If you like to think of yourself as eco-aware, and you know your solar panels from your rainwater harvesting, then you may be interested to learn about Passivhaus and the Passivhaus standards. The brainchild of Professors Wolfgang Feist, of the Institute for Housing and the Environment in Germany, and Bo Adamson, of Lund University, Sweden, Passivhaus is a set of voluntary standards for energy efficiency in buildings. Passivhaus design is not just limited to housing, but can be expanded to any structure, with Passivhaus offices, schools and even a supermarket having been constructed, and it can be retrofitted to existing structures as well as new designs. There have been an estimated 25,000+ Passivhaus structures built as of 2010.
The main concept of Passivhaus is the reduction of a structure’s carbon footprint and production of a building that is ultra-efficient in its energy usage, typically achieving an energy saving of 77% compared to conventional contemporary structures built to UK Building Regulations. This is achieved through a number of methods:
- Passive solar design, whereby a structure is designed to make the most of the sun’s energy for cold climates, but can also reduce or reflect solar energy in excessive heat. Utilising passive solar building techniques produces a stable climate within the building all year round, reducing the need for a separate method of heating.
- Superinsulation significantly reduces the amount of heat that transfers through the walls, floors and roofs of conventional builds.
- Advanced window technology, in particular triple-glazing with low-emissivity coatings, gas-filled inter-pane spaces, insulating glass spacers and specially-developed window frames, allow heat energy from the sun to enter the structure with minimal heat losses, even in winter.
- Airtight construction minimises the amount of hot or cold air that can enter the building and potentially disrupt the designed climate. A Passivhaus construction must not leak more air than 0.6 times the house volume per hour.
- Mechanical heat recovery ventilation systems with a heat recovery rate of over 80% can be used to maintain interior climates instead of installing conventional central heating systems.
- Space heating from alternative means, such as electrical lighting, household appliances or even waste body heat. Heating through such methods, combined with the above conservation methods, eliminates the need for a conventional central heating system, and a well-designed Passivhaus structure should not need any other heat source other than the ventilation heat recovery system outlined above.
- Lighting is first and foremost provided through natural sunlight for a Passivhaus structure, but when this isn’t appropriate low energy solutions are sought. LED, OLED (Organic Light-Emitting Diodes) and PLED (Polymer Light-Emitting Diodes) are often used, along with low-voltage solutions such as Xenon and Halogen lights. Timers and motion sensors can also limit energy loss and light pollution.
Due to these measures, a Passive House typically loses less than 0.5°C per day when its ventilation and heating systems are switched off, and stabilises to around 15°C in central European climates. Unlike zero energy structures, Passivhaus does not seek to balance the amount of energy used with the amount created through renewable energy sources, but rather seeks to reduce energy consumption to the lowest possible degree. Zero energy and renewable energy concepts can be used in conjunction with Passivhaus standards to create fully sustainable structures.
