According to Paul Lavelle, the developer of eco-friendly property, Barnsley Hill in Gloucestershire, the property is so energy efficient it leaves the carbon footprint of a two-bedroom flat.  Barnsley Hill Farm is a 400 year old six-bedroom house with 25 seat cinema and a pool.
Energy efficiency which lead to the extremely low carbon footprint for a property of that age and size was achieved by the property being made airtight, the wall and roof was sealed with polyurethane blanket. The ventilation system was designed to bring in filtered fresh air, which is heat up by a heat exchanger powered by the outgoing warm air. Outgoing warm air heating up incoming cold air alone is said to reduce energy consumption of the property significantly.