Loft, Oudenaarde

Hangar becomes passive loft

Download the full project file (Dutch, pdf)




Industrial building

Construction date/


Renovation date/


Heated surface/


Heating demand

14,7 kWh/m².year (PHPP calculation)


Van Dorpe


Dirk Baert


This project deals with the renovation of a hangar into a single-family home for a family with two children. Initially the building served as the current owners’ workshop, which eventually turned out to be too small and therefore had to be relocated. As a result they decided to turn the building into their home. Different lectures on passive construction aroused the owners’ interest and eventually brought about the outset of a passive renovation. The existing volume was almost entirely preserved, but the building arrangement was completely modified. Furthermore, a considerable number of window openings was provided, allowing the house to have the advantage of sufficient day light.


  • Orientation of window openings
  • Box-in-box construction: new insulated wooden frame construction on the inside
  • New insulated massive concrete floor
  • thorough roof insulation
  • Thermally interrupted wooden joinery (Umax 0,80 kWh/m²) with insulating triple glazing (Umax 0,6 kWh/m²)
  • Airtightness of building (η50=0,47 h-1 (limit value = 0,6 h-1))
  • Prevention / elimination of thermal bridges
  • Ventilation system with heat recovery and underground heat exchanger
  • Solar boiler (in a later stage)
  • Photovoltaic cells (in a later stage)


A new continuous insulation shell was installed on the inside of the existing structure (box-in-box construction): the walls were insulated using the wooden frame on the inside of the construction, the existing roof was thoroughly insulated and a new, completely insulated, massive concrete floor was constructed. The box-in-box construction ensures the absence of thermal bridges.


A ventilation system with heat recovery and underground heat exchanger was installed. The bathroom and storeroom were equipped with hygrometers, the living area with a CO2 indicator and the kitchen with a circulating cooker hood.


The ventilation system assures heating. If necessary, electrical heating elements will provide additional heating.

Sanitary hot water

In a later stage solar collectors will be installed for sanitary hot water preparation.

Occupant satisfaction

The room temperature is generally considered to be pleasant. However, during the summer period the bedroom temperatures are often experienced as somewhat too high. Consequently, the occupants express a certain amount of regret not having installed opening windows in these rooms.


Total costs (excl. finishing and installations): € 110 415,00
Net renovation costs per m² (excl. finishing and installations): € 392,00

Download the full project file (Dutch, pdf)