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Scheme Summary
The Green Futures housing project consists of 27 environmentally friendly
houses developed by Black Country Housing Group, in partnership with Dudley
Metropolitan Borough Council.
Scheme Details
The Green
Futures housing scheme began in 1997. Phase 1, completed 1998, has been
occupied for two years. Phases 2a and b were completed 2000. The final
phase is under construction (Feb 2001).
Each phase
has used a different construction technique, but all sought to show that
homes can be designed and built to provide affordable and desirable housing,
reduce negative environmental impact, make energy savings and use materials
from sustainable sources.
Environmental Features
The houses are mainly two storey terraced. The following features are
common to all phases.
Houses have
generally been orientated to maximise solar gain. Site characteristics
and the need to maintain privacy have affected orientation. Sun pipes
provide natural daylighting to unlit areas, e.g. stairwells.
Materials
were sourced locally, where possible. Bricks were made in the Black Country.
Timber and particle board, although not sourced locally, were sourced
in the UK.
Plastics
were used sparingly where economic alternatives were unavailable. Recycled
plastic was used for the external doors to Phase 2 properties.
The homes
were designed to be energy efficient with thermal insulation helping to
reduce the amount of space heating required. This was achieved through:
- Draught
lobbies front and rear of the homes (prevent warm air escaping when
outside doors are opened).
- 300mm of roof and wall insulation.
- 100mm of basement insulation.
- Low emissivity argon filled
double glazed timber frame windows.
Fresh air
is provided by mechanical ventilation with heat recovery, or passive stack
ventilation. Each construction phase is summarised below.
Phase
1
15 houses were built using a conventional brick and block construction
method. The cavity is wholly filled with 100mm of mineral wool insulation
and reduces the amount of heat lost through the building fabric. The resulting
U value is 50% better than the Building Regulations of the time.
Phase
2a
Phase 2 explored alternative construction techniques to improve insulation
and energy efficiency. The four houses in phase 2a developed a hybrid
construction method, increasing insulation levels whilst retaining some
thermal mass. The cross walls at the end of each house are constructed
with masonry. This provides thermal mass and improves fire and noise insulation
and security. The front and rear walls are lightweight highly insulated
prefabricated timber framed. The houses are quicker to erect and achieve
higher levels of insulation than phase 1. 150mm of wall insulation improves
energy efficiency by one third.
Phase
2b
Two houses were constructed of a proprietary system: Panablock. The system
is a good thermal insulator and allows easy construction; two trained
staff can erect an enclosed shell within a week (ready for finishing trades).
The system achieves a U value of 0.29Wm2C. An additional 150mm of insulation
was added to the cavity around the Panablock structure to improve the
U value by 50%. Due to the restricted nature of this part of the site,
three storey houses were built providing well insulated rooms in the roof.
Roof insulation is 300mm - twice that required by Building Regulations.
Phase
2c
Six steel framed houses are due for completion in 2001.
All houses
in Phase 2 include rainwater harvesting and grey water recycling systems.
Composting toilets are installed in one house and an Eco-Pod training
centre.
Thermal Efficiency
Despite the heat demand from Phase 1 houses being low, a traditional gas
fired central heating system is installed. A comprehensive control system
manages the heating effectively. Typically, weekly heating bills in Phase
1 have been halved to £4 compared with a regional average of £8 for a
three bed house. With the improved thermal efficiency of Phase 2 houses,
under floor heat systems connected to communal heat sources are used as
follows:
- Gas fired combined heat and
power combustion engine - more than 90% efficient.
- A ground source heat pump
takes heat from the ground, where the temperature is a constant 24°C.
Every 1kW of electricity used produces 3kW of heat.
- Two high efficiency gas-fired
condensing type boilers.
- A low temperature hot water
store provides a buffer between the various heat sources and heating
systems.
Together
the systems can deliver water at 60°C. In addition, 4m2 'flat-plate'
solar water heaters have been fitted to some roofs. It is expected that
these will save about 50% of the hot water fuel bill. Phase 2 heating
bills are predicted to be as low as £2 a week.
Costs
The total scheme will cost £2million. Dudley Metropolitan Council donated
the land and the scheme has been part funded by the European Regional
Development Fund. The nature of the scheme and the inclusion of a training
facility prevent a unit cost from being included.
Developer's Comments
This project
is exploratory and provides a valuable demonstration of a range of techniques
aimed to reduce environmental impact. The availability of a venue where
sustainability can be witnessed first hand and in action will be of value
to all social housing stakeholders.
Contact:
Richard Baines,
Black Country Housing Group,
134 High Street,
Blackheath,
West Midlands B65 0EE
Tel: 0241 561 1969
Fax: 0241 561 5694
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