New homes

Norwich City Council has built 100 council houses to a Passivhaus standard, leading to a 70% reduction in fuel bills for tenants, and smaller carbon footprints.

The Passivhaus Standard is a set of construction principles that results in homes having a stable ambient temperature of around 20C with very little additional heating or cooling.

Residents, pets, appliances (TVs, cookers, etc), and the sun all give off heat throughout the day: the idea behind Passivhaus is that this heat can be kept in a building through insulation, triple glazed windows and airtight seals on doors, then used to warm up the fresh air that is brought in through a mechanical ventilation system called an MVHR. In this way virtually no extra heating or AC is needed, so energy bills are much lower whilst the house is just as warm.

However, the Norwich development is more than just thick insulated walls and fully airtight construction: all the buildings are oriented to take 'maximum advantage of sunshine' and surrounded by communal play spaces to promote neighbourliness.

The same firm of architects responsible are now involved in a 600 home scheme for York City Council that will be net-zero from construction to completion.

Denise Craghill, York City Council's Cabinet Member for Housing, says:

We’re determined to build homes that are warm and comfortable and bring bills down to extremely low levels, but which are also great places to live. It’s about rethinking a holistic low-carbon lifestyle for the long term

Portsmouth City Council is giving permission for the building of 16 housing units to Passivhaus Low Energy Building Standards, with air source heat pumps. Heat pumps are electrical devices that work like an AC unit in reverse: drawing residual heat from the ground or air and using it to warm the house.

In this development, most of the heating and hot water will come from the heat pump, which will be powered mainly by solar PV and battery storage.

Andrew Waggot, Energy Services Team Manager, says:

One of our key concerns on this project is keeping tenants’ bill low whilst moving them onto an electricity-only setup. The batteries, solar and heat pumps have this effect when combined.

Early Passivhaus projects in the UK had cost 15-20% more than typical new builds, but some recent projects involving larger developments have seen the uplift reduced to between 0% and 5%.

There is emerging evidence of health benefits from Passivhaus homes, thought to be related to the use of filters on the ventilation systems which reduces humidity and the presence of pollen and particulates within the homes.

It is worth noting that health conditions exacerbated by poor housing are estimated to cost the NHS £1.4 – 2.0 billion per year.

Up to 75% of the carbon footprint of large modern buildings comes from the 'embodied' emissions of the steel, glass and cement, of which they are made. Architects in Sweden and Norway have pioneered the use of Cross Laminated Timber (CLT) and Glue Laminated Timber (GLT) to help reduce this construction footprint.

CLT is like super-sized plywood that is strong in all directions: perfect for walls and floor slabs. It is treated with fire retardant. and designed with a 4cm sacrificial layer on each side that chars in the event of a fire.

GLT is made from layers of lumber bonded together, with the grain running in the same direction, giving it a higher load-bearing capacity than both steel and concrete, making it ideal for columns and beams.

As timber can be left exposed, it is incredibly quick to build with, doing away with the usual wet trades of plastering and decorating. In the Sara Cultural Centre in Stockholm, a whole year was saved by using wood, compared with steel and concrete, with a storey completed every two days. The number of truck deliveries was also reduced by about 90%, as the pieces came from factories ready to be bolted together, while the trees were harvested from within a 60km radius of the site.

Andrew Waugh of Waugh Thistleton, the architects behind the Black & White timber office building in London, says:

We’re getting a really clear understanding of the biophilic benefits of natural environments, beyond the carbon savings. People sleep better in timber homes, study better in timber schools, heal faster in timber hospitals and have less stress in timber offices.

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