To generate heat in a sustainable way, Aquafin will soon be using sewage water as a source. It is the most striking element in the conversion of the labs and workshop of the sewage treatment plant (RWZI) in Aalst into a zero energy building.
At the site along the Spuimeersenweg, Aquafin collects all the sewage water from the wider Aalst area, where it is treated and then pumped back into the waterways. A two-story building houses not only a workshop but also the labs where samples and samples from the WWTPs throughout Belgium are examined. However, it dated back to the 1980s and was in need of a major upgrade both energetically and in terms of functional layout.
The building will be completely stripped down to the concrete structure. By demolishing as little as possible, rearranging functions more logically and adding a warehouse of only 200 m2, the building remains compact, with a total area of just under 2,000 m². The building envelope is made thoroughly airtight and insulated, with materials that can be easily recycled at the end of the building's life. The facade will be finished with wood, also an eminently circular resource. The architectural study, including design of the building envelope and choice of materials, will be carried out by Evolta.
The heating and cooling of the building uses sewage heat. The sewage water arriving at the site has a temperature of at least 9 to 10 degrees in the winter and, of course, a lot more in the summer. In the main sewer - with a diameter of 2 meters! - a heat exchanger is placed that extracts heat from the sewage water and sends it to the heat pump. This then heats the water to heat the building (40 to 50 degrees). The principle also works in reverse: the heat pump also extracts heat from the building - among other things to cool the labs - and releases it to the sewage water.
Choosing a 4-pipe heat pump has an additional advantage. In periods of lower heat demand, the heat pump can extract heat from rooms that need to be cooled and immediately use it to heat other rooms. In this process, no use is made of the heat from the sewage water. This results in a much higher efficiency of the heat pump, because the electricity to drive it provides heat and cooling at the same time, while the same amount of electricity would otherwise only provide heat.
While geothermal energy is already widely used, sewage heat is innovative as a source for heating buildings. With sewers as its core business, this is therefore an exemplary project for Aquafin, which also wants to use it to investigate whether they can use this principle to connect heat from the sewage network to heat pumps at clients.
Aquafin is, of course, also aware of the problem of water scarcity in our country. Therefore, economical use of water is a major focus of this project. On the one hand, rainwater will be reused for flushing toilets. On the other hand, there will be infiltration basins where surplus rainwater will be infiltrated into the soil as much as possible. Design of the water infiltration will also be carried out by Evolta .
Photovoltaic panels will be installed on the building and elsewhere on the site that will cover much of the site's electricity consumption, including the energy needed to heat and cool the lab building. As a result, RWZI Aalst will become a fossil-free site.
Like Ingenium, Aquafin is also choosing to make its vehicle fleet more sustainable. Therefore, 6 charging stations with 12 charging points for electric cars will be provided.
For more info on sustainable heating and cooling via riothermal, contact Joris Dedecker at 050 40 45 30 or joris.dedecker@ingenium.be.
