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The Skødstrupbakken housing estate, outside Aarhus, is one of the homes of the future. In construction, sustainable energy and power consumption have been thought of in a completely new way, in the form of a hybrid plant with solar cells and battery.
The building is one of the first of its kind in Denmark and aims to inspire housing associations across the country - both within new construction, renovations and energy optimisation.
You don't have to go far from the big city before you can experience one of the homes of the future. 15 km outside Aarhus, the Skødstrupbakken housing estate is located in scenic surroundings with its own protected lake.
The section, which is close to both forest and water, is for the housing association AlmenBo Aarhus one of their newest additions. With the solar and battery installation in Skødstrup, AlmenBo Aarhus hopes to get closer to the goal of a greener everyday life.
"AlmenBo Aarhus is in the process of a major green transition, as part of the municipality of Aarhus's goal to become CO2 neutral by 2030 - this is done, among other things, with the establishment of solar cells, hybrid systems, additional insulation, optimisation of heating systems and replacement of windows and the like," says Jesper Holze, project manager at the housing association.
The residents of Skødstrupbakken are primarily families who are all keen to contribute to the green transition. The residential section, built in 2018, is not only green in the classic sense of being surrounded by nature.
Skødstrupbakken is also green in the sustainable sense, which is reflected in the department's choice to install both solar cell and battery systems. A choice that should help to inspire other housing associations in the rest of Denmark.
The idea to equip department 52 and its 33 residents with a so-called hybrid system originally came from AlmenBo Aarhus itself. An idea that has been under way since the department's infancy.
"Right from the beginning of the project, we have been in dialogue with VisBlue regarding the establishment of a hybrid facility – but we also know that it is difficult to find the funds for such a facility based on the financial resources we have to do well with in a general construction project. In the construction phase itself, we therefore thought of including all the guide ways, from the roof to the technical room, as well as reserving space in the room for a battery solution. The latter can be a very expensive cost when it has to be done at the back," explains Jesper Holze.
Although the idea came from above, in the end it was Skødstrupbakken who made the final decision. And here a large majority of the department voted for the idea.
The decision pleases Jesper Holze, "We are extremely happy that the residents of Skødstrupbakken had the same attitude as us regarding the establishment of a hybrid system. It fits in very well with AlmenBo Aarhus' green profile."
The idea of not only installing solar cells, but also a battery system, also makes a lot of sense. It makes sense for the environment, but especially also for the wallet. With both solar cells and batteries, there is money to be saved on the residents' electricity bill.
If you ask Skødstrupbakken chairman of the board, Pia Mouritsen, the department's hybrid investment is the only right way to go for new construction.
"New build must be born with solar cells and batteries. It is undoubtedly the way forward. The green agenda is something we are passionate about in our department, but it is also a significant factor that with the hybrid system we will be able to sit cheaper in our homes," she says.
With the help of the right financing, Skødstrupbakken has been able to invest in both facilities without raising the rent. Pia Mouritsen explains, "it is crucial that there is no rent increase. If it does, the support from the majority will disappear – because even if the investment is green, it must not end up giving red numbers."
"New build must be born with solar cells and batteries. It is undoubtedly the way forward. The green agenda is something we are passionate about in our department, but it is also a significant factor that with the hybrid system we will be able to sit cheaper in our homes,"
- Pia Mouritsen, Skødstrupbakken
Both the solar panels and the battery come from local Aarhus companies which is a common thread in the grey brick construction in Skødstrup. The solar panels are produced by Mikael from Risskov Teknik & Solar and the battery by Søren from VisBlue.
The local suppliers make sense for Jesper Holze, “it means a lot to us that we succeeded in creating a collaboration with two local companies, enabling Aarhus to further develop sustainable solutions of the future together. So, a big thank you to VisBlue and Risskov Teknik & Solar for the valuable collaboration.”
The solar panels cover over 452m2 of the department’s roofs and generate on average 75,000 kWh per year, leading to an annual saving of roughly 11.4 kilos of CO2.
To translate these numbers into something comprehensible, it means, that the solarpanels produce enough power to cover the annual electricity consumption of 30 families. Further, the CO2-savings of the solar panels is equal to planting 556 trees every year.
Mikael Kjærgaard from Risskov Teknik & Solar is also pleased by the green hybrid project, “AlmenBo Aarhus and the residents at Skødstrupbakken have been eager to initiate the project and vi are pleased to be delivering a part of AlmenBo Aarhus’ first solar panel system with accompanying battery. We greatly appreciate the collaboration with both AlmenBo Aarhus and VisBlue, as both parties show great commitment in the sustainable development goals and sustainability – a passion we share with them.”
He continues, “throughout the project, there has been great interest from both the housing association and the department, and the solar panels and battery are in their own league, as well as one of the first hybrid installations of its kind.”
"It means a lot to us that we succeeded in creating a collaboration with two local companies, enabling Aarhus to further develop sustainable solutions of the future together. So, a big thank you to VisBlue and Risskov Teknik & Solar for the valuable collaboration."
- Jesper Holze, AlmenBo Aarhus
But without a battery, a large part of the green power from the solar panels will not be utilised by the department. By installing a battery solution, Skødstrupbakken is now able to collect and store the power that the solar panels generate during the day, and utilise it at any time of the day, even when the sun is not shining.
CEO at VisBlue Søren Bødker explains, “when the sun is shining in the middle of the day and produces a lot of green electricity most people are at work or in school and are therefore not utilising the electricity optimally. Therefore, it makes sense to install a battery which can collect and store the sustainable energy until you need it, e.g., during the evening and at night when you are making dinner or watching tv.”
The battery solution at Skødstrupbakken is a so-called redox flow battery – a different battery type where the power is stored in two tanks filled with liquid. The flow battery has multiple advantages over common battery types, among other things being scalable and providing a longer lifetime, and also being 99% recyclable and non-flammable.
The battery at Skødstrupbakken is 8kW and 40kWh, which means that they are now able to utilise approximately 10% more of the power produced by their solar panels.
The hybrid system helps the residents at Skødstrupbakken to contribute to the green transition at the same time as getting a cheaper electrical bill.
For the department in Skødstrup their journey is far from over. They have more projects under way.
“We would like to make a bigger garden with a utility bed, fruit bushes and insect-friendly plants to help the local biodiversity on the way,” Pia Mouritzen states.
Furthermore, the department has initiatives such as a common toolshed and cleaning days on the drawing board. Electric vehicle charging stations, so the department is able to make even greater use of the solar panels and the battery is also under way.