Housing Associations and sustainable construction. Jenny Wain. Contents:

Ealing Family on super insulation
- Wilton Road, Reading

Scheme summary

The scheme comprises 25 ultra low energy homes (12 flats and 13 houses) built on a brown field site. They offer affordable rents to residents and ensure reduced environmental impact in use. Environmental efficiency measures exceeded a SAP of 100 and it achieved BRE’s Environmental Standard Award. Completed in 2000.

Scheme details

The scheme was developed using the benefits of experience gained with the THERMIE project of 50 energy efficient homes at Amersham Road (see previous case study). It reused a derelict laundry site in a residential part of Reading.

The scheme was developed as an Integrated Housing Initiative. This provides homes where both landlord and resident running costs are reduced, and where environmental performance is improved. This is achieved through increased levels of insulation, improved construction air-tightness, and improved water efficiency.

As part of the initiative the following issues were considered at the design stage:
• energy efficiency – embodied and in use
• economical water usage
• environmental impact
• cost and life of building components.

Environmental features

As with many brownfield sites contamination issues needed to be addressed. Prefabricated foundations were used to save time on site mitigation works. Pre-cast piles and ground beams with an extruded floor and 200mm of mineral wool insulation were chosen over traditional piled foundations and cast in situ ground beams.

A lightweight steel frame system from Forge-Llewellyn was used to enable fast erection times and allow high insulation levels to be added on site.

The roof is a pre-assembled steel frame with 200mm mineral wool insulation and 75mm mineral wool batts.

Internal partitions are constructed with 75mm non-structural partitions, which provide layout flexibility and allow for future re-arrangements.

The windows and rooflights are softwood frame with double glazed argon filled low emissivity glass. The steel frame enables the roof space to be used as habitable space. Sun Pipes provide natural lighting into internal staircases for flats. Dedicated low energy light fittings and bulbs are installed.

Rainwater recycling systems use ECOVAT underground rainwater storage containers. The water is used for WC flushing (6 litre) and in washing machines. This system also addressed site drainage capacity problems economically.

Insulation levels are so high that a traditional wet heating system is not required. Heat loads are reduced to less than 3kW and a heat recovery system is sufficient to heat the homes. Whole house mechanical ventilation, with heat recovery (MVHR) system is installed to all units. Heating costs are expected to be in the region of £30 per year.

A service zone contains electricity, gas, drainage and telecoms. connections. Rewiring is made easier by the use of trunking.

Porous blocks are used for hard landscaping, providing a sustainable urban drainage (SUDs) system.
Wheelie bin stores and recycling points are provided to encourage household waste reduction and recycling.

The homes are draught free. Passive ventilation (Passivent) systems will provide fresh air to the rooms and reduce the risk of condensation.

Water conservation features include 6 litre low flush WCs, showers over baths, aerated taps and water butts.
The houses have been built to Lifetime Homes standard to enable flexibility to accommodate residents throughout their lifetimes.

Costs

The overall scheme cost is expected to be in the region of £958,000, with an average unit cost of £87,000 or £692 per m².

Additional costs arising from the small scale purchasing of timber cassettes has been offset, to some extent, by savings on site from faster construction times and the use of fewer trades. PCKO designed the homes to maximise off site factory production methods that could be replicated in future developments.

Residents pay standard rents, ensuring the houses are affordable. The energy efficient design and construction offers the potential for substantial energy and water savings to be made by residents.

Developers comments

Wilton Road was one of the first round Housing Forum Demonstration Projects to be approved and as such proved a valuable example of both the partnering approach (with contractor Llewellyn Construction) as well as of a sustainable urban development. Detailed monitoring of four of the MVHR systems are being undertaken for a 12 month period to establish real operating benefit. Already residents with asthmatic conditions have noted significant air quality and thermal comfort benefits.

The quality of the construction and the significant environmental benefits produced have combined to make this a highly successful flagship scheme for Ealing Family and Reading Borough Council.

Further information

Developers: Catalyst Housing Group: www.chg.org.uk