Step-by-step refurbishment

In order to facilitate the achievement of an optimal standard of thermal protection in building refurbishments, the Passive House Institute promotes the step-by-step refurbishment approach, also implemented in the SINFONIA project.

The idea of the step-by-step refurbishment is to retrofit the building component by component or part by part. In the first case, the whole building is being modernised, but only one or several components at a time. For example, in a first step, insulation of the building envelope is applied, in a second step the windows and airtightness are installed, and in a last step, a ventilation system and heating and RES concepts are implemented.
Buildings may also be retrofitted not as a whole, but partially. Starting with a section of the building only, then including all or at least most components, the efficiency of a certain part of the building is updated. This part can either consist of a building side or façade, a single or several flats or even whole building sections.

One of the main principles for refurbishments to be followed is: if it has to be done, it should be properly done! To stop at moderate insulation would be a waste of money. It should also be considered that it would be practically impossible to carry out “subsequent improvement“ with justifiable effort: while it is possible to carry out the better measures today at low differential costs, later installation would require the same effort once again for scaffolding, installing, protection from weather etc. (this would not be profitable under any circumstances). That is why, from the very beginning, great attention must be paid to a high quality of the thermal and energy-relevant aspects of each procedure. When it is time for the relevant building component to be renewed anyway, then scaffolding will be put up and all remaining measures will be carried out in any case, thus the additional effort for a qualitatively better implementation will be very small.
There are some other reasons why better measures should be preferred, more information can be found here.

Annual heating demand for different refurbishment standards

The comparison shows how important it is to achieve the highest possible level of energy efficiency that is economically viable. Only then will it be possible to reduce energy consumption to a level which is both affordable and ecologically sustainable. A variety of independent studies carried out on realised buildings have proven that the methods presented here are successful in all respects.


Achieving the Passive House Standard in refurbishments of existing buildings is not always a realistic goal, one of the reasons being that basement walls remain as barely avoidable thermal bridges even after refurbishment. Therefore, Passive House Institute has developed a quality assurance system for step-by-step refurbishments, called EnerPHit standard. The certification has been developed in the European IEE funding project EuroPHit. In this project, practical pilot projects of step-by-step retrofits were carried out to gain practical experiences.

Lessons learnt:

One of the main principles for refurbishments to be followed is: if it has to be done, it should be properly done!