Scheme Summary

The scheme consists of 66 homes for rent. 33 will be built to higher energy efficiency specifications with the remainder acting as a control for CO2 and energy monitoring. The scheme includes a mix of 1, 2, 3, 4 and 6 bedroom properties, with a community room and estate office. Completion is programmed for Autumn 2001.

Scheme Details

All 66 properties are being built to achieve the BRE's Environmental Standard Award (now EcoHomes). In order to achieve an award homes must be energy efficient with high environmental performance. Initially it was considered that the 33 homes 'greener' houses could incorporate:

  • full house mechanical ventilation and heat recovery system
  • triple glazing
  • grey water recycling

An independent environmental consultant was employed to assess the suitability of the systems, and to determine cost effectiveness and efficiency. As a result of the environmental assessment, Granta have amended the scheme specification to take into account the consultant's recommendations.

Environmental Features

The houses are constructed in high thermal mass brick and block. This specification has been developed to improve air tightness, reduce leakage and optimise energy efficiency.

The ventilation and heat recovery system has been included. This will extract warm moist air and circulate preheated fresh air to rooms. A conventional wet radiator system with a condensing gas boiler will be installed for space heating.

A decision was taken against the installation of triple glazed windows. Timber frame windows are installed with double glazed argon filled, low emissivity glass. These are a more cost effective option and are almost as energy efficient.

It was recommended that grey water recycling should be used in conjunction with water conservation appliances and rainwater collection to increase effectiveness. However, concerns over the risk of waste water contamination, long term maintenance issues and space constraints could not be overcome. As a result a grey water recycling system was rejected.

A simpler approach was taken instead. Water conservation appliances, including 6 litre low volume WCs, low flow taps and showers over baths, will be fitted to reduce water consumption. Once occupied monitoring will be carried out quarterly. An annual survey of resident satisfaction will also be carried out to evaluate the benefit of the greener elements.


The overall anticipated scheme cost is 4.2 million. The average cost of the control houses is 62,510. The average cost of the houses with a greater environmental specification is 65,244.

Contact: Rachel Heseltine,
Director of Property Services,
Granta Housing Society,
PO Box 900,
Tel: 02423 576756
Fax: 02423 472250