Sustainability and carbon-zero houses

This Issue This is a part of the Innovation and the future feature

By - , Build 109

Recently BRANZ and a Beacon-led industry group visited the bre Innovation Park near London to see how the uk construction industry is approaching the drive to increase the sustainability of new homes.

Insulation panel.
Osborne, Kingspan Lighthouse and ecoTECH Organics houses.
Hanson Ecohouse.
Barratt Green house.

To improve the overall sustainability of new homes the UK Government launched the Code for Sustainable Homes in late 2006, a national standard for sustainable design and construction. The standard gives the UK residential building industry guidance on designing and constructing homes with higher environmental standards.

The code provides an independent assessment and rating for new homes, covering areas such as energy and CO2, water, materials, surface water run-off, waste, pollution, health and wellbeing, management and ecology. It is also designed to assist homebuyers to obtain better information about the environmental impact and potential running costs of houses.

UK houses carbon-zero by 2016

Earlier this year, the UK Government made it mandatory for all new houses to receive a code rating from 0 to 6 stars – 1 being just above their current building code and 6 being a carbon-zero home. The target is that all new housing should be carbon-zero by 2016.

BRE Innovation Park

BRE (Building Research Establishment) has worked closely with the UK Government in developing the code and currently provides technical support. In 2005, BRE opened their Innovation Park in Watford, just north of London, to showcase the latest innovative sustainable construction methods, particularly those that are cutting-edge, practical and affordable. The park is sponsored by several government departments and partnered by UK and European construction companies. Other industry partners also use the park to showcase their latest technology.

Osborne, Kingspan Lighthouse and ecoTECH Organics houses.

There are currently seven demonstration buildings in the park. The houses highlight modern methods of construction and a range of technologies and processes involving prefabrication and off-site assembly, all aimed at speeding up house delivery and more effective use of construction materials. Landscaping is included with sustainable drainage, bioremediation and biofiltration.

Osborne house built in 2 days

The Osborne demonstration house was constructed before the code was launched. The aim was to create a contemporary and economic home with a design that could be adapted for many types of housing, from detached and terraced through to 3-storey flats.

The house was built in less than 2 days using a structural insulated panel system. It uses a third of the heating and cooling energy required by a conventional house built to the current building regulations. Other features are a ‘whole house’ heat recovery system and the use of recycled plastic slates. A data delivery system showing energy consumption and live public transport information is part of the smart technology used.

Hanson Ecohouse.

Different styles achieve 4 stars

The ecoTECH Organics house and the Hanson EcoHouse demonstrate markedly different innovative styles to achieve 4-star code ratings.

The ecoTECH Organics house uses integrated panels. Designed to make sustainable homes accessible to more people, this system allows for flexible design and construction from studio apartments through to 5-bedroom houses.

The Hanson EcoHouse uses high levels of thermal mass from prefabricated masonry external walls, heavy-weight block internal partitions, a precast staircase and concrete floors. The design is based on a traditional brick kiln, with its steeply pitched roof and central chimney. Using convection, hot air is drawn up the chimney while drawing cooler air from a lower level. The building can store heat during warm periods and release it when the temperature drops.

Both houses have water-saving measures, such as low-flow devices, and greywater recycling and filtration systems. The houses have also been designed to accommodate other technologies (such as photovoltaic panels and mechanical heat recovery systems) to allow them to be upgraded. Such energy-efficiency enhancements will result in the houses achieving higher code ratings in the future.

Achieving 5 stars

The Stewart Milne Sigma house is a 5-star construction. It is designed for higher density living and focuses on thermal performance, the integration of solar thermal, photovoltaic and micro-wind technologies for generating renewable energy and effective solar design. It also uses low water consumption devices and an inbuilt internal greywater recycling system. The house is based around a 3-storey Victorian terraced house but is arranged over four levels to make them more affordable and minimise the building footprint, allowing 45 units to fit into 1 hectare of land.

Net-zero carbon homes

The Kingspan Lighthouse and the Barratt Green house achieve the highest code rating of 6 stars, making them net-zero carbon homes. Both houses use super-insulation.

The Kingspan Lighthouse was designed to provide generous daylight levels. It has effective solar control and uses a timber portal structure to enable a range of living spaces to be achieved. Spaces can be left open or the floors can be slotted between the frames. The building services are integrated around a platform of renewable and sustainable technologies: a biomass boiler, a wind catcher, mechanical ventilation with heat recovery, building integrated photovoltaic panels and a solar-thermal array. The house achieves a zero carbon energy supply for space and water heating using advanced power and water efficiency techniques. Around 30% of the water is from rainwater harvesting or greywater recycling systems.

Insulation panel.

The Barratt Green house won the 2007 Home for the Future design award competition, run by a UK Sunday newspaper. The focus of the competition was to design a highly sustainable home that could be built by a mainstream volume builder. The prototype was then constructed within the Innovation Park by Barratt Development PLC. It is the only home in the park constructed by a mainstream house builder.

Together with advanced water efficiency and recycling technologies similar to the other houses on site, the Barratt Green house also has super-insulation, triple glazing, controlled ventilation and photovoltaic systems. Other innovative features are computer-controlled systems such as shutters, and central interactive power and data storage facilities to enable wired/wireless technologies.

The Re-thinking School

The Re-thinking School provides for an improved learning environment through the flexible and practical use of space combined with excellent lighting, ventilation and acoustics, and sustainable features. It has high levels of wall, roof and floor insulation and high performance, low emissivity double glazing. A wind turbine provides renewable energy. The school also has both rainwater and greywater harvesting and water-efficient fittings. The rooms have semicircular, movable walls that can be reconfigured to meet the varying needs of pupils.

Barratt Green house.

An unusual feature of the Re-thinking School is that the building is designed to be remountable and could be dismantled and rebuilt elsewhere. Retractable, reusable screws and screw piles are used for the foundations, which are suitable for difficult ground conditions.

R&D on demonstration houses

Although these are all demonstration buildings, at least two of them are also part of research and development projects. The houses will be monitored over the next 2 years to measure performance, thermal comfort levels, air quality characteristics, energy generation and thermal performance. To evaluate the houses’ performance when fully occupied, it is intended that families will live in them for periods of time during the study.

For more

Beacon Pathway are thanked for permission to use the photographs in this article and supplying additional information. Insulation panel.

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Insulation panel.
Osborne, Kingspan Lighthouse and ecoTECH Organics houses.
Hanson Ecohouse.
Barratt Green house.