Hastoe Housing Association Limited
Alsa Leys, Elsenham, Essex

Scheme Summary
The development comprises 24 houses, four 3 bedroom and eight 2 bedroom, built on the site of a former sewage treatment plant for the village. The houses were completed in 1999 and let on assured tenancies to local families. The houses were developed in partnership with Uttlesford District Council and funded by grant from the Housing Corporation.

Scheme details
The houses were built to demonstrate that environmental issues could be addressed in a mainstream housing project. Consideration was given to reducing the environmental impact of the property within social housing cost constraints, and using technology which did not require active intervention by the occupier on a daily basis.

Particular consideration was given to water conservation measures and a monitoring programme was set up in conjunction with the local Water Company.

Environmental Features
The design achieved the BRE's Environmental Standard Award (now EcoHomes). The design was assessed against a series of environmental impacts looking at global, local and indoor issues. The award is achieved by obtaining credits for particular design features. The following credits were awarded.


Mandatory credits

Optional credits

Global issues and use of resources:

  • maximum CO2 emissions:
    less than 50m2 31kg/m2/yr
    50-100m2 30kg/m2/yr
    more than 100m2 29kg/m2/yr
  • all insulation materials with an ozone depletion potential of 0.10 or less
  • all solid timber from well-managed regulated sources or suitable reused timber all timber panel products from well managed regulated sources or suitable reused timber
  • storage containers for recyclable household waste.

Indoor issues:

  • formaldehyde emissions minimised, timber treated only where necessary and always treated industrially prior to use; no asbestos and no added lead in paint.

Global issues and use of resources:

  • all insulation materials with an ozone depletion potential of zero
  • low energy lighting
  • provision of gas cooking point
  • timber frame construction

Local issues:

  • ecological damage to site minimised
  • reuse of existing site
  • ecological value of site enhanced
  • WCs with purpose-designed maximum 6 litre flush
  • rainwater butt

Indoor issues:

  • thermal insulation protected in lofts
  • provision of house log book


Timber frame construction was used with cellulose insulation (recycled paper) to the walls and roof. The average NHER score was 9 with SAP ratings of 88 to 93 across the range of house types. Passive stack ventilation was used in all of the houses.

Water Conservation
All the houses were fitted with low volume flush WCs to meet the Environmental Standard. In most properties these were 6 litre design, but with the permission of the Water Company and the Department of the Environment Transport and Regions, four houses were fitted with either 4 litre flush WCs or dual flush 2-6 litre models. Showers were fitted over baths. Water butts were provided externally for garden use or car washing.

The monitoring programme with the local Water Company was designed to establish the pattern of water consumption within the houses. Every water outlet (tap, WC, washing machine feed etc.) was separately metered. The data from the meters is downloaded via a modem and analysed by the Water Company. The data will provide a detailed picture of household water use, including the different uses of hot and cold water.

The overall cost of the 24 houses was 680,000, about 57,000 per house. The extra over cost of the environmental features was about 1,000 per house, but only part of this relates to achieving the Environmental Standard.

Developer's Comments
The 24 houses at Alsa Leys, Elsenham, demonstrate that environmental features can easily be incorporated into mainstream housing without incurring substantial costs or using complicated technology. Preliminary results from the monitoring of the water consumption indicate that, overall, household use may be lower than expected. The use of low volume flush WCs can have a significant impact in reducing consumption. Savings available from this cost effective technology will have an impact on the cost effectiveness of water recycling systems.

Contact: Jenny Wain, Director of Baker Homes, Hastoe Housing Association, Harlequin House, 7 High Street, Teddington, Middlesex TW11 8EE
Tel: 020 8943 0429 Fax: 020 8943 2163
Email: jwain@bakerstimber.co.uk