Why do I have to be self-sufficient

30 years without electricity from the gridA family lives self-sufficient

A spacious, bright room, lots of books - Siegfried Delzer is in his living room. At first glance, Delzer's house doesn't look that much different from others. But when you look outside, you notice double windows. Historic Black Forest houses in the area served the client as a model at that time:

"This idea of ​​the box window - transferred to more modern construction - a double facade. But if you have a double facade, then many say: double costs. How can you improve them? By increasing the benefits."

Siegfried Delzer is a graduate engineer in technical cybernetics and develops energy concepts in his planning office. The energy transition took place at Delzers 30 years ago. Without a power connection, the couple and their two children moved into their newly built house in the Haagen district of Lörrach. Since then we have been testing what is feasible in terms of energy:

"For the first time there is efficiency. Every kilowatt hour saved is worth more than one produced."

Learn from the ancient Romans

Delzer is certain: With a view to the energy transition, existing technologies are being overlooked because only new technologies make the goal seem achievable. The ancient Romans were already very far in terms of energy efficiency. The energy expert is now standing on his balcony and looking at a large window facade. "Warm air is created between the panes," he explains, "which goes into a hypocaust system".

That sounds very modern, but the idea is old. Warm air flows through cavities to transport heat. The hypocaust system comes from the Romans. They first used this form of energy generation and distribution in their thermal baths, later the system was also found in Roman houses. With the Delzers, the warm air flows through the floor, which consists of two layers. Back in the living room, Siegfried Delzer stops in front of a large tiled stove.

"In the center of the house we have an energy shaft where the warm air is drawn in from the facade, and from the energy shaft it flows into these hypocausts. Why this little detour? The energy shaft, as a vertical shaft, has the function of distributing and collecting all the heat Because a tiled stove is also connected to the energy shaft, and this tiled stove can produce the warm air if there is no sun outside, so that heat flows in via the hypocausts. "

Expandable solar system

An important advantage: surface heating like this does not need warm radiators, and it still keeps the house warm. Delzer also came up with something special for the solar system.

"Vertical in the facade means that no snow remains on it, and there is less pollution. That means that the system works safely in winter. And when you drive through the country in winter, you can see how the PV modules are covered with snow in winter. So precisely where the energy is needed, the systems are not in operation. "

The house was planned in such a way that technology and material can be exchanged for more efficient systems as required. The solar thermal system in the facade, which also provides hot water, is currently being replaced by a new, modern photovoltaic system. There is also a photovoltaic field about five meters wide and just as long in the garden.

"We have a 3.6 KW peak PV system, enough for office operation with five computers and for living and in summer also for cooking. If we expand that now, add another three KW, then it will be 6, 6 KW. Then cooking is 100 percent and then a small heat pump for heating, and we then increasingly eliminate wood heating, the tiled stove is then used less. "

Any excess electricity is stored in a 24-volt forklift battery in the basement of the house and given off in the form of heat.

"We make sure that bad days are overcome with the battery capacity. And if it is not quite enough then the combined heat and power supply provides us with heat and electricity. And that is actually well covered."

The principle has been working for 30 years. With the second generation of technology currently being installed, it will soon be a zero-energy house. Encouraging others with his concept to take the path to energy independence - that is Siegfried Delzer's goal.