Client: 3D Invest
Period: 2011 – 2014
Team: Robbrecht en Daem architecten, architecten Tania Van Den Bussche en Els Claessens, Dierendonckblancke architects, MJ Van Hee Architecten, VK Group, 3E, 3D Real Estate, Van Roey Vastgoed, etc.
The current fire department and academy site is a fascinating challenge in the area of sustainability due to its density, the inner city context and not least because of the integration of the existing buildings and infrastructures, regardless of whether or not they are listed. In order to transform this complex system into an innovative and high-quality residential area, it was necessary to include the various aspects of sustainability in the design from the start.
Despite the strict framework conditions imposed by the existing context, this site has a number of advantages which appeared even at the very start in an initial screening with the Ghent Duurzaamheidsmeter [Sustainability Meter]. These qualities are mainly in the categories of water, use of materials and liveability and accessibility. 3E developed these opportunities further and changed them in order to arrive at a highly innovative project.
The aim of this project is to limit the discharge of rainwater into the sewage system to the bare minimum, i.e. a closed rainwater cycle. In order to achieve this highly ambitious aim, the rainwater from the sloping roofs of the existing buildings is collected in 2 separate rainwater tanks. From there, via a pump and separate pipelines, this rainwater will be reused in the buildings for the toilets in the brasserie and the education centre and for maintenance and irrigation of the communal areas (indoor and outdoor areas).
For the new build homes, buffering and infiltration were chosen rather than reusing rainwater, mainly because of the limited storage capacity (roof area) compared to water consumption. The roofs of the buildings are constructed as green roofs and the remaining water, which is not buffered by the green roof, will be collected in a buffer with delayed infiltration. This buffer is currently being provided as a visible water element integrated into the environmental design. After initial purification by plants, the water in the buffer pond can be used for irrigating the communal gardens and the vegetable garden of the education centre during drier periods. The infiltration takes place via buried crates under the surface of the garden.
Taking into account the current downward trend in E-level, an E60 will be the norm in Flanders by as early as 2014. As this project is an innovative and future-oriented project, it will outperform this E60 in order to retain this innovative character at the time of handover. Additionally, the academy site requires a balance between architectural quality of the listed monuments and a high level of energy efficiency of the entire site.
To compensate for the more limited possibilities of the existing buildings, the market-compliant new builds are very low-energy (max. E40) builds. Additionally, some residential houses will be built according to passive house requirements.
Regarding the existing buildings, the aim is to strike a balance between energy-efficiency and visible preservation of the architectural quality of the monuments. In order to be able to make a realistic estimate of the E-level after renovation for the existing buildings, an initial EPB calculation was made of all individual thermal entities, taking into account the future function, the orientation of the entity, future technical installations, etc. Based on this rough EPB calculation, a number of measures were selected in order to achieve a maximum reduced E-level with a limited architectural impact.
Additionally to the energy efficiency of the buildings, the potential of renewable energy production on the site was also investigated. What immediately stands out is the huge advantage of supplying the urban heating network with the residual heat from the energy production by SPE/EDF running alongside the site. The former fire station as well as the Academy had been previously connected to this heating network. A review was done with SPE into whether it is possible to connect the new site, taking into account the planned expansions. This amounts to an initial estimated heat demand of approx. 1750 MWh/year (peak power 0.9-1.2MW) and would provide the entire site with sustainable heating and domestic hot water.
In terms of electricity production, the site has a smaller potential. If photovoltaic panels are installed on the new building roofs, an optimistic calculation shows that this could provide between 10-15% of the total estimated electricity demand of the site. Given that this production is rather limited, the preferred choice has been to use these roofs as rainwater buffers i.e. green roofs which is in line with the water concept of the neighbourhood.
A CHP system for the entire site will not be possible due to lack of space on the site; however application of the more experimental micro and mini-CHPs should be further investigated at a later stage. This site could produce a significant reduction of CO2 emissions by reducing energy demand on the one hand and providing green heating on the other hand.
The major materials envisaged for the design were screened according to the NIBE classification system to achieve the requested percentage having a class 3c or higher (25%). This is a first step towards making a choice from the extensive range of material of such a project, whilst still retaining a certain freedom of choice.
In addition to the NIBE classification, it is important to explore the market further for alternative s, i.e. materials with certain labels such as NaturePlus, C2C, etc., at a later more specific phase, as well as materials with a high recycling rate, etc. This would allow the quick build masonry (currently scoring 4b) to be replaced by brickwork with a high percentage of recycled material and a C2C-label. The same principle applies to the plaster, the metallic materials, etc. Obviously, the FSC label is required for all wood-like materials. If this is not available for certain products or in certain quantities, a slightly less efficient PEFC label will be used.