Passivhaus Design - A New Old Theory
Considering the push for sustainable living & the need & demand to reduce the impact on our planet, i felt it only right to explore the newest green design theory in the architecture industry. Yes i know it is a theory & practice that has occurred for over two decades already but in relative terms it is a baby when compared to other "Green" design theories, some of which have been used for hundreds of years.
The Passivhaus - definition
“A Passivhaus is a building, for which thermal comfort can be achieved solely by post-heating or post-cooling of the fresh air mass, which is required to achieve sufficient indoor air quality conditions – without the need for additional recirculation of air.”
(Courtesy of www.passivhaus.org.uk)
In essence Passivhaus design is a way of creating a home that is self sustainable with regards to its need for heating & cooling & its impact on the environment. A Passivhaus i not a carbon neutral house, however given the sustainable principles involved in Passivhaus design one can say that it is the perfect place to start when looking to carbon neutral architecture. The software used in Passivhaus design has the capability to determine what is required to make your home carbon neutral.
In order for your home to be deemed a Passivhaus it must achieve set targets set out in the Passivhaus standard for central Europe
- The building must be designed to have an annual heating demand as calculated with the Passivhaus Planning Package of not more than 15 kWh/m² per year (4746 btu/ft² per year) in heating and 15 kWh/m² per year cooling energy OR to be designed with a peak heat load of 10W/m²
- Total primary energy (source energy for electricity and etc.) consumption (primary energy for heating, hot water andelectricity) must not be more than 120 kWh/m² per year (3.79 × 104 btu/ft² per year)
- The building must not leak more air than 0.6 times the house volume per hour (n50 ≤ 0.6 / hour) at 50 Pa (N/m²) as tested by a blower door,
(Courtesy of Wikipedia)
When looking at how to design your Passivhau there are quite a few areas which need to be looked at when we talk about Passivhaus design. Passive solar building design supports the Passivehaus energy conservation and is a way of integrating them into local neighborhoods and environment.
The use of solar gain in Passivhaus design is; however a secondary thought when considering the overall house energy requirements. In warmer climates like Australis the need to reduce solar heat gain throughout the warmer months can be done in a myriad of ways such as the following; Fixed & moveable pergola's, deciduous trees & vines attached to the structure, green roof systems, High end glazing techniques & other design techniques.
There are no set methods or material choices with which to design & build your Passivehous however there are some set ideals on how to achieve a good Passivhaus design such as internal thermal mass which will assist with stabilising winter temperatures. There are generally thought to be 6 main items to consider when designing a Passivhaus. These areas are Windows, Insulation, Ventilation, Airtightness, Space Heating & Lighting/Electrical Appliances.
In order to have your home certified as a Passivhaus in the UK/Europe it is required to achieve certain targets with regards to heating/cooling/heating load & energy demand. These targets are shown below.
Energy performance targets
Specific Heating Demand≤ 15 kWh/m2. yr
Specific Cooling Demand≤ 15 kWh/m2. yr
Specific Heating Load≤ 10 W/m2
Specific Primary Energy Demand≤ 120 kWh/m2. yr
According to passivhaus.org.uk Passivhaus Standard can be achieved when refurbishing buildings although this can prove costly.
In closing Passivhaus theories in my opinion are very much the taking of general sustainable design principles that are then pushed to the extreme in order to achieve a home that has the capabilities of heating & cooling itself & acheiving sustainable targets never before thought possible. When used in conjunction with Carbon neutral design principles a Passivhaus home is the ultimate in sustainable living & something we all should be looking at acheiving when we go through the design/construction proces.
we as designers & clients need to understand that a larger home with visible opulence is not necessarily the best way to go. We should take more time to consider our impact on the environment & how a Passivhaus design & sustainable building material choices can reduce our impact on the environment & enrich our lives.