Peter Kaufmann has wood in his blood, figuratively speaking. His father Günter started a one-man business in a former pigsty in Emerkingen in 1992 as a young master carpenter, the current managing director told readers. “He wanted to build stairs there,” said Peter Kaufmann. But just three years later he built his first timber-framed house with high energy efficiency – the so-called “3-litre house” with energy costs at the level of less than three litres of heating oil.
“Today our houses generate more energy than they need,” added Peter Kaufmann. How does that work? With appropriate technology such as PV systems, heat pumps, geothermal energy, ventilation systems and more. “Today, building technology is an important part of our range of services,” reported the managing director. Kaufmann now installs a comfort ventilation system in every house, which, in conjunction with an energy-efficient shell, ensures constant temperatures, pleasant humidity and fresh, oxygen-rich air.
Many people open a window in the bathroom after showering so that the moist air can escape and no mold can form. This is an environmental sin, especially in winter when the heating is on, Peter Kaufmann explained. This can be prevented with a ventilation system that directs the moist air outside, absorbs the heat it contains, releases it back into the room and brings in fresh air from outside. This technology works throughout the house, including in the bedroom, where a comfortable climate and plenty of oxygen are the prerequisites for a deep and healthy sleep.
How the dowel wood technique works
The focus of the tour was, of course, the dowel wood construction method, which the Kaufmann company played a key role in developing. Long slats are cut from the tree trunks – the thick fillet pieces in the center serve as ceiling elements, the thinner side pieces for walls. Hardwood dowels are inserted into the wood – usually spruce or fir – which absorb the residual moisture from the softwood and swell as a result. “This means the slats hold together without glue,” explained Peter Kaufmann, pointing out the many advantages of solid construction with dowel wood, such as outstanding heat and cold protection, high stability and strong sound and fire protection properties. “Insurance is more expensive for prefabricated houses than for our solid wood houses, which are classified in the same way as brick houses,” explained Kaufmann.
Peter Kaufmann (right) explained the dowel wood construction method during the tour. (Photo: Schick)
During the tour of the site, the participants learned that the leftover wood is used to make insulation, while the resulting chips are used for two purposes. Some of it is burned to generate heat, and because electricity is produced using its own PV systems on the hall roofs, the Kaufmann company is energy self-sufficient. The other half of the chips are sold to the food industry. Peter Kaufmann visibly surprised the readers with this information. “Every one of you has eaten a cubic meter of wood in your life,” he said. Chips are used as a binding agent or filler in many ready meals, but also in bread, ice cream and toothpaste.
The wood processing is carried out using state-of-the-art, computer-controlled CNC milling machines, which are programmed based on the plans and can cut the wooden elements with millimeter precision. Production in Oberstadion is carried out in two shifts, while the construction sites work four-day weeks. “Our people work two hours more per day and are happy about the extra day off,” said Peter Kaufmann. His company has around 100 employees in total.
I find it very interesting what you want to know
Peter Kaufmann during the tour
Kaufmann led the visitors through the production halls, which have been expanded over the years, and in which the construction progress from the raw wood to the finished wall element, which is ready for collection on the truck trailer, can be seen. The managing director patiently answered many questions such as: Does the wood creak? How are cable ducts laid? How many individual parts does a finished wooden house consist of? How is the blown-in cellulose insulation prevented from sinking? What does the boss’s personal working day look like? “I find it very interesting what you all want to know,” said Kaufmann, pleased with the questions, which he sometimes answered with a pinch of humor. “Our houses last 500 years,” he said with a grin. He knew this from his own experience.
Sustainability as an important topic
Nevertheless, the future and sustainability are a serious and important issue for the Kaufmann company, the managing director made clear. Almost all of the wood is sourced from Baden-Württemberg, most of it from the Biberach district. Provided that it is reforested, it has an unbeatable ecological balance, says Peter Kaufmann, referring to the wood-concrete comparison: “One cubic meter of wood stores one tonne of CO2, the same amount is released when producing one cubic meter of concrete. Concrete therefore accounts for twelve percent of total global CO2 emissions. The much-cited flying causes three percent.”
It is best to set a budget and not dream about things that are unaffordable.
Peter Kaufmann’s advice to home builders
But how much does a house made of doweled wood cost? This was a burning question for some participants. Is half a million enough? “Yes, if you build compactly. Most of our houses cost between 400,000 and 600,000 euros,” said Peter Kaufmann. He advises home builders to plan cost-oriented from the start: “It’s best to set a budget and not dream of things that are unaffordable. Otherwise you’ll experience nasty surprises and run the risk of getting into debt.”
In order to be able to serve limited budgets, Kaufmann is increasingly relying on AI-supported architecture programs that are modeled on mobile homes: “They have the most compact architecture.” Since land use is also becoming an increasingly important issue, a concept has also been developed to build multi-family houses on old farmsteads, for example. AI-supported programs also help with this. However, tiny houses are not being built, said Kaufmann. “Our building technology is not designed for this.”
Overall, the managing director revealed, building elements for around 60 single-family and multi-family homes leave the company in Oberstadion every year, but the company also looks far beyond the region. Kaufmann presented an award-winning sustainable housing development in Allensbach on Lake Constance, as well as the “The Länd” pavilion at Expo 2020 in Dubai and its own dowel wood construction research projects in Canada, Chile and Japan. The company’s goal is to be the market leader for sustainable housing in the greater Stuttgart-Munich-Lake Constance area, according to the website. “We already are in dowel wood construction,” says Peter Kaufmann.
