A case for Passivhaus

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In the first of a series on Passivhaus sustainability expert Henrietta Lynch runs through the basics principles behind what is rapidly growing as a standard for low energy design for all types of buildings on the Continent

My passion for Passivhaus was sparked by the 12th annual Passivhaus conference, which I attended in Nuremberg. For those who have not yet heard of Passivhaus, this is the name of a performance based set of design criteria for very low energy buildings. It was developed in Darmstadt, Germany at the beginning of the 1990s by professor Wolfgang Feist together with professor Bo Adamson from Lund University in Sweden.

In 1996 the first Passivhaus Institut was established in Darmstadt with the aim of progressing and promoting the development of Passivhaus design. Since this date many other Institutes have been set up across Europe.

In the UK Passivhaus is represented by BRE, but the AECB (Sustainable Building Association) has also been doing work to promote and understanding of Passivhaus.

Benefits of Passivhuas designs

Passivhaus designs seek to eliminate the need for space heating and cooling through the use of Passive Solar Design principles (PSD), super-insulation, extremely air-tight fabric, no thermal bridges and the use of MVHR (Mechanical Ventilation with Heat Recovery).

To date well over 10,000 Passivhaus projects have been constructed around the world, these include for some schools, offices and apartment blocks

They rely on the use of good architectural detailing to work, and have been proven to be extremely successful with buildings built to Passivhaus standard typically showing a reduction in the need for space heating of 80% or more.

The first Passivhaus designs constructed were residential, however the specification is applicable to many other building types and also to refurbishment projects.

To date well over 10,000 Passivhaus projects have been constructed around the world, these include for some schools, offices and apartment blocks. Most of these are in Europe, but examples exist in the US, Korea and in various other climatic zones around the world with some Passivhaus developments planned for China.

Until now only a few pioneer UK architects have been working on Passivhaus designs and there are currently no accredited Passivhaus buildings in the UK although it is expected that some will be completed this autumn.

How to meet standards

In order to meet Passivhaus design standards a building must perform to energy use criteria for heating and cooling of no more than 15kWh/m²a and have an overall primary energy consumption (inclusive of energy use for electrical appliances and lighting) of no more than 120kWh/m²a.

The building envelope should also have ‘U’ values of 0.15W/m2K or less and the air-change rate should be less than 0.6 of the house volume per hour since the efficiency of the MRVH relies on a very air-tight fabric.

the US government has shown interest in Passivhaus with the US military currently building some test Passivhaus designs for their troops in Germany in order to see if this method of design could be applicable for all their military housing worldwide

The UK government has recently introduced the Code for Sustainable Homes (CSH) which outlines targets for low energy housing design with the eventual goal that all new homes being built in the UK be ‘zero-carbon’ by 2016, this target is 2011 for Wales.

The target for ‘zero-carbon’ non-residential building is currently 2019. Passivhaus relates to roughly CSH Level 4 in terms of energy performance or a 44% reduction in CO² against the requirements of the Building Regulations Part L 2006. The government target for all housing to meet CSH Level 4 is 2013.

Passiv is spreading

According to the Passivhaus Institut, the city of Frankfurt has now adopted the Passivhaus standards as requirements for all new public buildings and Germany as a whole is looking to adopt the standard for 2012.

Denmark has also set a target that all new housing should meet Passivhaus standards by 2020. And the interest is not confined to the Continent - the US government has shown interest in Passivhaus with the US military currently building some test Passivhaus designs for their troops in Germany in order to see if this method of design could be applicable for all their military housing worldwide .

Later this month I will be going to visit the ‘Passivhus Centrum’ in Alingsas, Sweden to look at what they are doing there to promote Passivhaus design and provide training for designers and contractors and see how this might be relevant to the UK.