Specifier Review


Forty-eight houses in Luton are benefitting from the retrofit of external wall insulation (EWI) from Sto as part of the Council’s on-going refurbishment programme.

The post-war properties are Orlit houses made of precast reinforced concrete.  This building method has long been recognised to have a particular problem with thermal insulation.  Designed  to improve the comfort and insulation levels, the refurbishment was in this case funded by the Carbon Energy Saving Programme (CESP) designed to target areas of deprivation.

These houses were identified by Luton Borough Council as being in immediate need of upgrade.  Abdul Kahir, Programme Manager at Luton Borough Council was clear about the reasons for specifying EWIS. “There was no option.  The concrete walls provided no effective thermal insulation and the retrofit of external insulation was the only viable solution.”

Thermal insulation is provided in this project by 90mm of LambdaTherm EPS (this insulation material includes graphite to maximise the thermal properties). The system is finished with a robust silicone render, specified in a colour to match as closely as possible the original paint finish.   The resulting walls have a U-value of 0.28W/m2K.

The entire refurbishment programme was contracted to Wates, whose Quantity Surveyor was responsible for the specification. “The properties have met the low U-Values that we specified and the tenants are happy, they say it’s a lot warmer.”


With the CESP programme finishing in December 2012, further funding for refurbishment projects such as this one will come through the Energy Company Obligation (ECO) and Luton is well into the planning stages for the next tranche of refurbishment projects also designed to improve the thermal insulation of the properties.