ARTICLE

Zero emissions development: How does it work?
The BedZED example

By Astrid Kirchner, EcoEng-Correspondent


106 b Teesdale Street
London, E2 6PU
United Kingdom

Astrid Kirchner was born in Zell am See, Austria in 1977. She studied Environmental Systems Sciences at the Karl Franzens University in Graz, Austria. After finishing her Master's degree in 2001 she moved to London. She has been a correspondant for the EcoEng-Newsletter since 2001. Astrid runs her own artproject "Living In A Tubemap", encouraging Londoner's to challenge their perception of their city. She currently works for a charity in London.

Introduction:

ZED, Zero Emission Development, is based on a holistic approach to property development. It includes considerations for a sustainable lifestyle and incorporates green design principles. The main aim of this approach is to reduce carbon emissions to its minimum, ideally to zero. The intellectual rational for this approach results from the climate change debate and the efforts to reduce carbon emissions in order to reduce the eco-footprint humans leave on the planet.

Reports show that an average UK family's carbon emission in any given year is broken down as follows:

• 1/3 used for heating and powering a home
• 1/3 for food-miles (how far a meal travels from farm to dinner plate. It is estimated that a meal in the UK travels 2000 miles)
• 1/3 for travel (e.g., private car use, commuting)

A ZED approach tries to address all three of these main sources of carbon dioxide emissions coming from households, which will be discussed in more detail below.

BedZED (the name derives from its location: Beddington ZED Development) is seen as UK's first energy efficient, environmentally friendly, high density, mixed-use urban development. According to the project team, the development effectively combines the image of a suburban garden village with the office park idea, while also integrating communal facilities, such as leisure facilities and bar.

The site provides 82 homes (1-, 2-, 3-, & 4-bedroom houses and flats), 18 live/work units and 1560 m² of workspace and community facilities. The residential densities reach over 100 homes/ha, excluding live/work units. The residents are comprised of 1/3 Peabody Tenants (social/affordable housing), 1/3 key workers (such as nurses and firefighters) in shared ownership (one half of the property is owned and one half is rented) and 1/3 private ownership (leasehold only).

Design Features

Building materials have been sourced locally from a 35 mile radius, except for special features such as the photovoltaic panels. Buildings are designed to maximize sunlight and solar gain and also feature passive heat recovery ventilation, which means that no conventional heating system is required on south facing units. This is also made possible by the use of high specification windows (triple glazed) and superinsulated thermal mass walls (storing heat and only releasing it slowly to maintain constant internal temperatures). Fitted appliances, such as refrigerators, are all A-rated for environmental standards. North-facing units are naturally lit via generous skylights. Incorporating these design features, some of which are further outlined below, it has been possible to reduce the energy demand by 25% of a conventional home similar in size. The development achieves water savings of 20% and a saving of 40% for energy required to heat hot water. Heating requirements are about 10% of conventional homes.

Combined heat and power plant:

A 130kW bio-fuelled combined heat and power plant (CHP), connected to the national grid, is used to provide power and electricity. Heat generated as a byproduct is captured and used to supply hot water across the development. The idea for the CHP is to use woodchip provided from the BioRegional urban tree station, taking tree waste from the London boroughs of Croyden and Sutton. (Tree waste had conventionally been disposed of in a landfill.) Problems have been reported with the effective use of the CHP, and the site is currently being powered by the national grid. Solutions are sought to re-establish the use of the CHP.

Solar Urbanism, Biodiversity, Water and Wind

Access to green spaces is provided through gardens or roof gardens (sky gardens with 300 mm of soil). Conservatories are provided on all south-facing units and a football pitch is also provided on site.

Roofs are covered with sedum to reduce run-off and to increase biodiversity. Rainwater is also harvested from the roofs and used for toilet flushing.

Wastewater is treated on site via a greenhouse-based treatment plant on-site and the effluent is used to top up water supplies for toilets.

The development is designed to maximize passive solar energy. Solar gain is maximized, and specially designed photovoltaic (PV) panels generate electricity to power electric cars.

A wind-driven heat recovery system, fed by highly visible colored ventilation cowls mounted on the building roofs, further reduces heat loss.

Lifestyle

BedZED also tries to address the issues of carbon emissions presented by food miles and travel. Lifestyle officers were employed when residents first moved into the development to explain features of the site to everybody. This option will not be available for future residents, but it is hoped that people will pick up on the ideas. A manual is provided to "induct" residents. Also, BioRegional (the organization bringing local sustainability into the mainstream: www.bioregional.com ) are based at BedZed to offer advice. Healthy living is built in, and residents are able to monitor their use of water and power via meters installed in kitchens.

Food-miles:

ZED's assist residents in purchasing more organic, fresh, and locally available foods with less packaging. This is achieved through on-site farm shops, communal gardens (with composting facilities), local organic farm food delivery schemes, or co-ordinated mainstream supermarket internet delivery. Skygardens (most units have access to their own green space) can also be used as vegetable patches. The on-site recycling facilities are complemented by a community composting scheme.

Transport:

ZED's also encourages the reduction of personal car use. The scheme is built around good public transport connections, but also incorporates an electric carpool plan (it is claimed that the three car pool cars have replaced 15 privately owned cars). The car pooling works in a very flexible way via a smart card and is provided with car club partners Smart Moves (www.citycarclub.co.uk). Designated parking spaces are allocated for this scheme.

Electric vehicle charging points are also provided on site. Electricity is provided free of charge as it is generated on site via PV panels. The electric vehicle idea has not grown since people moved in, primarily due to the fact that the electric cars can only drive about 50 miles before they need to be recharged.

On-site mixed use (like live/work units) as well as communal facilities (such as nurseries or sport facilities) further decrease the need to travel. One of the ideas of providing business/work spaces on site is to allow residents to give up daily commutes.

Bicycle use is also encouraged and BedZED operates a pedestrian-first policy, by locating car parking spaces at the edge of the site, leaving the core of the development a pedestrian zone, safe for children to play in.

Internet-delivery schemes further help to reduce the need to travel.

Resident views

A recent survey (46% response rate) carried out by the post-graduate student Samantha Elvy as part of her Ph.D. (sponsored by the ESRC - the Economic and Social Research Council - and Peabody Trust) reveals that residents are overall highly satisfied living at BedZED. Features such as the design of homes, gardens, and the sense of community were positively commented on. Negative views were expressed about problems with the heating system (CHP) or noise between properties.

Discussion

It is recognized that the extensive research on environmental design and living embodied in this project cannot be economically reproduced for all sustainable design projects. Certain standards and a toolkit are, therefore, produced to allow for wide-scale use. ZED in a Box, defines these first standard house types.

The additional costs of the highly specified, carbon-neutral environmental design are partly offset by the added value of doubling up land use, achieving higher densities. Reduced bills and long-term savings throughout the lifespan of the development account for the other source to make up initial higher costs.

It is interesting to note that only one third of the residents (private owners) actually chose to live at BedZED for its environmental performance. The other two thirds did not show a particular interest in sustainable living before moving to BedZED, however, as shown in the resident satisfactory survey, they do enjoy living there.

BedZED has a very unique design which evokes mixed feelings within the architectural, developers and planning community. Also the sustainable living features and lifestyle advocacy have been subjected to criticism.

BedZED, however, does depict a working model of sustainable design and environmental living and thus has been widely publicized.

Sources and useful links

Most content provided in this article was extracted from Beddington Zero Energy Development promotional material available on BedZED tour, as well as by information provided on this tour. The tour was led by BioRegional. Other sources are included below:

• ZEDBook: "From A to ZED - Realising Zero Emission (Carbon) Development" - the book can be ordered here: http://www.zedfactory.com/zedbook/zedbook.html
• Bill Dunster architects zedfactory Ltd: www.zedfactory.com
• BioRegional: www.bioregional.com http://www.bioregional.com/programme_projects/ecohous_prog/bedzed/bedzed_hpg.htm
• ESRC: http://www.esrc.ac.uk
• ZED Standards to download: http://www.zedstandards.com/ a PDF version is downloadable from this site: www.bestfootforward.com/downloads/Roadmap%20v12.0.pdf
• CABE: http://www.cabe.org.uk/library/casestudy.asp?id=117&show=intro&PARMAS

Other ZED examples

UK:

• BedZED - local scheme in Hackbridge, South London (built)
• SkyZED - High density vertical urban living (planned)
• Harrow ZED - second ZED built after BedZED in Harrow, London
• BowZED - block of 4 flats in Bow, East London

International:

• Johannesburg Ecovillage, South Africa

Data on BedZED