The standard for low energy social housing

Passivhaus has moved from being a specialist activity for one-off projects and is now a viable alternative for developers and housing associations building multiple units to tight cost parameters. It is particularly suited to the social housing sector because of its focus on occupant health and thermal comfort, and its effectiveness in reducing fuel poverty by reducing heating bills to minimal levels.
    
Close to three hundred units have now been completed and certified in the UK (December 2013), alongside over 40,000 Passivhaus buildings around the world. In the UK social housing sector, Willmott Dixon have just completed the largest social housing scheme to date, Chester Balmore, a 53-unit project for Camden Council, Octavia have completed a 34 unit mixed tenure housing scheme in West London, and construction is underway on Circle Housing’s 51 unit scheme in Essex.
    
Other notable schemes in the pipeline that have received planning permission are the 150 unit scheme in Herefordshire by ArchiHaus, the 250 unit scheme by Broadland Housing in Norwich, and a programme of four further Passivhaus sites being developed by Hastoe Housing. It is expected that over 1,000 Passivhaus homes will be completed by 2015.

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 quality, with dramatically lower running costs – possibly as low as £80-£100 per year for heating bills. Initial capital costs may be higher (but not always), but they should be offset over time by the lower running costs.

In particular, we are starting to see a variety of supply chains emerging that can deliver Passivhaus at a range of costs. If capital cost is your main driver, then several companies now claim that they can build Passivhaus schemes for the same cost as a Code or Building Regulations scheme. Alternatively, if you are taking a whole-life approach, then the higher quality buildings created through the Passivhaus process should lead to lower lifetime costs, through lower running costs and probably lower maintenance costs as well.
    
John Barnham, head of sustainable development at Orbit Group believes that Passivhaus can indeed work for social housing: “Our findings at Sampson Close, Coventry provide strong evidence that Passivhaus does work – providing low cost (affordable) housing to occupiers. Improved health and well-being are also recognised and attributed to Passivhaus as well as improved occupier satisfaction with their home. Importantly, within a social housing context, satisfied customers do result in reduced management and maintenance costs.”

Meeting regulatory requirements
Passivhaus can also help by providing a proven method of meeting current and future requirements.
 
Building regulations are tightening, requiring more energy efficient buildings, and targeting zero carbon new homes by 2016.
    
Passivhaus can help to reduce the risk and uncertainty of meeting this challenge by providing an approach that is quality assured throughout. This ensures that Passivhaus buildings really deliver reduced energy use, as well as providing good indoor air quality and comfortable temperatures throughout the year.
    
Kevin Hartnett, Business Development Director at rural housing specialists Hastoe Housing Association talks about how they have managed to deliver their Passivhaus schemes across the East and South East: “Passivhaus is the common‑sense approach to delivering well-designed, green and energy efficient homes, especially in rural areas where fuel poverty is highly significant. Hastoe has completed two Passivhaus schemes – Wimbish, Essex and Ditchingham, Norfolk. We have a further four schemes in the pipeline for 2014 and our development programme will include 20 per cent Passivhaus schemes moving forward. Using Passivhaus techniques reduce carbon emissions and fuel bills to around 10 per cent of the average UK dwelling.

Benefits to building occupants    
The benefits for occupants living and working in a Passivhaus building can be impressive. The Passivhaus standard was originally designed 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.
    
In addition, a Passivhaus building is designed to respond to the climate, and provides protection from summer overheating as well as winter cold. Careful design using PHPP, the Passivhaus Planning Package, 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.
    
Careful monitoring of completed buildings shows that Passivhaus buildings actually deliver the required levels of performance on a consistent basis. Kevin Hartnett, of Hastoe explains: “From the monitoring we have done, residents are reporting up to 90% reduction in fuel bills annually. Design was a key component of the project’s success; not only in terms of making Passivhaus work but also in creating homes which are comfortable for residents and reflect the local area characteristics.”
    
And the residents on the same scheme are equally enthusiastic. A Wimbish resident described the benefits 16 months after occupation: “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.”

Understanding Passivhaus    
Passivhaus is a fairly new concept in the UK and we need time to get used to how it works. Windows and doors are of much higher quality than in a typical UK home, and they consequently reduce noise, meaning that a Passivhaus home is likely to be unusually quiet. E

Similarly, the mechanical ventilation system does require filters and these must be changed regularly, and the heating system is likely to be much less extensive than in a typical home.
    
The occupants of a Passivhaus need guidance and support to understand how to manage these characteristics and to get the best out of their home. “As with any new product, providing the correct advice in how to ‘operate’ the home is imperative especially as behaviour and lifestyle can impact upon the performance of any home,” says John Barnham.
    
However, if the building and controls are designed well, living in a Passivhaus building can be 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, without increasing heating demand by a significant amount. The feedback from occupants of Passivhaus homes is certainly very encouraging.
     
A resident of Elliot Drive, an Orbit build, says, “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.”

Passivhaus Social Housing    
The Ditchingham scheme in Norfolk, with client Hastoe Housing Association and architects Parsons + Whittley, is made up of 14 rural exception site dwellings in a single curved terrace. The development is set on a challenging site in a conservation area and adjacent to significant Tayler & Green Grade II listed buildings.
    
Innovative foundation and floor slab detailing, and the use of a 300mm fully‑insulated cavity, along with simplicity of detailing and construction (including the MVHR inlet housed in the ‘chimneys’ for aesthetic effect) have helped to deliver the exacting Passivhaus performance and reflect the character of the Tayler & Green historic context.
    
The resulting homes maintain internal temperatures averaging around 21‑22°C, deliver good indoor air quality, and support a relative humidity of 55 per cent – all in all providing a very comfortable internal environment.

Thamesmead project
Construction is also underway on Gallion Housing Association’s five-storey Parkview Hub development in Thamesmead, south-east London – a scheme of 18 three- and five‑bedroom maisonettes, being completed to the Passivhaus refurbishment standard EnerPHit.
    
Contractor Gumpp & Maier UK are working with architects sustainableBYdesign and engineer Alan Clarke on the scheme, using a prefabricated system. Timber stud external wall cassettes are assembled with the insulation, linings, triple-glazed windows, service penetrations and cladding in place in Gumpp & Maier’s factory, transported to the site and craned into position on the outside of the existing pre-cast concrete structure – a speedy process that can be undertaken whilst residents are still in occupation.
    
At street level, the existing garages are being converted for use as retail and community spaces, in line with the wider regeneration masterplan. Externally, the mineral paint-coated timber cladding panels, zinc shingles and pitched metal roof will transform the look of the building. Internal changes should be equally dramatic in improving comfort standards for residents.

Further information
www.passivhaustrust.org.uk