In England, a handful of efficient demonstration homes have been built on the grounds of the Building Research Establishment Ltd, including “The Lighthouse,” which is the first net zero carbon house in the UK. The house is also the first to attain level six in the Code for Sustainable Homes, which indicates that it is carbon neutral. The two-bedroom house is only 93.3 square meters (barely over 1000 sq. ft.) in a 2-1/2 story building. The building has solar panels and evacuated solar tubes on its roof, as well as making use of passive measures with ventilation chimneys. It also incorporates rainwater catchment as part of the building design.