A Super-E Airtight Kit House

"As a child I always wanted to be a builder, and started out working as a bricklayer which meant that it took me some time before I realised the benefits of building with timber frame," says Doug Stewart. "I'm currently doing a degree in Building Processes, which has made me far more aware of sustainable options, and attended a seminar promoting Super E housing which really inspired me."

Doug's interest in sustainable construction has led him to be among the first in the UK to embrace the state-of-the-art technology embodied in the Super E programme: the recognised brand name for high quality Canadian housing, designed to help Canadian exporters deliver healthy, energy efficient housing to other countries. This airtight construction with a heat recovery ventilation system, high levels of cellulose insulation and underfloor heating, is extremely comfortable to live in and drastically reduces heating bills.

Doug is managing director of DGS Construction Ltd, a building company based in Milton Keynes which specialises in building and renovating individual houses and small scale developments. Recently, the company has entered into a partnership with DAC International, a Canadian company producing bespoke Super E homes. The result of this collaboration is the first bespoke self-build Super E home to be built in the UK.

Doug and his wife, Sarah, had spent five years searching Cornwall for a suitable site on which to build their new house, eventually discovering a piece of land near Torpoint, on which stood a tumbledown timber clad bungalow. The 0.3 acre plot was overgrown with brambles and littered with old cars and refrigerators, but the stunning elevated site is situated in open countryside within walking distance of the sea, and was exactly what the Stewarts had been waiting for.

Convincing the planners to allow them to replace the dilapidated bungalow with a two storey house proved far harder than Sarah and Doug had imagined, however.

"Catchfrench, our architect, took our concept from a rough sketch and made a convincing case to the planners, and we had great support from the Super E supplier in Canada," says Doug. "We had to prove residential status, and I went into the village and asked around until I found the last two occupants, who gave written evidence which satisfied the planners. It was a struggle, and I didn't tell Sarah just how difficult things had been until after planning permission was granted, as I knew she would worry."

The new house has been designed with flexible accommodation in the form of two spacious flats, enabling Sarah and Doug to live primarily on the first floor. "It was only when I stood on the roof of the old bungalow and looked over the hedges that I realised what wonderful views the upstairs rooms would have," Doug explains. "This fact has influenced the whole design, and we have our master bedroom suite and main living spaces upstairs, with three additional bedrooms, a kitchen, bathroom and lounge downstairs for guests. If you are considering building a Super E house it makes sense to experience what it is like to live in one, and we hope to be able to offer accommodation to other self-builders who would like to find out more about this kind of building."

Doug visited Canada and spent three days working closely with kit supplier DAC International, its design team and the frame erector. He was extremely impressed by the detail and quality of the timber frames and the technical support.

"Bringing three huge containers into the country from Canada proved to be a real learning experience," Doug recalls. "Not only did we have to navigate the red tape to pass customs, but we were shocked to discover that VAT and import duty would have to be paid up front before customs would let the containers into the country. We were able to reclaim the VAT at the end of the project, but it was still an unwelcome addition to the budget."

Building a new home 250 miles from where you live and work was never going to be easy, but Doug's son, Matthew, ran the family business in Milton Keynes while Doug stayed in Cornwall. Sarah was very supportive, but refused to move into the shack on site where Doug camped throughout the summer of 2003. Later, some neighbours rented the couple a holiday property close by, which enabled Sarah to become involved with fitting out all of the interiors.

In addition to designing the house and project managing the build, Doug was responsible for constructing the foundations, drains and central core, which incorporates the chimneys although he travelled to Cambodia once the timber frame had been erected, leaving Sarah to organise the roofing.

Renewable and sustainable resources were used wherever possible. The engineered timber structure with panelised walls has been clad with cedar on a local stone plinth. Heavy Fermacell boards, produced from recycled paper and gypsum, were used for the floor, walls and ceilings instead of plasterboard and chipboard, providing a tougher finish, enhancing fire retardancy and limiting the transfer of sound within the house. Excel Warmcel cellulose insulation, made from recycled newsprint, has been blown within the 140mm frame, and every effort was made to ensure the building would be as airtight as possible.

"We were fortunate to find subcontractors who were interested and sympathetic to our requirements - even if they did not always agree with our ideas," says Sarah, 41. Our Cornish neighbours were sceptical at first, but always offered a helping hand, and even the use of their forklift truck."

One of Doug and Sarah's biggest setbacks occurred when the house failed to pass the air pressure test which is required for Super E certification, and is based upon the Canadian R-2000 standard, adapted for local climates. "Most houses in the UK can expect at least ten air changes an hour but 1.5 is required for certification, and we finally achieved 0.9 following remedial work to the garage," Doug explains. "Air had been getting in through this area, and there was a moment of panic during the second test when we thought the house would fail again until we realised that someone had left the plant room door open!"

A sophisticated heat recovery and ventilation system minimises heat loss by maintaining between 0.5 and 1.5 air changes per hour at 50 pascals of pressure, and a ground source heat pump supplies heat to the underfloor heating and hot water from underground heat collecting panels, with independent hot water cylinders on each floor which have the facility to add solar heating in the future. The heat pump converts 1kW of electricity into 4kW of heat.

"People wrongly assume that with an airtight house you need to keep all of the windows shut, which just isn't true," says Sarah. "In the summer we open the windows, which are fitted with fly screens to keep insects out of the house. The Super E system really comes into its own during the winter, however, and we have yet to turn on the underfloor heating because the house has been so warm. We've also installed Scandinavian soapstone log burners on each floor, which are 95 per cent efficient and require an external combustion air source to maintain the buildings air tightness."

"I am very keen to keep pushing the boundaries of sustainable building," says Doug. "Tackling something new is always going to be fraught with problems, but we were very impressed with the Canadian package, which included everything we needed to build the shell of the house - from the low-e, argon-filled double glazing to the cedar cladding. Hopefully we will inspire more people to take this route, because the house has exceeded our expectations and is really wonderful to live in."

Further reading:

• The A to Z of Green Homes
• A SIPs Self-build
• Whole House Ventilation and Built-in Vacuums