It’s a simple solution that keeps your passive house from sucking up more energy.
Building a house in flow with the seasons is yet another ingenious way to optimise nature and reduce the need for additional energy. Designing with proper orientation allows builders to position the house in a way that it can be warmed by the sun in the winter and shaded in the summer to keep it cool.
Adoption of heat recovery ventilation
Heat recovery ventilation, or HRV, allows fresh air to circulate through the house without letting the heat out. Again, this simple system uses the warm air already inside, combined with the cool air from outside, to create an internal system that safeguards against losing heat.
With all of these elements combined, Dr Feist found that a Passivhaus uses 90% less energy than a typical house for cooling and warming. Because those energy needs are so low, that means that they can often be met through sources that don’t involve switching on a heater or air conditioner. For example, if you have a family full of high energy kids, those little bodies are producing a considerable amount of energy that is helping to heat your house. The same is true of your day to day use of appliances and light bulbs, and then, of course, you have the sun.
Passivhaus is for all builders
Although marketers of this concept often point to high-end projects to show off the efficiency of the Passivhaus strategy, the reality is that all builders can benefit from the Passivhaus standards. You don’t have to be “high-end” to be eco-conscious and build smarter buildings.
Here in the UK, we’ve signed up to go net-zero by 2050. That means all builders and construction crews need to jump on board with smarter building practices that save energy and make clients very, very happy.