Eco-friendly and sustainable building is growing in popularity to help reduce carbon emissions and save energy.

One of the original movements towards a sustainable way of building and living is PassivHaus. PassivHaus is a voluntary building standard and concept that was developed in Germany in the 1990's and is a high standard implemented to build low-energy homes around the world. It enables energy efficiency in the home and keeps energy costs to a minimum as well as reducing carbon emissions.

PassivHaus is based on the principle that reducing heat loss to a minimum is the most effective way of achieving a low carbon and green building and this standard used in a variety of buildings including homes, offices and schools.

There are six main criteria for building a PassivHaus which are:

• Super insulation with optimum heat retention within the building

• Maximum draft proofing

• Ventilation combined with heat recovery

• Solar panels to harness the sun's heat

• Renewable energy sources for instance using solar photovoltaic panels that convert solar radiation into electricity

• Energy efficient appliances which reduce energy consumption.

A PassivHaus is built to be completely airtight and is essentially a constructed shell with the optimum level of insulation that preserves heat and therefore requires little or no additional heating inside the building. Insulation includes high performance thermal windows and doors with double and triple glazing, an insulated roof and floor and insulation fitted in exterior walls.

The PassivHaus philosophy of optimum insulation is also combined with the use of a mechanical ventilation with heat recovery (MVHR) system which provides ventilation and captures and re-uses that ventilated air for heat which would otherwise be lost through draft gaps in the home. The MVHR system continuously purifies the air, expelling stale air and drawing pure air from the outside of the building as well as recovering the air in the building to use for heat. Up to 94.4% heat recovery can be achieved with MVHR systems. Outside air is rolled into the heat exchanger within the system which warms the air and when warm it is distributed evenly around the building.

A MVHR system is also the method used for cooling a building when the climate is warm so that warm air is actually cooled instead of heated and distributed evenly around the building. Shades on the building are also used to minimize the amount of heat that a building is exposed to and keeps the building cool in warm climates.

Solar panels are placed on the roof to capture the sun's radiation and to use this natural source of energy to generate electricity.

The energy savings in a PassivHaus achieved compared to typical Northern European properties is 90% and compared to new build homes over 75%.

Where a PassivHaus building is located and if it is facing North, South, East and West can determine the building design and where the coolant shades and solar panels are situated. PassivHaus can be used both at the point of constructing a new building or incorporated into a renovation or refit of an existing building.