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Passive certified Office building "Aeroplis II"

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Office building designed to use minimum energy and take what it needs from renewable sources, while offering optimal comfort for occupants – which was delivered in 06/2011

Aeropolis is an urban UFO. Its compact form sits square on street alignment south just to show it does belong there, discretely steps back west liberating a sunny plaza like a breather off the busy boulevard, and humbly aligns its cornice levels with the massive KINETIX next door. The resulting built form wraps itself around a federating patio ensuring optimal daylight entry for all occupants. So it is a respectful UFO.


Aeropolis is also an eco-UFO, being at design stage Europe’s largest passive office building, Belgium’s largest when finished. Environmental concerns were an integral part of the client brief at competition stage already, so from the onset priority was given to investments and construction principles reducing energy consumption and the use of non-renewable resources. Highly-effective thermal insulation and efficient natural (daytime) and forced (night) ventilations (without resorting to the use of « energy-squandering » cooling systems) help reach these goals.


The compactness achieved limits façade surfaces, thus lowering thermal loss. The main load-bearing structure is bare pre-fabricated concrete, for its thermal inertia. Façade walls are composed of one-story high pre-fabricated timber frames of two types : opaque or glazed, of variable widths allowing them to be placed according to the varying organization of office spaces on each level … the resulting hopscotch of solids and gaps amplified by projecting volumes incorporating the automatically-opening ventilation frames.


The reduction of window surfaces down to 42.5% for each standard office and down to 29% for total window surfaces adds to the significant reduction of heat loss in winter, and reduces heating during cold spells. Along with the exterior solar protection, it is critical in limiting cooling during warmer periods. These reductions in no way hinder the generous flow of natural light (22%), reducing even more drastically total energy consumption.



Avenue Urbain Britsiers, 5 1030 Brussels



Groep Arco - KWB - KAV – KAJ


Structural engineering



Services engineer

Cenergie - ingenieursbureau Stockman


Project Manager




7 388 m² above ground level and 2 702 m² below ground level

Author(s) information


Architect Architectesassoc / Services engineer Cenergie + ingenieursbureau / Contractor Jacques Delens + Vanderstraeten Stockman


avenue de l'observatoire, 11 e 1180 brussels - belgium


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Additional documents

Available link languages

Operational date

Τετάρτη, 1 Ιούνιος, 2011

Relevant tools

PHPP 2007: Passive House Planning Package


Source of funding

Economic effect

Direct construction cost of 1260€/m² 3% estimated of additional cost compared to a conventional construction – including design & technical studies. Calculated gain of 32.000€ of annual energy savings with a 5 years return time for recovering this initial extra cost.