Ecohomes Development, Upton

CHALLENGE

A lot of housing developments fail to deliver high standards of energy efficiency and sustainability. However, at Upton a southwest district of Northampton an eight year £41.5 million project is under way to extend the town in a way that demonstrates best practice in sustainable urban growth.

The plan is to create 345 traditionally designed houses and flats, all designed to meet EcoHomes high standards and achieve a National Homes Energy Rating (NHER) of ten. The development retains warmth during the winter and maintains cooler temperatures in hot summers.

The design team are using the ZED passive standards for airtight, super-insulated building fabric, with heat recovery ventilation on all buildings throughout the site. The effect of super insulating the building results in a lower requirement for heat and power, which in turn means that these requirements can be met by renewable energy sources on site, resulting in significantly lower carbon emissions and energy costs.

SOLUTION

In phase one of the Upton project, developers Mansells Construction specified 5,200m2 of Knauf Insulation's Crown DriTherm Cavity Slab 32 for use in 300mm cavities, using two layers of 100mm thickness and one layer of 75mm thickness. Crown DriTherm Cavity Slabs are semi-rigid or rigid slabs of non-combustible, glass mineral wool with a water repellent additive and are 455mm wide to suit standard vertical wall tie spacings, ensuring a closed joint with adjacent slabs. Crown DriTherm Cavity Slab 32 has a thermal conductivity of 0.032 W/mK.

According to the Promotion of European Passive Houses (PEP) document produced in 2006, to be able to achieve a zero carbon home, we need to drastically reduce the U-value of a building with roofs, floors and walls, all achieving U-values of 0.15 W/m2K or below. The inclusion of Crown DriTherm Cavity Slab in the Upton dwelling's wall cavities reduces the wall U-value to 0.11 W/m2K while also creating a 60% reduction in carbon.