Art Nouveau with heat pump - Palm house Krefeld

The house inside the house


  • Client: Interior designer Mr. Klein-Wiele
  • Location: Krefeld
  • Year of construction palm house: ca. 1920
  • Year of construction residential building: 2020
  • Heating system: alterra SWC 82K3 + 300l domestic hot water storage tank
  • Purpose: heating, cooling and domestic hot water preparation
  • Installer: Lumitronic GmbH

Art Nouveau greenhouse

The glass Art Nouveau building was built in the 1920s at the instigation of the Krefeld city fathers at the time as a greenhouse in order to be able to overwinter the sensitive urban plants undamaged. It functioned as such until the end of the last century.

Different usage concepts followed, but they never turned out to be particularly sustainable. For this reason, the building had been largely unused for some time. A condition that called for remedial action.

When Martin Klein-Wiele was planning to move from Düsseldorf to Krefeld a few years ago, he first sounded out the market for a suitable property for himself and his family. It was precisely in this situation that his colleague Jochen Usinger confronted him with the question of whether he didn't want to buy the palm house. And thus triggered a rollercoaster of emotions at Klein-Wiele. "The thought was fascinating, but I had doubts whether the 300 square meter building wasn't too big."

Decision support came from a friend and colleague who teaches energy-efficient building as a research assistant at the Basel University of Applied Sciences. "When I asked him whether it would be feasible and sensible to build, live and live in such an object, he said: Definitely."

The idea: a house within a house

The idea of ​​integrating a wooden house into the palm house was soon born. Because it was necessary to meet the special framework conditions as well as the requirements of the monument protection.

For the heating, Martin Klein-Wiele initially wanted to use gas in order to keep the one-time investment as low as possible. Nevertheless, he sat down with Ulrich Konen to explore the possibility of environmentally friendly and even more energy-efficient heating.

Konen, owner and managing director of Lumitronic GmbH, is a proven heat pump specialist. In 2019 the Federal Association of Heat Pumps (BWP) named it “Heat Pump of the Year”. For 20 years, the Lumitronic boss and his team have only been installing heat pumps from the alpha innotec brand.

When Ulrich Konen calculated what the geothermal heat pump including drilling, installation and underfloor heating would cost him to buy, he was quickly convinced. Especially since he was able to take advantage of considerable government funding. "Now we have a permanent and environmentally friendly solution with very low operating costs," says Martin Klein-Wiele. A solution, by the way, that additionally increases the value of the property.

Energy from the earth

The geothermal borehole was drilled on the east side of the palm house and the probe was driven to a depth of 113 meters. Due to the relatively low heat requirement - inside the palm house the temperature never drops below zero degrees Celsius - a single geothermal probe is sufficient to supply the heat pump with sufficient primary energy from the earth.

“We installed an alpha innotec alterra SWC 82K3 with an output of 8 kW”, explains Ulrich Konen. He did not have an extra buffer storage tank for the heating, because “Buffer storage tanks and individual room control always act as a resistor. Instead, we use the underfloor heating as a buffer storage. With a proper setting of the system and the hydraulic balancing, the actual heating costs are usually ten to 15 percent below the information calculated in the thermal insulation certificate. "

The domestic hot water is also prepared directly via the heat pump. “Our solution is completely monovalent, so it works without a heating element. The storage tank for the domestic hot water has a capacity of 300 liters. "

For reasonable temperatures on hot summer days, Martin Klein-Wiele relies on several factors: “We have 430 square meters of roof area. We regulate the shading with a cloth attached inside, which reflects 68 percent of the sunlight but lets air through. There are also windows in the ridge and tilt-and-turn sash, as are typical of a greenhouse. This gives us 40 air changes per hour. That means we always have fresh air in the room. "

alterra SWC
Compact ground source heat pump

The ground source heat pumps SWC from alpha innotec are more flexible in installation than almost any other device and can be optimally combined with other energy providers, such as photovoltaic or solar systems, and thus perfectly adapted to a wide variety of conditions and requirements. But the device is not only convincing on the inside, the "packaging" is also impressive: With its elegant and modern design, the heat pump fits into any living environment and can therefore also be placed in living rooms if there is not enough space or a basement. And don't worry: the heat pump is barely audible when it is operating! With the alterra SWC, you can heat and prepare domestic hot water in an environmentally friendly and efficient manner, enjoy the individual feel-good climate throughout the house and the hot water when showering and bathing.

Cooling included

No other heating system can do this: heating in winter, cooling in summer. Natural cooling is a very cost-effective way of using the low temperatures in the ground for pleasant and environmentally friendly cooling of the rooms in summer, because the heat pump remains switched off during the cooling phase. The room temperature is lowered via surface heating or fan-assisted convectors. Depending on the equipment, the cooling function is already integrated or available as an optional accessory.

Service room: SWC with hot water storage tank

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