Airtight dwelling – built to prevent warm air leaking out and cold air leaking in.

Passive House - a voluntary building standard producing ultra low-energy dwellings that require little energy for space heating or cooling.

Healthy Home - a house that is healthy for its occupants as well as for the global environment.

Solar PV – electrical power provided by the sun.

MVHR – Mechanical Ventilation and Heat Recovery, a low-energy system for ventilating an indoor environment at the same time as reusing the warmth in the old air.

Timber frame - Modern method of construction recognised in sustainable building for environmental impact of materials, responsible sourcing, construction waste reduction, airtightness and sound insulation.

Prefabricated wall panels - pre–assembled panels that can accelerate the build process. They typically include insulation, moisture control layers and the weathering envelope and have high insulating properties.

Hemcrete - a blend of a lime based binder and the woody core of the hemp plant, now an established walling material for highly thermally efficient walls.

AECB – an independent network of builders, architects, designers, manufacturers, housing associations and local authorities, working to develop, share and promote best practice in environmentally sustainable building www.AECB.net

The Green Register - a not-for-profit organisation offering expert and unbiased training in sustainable building practices to all disciplines of the construction industry www.greenregister.org.uk

Natural insulation – insulation made from recycled and sustainable materials such as sheep wool, hemp, recycled paper, wood fibre and recycled plastic bottles.

U-values - a measure of how well a building component such as a wall, roof or a window, keeps heat inside a building, or in a warm climate how long the inside of the building can be kept cold.

Sustainable envelope system -

Zero C Home – Zero-carbon homes produce zero or even negative CO2 emissions by maximising the use of energy efficiency and renewable energy. All new houses must be zero-carbon from 2016 onwards.