Extruded Polystyrene Insulation Dow Styrofoam from DCT

project profile

Dow Styrofoam™ extruded polystyrene insulation key to
England's first Certified Passive House

Dow Building Solutions Styrofoam™ has been used to extensively insulate the floor, roof and basement walls of Underhill House, the first certified Passive House in England - a project recorded for the UK's Grand Designs TV series.

Underhill House in the Cotswolds at Barton-on-the-Heath in Gloucestershire is entirely glazed to the south. The rest of the building is earth sheltered and highly insulated, creating the perfect passive solar design. The structure of the underground house is constructed from concrete, much of which has been left exposed internally to exploit the benefits of its thermal mass. The basement walls, floors and roof are all insulated with Dow Styrofoam™. Using the insulation in this way helped to avoid thermal bridges at floor and wall junctions and meant the concrete structure of the building could be left exposed.

Exposed concrete absorbs heat in warm weather effectively cooling the building, and releases stored heat during cooler weather to provide a natural heating regime.

The Passive House concept was developed in Germany in the mid 1990s and is widely regarded as the world's leading standard in energy efficient construction. The standard requires very high levels of insulation, a design that makes the most of solar energy and that creates a well-sealed building.

"In order to meet Passive House standards we needed insulation which could maintain good thermal performance outside of the waterproofing envelope, as this would allow us to expose concrete within and make the most of the internal space," said architect Helen Seymour-Smith who now lives in Underhill House with her family.

"Insulation that can perform effectively in its environment for the expected lifetime of a building is key" she continued. "There's no point installing photovoltaic or a ground source heat pump if you're still leaking heat through the building fabric!"

Matthew Dyke for Dow Building Solutions states, "we believe that as regulations around the thermal performance of buildings become tighter in the drive towards more energy efficient buildings, insulation that can perform for the long term in such demanding environments will play a vital role".

Some grades of Dow Styrofoam™ products are now manufactured using technology that takes CO2 from industry and uses it as a blowing agent in order to create blue extruded polystyrene foam with a Global Warming Potential (GWP) of less than five. They offer lightweight yet robust performance, high strength and excellent moisture resistance, making it ideal for below-ground and exposed roof-top insulation demands.

Underhill House is a fantastic demonstration of how a combination of effective materials and an architect's vision can result in a beautiful yet practical family home that directly addresses environmental issues.

BBC - Grand Designs
Episode 14 - Series 7

Dynamic Composite Technologies is the authorised Australian distributor of Dow Building Solutions products including Styrofoam. For more information on the range of Dow Building Solutions contact us on 1800 051 100 or visit our website: www.dctech.com.au