Project: Complete renovation from oil to heat pump

Complete renovation of house and heating system

Apartment house modernisation

  • A complete renovation of the building with its four residential units is planned. This also includes switching from heating with oil to environmental heat.
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  • Modern thermal insulation, new windows and exterior doors, a new heating system - the work will be extensive.
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From an old house to an ecological house

The owners’ association of a 1970s apartment block is planning an extensive renovation project. Read on to find out which solutions they ultimately use.

The ecological thought counts

Oil heating systems are no longer politically endorsed because they emit relatively high levels of pollutants. There are even mandatory requirements in place stipulating that old oil heating boilers must be replaced. The owners therefore want to opt for an ecologically sound solution when modernising their system. This will also have a positive effect on future heating costs.


Renewable energies require no fossil fuels of any kind so do not release any greenhouse gases. This also frees the owners’ association from continually rising fuel bills. At the same time, they are doing their bit towards protecting the environment and climate.

Project challenges

As expected for its age, the building only has poor thermal insulation. The building needs a high standard of thermal insulation to cut energy costs significantly. To this end, all exterior walls and the roof will be fitted with new thermal insulation. The owners also want to have the old windows and exterior doors replaced with modern elements with low heat transfer coefficients. These structural measures alone are very costly but worthwhile in the long run.

People on an excursion

Reasons for choosing the new system

The owners decide to convert from the old oil heating system to a modern heat pump heating system for the following reasons. They also want to install a controlled mechanical ventilation system.

03. Durable, efficient, flexible

Modern appliances are produced from high-quality materials. They require little maintenance and work very efficiently. In addition, heat pump heating systems do not need to be connected to a chimney and so can be positioned almost anywhere in the building. Moreover, the system under consideration has a compact design that takes up very little space.

04. Environmentally friendly heating system

The models in question are environmentally friendly as they do not consume any fossil fuels or produce exhaust gases that are harmful to the climate.

If the electricity needed to run the heat pump heating system is obtained from renewable sources, the ecological footprint is better yet.

Environmentally friendly

05. Predictable costs in the long term

The cost of fossil fuels will rise over the next few years as a result of the CO2 tax alone, quite apart from the normal fluctuations of market prices. In contrast to heating systems based on fossil fuels, modern heat pump systems minimise operating costs.

A modern ventilation system can lower the heating costs still further. They use the heat contained in the extract air to prewarm the supply air via a heat exchanger so no heat is lost.

Furthermore, the entire project is eligible to receive a state subsidy.

Product solutions for the modernisation project

After consulting experienced heating system and energy efficiency experts, the owners have decided to install appliances made by the renowned manufacturers WOLF GmbH, based in Mainburg, Germany. They were won over by the high quality, good value for money and five-year guarantee.

WOLF decentralised living space ventilation CWL-D-70

CWL-D-70 mechanical ventilation

This system improves the comfort of a home by supplying fresh and healthy air as required. It can also be used to prevent mould formation.

WOLF CAT home station

CAT floor station

Where multiple residential units are present, hot water requirements can fluctuate greatly over the day.

CAT appliances can compensate for these fluctuations, which lets the central heating system work more smoothly.

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.

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Older buildings and environmental heat: it is possible

It is possible to switch to heating with environmental heat even in older apartment blocks if the structural requirements are met. Modernisation involves a considerable investment. In the long term, these expenses will be recouped as heating requirements are cut and the owners are no longer subject to the rising cost of fossil fuels.


When combined with a controlled mechanical ventilation system, comfort is improved by the generation of a pleasant, healthy indoor environment. Once the owners have a sufficient budget available again, they want to install a photovoltaic system on their roof. There is ample space available to generate the electricity required for the heat pump heating system. Thus, the operating costs will drop still further.

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