Norwich, a city of over 200,000 people in the east of England, has set its sights on becoming the Passivhaus capital of the UK.
The capital of Norfolk County is supporting social housing new build projects as part of its ambition to make a low carbon city, with the city council hoping to see 1000 passive houses built locally in the next 10 years.
Architect Hamson Barron Smith is designing more than 120 of these homes and Mikhail Riches Architects is delivering a further 100 homes.
Sarah Lewis, project architect with Hamson Barron Smith, said it was “exciting times”. She is pictured (left on the front row) receiving a RIBA East Award with other members of the team for , a 14-dwelling Passivhaus development in Hellesdon, Norwich. She is an influential figure in Passivhaus and moved to Norwich in 2014. She qualified as a Passivhaus designer after completing London’s first Passivhaus building in 2010 for the pioneering company bere:architects. She then created the PHPP modules for the east of England’s first Passivhaus design course.
She : “Local authorities in Norwich are pushing the Passivhaus standard partly because it addresses issues of fuel poverty and environmental regulations. The message is getting out that councils can think on a grand scale. A lot of councils around the UK are looking at Passivhaus as a benchmark because it provides more quality than the marketplace.”
Fabric First Framework
Hamson Barron Smith is responsible for managing the council’s “Fabric First Framework”. This is the principle of designing a building fabric that keeps in heat – through a well insulated, airtight structure that is free of thermal bridges – before thinking about “bolt-on” technologies like renewable energy.
This housing construction framework brings together contractors with the necessary expertise to carry out Passivhaus projects. The council hopes it will be used by other local authorities and housing associations wishing to carry out similar projects.
Inexperienced contractors wishing to take part in a project must undergo training. Jackie Richards, director of Whole House Energy and responsible for the Fabric First training, says Passivhaus training schemes for tradespeople normally take three days to complete and cost at least £1000 (AU$1742). She is delivering the essentials instead in just one day. There are also three-day and nine-day courses, the latter resulting in a Passivhaus designer certification.
The framework, which will be open to all local authorities and housing associations, and which has a projected total value of £300 million (AU$524 million), is designed to facilitate developments through traditional and design & build (single and two stage) methodologies.
Goldsmith Street, one of the largest collections of Passivhaus homes currently under construction in the UK, contains 105 homes: 56 one-bed flats and a mix of two, three and four bedroom flats and houses, all of which will be let for social rent through .
This yields a high density of 83 dwellings a hectare, at £1350 (AU$2359) a square metre, a competitive and economical price.
Other Passivhaus social housing projects commissioned by the council in the city include Three Score, 172 units (of which 112 are Passivhaus); Hansard Close, 10 homes (all Passivhaus); and the recently completed Carrowbreck Meadow development nearby to Goldsmith Street.
Carrowbreck contains 14 units, of which six are affordable homes. All are Passivhaus.
It was one of the first UK projects to use 300mm Porotherm poroton blocks, which require 95 per cent less water than traditional blockwork to manufacture, and come with an A+ BRE Green Guide rating, having 30 per cent of their composition derived from alternative, recycled or secondary sources.
Hansard Close was the first pilot project, and, at £1.5 million (AU$2.62 million), brought in the flats – eight one-bedroom flats and two two-bedroom flats – at £150,000 each (AU$262,000). The total number of Passivhaus homes in the city will therefore soon be 241.
Councillor Gail Harris, Norwich City Council’s deputy leader and cabinet member for council housing, : “We hope Goldsmith Street will be one of the largest collections of eco-friendly homes ever built in the city. This will help realise our ambitions to make Norwich a low carbon city with good housing for all.”
Following an international architectural competition, London-based Mikhail Riches Architects’s design was chosen because it reinstates a terraced street pattern to an area that had been blighted by unpopular post-war apartment blocks.
It is situated close to parks and shared secure alley spaces to encourage children’s play and communal gathering. It’s also a short distance from terraces of upmarket Victorian housing, which has influenced the design and feel of the new project.
Each home faces south in order to maximise solar gain and exposure to natural daylight. The terraces’ asymmetrical pitched roofs have their longer, lower and shallower profile to the north, letting no flat experience overshadowing from the one in front of it and permitting a narrower 14-metre street profile that references the nearby Victorian terraces.
The higher upfront costs of Passivhaus – greater insulation and triple-glazing plus increased labour costs to ensure airtightness – have been compensated for by using timber frames, common detailing and two different types of brick to give visual variety, with a simple design and layout that maximises the use of natural light.
The terraces come in regular, orthogonal blocks to reduce the form factor (surface-to-volume ratio, making them easier to heat), which also makes them cheaper to build.
Inside, the habitable rooms – bedrooms and sitting rooms – have larger south facing windows, and smaller rooms – studies and bathrooms – are north facing with small windows to lower heat loss.
The following drone footage gives an idea of the recent state of the project:
The number of soil vent pipes are minimised to reduce heat transfer. Piping is located in such a way as to reduce puncturing of the building envelope, and boilers and mechanical ventilation with heat recovery units sit against external walls where possible to reduce the amount of ducting to the exterior.
As a result of all this effort residents’ fuel bills are anticipated to be just £150 (AU$262) a year.
Three Score, Bowthorpe
The layout and street design of Three Score development is also sensitive to Norfolk’s vernacular architecture and historical context and incorporates cycle ways and allows pedestrians and cyclists to use all roads.
Houses range in size from one to five bedrooms, with one and two-bedroom apartments also available and a total of 57 affordable homes.
R G Carter Ltd is building these homes on behalf of the city council, with project management provided by Hamson Barron Smith.
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