Towards a genuine sustainable energy concept
With the ZERO ENERGY BUILDING CONCEPT, Van Wellen Group introduced a sustainable near-zero energy building in the Schoem housing project from the very first stroke. Not only is it CO2-neutral, but it also generates enough energy to largely cover its own energy needs. Each building is conceived as a compact volume whose roof area has been optimised to harvest as much sunlight as possible. The airtight building envelope is highly insulated and constructed of sustainable materials.
Solar panels will be installed on the flat roofs. In addition to solar energy, use is also made of seasonal storage in the soil. Deep boreholes are linked to a heat pump, and innovative delivery systems ensure a pleasant indoor temperature in both summer and winter via high-temperature cooling and low-temperature heating. The sun blinds, LED lighting and balanced ventilation with heat recovery also contribute to a pleasant living environment.
In the Schoem housing project, the solar panels will be oriented towards both the east and the west. This will better match the yield profile with the usage profile and more solar energy can be harvested. The solar roof generates electrical energy to cover the building's total energy requirement and make a significant contribution to the energy needs of the users (household electricity) and to sustainable mobility.
Daylight concept
In order to maintain contact with the green environment and to make maximum use of daylight, generously proportioned daylight openings are provided in all user areas. Exterior blinds are provided for sun-sensitive orientations to prevent overheating in summer. These blinds also allow the amount of daylight and solar radiation to be controlled according to requirements.
Passive house principles
By investing in low-tech solutions such as extensive insulation, robust windows with triple glazing and high air-tightness, the heating and cooling requirements are drastically reduced throughout the life of the building. These interventions require no maintenance or replacement costs and will pay off over the building's lifetime. If you know that the average age of buildings in Flanders is 70 to 100 years, it is clear that a high-performance building envelope is just as important as a stable foundation.
The windows function as solar collectors. In winter, the south-facing glazing allows more solar heat to penetrate the building than the heat loss it causes to the outside. These passive solar gains, together with the so-called free heat gains of people and equipment in the building, provide the bulk of the necessary heat input. Hence the name "Passive" building.
In summer, the sun blinds prevent the sun from penetrating the building to avoid overheating.
The passive house principles offer a good guideline for arriving at a sustainable building concept. In the Schoem residential project, we guarantee an S-level of maximum S28 through an optimal mix of thorough insulation, an airtight building envelope and sun blinds.
Heating and cooling with floor activation
Heating and cooling are provided by floor activation. The floor heating with passive cooling ensures that, depending on the season, the floors cool or heat. The heat or cold comes from the ground. A borehole energy storage system or BEO field with wells up to 150 metres deep uses the coolness from the ground in the summer. In this way, the ground is locally warmed up - compare it to a large thermos. This heat is used in the winter to heat the building. With the help of a heat pump, the ground heat is raised to the required 30 to 35 degrees for the water flowing through the floors. In this way, the rooms are heated to a comfortable 22 degrees.
Energy performance
By focusing on the first two steps of the trias energetica, i.e. reducing energy needs and using renewable energy sources, the third step, i.e. the efficient use of fossil fuels, has become superfluous. The result is a CO2-neutral and near-zero energy building that more than meets the BEN-requirements.
A breath of fresh air... but without draughts
Good air quality is elementary for pleasant comfort. In the building, fresh air is continuously blown in and polluted air is extracted. We speak of balanced ventilation when these two air flows are in balance. A heat exchanger recovers the heat. If it is -10 °C outside and 22 °C inside, the fresh air can be pre-heated to 19 °C without external energy input. Economical EC fans with intelligent control guarantee minimum energy consumption.
CO2-neutral means no fossil fuels
Another aspect of sustainability is avoiding fossil fuels and switching to technical systems that work in a CO2-neutral manner. This means finding an alternative to the familiar gas boiler for heating and hot water preparation.
Heating and cooling with a heat pump
An electric heat pump offers the solution. This device does not use fossil fuels such as natural gas or fuel oil and, in contrast to conventional electric heating, is much more efficient. With 1 kWh of electricity, a heat pump produces 3 to 5 kWh of heat.
An additional advantage of a heat pump is that you can also use it for cooling, which is impossible with a gas boiler.
There are various types of heat pumps. The most comfortable heat pumps are connected to the floor heating system and extract the necessary heat from the underground: we then speak of ground water heat pumps.
In winter, this type of heat pump has the highest efficiency of all heat pumps and in summer, cooling is possible through direct energy exchange with the ground as it has a stable temperature of approximately 12 °C. In cooling mode, the heat pump itself does not have to operate, only the circulation pumps. This makes it possible to cool without consuming much energy.
A comfortable and energy-efficient ventilation system
In order to guarantee good air quality without heat loss or noise pollution, each flat is equipped with a balance ventilation system with heat recovery. As much air is extracted from the kitchen, bathroom and toilet as is supplied to the living room and bedrooms. Both airflows pass through a heat exchanger in which the extracted air is used to heat the fresh air. In this way, ventilation can take place without heat loss and without cold draughts.
Central heat pump and free cooling for the whole complex
The scale of this project allows us to work with a central system for heating and cooling, so that these sustainable energy systems can be implemented in a cost-efficient manner. Feasibility studies of similar projects show that the total cost of ownership (investment + energy cost) is more favourable than with conventional systems.
Energy performance
Thanks to the use of these future-oriented technologies, these flats score extremely well in terms of energy performance. Not only are they CO2-neutral because no fossil fuels are used, they also comfortably meet the BEN-standard for Near-Energy-Neutral Residential Units.
