The Passivhaus Trust is an independent, non-profit organisation that provides leadership in the UK for the adoption of the Passivhaus standard and methodology. Passivhaus is the leading international low energy, design standard. Over 37,000 buildings have been designed, built and tested to this standard worldwide .The Trust aims to promote the principles of Passivhaus as a highly effective way of reducing energy use and carbon emissions from buildings in the UK, as well as providing high standards of comfort and building health.
The Trust’s latest guide – How to Build a Passivhaus: Rules of Thumb – was published on 03 March 2015 and highlights the key aspects of the do’s and don’ts on how to successfully build a Passivhaus.
It follows the success of two existing guidance documents explaining what is Passivehaus, and why choose Passivhaus. The new guide explains how to build to Passivhaus [DOWNLOAD: Chapters 1-4 and Chapters 5-9].
Why is this important?
In 2007, Exeter City made the decision to look at the land that it owns to see whether any development opportunities existed. The aim of this land review was to identify small infill type sites to develop into housing schemes for affordable rent.
Early on in the process the Council decided to develop a number of these schemes for downsizing. That is, to build good quality, desirable one and two bedroom homes for people in larger accommodation to ‘downsize’ to. This frees up much needed family-sized accommodation to be let to those registered on Home Choice.
The design ethos of all the sites was to deliver good quality homes that are both environmentally responsible and healthy places to live in.
It was decided that these the homes would be designed and built to ‘Passiv-Haus Principles’ so that minimum energy and water are used by the occupants of the buildings.
A ‘passive’ house is a building in which a comfortable interior climate can be maintained without active heating and cooling systems. The house heats and cools itself, hence “passive”. The ‘Passiv-Haus‘ was developed in Germany and now the term, as it is used here, describes the same general principles used to achieve the highest levels of energy efficiency and ecological design standards.
Increased insulation standards, exceptional levels of air tightness and a compact building skin are elemental components for this relatively new standard. Heat losses can be reduced to a minimum resulting in a requirement for space heating as low as 15kwh/sqm/year. (Heating requirements for a standard new residential building are usually around 130-180 kwh/sqm/year.)
By choosing the best orientations for the building and by optimising solar gains, the energy performance of the proposed design has been improved so that a conventional heating system is not required.
This will dramatically reduce the running costs and carbon emissions of the homes, making them more affordable and environmentally sound.
And so Council Own Build [COB] Sustainable Design Principles were developed, based heavily on Passiv-Haus principles.
Thus, on 10 December 2010 Rowan House in Sivell Place, Heavitree, partly funded by a grant of £195,000 from the Homes and Community Agency [HCA], was officially opened – not only as ECC’s first new council homes in more than 20 years, but also the first social housing scheme in the UK to enjoy the eco-home energy benefits of Passivhaus standard. The homes are also built to Level 4 of the Code for Sustainable Homes [this code was scrapped on 27 March 2015, in the dying days of the previous Coalition Government].
Architects Gale & Snowden have a useful comparison of Passivhaus vs Code for Sustainable Homes.
The flats (2x 1-bed and 1x 2-bed units) also benefit from solar hot water panels, ceramic tiles to reduce dust mites, radial electrical circuits to reduce electro-magnetic fields and a reduction in volatile organic compounds by the elimination of PVCs and glues.
The flats at Rowan House are specifically for people over the age of 55 paying social rent, with priority for those downsizing from larger homes.
Rowan House was designed by Exeter-based architects Gale & Snowden, who specialise in energy-efficient and ecological projects [More on Rowan House from architects Gale & Snowden’s website]
There’s also a useful article on the Green Building Press website, Passivhaus Flats For Exeter Tenants [16 March 2011].
ECC then developed a larger project – Knights Place off Merlin Crescent in Beacon Heath. The scheme of 18 one- and two-bedroom flats was opened on 30 June 2011.
The PassivHaus Trust highlights the benefits of Knights Place project:
When the client, Exeter City Council, was offered a funding opportunity by the HCA to develop the first council housing in Exeter since 20 years, it was decided to use this chance to provide exemplary, truly affordable housing, built to the highest standard of energy efficient construction with the aim to successfully target fuel poverty and combat climate change at the same time.
And hence they went down the Passivhaus route.
In addition the design has been developed using future climate data to future proof the designs from changes in temperature under future climate scenarios.
The design and material specification follows Building Biology best practice guidance to improve the health of the tenants including the use of ceramic floor tiles to reduce dust mite infestation, minimal VOCs, PVC free, best practice daylight level and radial electric circuits to reduce electro-magnetic radiation.
[More on Knights Place from Gale & Snowden’s website]
Theses two projects have been award-winning:
In 2011, at the LABC South West Building Excellence Awards Rowan House was shortlisted for the following awards:
Best Social Housing Development
Best Technical Development
Best Sustainable Development
Also in 2011, Rowan House, along with Knights Place was the winner of Innovation and Sustainability category at Association of Retained Council Housing (ARCH). The award recognised that Exeter successfully bid for grant funding to build 21 new homes and worked closely with tenants to understand their preferences in relation to sustainable housing.
In August 2012, Knights Place was winner of the Eco Building of the Year category of Michelmores/Western Morning News Commercial Property Awards and this was reported in New housing scheme sets eco-efficiency benchmark [WMN, 16August 2012].
Well the above forms COB Wave 1 and Exeter City Council are currently working on COB Wave 2, with PassivHaus schemes in Bennett Square and Brookway (Whipton Barton) already complete, with Newport Road (Countess Wear) due in the summer.
Bennett Square – Barberry Close
This site was formally a small underused green space with some old, battered pieces of play equipment. As part of the development new play equipment will be installed at a nearby location. Two council houses were demolished in order to facilitate vehicle access onto the site.
The new build consists of 6 No 3 bedroom family houses, of which 2 have been built to fully wheelchair accessible standards at 115m2 each and feature a downstairs bedroom and bathroom, the other four houses are 87m2 each.
Cost –Total build cost £1,796.83 Basic house, substructures and services £1,303.63
Brookway – Silverberry Close
This was formally the site of a Methodist Church that was purchased by the Council following its closure. Originally the plan had been to convert the existing building into flats, but due to changes in housing needs and supply this was revisited and scheme proposed to demolish the existing building and construct family sized homes.
The site features 8 No 3 bedroom houses at 87m2 each.
Cost – Total build cost £2,242.54 Basic house, substructures and services £1,630.46
Newport Road – Reed Walk
This site was formally occupied by Council garages, these garages were demolished and utilising part of a green area adjacent the Council are in the process of building 6 No 3 bedroom family houses, of which 1 is being built to fully wheelchair accessible standards at 115m2, the remaining houses are 87m2 each.
Cost – Total build cost £1,935.22. Basic house, substructures and services £1,237.10
These three development sites were the subject of a tour by the RIBA Exeter Branch on 21 February 2015.
The visit was publicised with this text:
Exeter City Council has previously disposed of housing sites at little or nil cost to Housing Associations to facilitate the development of additional affordable housing in the city. In 2009 this changed, with the input of some Government Grant and a greater freedom within the Housing Revenue Account, Exeter City Council was able to embark on its first housing project in well over 20 years.
The first two schemes of 21 homes were completed in 2011, and were the start of an ongoing development programme for the Council.
These three sites represent the second phase of the Councils development plans – with planning in place for over 50 more homes and ambitions for well over 200 more.
Given the links between poor housing and health, issues with fuel poverty and research carried out by Gale & Snowden Architects with TSB funding on design for future climate, the Council were keen to build to a standard that would mitigate these issues, now and in the future. The result was that all current and future ECC housing projects will be built to the Passivhaus standard and the Council will obtain certification for all schemes.
Passivhaus is a performance standard that requires, amongst others, a space heating requirement of no greater that 15kWh/m2.a and an airtightness of less than 0.6 air changes per hour (m3/m2.h)
To put this into perspective, a standard building stock property has annual energy consumption for heating of approximately 160kWh per square metre of property. A modern low energy property would be approximately 66kWh per square metre. In order to be certified as Passivhaus a property must have an annual energy consumption for heating of no higher than 15kWh per square metre – a reduction of 90% against standard stock housing.