Energy efficient house designs can be generated using thermal performance assessment techniques. Building thermal performance is the assessment or rating of a building’s ability to create internal conditions that are comfortable for the occupants, with a minimum of mechanical input. Mechanical input refers to the consumption of energy by heating or cooling appliances. Energy efficiency refers to the effectiveness of a building’s ability to influence, control and facilitate user control over the movement of heat energy within a building and between the building and its surroundings.
The most important attribute of a building in relation to its energy efficiency is the building envelope, which refers to the exterior fabric of the building. The movement of heat energy within a building has a less important affect. Residential thermal performance refers to the energy efficiency of a residential building (generally single dwelling houses and multi-dwelling apartments).
A number of factors affect the energy efficiency of house designs, including:
* climate and wind
* location, landform, vegetation and environment
* building orientation, form and design
* materials used and how they are employed
* occupancy and occupant behaviour
An energy efficient house stays naturally cool in summer and warm in winter. The house will be even more comfortable if the occupants perform simple operations and management tasks. This allows the occupants to maintain comfortable conditions in their home, without the excessive use of heaters and air conditioners. Accordingly, this reduces the mechanical input required and reduces the energy consumption of the building. Reducing energy consumption means less burning of fossil fuels, less carbon emissions and less general pollution generated by the building. That is, high residential thermal performance gives the occupants the opportunity to have a healthier and more comfortable home that costs less to heat and cool and also reduces the impact of energy consumption on our environment.
The Star rating system in Australia rates the thermal performance of a building on a scale of 1 to 10. A 10 Star house would be one in which no energy is required to be consumed in order to maintain comfortable conditions for the occupants. Theoretically a 10 Star house is possible, however in practice a 9 Star house is typically the best rating that can be achieved.
Such a high thermal performance house is commonly referred to as an energy efficient house. If the owners or designers of the home also include other environmentally aware features such as waste water treatment, environmentally friendly and low life cycle cost building materials, rain water gathering and treatment, solar and/or wind generation devices, etc, one might refer to it as a sustainable house.