From the cowshed to the cultural institution, from the 80-year-old air raid shelter to the elegant penthouse – it is historical buildings that fascinate building physicist Karsten Gerbes.

Always with the question of how to preserve them, how to use them in the future and how to solve the associated higher requirements in the most energy-efficient way possible.

The high-rise bunker from 1942 is a good example of this: the outer walls of the building in Hamburg are 1.30 meters thick, an inert mass that absorbs a lot of heat in summer and cold in winter, explains Gerbes.

“How do you deal with the stored energy?” he asked himself when he was involved in the project.

The bunker was to be turned into a modern apartment building.

"In terms of building physics, this is extremely exciting."

No question, Karsten Gerbes has found his dream job.

Where other people see nothing but walls, he reads buildings like an open book: "The plaster is crumbling from the wall, there is moisture in it, cracks appear - you can see the weaknesses," says the 48-year-old.

Strictly speaking, his "Engineering Office for Building Physics and Building Renovation" arose out of a weakness 20 years ago.

At that time, the construction industry was on the rocks, and the newly minted civil engineer couldn't find an office that wanted to hire him.

At the same time, the Energy Saving Ordinance promised a ray of hope – for order books as well as for old buildings.

"For the first time, the building was considered holistically, it was no longer enough to improve just individual components," explains Gerbes.

Unemployed architects and master bricklayers sensed the dawn: it took experts to evaluate the energy efficiency of a building - the service of energy consultants was born.

Separating the wheat from the chaff

“New job, new state-sponsored field of work – there was almost a glut,” remembers Gerbes.

However, the fact that there were also resourceful profiteers who sold their insulating materials under the guise of energy consulting did not help the image.

But the tide has changed in the meantime: The funding criteria have become stricter, climate protection and energy saving are the big issues, and young people are urgently needed.

"Energy consulting has an excellent future," says Katharina Bensmann.

The architect is Head of Planning and Consulting at the German Energy Agency (Dena).

"My teams and I help the experts to rock the energy transition," Bensmann explains her job.

One component of this is separating the wheat from the chaff and deciding who is allowed to advise on the federal funding programs.

To this end, Dena maintains a list of around 13,000 energy efficiency experts.

Among them are many engineers, architects, but also structural engineers or graduates of new courses related to renewable energies.

In addition to the academics, there are the master craftsmen, such as heating technicians or carpenters, who make up almost a quarter of the experts.

Still, because the high demand in the trade leaves no room for further training to become an energy consultant, which comprises 200 hours and has to be refreshed every three years if you want to end up and stay on the federal energy efficiency expert list.

“The exam is quite demanding”

The further qualification is, for example, about systems engineering, building materials and fire protection, says Karsten Gerbes, who went through the training himself and four years ago taught future energy consultants at the Hamburg Chamber of Crafts.

"The test is quite demanding," says Gerbes.

On the one hand, you have to submit a complete energy consultation according to regulations as a project, on the other hand, you have to prove in writing that you can apply building physics and thus have a say in energy savings.

"You learn to calculate how much heat goes through an outer wall made of bricks, how much energy is lost through a pane of glass and what that means for the interaction of the components window, wall and heating," explains Bensmann.