APPENDIX 7: NOTE OF THE VISIT TO BEDZED |
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
housingup to 116 homes per hectare, which was significantly
higher than the adjacent Laing sitewhilst 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 andunless chlorinatedwas
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
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 MBRalong with the Living Machinewould 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 authoritiessuch
as Suttoncould 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
12. The Committee was subsequently given a tour of
the BedZED show apartment. It was emphasised that the provision
of highly water efficient devicesdual flush toilets, water
efficient dishwashershad 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.