The practice was initially granted planning consent to extend the existing 1970s house, providing a new entrance and increasing the floor area.
Practice principal Robert Dye said: 'We've been able to expand the area of the building by about a third, it's now approximately 450m2.
'We originally wanted to simply extend the existing house, but the client realised it would be more efficient to demolish and rebuild.
'The existing house is not as energy efficient, they took a rather commercial building approach to the house. We believe we can create a more sustainable home; we are using green roofs and providing better thermal massing and insulation,' Dye added.
The new house will start on site early next year, with completion scheduled for early 2009.