Passivhaus Myths

By Gwilym Still

19 August 2020

There are lots of preconceptions about what makes a Passivhaus building… and many of them are wrong!

Passivhaus gives a way of designing and delivering low operational energy, high thermal comfort buildings.

It uses proven building physics principles, robust modelling software, real life feedback, and a tried and tested quality assurance process.

Here’s the most common misconceptions we’ve encountered:

1 - It's just for houses

While Passivhaus has domestic roots, the building physics principles, modelling tools, and quality control have been successfully applied to all sorts of buildings, including schools, offices, museums, hospitals, and swimming pools.


2 - You can't open the windows

Not true; a Passivhaus building ensures good air quality throughout the year without relying on opening the windows, but if they’re designed to be openable, you can still open them. In the UK, opening windows is often part of the summer comfort strategy. You can still open them in winter, but the building will use a lot more energy to stay warm and may cool down.


3 - They don't have any heating

A Passivhaus building is designed to optimise the use of passive heat sources like sunlight and body heat. The amount of heat they lose is limited by efficient building form, insulation, detailing, glazing, and ventilation. The small amount of remaining heat needed is provided by a heating system.


4 - They're too dry

Passivhaus provides reliable ventilation throughout the year. This does mean the building will have less moisture in it than a poorly ventilated building in winter, but that’s not necessarily a bad thing. Too much moisture can lead to mould growth and health issues.


5 - They're too stuffy

This concern arises because a Passivhaus building is very airtight. However, in reality, the mechanical ventilation system provides reliable ventilation in all weather, putting fresh air where it’s needed and taking stale air away.


6 - They're too complicated

Passivhaus prioritises a fabric-first approach, so any heating or cooling is minimised. The energy required can be provided by simple systems, often using less equipment than a conventional building. While it’s technically possible to build a complicated Passivhaus, most designers try to avoid it. Some of our simplest buildings are our Passivhaus projects.


7 - The ventilation is too noisy

When designed, installed, and commissioned correctly, the ventilation system in a Passivhaus building is very quiet. On some of our projects we’ve had to look at the ventilation unit to make sure it’s actually running!


8 - It's too expensive

It depends! A building with an efficient form, designed with building physics in mind from the outset – which are inherent features of a Passivhaus building – can be delivered cost-effectively. Turning a complicated and inefficient design into a Passivhaus will be expensive, as will making it energy efficient without Passivhaus.


9 - They look ugly

Not necessarily! Passivhaus is a performance standard, so there are as many ways of achieving it as there are buildings. An ugly box could fail to achieve the standard, and a beautiful building could pass with flying colours.


10 - They get too hot in summer

Well insulated airtight buildings are good at keeping heat in, so can overheat if not correctly designed. They are also good at keeping heat out and there are plenty of examples of Passivhaus buildings which achieve excellent summer comfort – including Max Fordham’s own home!


If you're interested in finding out more about our Passivhaus service or have a project that you'd like us to get involved in, please contact Gwilym Still.

We're also hosting a webinar about 'Passivhaus Myths' on 9th September, 11am - 12pm. Click here to sign up.


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