New homes Low carbon
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Barratt
Hanham Hall,
Gloucestershire
Location: Suburban site
in south Gloucestershire,
between Bristol and Bath.
Development type: Up
to 200 homes, built to
Level 6 of the Code for
Sustainable Homes.
Around 30 per cent
two-bedroom flats and
houses, 30% three-
bedroom houses, 10%
1-bedroom flats, 30
per cent four and five-
bedroom houses. One-
third to be affordable
rented, the rest privately
owned.
Schedule: Demolition
work began November
2009, completion due
2013.
Build system: Structural
insulated panel system
(SIPS).
Key sustainability
Hanham Hall in Gloucestershire, Britain’s largest zero-carbon development, is due to be completed in 2013.
features:
• Building U-values: Walls
> system. The ventilation systems are also fitted with heat inward-opening windows developed by Jeldwen will be
0.11, Roof 0.11, Floor
recovery, whereby heat is extracted from the stale air used extensively alongside double-glazed windows.
0.16, windows vary from
0.8 to 1.4, doors 1.4
taken out of the homes and sent back inside with the The use of SIPS panels, which are manufactured
• Envelope air tightness
fresh air, which further reduces space heating needs. off-site, has affected the shape of the houses: ‘They’re
aimed for: 1cu m/h/
The team is negotiating to sell excess heat from the quite simple in shape, there aren’t lots of bits that jut
m2@50Paschals
• Mechanical ventilation
plant to buildings next to the estate, including a doctors’ out and cross each other at funny angles. It’s designed
and heat recovery
surgery and another NHS building. Although Hanham to make it possible to construct them all in a fairly easy
systems
Hall will be self-sufficient in energy, the plant will be way,’ says Bergin. He stresses that residents will still
• Heat and electricity for
the whole development
connected to the national gas and electricity grids. be free to open their windows as they wish, although
comes from a wood
Excess electricity will be sold back into the grid during naturally this will affect space heating needs.
chip-fuelled, combined
winters when production is at its peak. In summer the The mechanical ventilation system will keep humidity
heat and power plant
• Rainwater harvesting,
CHP plant may be shut down, with gas and electricity down and prevent excessive condensation, he adds.
low-flow water
taken from the grid. ‘The point is that on an annual Some of the homes will be fitted with sliding external
appliances
basis, you import the same as you export,’ says Rory
• Triple-glazed windows
• Sliding external shutters
Bergin, head of sustainability at HTA.
to prevent over-heating
Rainwater harvesting units are configured in clusters
of 10 or 15, feeding a shared tank. Bergin says around
We simply cannot afford to build
Post-occupancy
evaluation: 10 homes will
30 litres will be collected per person per day, while new homes that add to our carbon
be monitored by Oxford
Brookes University for
dual-flush toilets and low-flow taps and showers will
footprint, with existing stock so
temperature, humidity,
reduce daily consumption by 40 litres. These measures
CO2 emissions
are expected to cut the demand on conventional water
difficult to upgrade – Chris Twinn
Build cost per square supplies from 150 to 80 litres per person per day. The
metre: not disclosed
homes will be fitted with A-rated white goods for shutters to prevent them from overheating in the sun;
Lead consultant: HTA maximum energy efficiency. all will meet CIBSE standards on overheating.
Engineer: Arup
Bricks and mortar have been eschewed for a Bergin declines to comment on how much building
structural insulated panel system (SIPS) from to Level 6 will add to the construction costs of Hanham
Housebuilder: Barratt
Kingspan, which comprises 112mm of rigid insulation Hall. It has previously been estimated that Level 6 will
sandwiched between two layers of oriented strand add 40 per cent to building costs. Conversely, the land
board. An extra 80mm of rigid insulation will be in the Carbon Challenge programme is provided at a
installed on the internal face. Bergin says this will help discount to help get exemplar developments up and
to achieve U-values as low as 0.11 in walls no thicker running. Bergin thinks it unlikely that the Level 6
than the current standard of about 300mm. The roofs homes at Hanham Hall will fetch higher prices than
will also be made from SIPS panels clad with metal other homes in the area, pointing out that the Council
sheets. The overall air tightness of the envelope is of Mortgage Lenders does not factor the lower running
expected to be 1cu m/h/
m2@50Paschals.Triple-glazed, costs of energy-efficient homes into its valuations. l
42 CIBSE Journal February 2010
www.cibsejournal.com
CIBSEfeb10 pp36-42 zero carbon.indd 42 28/1/10 16:36:24
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