“Am Buir”, Wassenberg, Germany – the world’s smallest Passive House

Author: Rongen Architekten
Propsteigasse 2, 41849 Wassenberg, Germany

Architecture is more than just superficial design. Good architecture means finding solutions to combine function and artistic value with comfort, affordability and ecology.

The Passive House provides a successful and sustainable concept to adress this challenge. However, achieving the Passive House Standard is a particularly challenging task in the case of a building which has a total living area of only 83m² and whose rear wall is part of the historical city wall – and even more so if a considerable part of the original building has to be retained due to building preservation requirements.

In the case of the “Am Buir” building located in Wassenberg, Germany, the historical buildings preservation authority required that the volume and shape of the building be retained to conform exactly with the original construction.

Street view - before
photograph: Rongen Architekten
Street view - after
photograph: Rongen Architekten

Rear view - before
photograph: Rongen Architekten
Rear view - after
photograph: Rongen Architekten

The surface-to-volume ratio has a decisive influence on the heating demand of a building. This ratio is disproportionately large in small free-standing houses – therfore transmission heat losses are particularly significant. Achieving the Passive House Standard is therefore all the more difficult in small buildings.

am_buir_abb_5_exterior_.jpgSAMSUNG DIGITAL CAMERA
Street view
photograph: Rongen Architekten
The city wall and the house are one structural unit
photograph: Rongen Architekten

Despite its unfavourable size, the “Am Buir” building achieved the Passive House Standard through a series of measures ranging from windows with excellent U and g-values oriented towards the sunny side to a ventilation system with a high level of heat recovery.

The insulation of the facade plays a key role: The application of an exterior insulation system based on rigid resol foam with excellent thermal qualities (ʎR = 0.022 W/mK) allowed for the thickness of the external wall insulation to be limited to 240 mm. For comparison: today’s “standard” exterior insulation systems (ʎR ≈ 0.040 W/mK) would have required an insulation thickness of approx. 430mm. Rigid resol foam belongs to the building materials class B1 and thus also has good fire-resisting properties. The material does not contain CFC and HCFC and therefore does not pose a health hazard.

The insulation material was applied in two layers, each being 120mm thick, thus preventing continuous gaps and unnecessary thermal bridges. The first layer of insulation panels was applied using adhesive and dowels. Three vertical lines of adhesive cement were applied at the edges; the evenly applied cement ensured that at least 60% of the area was in contact with the subsurface after pressing the panel to the wall. In order to minimise the risk of cracks, the insulation panels were notched at the corners of windows and doors preventing gaps in the insulation. Finally, the panels were additionally dowelled. Afterwards the second layer of insulation panels was attached by applying a continuous layer of adhesive all over the panels. In the next work step, reinforced mortar with a particle size of 0.5 mm was applied, which gave a fine surface structure. The light finishing coat was selected because of its high water vapour permeability which helps to create a healthy indoor climate.

After the plaster had dried, the white facade paint was applied. It provides an interesting contrast to the dark and almost frameless appearance of the window areas and the external walls which are partially panelled with anthracite-coloured larchwood slats that have been pre-varnished (thus anticipating the natural weathering process of the wood).

Despite the two layers of insulation with a total thickness of 240mm, the facade remains slender. The implementation of this particularly small Passive House disproves the misconception that Passive Houses are poorly designed and bulky blocks.

Far from being a “shapelsss eyesore”, this house is an inseparable part of the historical city wall with its medieval “Verlorenenturm” (a prison for the condemned).

am_buir_abb_7_exterior_.jpgTechnical data:

→ Triple-glazed, wood/fibreglass windows
Uw=0.65 W/m²K, g-value= 52%

→ Ventilation system with a heat recovery
rate of 92%

n50 = 0.3 h-1

→ Specific space heating demand:
13.7 kWh/(m²a)

→ Primary energy demand:
112 kWh/(m²a)
View from the south; photograph: Rongen Architekten

Impressions of the interior; photograph: Rongen Architekten

Architects: Rongen Architekten
Propsteigasse 2, 41849 Wassenberg, Germany

examples/residential_buildings/single_-_family_houses/central_europe/am_buir_wassenberg_germany_the_world_s_smallest_passive_house.txt · Last modified: 2014/09/18 18:19 by