Select Committee on Science and Technology Eighth Report


Tuesday 24 January 2006

1. Members visiting Beddington Zero Energy Development (BedZED) in Sutton were the Earl of Selborne (Chairman) and Lord Oxburgh. In attendance were Tom Wilson (Clerk) and Professor Richard Ashley (Specialist Adviser).

2. The Committee was welcomed by Peter Wright, a consultant to the Peabody Trust which developed BedZED, and Pooran Desai, co-founder of the environmental consultants BioRegional, which also worked on the development. Also present during the visit were: Bill Dunster, the architect of BedZED; Professor David Triggs, who redesigned the Living Machine wastewater treatment system; Chris Shirley-Smith, who worked on the Living Machine; Jane Durney, Project Manager of Z-squared, a proposed BioRegional development in the Thames Gateway; and Kendal Marsland-Murray, One Planet Living Australia Manager and BedZED resident.

3. The rationale behind the BedZED development of around 100 properties was outlined by the architect, Bill Dunster. He explained that the designs had offered a high density of environmentally-friendly housing—up to 116 homes per hectare, which was significantly higher than the adjacent Laing site—whilst maintaining amenity by providing all units with a garden. The development was highly energy efficient and Combined Heat and Power (CHP) energy was generated on-site, although the CHP system was no longer working and needed to be modified. Moreover, there was an advanced sustainable water management system, which is discussed below. Mr Dunster admitted that the units (housing and a small office) were rather more expensive than average new built properties, but insisted that much of this cost came from the quality of the building materials and the provision of aerial roof terraces, rather than the eco-friendly nature of the development per se. He also noted that all of the properties had been sold and had increased substantially in value since being built.

4. Mr Wright gave a presentation on behalf of the Peabody Trust, which is a housing association with 20,000 properties in London. The Trust had seen the BedZED development primarily as an exemplar for sustainable construction.

5. Turning to water management at BedZED, there were two main schemes: collection of rainwater from the green roofs and recycling of wastewater through the "Living Machine". The rainwater, having been collected by the green roofs, was filtered and delivered to the green water storage tank, which in turn supplied all toilets in the development. Unfortunately, the rainwater had been contaminated by the green roofs and—unless chlorinated—was potentially a health risk, with e-coli being a particular problem. The water also had turned brown through contact with the green roofs and had therefore proved unacceptable to many residents, even though it was being used solely for toilet flushing purposes. Finally, it was established that the volume of recycled waste water (from the sewage treatment, below) was sufficient to supply the toilets without the need for rainwater. Therefore, the rainwater was to be diverted to soak-away instead. However, Mr Wright noted that the green roofs would still provide a useful "interruption" to water run-off, allowing evaporation and re-cycling to groundwater whilst providing a habitat for flora and fauna.

6. The other main element of the water management system at BedZED was the on-site Living Machine, a small-scale treatment plant for wastewater and sewage. This system would extract the nutrients for plants and treat the water to a reasonable standard, allowing the water to be piped to the green water storage tank and, together with the rainwater, used for toilet flushing. The Living Machine itself was situated in a greenhouse (which was intended to provide a pleasant setting with a range of plant life) in a prominent position to make sure its presence was apparent.

7. Accordingly, an attempt had been made to secure an inset agreement, allowing an alternative water and sewage treatment utility to operate the system inside Thames Water's area of operation. However, Mr Wright explained that this had not been possible because BedZED only requires 6,000 cubic metres of water per year, whereas a minimum supply of 50,000 cubic metres per year was necessary to obtain an inset agreement. Therefore, the contract had been given to a private company called Envirologic which was supported by South West Water. However, the lack of an inset arrangement caused problems with Sutton Borough Council, which had been in favour of a sustainable development but had raised numerous health and safety concerns when it was made clear that the water recycling system would not be run by one of the established water and sewerage utilities.

8. The Living Machine was based on a design by Living Technologies and adapted by Professor Triggs. The system had worked but Professor Triggs had found that, to process the waste water at an adequate rate, it was necessary to bypass the reedbed (living) tanks and to run a conventional activated sludge system. However, this modified system required constant supervision and no financial provision had been made to employ anybody. Moreover, the Living Machine had used far more energy than would have been the case if the mains water and sewage system had been used, mainly due to pumping and process aeration. It also produced more waste sludge than anticipated. As a result, the Living Machine had been abandoned.

9. However, as part of a £400,000 research project, Thames Water had recently proposed to install a Membrane Bioreactor (MBR) unit at BedZED which would treat the sewage and wastewater. The MBR—along with the Living Machine—would then be evaluated over a period of time by on-site researchers. It was hoped that this arrangement would provide a long-term water management solution for BedZED.

10. In conclusion, Mr Wright felt that the type of water management system originally proposed for BedZED was not commercially viable for such a small-scale development whilst mains water was available at the site boundary and prices remained so low. If water prices remained as low as at present, only additional inward investment or Government support could make this kind of small-scale scheme viable. He also noted that local authorities—such as Sutton—could present bureaucratic obstacles in the way of water management schemes that were too small to be given an inset agreement. Finally, Mr Wright suggested that there should be a universal standard for required green water quality, as there was in several other countries. The required green water standard for BedZED had been set on a site-specific basis by the Environment Agency but a national standard would make it easier for developers to design and construct systems for water re-use. This was illustrated by Thames Water's intention not to rely on ultra-violet treatment of the product of their MBR plant, which would be near potable standard, but to chlorinate the water in the holding tanks as an additional precaution.

11. Following the presentations, the Committee was given a tour of the defunct Living Machine by Professor David Triggs and Chris Shirley-Smith, formerly of Envirologic. Professor Triggs explained how the system had worked, detailed some of the problems encountered and discussed the proposed investment by Thames Water.

12. The Committee was subsequently given a tour of the BedZED show apartment. It was emphasised that the provision of highly water efficient devices—dual flush toilets, water efficient dishwashers—had led to considerably lower per capita water use compared to the average, but it was also pointed out that some residents had replaced such devices with more favoured versions. In addition, in all units the electricity, gas and water smart meters were on display behind a glass panel in a prominent position in the kitchen, enabling residents to keep track of their use of resources. Furthermore, all of the meters could be read remotely, which was highly convenient for residents. However, it was noted that the meters looked unattractive and it was agreed that more aesthetically-pleasing and user-friendly models might ward off the danger of residents covering up the glass panel, which had happened in several cases.

13. Finally, the Committee heard presentations from Jane Durney and Kendal Marsland-Murray of BioRegional. The aim of BioRegional was "to work with partners to implement commercially viable solutions for sustainable living". Central to this aim was the concept of One World Living, a joint initiative with WWF. Ms Durney explained that, if everybody in the world had the same "ecological footprint" as the inhabitants of Europe, then three planets would be needed to support the global population. Therefore, the One Planet Living project sought to provide ways for people to live comfortably "within the carrying capacity of one planet", primarily by creating a global network of One Planet Living communities in different countries.

14. Z-squared, for which Ms Durney was Project Manager, was a One Planet Living development of 2,000 homes for up to 5,000 people in the Thames Gateway. Water efficient appliances would be used in the development but, of note, Ms Durney felt that water recycling did not make financial or environmental sense for small-scale households where the toilet would only be flushed a few times each day. Nonetheless, local on-site wastewater treatment comprising co-digestion with organic solid wastes (from kitchen sink grinders) was proposed, with energy recovery, followed by reed beds for the residual liquid and direct use of the digested solids as fertilizer. It appeared to the Committee that the main concerns of the development were efficient energy use and eco-friendly treatment of waste, rather than water re-use.

15. Lastly, Ms Marsland-Murray told the Committee that several projects were being planned in Australia along the same lines as the Z-squared development. For example, one community of 35,000 people was being planned on a green field site outside Melbourne and another of 1,500 people was mooted for a brown field site in Sydney.

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