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planning:thermal_protection:external_walls:passive_house_suitable_wall_systems

Passive House suitable wall systems

The Passive House Standard, being a quality standard, dictates no particular methods of construction. Whether solid construction, wood or composite - architects can design Passive Houses according to their own preferences. Also manufacturers of prefabricated houses are offering Passive House designs. Decisive for the choice is the the previous knowledge of the project manager/planner in charge, which is important for a high quality implementation, and the requirements of the clients. In some cases further parameters are essential: If the plot prices are extermely high, e.g. in inner city locations, narrower build-ups like lightweight constructions are preferred and used at least in the external wall construction. In buildings with particularly high internal or solar loads massive building materials are preferred in order to add more termal capacity and prevent a too rapid heating up of the rooms in the diurnal variation.

In solid construction non-insulating masonry (for example lime-sandstone) or reinforced concrete with an Exterior Insulation and Finish System (EIFS) can be used. There are lots of materials suitable: e.g. polstyrene (thermal conductivity 0.032 to 0.04 W/(mK)) or mineral wool (thermal conductivity 0.04 W/(mK)), but also resin foam (thermal conductivity as low as 0.021 W/(mK)) or cork. Sometimes the masonry also consists of an insulating stone (e.g. porous concrete). The insulation thickness of the EIFS as a rule is between 150 and 300 mm in a Passive House, but can be bonded as single-layer up to 400 mm. Also monolithic systems of porous concrete or brick are available on the market. At the end, its the U-value, that counts - and it can be achieved in a lot of different ways.

In timber construction plywood I-beam structures are often used so that the proportion of thermal bridges through wood can be reduced, but solid timber constructions are also used as they can be put into effect by a wider range of craftsmen. Often a cross layer or a combination with EIFS is used to reduce thermal bridges. The total insulation thickness here is more likely to be between 250 and 400 mm in the cool moderate climate zone - less in warmer climates, more in the arctic e.g.

Just as common is the mixed construction with a solid supporting structure (reinforced concrete partitions or reinforced concrete skeleton structure) together with timber panel components for the external walls. Both can also be unitised which allows for shorter construction times.

Concrete formwork bricks of polystyrene or PS (“insulated concrete forms, ICFs”), sometimes with expanded clay, are used mostly for detached houses. Wall systems with vacuum insulation panels using films or steel plates are used more and more frequently, but due to the technique and the required quality control they are still relatively expensive. Passive House suitable solutions are even available for classic steel constructions.

Overview of Passive House suitable external wall systems (cool moderate climate)

ph_suitable_ext_wall_systems.jpg
*VIP = Vacuum insulation panel


See also

Literature

W. Feist: Gestaltungsgrundlagen Passivhäuser. Darmstadt 2001; This is on Passive House Design Fundamentals, PHI Darmstadt 2010.
W. Feist: Wohnbauten mit Stahltragwerk als Niedrigenergie- oder Passivhäuser - Anforderungen an die Gebäudehülle, NRW-Stahlbau-Kongress, 2006

planning/thermal_protection/external_walls/passive_house_suitable_wall_systems.txt · Last modified: 2015/09/13 11:45 by wfeist