A retired couple from Northumberland who built a house of their own to be efficient to run, comfortable and carbon neutral have turned to STYROFOAM-A extruded polystyrene insulation to help them achieve their dream.
Their so-called ‘Green House’ is built on a plot of land sloping away from what was Bryn and Pam Owen’s rear garden. Planning restrictions in an Area of Outstanding Beauty demanded a design that would have minimal visual impact – and the sloping site was turned to advantage by opting for a subterranean house.
“We decided we would have nothing above the road level which would not normally be found in a large country garden,” explained Pam. “We wanted to make a minimal impact and as one as our grandsons so nicely put it, it also has the advantage that when we die we will already be six foot under!”
The house is built into the hillside, with the main living rooms looking through large windows which face east. The design incorporates a central courtyard with a glass lantern to allow light into bedrooms, and is topped off with a green roof which supports a chalet-style building to house the entrance at street level. The roof also includes solar panels and rainwater collection facilities.
With a design aimed at achieving standards equivalent to Level 6 of the Code for Sustainable Homes – even if registration was not mandatory for such a one-off, private dwelling – the Owens designed insulation, heating and lighting systems to ensure the house would be carbon neutral. This meant installing insulation which would deliver required U-values and maintain effective thermal performance even in a harsh, underground environment.
“We decided to work to target U-values of 0.15W/m2K for surfaces next to air and 0.2W/m2K where they were in the ground, as the temperature rarely drops to -50⁰C in our region and the calculated heat requirement of 3KW could easily be provided by a simple heating system,” added Bryn.
Key to achieving the U-value targets for the floor was below-slab insulation which needed to withstand the load of the building and perform in an external environment. STYROFOAM-A material FLOORMATE 500-A was specified thanks to its high compressive strength and moisture resistance. The Owen’s structural engineer recommended a thickness of 100mm to achieve the desired U-value at the same time as meeting mechanical strength requirements.
In addition, basement walls were also insulated with a STYROFOAM-A product, chosen not just for its effective moisture resistance and good thermal performance but its design. PERIMATE DI-A was specified for the underground walls as it contains vertical drainage channels protected by a geo-textile fabric to help prevent them becoming clogged with soil. According to the Owens, other areas of the building did not have such specific structural requirements, meaning less specialised products could be specified elsewhere.
“The total insulation package, combined with high technology glazing, has allowed us to achieve a predicted carbon positive house which calculations show will require little or no heating for all but the coldest of days,” enthused Bryn. “We have gone above and beyond Building Regulations in terms of the amount of insulation required but modelling we have done shows that this cost should be more than off-set by eliminating the need for a central heating boiler and lower energy bills.”
STYROFOAM-A extruded polystyrene materials are highly durable with proven moisture-resistance and compressive strength, enabling the insulation to perform outside the waterproofing envelope. Installing insulation below concrete floor slabs also helps to minimise thermal bridges at floor and wall junctions and further reduce heat loss.