Social housing Sustainability
material is a hemp and lime mixture that has excellent
Key features
Survey
environmental and thermal properties and literally locks
Project uses
But how did the tenants cope with the buildings’
carbon into the very fabric of the building.
range of
functionality? A full survey is currently taking place, but the
“When hemp grows it absorbs carbon, when it degrades
eco-friendly
controls are fairly standard, with a timer and thermostat
it releases methane,” says Pegg. “When hemp is used for
initiatives
for heating, and instantaneous hot water when tenants
buildings it does not degrade. The hemp displaces bricks, turn their taps on.
which require energy input to make and transport, and Biomass community “The ventilation works in the background with no
this reduces CO2 further.”
heating network powered
user interventions, except operating the cooker hood,”
by locally supplied wood
In another nod to the use of natural materials, the
pellets
Pegg adds. “In summer, the occupants open windows as
insulation is made from local sheep’s wool. required.”
Whole-house ventilation
with heat recovery
The designers say that energy efficiency at Clay Fields
Teething problems is primarily achieved by whole-house ventilation with
Controlled mechanical
The developers also encountered some snags, explains
ventilation with heat
heat recovery, improved air-tightness and highly insulated
Pegg: “There were a number of teething problems that
recovery
walls.
needed to be resolved shortly after completion.”
Rainwater collection,
While building regulations demand a U-Value of 0.35
There was a blockage in one of the dwellings’
filtration and usage
W/sq m K, Clay Fields achieves 30 per cent improvement
rainwater tanks, which caused a temporary leak, but
for toilet flushing and
on this through hempcrete insulation. There is also a 50
gardens
water monitoring carried out by the company identified per cent improvement in air-tightness.
the problem before it caused major physical damage.
Use of open, marshy
drains to deal with water
Clay Fields uses controlled mechanical ventilation
This problem was resolved by the manufacturer of the
run-off
and heat recovery. Air is extracted from wet rooms,
tanks.
Use of hempcrete on
bathrooms and kitchens, and heat is released to
Buro Happold also had some issues with the wooden walls to ‘lock’ incoming air for living spaces, such as bedrooms and
maintenance contract, finding that some of the local
carbon, from locally-
living rooms.
produced hemp
companies were not familiar with the biomass boiler “We have found that energy consumption varies greatly
technology. Again these issues were quickly resolved by
Wall insulation from
between dwellings, almost entirely due to occupant
locally-produced sheep’s
finding a new maintenance contractor.
wool
behaviour. Again, we are looking into this through
The shape of the building is designed to exploit the detailed monitoring and through our [current] survey,”
Modelling of building
area’s famously flat landscape and low-angled winter
envelope and glazing
says Pegg.
sun. All houses face south and are grouped so that short ratios to meet lighting “We are interested in using our feedback as an
terraces of three-storey properties front the backs of two-
and design needs
intervention to get occupants to reduce consumption. For
storey terraces – always to the south, to make sure low Ongoing: in-situ example, we found that people were heating their houses
sunlight passes over them.
monitoring of energy
to high temperatures, including 27 deg C in one case, and
consumption and
The scheme is described as being organised “on a
performance of each
had not optimised their usage of timer control.”
human scale and rhythm”. It is a staggered vertical section dwelling The development acknowledges that water is a valuable
that maximises passive solar gain in winter and minimises
Source: Buro Happold
resource and has a carbon cost. Rainwater is collected in
overshadowing. 1,000-litre underground storage tanks, filtered via a sieve
The homes feel well day-lit, especially the kitchens in and a 35-micron final filter, for use in flushing toilets and
the two-story houses. The design allows improved day- watering gardens.
lighting of living spaces but also optimum solar gain and Excluding landscape, biomass and consultancy fees,
daylight penetration. the construction costs come to £1,300 per sq m, which
This also means the homes save money by low energy compares favourably with the housing association’s usual
use, are ecological through reducing carbon emissions, design-and-build cost.
and meet architectural aspirations for a scheme that The outside spaces also contribute to a shift to a less
reflects its local environment. carbon-hungry lifestyle. Not only is there a communal
Key measures help keep carbon emissions low, which allotment where the community can collect compost and
is also a key factor for low-income tenants. A wood pellet- grow vegetables to share, but there is also a wildflower
fired biomass community heating network provides meadow, an orchard growing apples locally, and a playing
heating and hot water that is fully automated, with each field.
dwelling individually controlled. The scheme revives natural techniques to combat
There were issues with delivery of biomass in the early the problem of waterlogging in winter, with run-
months, meaning a larger consumption of gas than
There were
offs going into open, marshy drains. The drains also
initially expected. This was resolved fairly quickly and now
a number
separate the pathways, play areas and planted areas,
there is a regular supply.
of teething
while mimicking the pattern of ploughed fields. Local
Energy usage is “massively variable and not solely linked clays, earth and chalk also reflect the English rural
to construction”, according to Pegg.
problems that
vernacular, with no steel and minimal concrete used
“We found that, in the early months, the biomass was
needed to
throughout the site.
only supplying 30 to 40 per cent of the heat, but we are
be resolved
This development may have won the future proof
now consistently at around 70 to 100 per cent per month. award at the Housing Design Awards this year, but the
We will have to review our numbers at the end of the
shortly after
materials and ideas employed are firmly rooted in the
monitoring period.”
completion.
local area. l
www.cibsejournal.com September 2009 CIBSE Journal 37
CIBSEsep09 pp36-37 social-clayfields.indd 37 21/8/09 10:33:11
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