The Passivhaus Choice

There are two major technical challenges presently facing the UK housing industry. Firstly, building regulations are tightening, and require more energy efficient buildings, with zero carbon new homes the target by 2016.

Secondly, many conventional buildings designed and built in the past few years are demonstrating poor performance compared to predictions (a performance gap) in terms of their energy use, Ventilation and indoor air quality, and thermal comfort/overheating.

Passivhaus was developed to address these challenges and provides an approach that is quality assured throughout, ensuring that Passivhaus buildings really deliver reduced energy use, good indoor air quality and comfortable temperatures throughout the year.

As understanding of Passivhaus grows in the UK, close to two hundred units have been completed and certified (February 2013), alongside over 30,000 Passivhaus buildings in a range of climates around the world. Passivhaus buildings can now be found across all regions of the UK, ranging from small scale self-build projects, through to large- scale housing developments, schools and offices. Passivhaus has moved from being a fringe activity for one-off special projects and is now a viable alternative for developers and housing associations building multiple units to tight cost parameters.

In the housing sector, Hastoe Housing Association have just completed their second multi-home Passivhaus scheme at Ditchingham in Norfolk; Lomand Homes are building phase 2 of a 66-home private housing scheme in Portland, Dorset, and; Willmott Dixon are building the largest social housing scheme to date, Chester Ballmore, a 54-unit project for Camden Council that is due for completion later this year.

Why invest in Passivhaus?
Increasing numbers of developers and clients are choosing to invest in Passivhaus because they know that it will deliver a building of real value with much lower running costs, possibly as low as £80-£100 per year for heating bills. Whilst initial capital costs may be higher, there are ways of reducing these to a minimum, and they should be off-set over time by the lower running costs. In particular, good design can simplify the building form and services, reducing capital costs as well as those associated with heat loss. In Germany, estimated extra construction costs are typically somewhere between 3-8 per cent compared with standard buildings. However, experienced Passivhaus designers have managed to build Passivhaus buildings at no extra cost in Germany, Austria and in the UK.

Careful monitoring of completed buildings shows that Passivhaus buildings actually deliver the required levels of performance on a consistent basis. By considering improved performance in terms of the whole building and the processes throughout, and bringing these together into a design tool – the Passivhaus Planning Package (PHPP) – the Passivhaus approach also simplifies the work needed to deliver a real high quality, healthy, comfortable, low energy building.

The benefits of Passivhaus
The benefits for occupants living and working in a Passivhaus building can be impressive. In fact, the Passivhaus standard was originally derived by considering how to provide an ideal comfortable and healthy indoor environment, whilst minimising the energy demand of the building. The warm surfaces, lack of draughts and comfortable temperatures during both winter and summer make Passivhaus buildings more comfortable than a standard building. Additionally, many occupants feel that the quality of the air supplied by the effective ventilation system is very good, and this can help to reduce the risks of allergies and other health problems.

If the building and systems are well designed and kept simple, controlling the building can be easy. This makes living in a Passivhaus building simpler and more flexible than many people assume. For instance, one of the main concerns is that occupants won’t be able to open windows. But, as well as being encouraged in the summer to aid cooling, window opening is of course possible in winter and studies show that doing so will not usually increase heating demand by a significant amount.

In addition, a Passivhaus building that is designed to respond to the climate, and is well insulated and ventilated, provides protection from summer overheating as well as winter cold. The qualities that prevent heat from leaving the building in the winter also prevent heat from entering the building in the hot summer months. Careful design using PHPP guides the appropriate use of orientation, solar shading, thermal mass, and bypass of the heat recovery ventilation system in order to maintain stable internal comfort conditions.

Passivhaus myths and misconceptions
There are those who still have questions about Passivhaus, including concerns about aesthetics, materials and ventilation. Some common myths include:

You can’t open the windows; It’s a German standard; It’s not suitable for the UK; Passivhaus restricts design choice; Passivhaus buildings look like square boxes; It  uses MVHR, which doesn’t work. I hope that this article has helped to dispel these myths. Passivhaus buildings have been built in the UK in many different styles and using many different building systems and have openable windows. Post occupancy evaluation in the UK and across the world shows with hard evidence that these buildings work as intended, including the MVHR systems, and are ideally suited to the UK climate.

But don’t take our word for it – read some of the quotes from occupants (below), and then visit a Passivhaus building and see for yourself.

“I feel very fortunate to be one of the customers involved in this project.  It’s amazing to think that things such as improving the insulation and the installation of the triple glazed windows could all add up to such a huge saving on energy bills.  As well as being good for the environment, it’s good for the pocket too and I am grateful to Orbit Heart of England for investing in my home.”
Mrs Baggerley, Elliot Drive (Orbit) resident

“Unlike older houses the temperature in winter is much the same throughout the house. Wall to wall, floor to ceiling. None of the internal surfaces ever get cold, not even the windows. So there is no condensation. Even when it’s -5°C outside it is still comfortable to sit on the window banks and use the window as a backrest.”
Mark Tiramani, Occupant, Y Foel

“The house is very quiet; you notice the slightest sounds because there is no ambient noise. We expected it to be stuffy inside but were surprised how fresh and airy it turned out to be, It is very liberating not having to think about keeping warm or continually having to adjust thermostats or other settings. The house just seems to take care of you.”
Adam Dadeby, resident & CEPH designer, Totnes Passivhaus

“It’s probably nicer than an ordinary house because of the massive windows and all the sunlight, but the bills are the great thing, having cheaper bills”
Wimbish resident’s feedback in November 2012, 16 months after occupation