Energy-efficient renovation of a single-family house in Kreuzlingen

Einfamilienhaus mit Baugerüst

When it comes to renovating old buildings for energy efficiency, one question arises relatively quickly at the beginning of the project: What should be the subject of the renovation? 


If you look at the building, you will see that it consists of several structural, technical and architectural components, all of which have a different lifespan. The building owners have their wishes and ideas about what should be renewed, i.e. replaced or renovated, but a precise analysis by a specialist often reveals a different picture of what ultimately needs to be renovated.

The first and foresighted step that the building owners took in this project was the preparation of a GEAK report for their property by a certified GEAK expert. The GEAK, which is subject to a fee, has several advantages. On the one hand, the GEAK report serves as a planning aid by showing in a detailed, systematic and standardised way how much energy the building consumes in normal operation and where there are energy and structural deficiencies that require action.

Among other things, the GEAK Plus report contains three concrete proposals on how energy efficiency can be improved and in which stages, i.e. with what priority, the proposed measures can be implemented. The GEAK Plus also offers the possibility of applying for subsidies for the renovation measures. Last but not least, most cantons and also many municipalities support the costs of preparing such a report with a subsidy.


This project has shown that some cost-intensive renovation measures could be dispensed with, as the building components continue to serve their function and effectiveness over an extended period of time, whereas other measures were given preference instead.


For this single-family house constructed in 2000, the windows and skylights that originated when the house was built were replaced. All folding shutters were converted to push-button operation. In addition, a structural sun protection was installed on the existing patio to provide more shade during the hot summer months.

Since the existing exterior insulation still provides efficient insulation values and is in good condition, a renovation was dispensed with. 

In a second step, the existing fossil-fuel heating system will be replaced by a ground-source heat pump. The ground-source heat pump is equipped with a cooling function and is ideally suited for underfloor heating. In a further measure, rooms that are oriented towards unheated and are not insulated are to be retrofitted with insulation.

Project information

Area of expertise Architecture, conversion and refurbishment