External wall insulation system specified for Passivhaus project

alsecco’s Basic 1 external wall insulation system has been specified for use in the construction of 14 Passivhaus units in Exeter.

The energy demand of a building can be reduced by up to 90% of a standard UK buildings’ by using the Passivhaus methodology.

Following a successful Passivhaus scheme, Exeter City Council contracted Gale & Snowden Architects to design the new properties, which have been built on unused infill sites.

The development forms part of the Council’s on-going strategy to address fuel poverty by building more council homes.

By using a fabric-first approach, the architect was able to design the properties to achieve the Passivhaus Standard; the new homes both address the issue of fuel poverty whilst offering lower fuel bills.

The developments also incorporate radial electric wiring to reduce the amount of electro-magnetic radiation, along with a range of additional measures to ensure a healthy and comfortable internal environment.

To achieve the Passivhaus Standard, the properties have been fitted with triple glazed windows, which complete the airtightness and insulation of the envelope. Each house will also have a mechanical ventilation system to ensure that it is properly ventilated.

alsecco’s Basic 1 external wall insulation system was also specified for use in the project.

Basic 1 external wall insulation system

Designed to eliminate the danger of interstitial condensation and thermal bridging, the EWI system was installed to the exterior of the medium density blockwork construction.

The system incorporates 250mm of grey expanded polystyrene above the DPC and 250mm extruded polystyrene below the DPC, with the insulation situated on the outside and the thermal mass of the block wall retained on the inside.

PRS Group was tasked with fitting the system; a Silitect top coat was then used to complete the installation, in cream on some properties and three shades of red on the others.

The system has helped the homes achieve U-values of 0.12W/m², allowing for fuel bill savings of approximately one-tenth, compared to traditionally constructed homes.

Since its completion, the project has achieved an award in the Domestic New Build category at the recent INCA (Insulated Render and Cladding Association) Awards.

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