What is Passivhaus Design?

Home building, development and design continues to follow more sustainable approaches due to increasing regulation in the space and changing consumer attitudes. One such design approach is Passivhaus, which is fast becoming a more mainstream choice for properties worldwide. But what is it, and is it suitable for your new development? Read on to learn the ins and outs.

What is Passivhaus?

Passivhaus, or simply ‘passive house’ in English, refers to properties built to a rigorous energy efficient design standard so that they maintain an almost entirely constant temperature at all times.
Designed specifically to take in, insulate and retain heat from the sun, passivhaus buildings require very little additional heating and cooling; so are extremely energy efficient and cheap on household bills.

Where did Passivhaus design come from?

The energy efficient building principles used in passivhaus design were developed by the Passivhaus Institute of Germany. An internal research project was carried out to investigate on the gap between the expected and actual energy savings of low energy buildings, and the findings put together to create the new standard.

How does a building become Passivhaus accredited?

When a building is developed from scratch, it can be certified by the passivhaus standard to be given official passivhaus status.
The specific passivhaus planning system is used by the developer and this allows for the design to be adjusted continuously until it reaches the required energy efficiency standard. This makes for a flexible yet robust design that doesn’t compromise on quality but does provide resilience and support for those who perhaps haven’t worked with the guidelines before.

Can an existing building be Passivhaus accredited?

Older properties can be retrofit to meet passivhaus standards, but a large degree of work may be required to reach the full accreditation – although full certification may not be achievable for all buildings. That said, it’s always better to integrate what passivhaus techniques you can rather than none at all. Although such renovations do come with upfront costs, the ongoing significant cost savings and energy security implications are worth it over time and are considered favourable for local authorities and housing associations, who look to create more sustainable communities.
There is a separate certification through the Passivhaus Institute to recognise appropriate retrofitting work that acknowledges and rewards the principle of reducing energy demand through homes.

How are Passivhaus properties built?

The passivhaus building approach differs from other carbon neutral building techniques, which tend to combine energy efficiency measures with clean energy generation to offset typical use. Instead, passivhaus buildings aim not to use as much energy in the first place through efficient sealing and insulation against the outside elements.
Every passivhaus building is constructed in a slightly different way dependent on the project’s scope, but all have the following features in common:
- Robust and well-sealed insulation (much more so than the insulation standards found in a typical household)
- Triple glazing with insulated frames on all windows and/or skylights
- Strict airtightness levels (some 20x stronger than a standard household build)
- A mechanical ventilation system installed with a heat recovery system attached.

Does a Passivhaus home still need to be heated?

While passivhaus buildings are designed specifically to reduce the need for conventional heating, it’s almost impossible to negate the need for it entirely; especially in cooler countries. Some form of heating mechanism will be attached to the property, and is usually a small heating element attached to the mechanical ventilation system which already makes up part of the design.
This type of heating uses very little energy and is typically set only to kick in when the temperature outside falls below zero so energy bills keep very low.
Of course, a heating mechanism is also required to heat water throughout. There are two main options for this: solar heating or an air-source heat pump, both of which produce no emissions at the point of use.

Are Passivhaus designs common in the UK?

Passivhaus developments are becoming increasingly popular in the UK, and are very much favoured by local authorities who want to boost their sustainability credentials and offer affordable housing to their communities – as those living in a passivhaus are much less likely to default on or get into arrears with their rent. Indeed the southern English Housing Association in Hastoe claims that rent arrears are zero across their passivhaus developments.
The largest residential passivhaus development in the UK at present is Primrose Park in Plymouth; a development of 72 houses. The land was considered too expensive for commercial developers and with the council favouring affordable housing construction, they offered the site to passivhaus development for a token £1 fee.
This isn’t to say that only the south of England is benefitting from passivhaus design. There are currently several passivhaus developments in progress across Scotland: with Fife Council granting permission for 30 homes to be built near Dundee and in Loch Lomond, permission given for 15 new homes in the Trossachs National Park.

Who can help me decide if a Passivhaus design is right for my renovation or self-build?

Refresh Renovations have worked with both new passivhaus developments as well as the retrofitting of passivhaus features to existing properties across the UK. Contact your local Refresh Renovations to arrange for a free, no-obligation home visit. We can walk through your property, plans and/or land to discuss the project potential and proposed scope, as well as your needs and wants for the build. Even if you decide that a passivhaus design isn’t right for your home, there is a myriad of energy efficiency measures that we can help advise on and install; improving your sustainability credentials, lowering your energy bills and ensuring you’re warm, happy and healthy through all weathers.
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