People on an excursion

Renovation to create an ecological apartment building

Apartment house modernisation

  • The apartment building with eight residential units is not well insulated and, together with the old gas heating system, causes high ancillary costs. Through a complete renovation, the investor upgrades the entire building and thus creates an attractive capital investment.

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  • The comprehensive renovation requires cost-intensive investments and a skilful selection and coordination of the future building services.

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Converting from gas to environmental heat

The apartment block in a popular Frankfurt suburb is currently vacant. A businessman is intending to modernise the building to meet the KfW energy-efficient house standard – a project that could act as a model for other buildings in need of renovation.

Highly promising renovation project

The investor definitely wants to rent out the apartments again after renovation. To this end, the 1980s building will not only be brought up to current technological standards, it must also fulfil energy-efficiency requirements for at least the next 20 years. The businessman will exclusively use renewable energy sources to meet these criteria.

Project challenges

The thermal insulation must be replaced and brought up to modern standards throughout the entire building. This includes replacing all windows and exterior doors. But well-insulated buildings have an insufficient supply of fresh air, which increases the risk of mould formation.


Therefore, it is sensible to install ventilation ducts as well. All in all, the cost and the amount of work required are high.

Heat pump in the garden

Reasons for choosing this heating system

After talking to their construction advisors and energy consultants, the house owner decides to replace the old gas heating system with a modern heat pump. They also plan to use a modern ventilation system on every floor to prevent mould from forming and protect the substance of the building.

These two systems have been tried and tested in practice and continually improved for many years. They will still be state of the art for many years to come.

01. Environmentally friendly heating

Heat pump systems use energy from their surroundings. They do not need any fossil fuels or produce exhaust gases that are harmful to the climate. The electricity required to run them is converted into heat with great efficiency. The owners can generate this electricity using an on-site photovoltaic system installed on the roof. This improves the ecological footprint of the system still further.

02. Space-saving, flexible installation

The technology itself takes up little space. As no chimney connection is required, the heating system can be set up just about anywhere.

The ventilation units are slim and can be positioned at suitable points on the ceilings or walls.

Cross-section indoor climate

03. Convenient operation

Modern appliances feature practical automatic functions. More and more manufacturers are starting to equip their systems with smart home interfaces and provide apps for controlling the systems from a smartphone. These allow the owners to monitor and adjust the appliances even when they are not at home.

Save costs

Economically sensible investment

The investor can claim high subsidies for the entire renovation. This saves a large part of the investment costs.

The remaining investment costs pay off in the long term. This is because the heating demand of the building is reduced to such an extent that it can be completely covered by the heat pump heating system. The owner of the house makes himself independent of the costs of fossil fuels, which have been high up to now and will continue to rise in the future. The running costs are very low. The heat recovery of the ventilation system saves additional energy.

All this reduces the service charges to be passed on to the tenants and makes the flats even more attractive. In addition, the owner creates more security for himself. Because with this particularly sustainable heating system, he also fulfils the legal requirements in the long term, which may be extended in terms of climate protection.

Product solutions for the project

At the recommendation of their construction planner, the investor has chosen to use WOLF products. The combination of high-quality materials and sophisticated design means that the appliances function perfectly and are long-lasting. This is also reflected by the five-year guarantee.

WOLF Living space ventilation CWL-F-Excellent

CWL-F-150 ventilation unit

These slim, ceiling-mounted or wall-mounted ventilation units can each supply one story of the building with fresh air and remove used air.

The appliance is located centrally in the corridor of the floor in question and can be connected to the apartments by ducts.

Sounds complicated? Not for us!

It can be complex and time-consuming to find the right solution for your home. We can help you to understand everything that is really relevant to your project in only a few minutes.

Renovating older buildings is worthwhile

By optimising the building envelope of the old apartment block and coordinating the systems precisely, the owners can run the heating system exclusively using renewable energy. This also makes the project eligible for attractive subsidies and will be extremely convenient for future tenants when it comes to heating their apartments. Furthermore, the building will continue to fulfil efficiency requirements in coming years.


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