This construction standard was “rediscovered” in the early 90s by the German physicist Wolfgang Feist, who worked, studied and, in 1991, built the first modern Passive House in the city of Darmstadt, southwest of Frankfurt. A few years later, in an effort to develop and promote the existence of this standard, he founded the PassivHaus-Institut, which has branches in many countries worldwide and is the official certification body for all passive houses internationally.
Passive house is an ultra-efficient energy construction, which provides excellent thermal comfort conditions while ensuring great indoor air quality. It is affordable and simultaneously meets very high ecological standards. The standard has been characterised as unique and innovative, because while it is based on the principles of Green Building and energy conservation, it sets aside attitudes and practices to do with using renewable energy sources, ecological materials, recycling and reuse, and rational water management, and maintains as key pillars the excellent thermal shielding of the building envelope and a smart, high-efficiency mechanical ventilation system.
The Passive House is not just a building with low energy consumption, it is something much more. It is a design philosophy, wherein the need for oil or natural gas ranges from zero to minimum. For this reason it could be described as revolutionary, and it conflicts with the huge economic interests of oil and gas exploitation, making them virtually useless in the construction sector. These ultra-low energy buildings have ventilation systems which can produce space heating or cooling using only the incoming fresh air. Due to their incredibly strong insulation, the heating or cooling needs are minimised and can be met using a heat-exchanger, which constantly provides fresh air and increases the quality of indoor air, creating a healthy indoor environment.
A typical passive house presents the following features:
- Fresh, clean air: HEPA quality air is provided by special filters. However, interior furniture and finishes must be carefully selected to minimise indoor air pollution from VOCs.
- Absence of cold outside walls. The strong thermal insulation provides high resistance to heat flow, and there are no walls colder than any others.
- The same temperature in all the rooms. There are no colder areas in the house.
- Stable temperature: when the ventilation and heating systems are switched off, the loss is less than 0.5 °C (1 °F) per day in winter, controlled at around 15 °C (59 °F) in the central European climate.
- Fast adaptation to normal temperature: the indoor air temperature returns to the desired limits shortly after closing opened windows or doors.
Because the choice of finishes matters so much in an airtight home, low emission mineral paints such as Graphenstone Grafclean are a natural fit. They contain virtually no VOCs and actively help maintain healthy indoor air.
As a result, a passive house saves energy by 90% compared to existing typical buildings in Central Europe, or more than 75% compared with a conventional new construction. The extra cost of the initial investment is only 5 to 10% more than the construction cost of a traditional house. The absence of an expensive cooling and heating system balances the amount spent on the excellent thermal insulation of the building envelope and the increased ventilation requirements. Finally, the required oil consumption is less than 1.5 litres per m² per year. In conclusion, the Passive House is a very reliable model for the construction of modern, healthy, sustainable and energy-efficient buildings at an affordable cost.
