Generation homes project - Woodfield - Kingsley

November 2006 March 2007

Refurbishment Location: Kingsley, Nr. Bordon, Hampshire. GU35 9NB
House Types: Semi-Detached House X 3 and Bungalow X 3
Age Bands: 1945-1964

Summary

This refurbishment of six homes has been undertaken as part of the ֑Generation Homes project initiative in partnership between Drum Housing Association, Energy Saving Trust and Energy for  Sustainable Development Ltd. (consultants). The work overall was project managed by Drum.

Generation Homes aims to establish systematic approaches to addressing the challenge of 60% national carbon emission reductions by focusing on the key sector of UK existing housing.

The homes are located in a rural area off the gas supply network and were previously heated by a combination of solid fuel and electrical storage heaters. A survey of 'residents' running costs prior to the works being undertaken revealed annual costs of around 1,000-1,250 on average. From Drum's perspective, the need to provide easily controllable Affordable Warmth for the predominantly elderly residents was seen as of equal importance to carbon reductions.

A further objective is to run the homes, both pre and post refurbishment, through the EcoHomes XB methodology to fully aid understanding of the effect that the improvements have made. 

Sustainability features

In terms of the project outcomes, it is projected that carbon emissions for the 3 bedroom homes have been reduced from 9.8 tonnes CO2 / year to 2.4 tonnes CO2/ year as a direct result of the improvements undertaken, representing a 75% reduction. New annual running costs will also be closely monitored and it is anticipated that around 50% savings will be realised in use.

Fabric energy loss

The homes already had double glazing, cavity wall and loft insulation. The loft insulation was however, upgraded from a thickness of 150mm to 300mm. To reduce heat loss, the air tightness of the buildings was improved with draught proofing, plus redundant flues and air bricks being in filled.

Heating

A new heating system was installed comprising of Ground Source Heat Pumps rated at 3.5kW for bungalows and 5kW for houses. Boreholes were sunk into the ground to a design depth of 60m and 80m to take advantage of the stable temperature of around 90C stored in the ground. The coefficient of performance (COP ) of the heat pump is 3 in space heating mode and 2.25 when producing hot water at higher temperatures. Hot water for space heating is delivered by specially designed low surface temperature radiators controlled by a room-stat and partial TRVs. Domestic hot water is stored in a new cylinder from where it is drawn off on demand.

Heat Recovery

The three houses additionally benefited from the installation of waste water heat recovery. This took the form of a 'Power-Pipe' which was installed in a section of vertical waste water stack pipe. The heat exchanger recovers up to 60% of waste heat and recycles it in this case back to the shower head. The Power-Pipe was insulated and neatly boxed in externally.

Energy Efficiency

As part of the Generation Homes approach, a solar electric photovoltaic array was installed on the southerly aspect of each home's roof. The combination of the two renewable energy technologies on site collecting heat and generating electricity, enable significant carbon savings to be made. The 6 x 1kWp photovoltaic arrays will produce a minimum of 750kWh/pa/unit. This is used to feed the base electrical load of the homes. Some residents have chosen to install export meters enabling any surplus electrical generation to be sold back to the grid, as a contract with their energy supplier.

Low energy (CFL) light bulbs were installed internally throughout all the homes further reducing energy consumption and running costs.   

Water Conservation

Two of the homes previously didnt have a shower installed and therefore the opportunity was taken to provide these and in so doing also reduces resident's mains water consumption. The decision was also taken to install in each of the bathrooms containing the showers, mechanical extract ventilation with heat recovery controlled by a humidistat.  Water butts were installed where requested by residents and composting units similarly provided.

Resident Advice/Education

Residents were provided with clear operating manuals / instructions relating to the new installations and were briefed face to face on the same.

Table 1: Sustainability Features - Summary

Sustainability Feature		Summary
Insulation		Top up loft insulation from 150mm to 300mm Double Glazing and cavity wall insulation pre existing
Air Tightness		Draught proofing windows and doors׷ Infilling redundant flues and air bricks Passive ventilation
Heating		3.5kWp and 5kWp Ground Source Heat Pumps installed for bungalows and houses respectively. New radiators and insulated hot water cylinder.׷ The three semi-detached houses received a waste heat recovery system Power-PipesӔ extracting heat from wastewater down pipes and recycling heat back to showerhead.
Energy		6 x 1kWp photovoltaics were installed to provide base load power for homes. Expected output 750kWh/property minimum.
Lighting		Low energy light bulbs were installed throughout homes.
Water conservation		Installation of water efficient showersҷ Provision of water butts where residents requested them
Waste		Compost bins were provided to residents that requested them.

Cost Implications

As the project was an exemplar, considerable sums were invested. Approximate average cost breakdowns are provided in Table 2 below:

Table 2: Cost Implications

Feature
Loft insulation		200
Air Tightness		1,500
GSHP*, heat plant enclosure, ground works, electrics		7,250 total 6,000 (bore hole and heat plant) 1,250 (Associated ground works, electrics etc.)
Hot Water cylinder and radiators		3,000
Heat and kWh meters		250
Photovoltaics		8,000
Low energy light bulbs		Free from Scottish & Southern Energy

Total cost per unit: 22,700

Total cost for project (6 units): 136,000 + 5% VAT

Funding:

Low Carbon Buildings Programme: 19,000 (photovoltaics) Energy Savings Trust (Generation Homes): 30,000 (consultancy & promotional material) Drum Housing financed the balance: ( 87,000 total, 14,500/unit)

Lessons Learned/Comments

Key to project success was a partnership approach where all stakeholders including client, consultant, contractors, suppliers and residents were fully involved in progress throughout. Effective communication was also central, especially at the key stages when residents were briefed on proposals and on completion regarding operation of the new technologies incorporated.

A large number of contractors were employed on the site and delays with progress of specific operations on occasion caused knock on delays. If a high number of GSHP installations are planned on a site (19 were provided at a site adjacent) it is worth considering a soil investigation as the unforeseen soil conditions resulted in delays with progress. The works, all undertaken without additional cost to residents, were offered to another tenant in the road; however, they refused works owing to perceived upheaval.

Contact details:

Paul Ciniglio Innovations & Environmental Manager, Drum Housing Association.
Tel: 01730 403055
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Assen Gasharov ֖ Project Consultant, ESD Ltd.
Tel: 020 73820354
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