A closer look into Passivhauss
On January 17 we attended the RIBA Passivhaus debate: Rewards and challenges in social housing at the SS Britain in Bristol, where we could listen to experts on the current passive house situation in the UK. This conference has encouraged us to study the Passivhaus more thoroughly.
1. What is a Passivhaus?
The term "Passive House" refers to a truly energy efficient and a comfortable house designed not to lose any energy through the build-ups, creating an affordable and ecological house at the same time.
The 5 basic principles apply to the construction of a Passivhaus:
- Thermal insulation
- Well insulated frames and triple glazing windows.
- Ventilation heat recovery
- Airtightness of the building.
- Absence of thermal bridges.
A Passivhaus will allow lower energy bills and independence of the fuel price increases. The house will be warmer in winter and cooler in summer due to the construction system.
2. A little history of the Passivhaus
In 1996, the Passivhaus-Instut was founded in Darmstdt, Germany, after the first Passivhouse residences were built in 1990. This institute was created to promote and maintain Passivhaus standards as energy efficiency in a building.
It is estimated that by 2008 the number of certified Passivhaus around the world ranged between 15,000 and 20,000 structures. In 2010 there were approximately 25,000 certified structures in Europe, mainly in Germany, Austria and Scandinavia.
3. How does a Passivhaus work?
We could say that a Passivhaus is a building so well insulated that it keeps all the heat inside the house. Heat recovery systems are used for ventilation to keep a house ventilated but without losing energy inside. The maintenance of a passive house will be very cheap because the "free" heat is generated in all electrical and gas appliances, such as ovens, refrigerators, computers and light bulbs. The envelope of a Passive House building will be extremely well insulated and sealed, so that this "free" heat can not accidentally escape from the building.
When we talk about super insulation, we are referring to a much greater level of insulation and airtightness than usual.
4. Requirements for a Passivhaus:
For a building to be considered a Passivhaus, it must meet the following criteria:
1. The Space Heating Energy Demand is not to exceed 15 kWh per square meter of net living space (treated floor area) per year or 10 W per square meter peak demand.
2. The Renewable Primary Energy Demand (PER, according to PHI method), the total energy to be used for all domestic applications (heating, hot water and domestic electricity) must not exceed 60 kWh per square meter of treated floor area per year for Passive House Classic.
3. In terms of Airtightness, a maximum of 0.6 air changes per hour at 50 Pascals pressure (ACH50), as verified with an onsite pressure test (in both pressurized and depressurized states).
4. Thermal comfort must be met for all living areas during winter as well as in summer, with not more than 10 % of the hours in a given year over 25 °C.
5. Difference between Passivhaus and solar passive design
When we talk about passive design, we are thinking about building location and orientation on the site, shading and ventilation.
A sustainable design achieves this by using free, renewable sources of energy such as sun and wind to provide household heating, cooling, ventilation and lighting, thereby reducing or removing the need for mechanical heating or cooling
Solar Passive design and Passivhouse overlap in a high insulated envelope and thermal mass but is really easy to incorporate passive design features once the building is completed (you can update the insulation or install new windows) a Passivhaus is only achievable from the beginning.
6. Passivhaus & Architecture
Having a superisulated house doesn’t means that you have to give up an astonishing design.
- The Hudson Passive Project, New York State, USA, 2010
A prototype house-of-tomorrow where they apply all the Passivhouse principles is the first certified passive house in New York State, USA.
- La Maison Bambou, Val d’Oise, France, Karawitz Architecture, 2009
La Maison Bambou Is the first certified Passivhaus in France.
- Lime Tree Passivhaus, Swaffham, Norfolk, UK, Parsons + Whittley Architects, 2015
- Dursley Treehouse, Dursley, Gloucestershire, UK, M+H Workshop, 2016