Why the self-build community is starting to actively embrace Passive House design

“So, we need self-builders, more than ever, to pick up the mantle of Passive House construction and set the example. Whether you decide to go for full accreditation with the Passive House institute, or whether you build to a now-fictitious Code level, or whether you just try to make your house as energy efficient and airtight as you can, look at the example that Passive House buildings set.”
– Kevin McCloud, Grand Designs magazine

Passive House and the self-build community

Building a Passive House need no longer be a grand design.

As previously exclusive materials become mainstream, methods better understood and MVHR technology and installation drops in price, a Passive House is now an eminently achievable goal.

There are 65,000 Passive House developments in the world, mainly in Germany and Scandinavia.

The UK, by contrast, has only just reached over 1,000 builds completed to the Passive House
standard, but there are many more built to its principles without accreditation.
And these projects are mainly coming from local authorities and the self-build community – with many more expected as the word spreads and costs reduce.

Back in 2015, the Passive House Trust estimated that meeting their standards could add between 15 per cent to 20 per cent onto the cost of a build. However, the latest data suggests that the extra costs have fallen to eight per cent and are likely to reduce further to four per cent in the very near future.

Let’s outline exactly what a Passive House is – and why it is a construction method that is taking the self-build market by storm.

What is a Passive House?

Simply put, a Passive House is as close to heat energy efficient as we are ever likely to get. It also offers ideal indoor air quality.

It’s a very nice environment to live in!

Passive House builds achieve a 75 per cent reduction in space heating requirements, compared to standard practice for a UK new build.

It does this by focussing on reducing the heat losses of a building so much that it hardly needs any heating at all. The sun, human occupants, household appliances and the warmth supplied by air extracted from the house cover a large part of the heating demand.

Construction standards include immaculate levels of insulation (with minimal thermal bridges) and well-planned use of solar and internal gains.

Since the houses are highly airtight, whole house mechanical ventilation systems are installed to provide excellent air quality, with highly efficient heat recovery. For instance, Zehnder’s mechanical ventilation and heat recovery systems (MVHR) offer ultra-efficient counterflow heat exchangers. These can recover up to 96 per cent of the heat from extracted air that would have otherwise been exhausted to the atmosphere.

What are the benefits of a Passive House?

  • Lower energy bills and protection from fuel price rises – savings of as much as £1,000 annually can be made living in a Passive House
  • This also obviously means fewer carbon emissions and an eco-friendlier life
  • Warm, snug rooms without draughts or cold spots in winter
  • Cleaner, healthier air quality
  • Low maintenance costs
  • A noise-free environment

The ‘PassivHaus goes personal’ campaign from the Passive House Trust, delivered in 2016, emphasised all the key deliverables and benefits from adopting the Passive House standard which still remain today.

Now, who wouldn’t want to live in a house like that?

Why is Passive House being embraced by the self-build market?

We have highlighted the reasons why Passive House has not become adopted by social housing providers or construction companies, to date.
To recap, these include:

  1. A long-held misperception that Passive House was a fad, and an expensive fad at that.
  2. The withdrawal of the Code for Sustainable Homes (CfSH) in 2015 effectively removed the main system for assessing and encouraging improvements in the environmental design of buildings. We are left with little to encourage builders to go beyond basic regulatory needs.
  3. Even our ambitious Net-Zero targets for carbon emissions lead developers away from a Passive House approach. Zero carbon buildings focus on emissions of carbon dioxide rather than energy use per se, with a degree of flexibility occurring depending on the energy source. In short, UK legislation uses carbon as a main compliance metric with less stringent requirements for fabric performance and air-permeability.
  4. Finally, a recent research paper into the limited uptake of Passive House in the UK highlighted the lack of knowledge and skills many architects, designers and installers have in relation to MVHR, a technology that is intrinsic to the Passive House standard.

In effect the traditional housing providers are leaving open a simple way to build homes that will be cheaper to run and command more money when they are sold.

A house that needs only a tiny amount of heating seems something of a miracle, but it’s easy to achieve at little extra cost. The result is a house that is comfortable to live in, come summer or winter, requiring minimal heating thanks to its energy efficient construction.

As Kevin McCloud, a wholehearted advocate of Passive House points out: if you’re building a house for yourself, you are effectively building in savings every year. And, when you come to sell it,

“These days, the greener your home, the more attractive it will be to potential buyers and the sooner you’ll sell it.”

Passive House, in effect, provides a blueprint for self-builders to follow to create homes that go well beyond the standards of those on the market.

And that’s something to be truly proud of.