Stefan Diez

Stefan Diez made his name with products that are as innovative as they are imaginative. In his work he is forever exploring the boundaries and possibilities of materials. While the chairs and tables he has conceived for the likes of e15, Thonet and Hay are decidedly minimalist in character, they are not simply reduced but have something charming about them – and are absolutely well designed. Now the 44-year-old has developed heating inserts and wood burning stoves for Buderus/Bosch. Uta Abendroth spoke with the German designer about his output, about paneling and making compromises, and about the aspect of integrating market research into the design process.

Uta Abendroth: At this year’s ISH, German manufacturer Buderus, which has been affiliated with Bosch Thermotechnik since 2003, will be showcasing two of your wood burning stoves. You are breaking new ground here, aren’t you?

Stefan Diez: We’ve been working with Buderus for almost four years now. Two years ago we presented the „Logaflame HLS“ heating element and „Logaflame HWS“. This is a combustion space for wood and coal, which supplies around 70 percent of its heating power to the domestic heating circuit in the form of hot water. What’s interesting here is that contrary to common perceptions „Logaflame“ is not operated in the basement but in the living room. Thanks to its glass door it exudes an atmosphere of comfort and coziness.

How did the collaboration come about?

The Bosch design division got in touch with us because we have a great deal of experience in the fields of interior living and furniture and have earned recognition for applying our technical expertise in our projects. Quite often we even become involved with product development tasks. So from that point of view I was very happy to take on the challenge of working with a company that has such a clear focus on technology.

The name of the new models is „LogaStyle“. What do they have in common?

The „Logaflame HLS116“ heating element has a power output of approx. 6 kilowatts. In time for ISH 2015 Buderus has further advanced the combustion space and is now launching an additional heating element with considerably more power output and the ability to burn larger pieces of wood and, most importantly, you can see the fire a lot better. This may sound banal, but don’t forget that large glass windows give off a lot of heat that spreads into the room, which means it is no longer available for the heating circuit. The inserts now come with insulating panels, meaning they can be operated in the center of the room as freestanding units. These combinations go by the name of “LogaStyle”.

And what’s the difference?

For Buderus we designed a number of panels that form units with the combustion chamber "Logastyle“. Our approach had a very clear focus on materials. There are panels made of aluminum and glass; additional materials such as stone are in the pipeline. In the design process we made full use of the possibilities offered to us by fundamentally different manufacturing techniques. These materials are not supposed to work like wallpaper or mobile phone casings, rather they should form an independent, coherent whole with the combustion space.

How much time did you spend developing those wood burning stoves?

We devoted about 12 months of intense work on the combustion space and the paneling. The second year we teamed up with product development for the fine-tuning.

During the project phase you ran a market research session in your studio to which you invited architects, designers and journalists. You presented four different wood burning stoves in four different interior settings, asking those present to be open with their criticism and suggestions on different aspects and details. What did you gain from interacting with those experts and did it influence your final decision for two stoves?

In contrast to most other companies we work for, Bosch and Buderus do not have an art director whose job it is to promote the design at all levels and assume responsibility for it. Which meant that we often faced the task of having to convince people of our take on design. So we took the bull by the horns and, together with the Bosch market research team, organized two days at our firm to present prototypes to very different groups of people. Some of these were invited by Bosch, the others we invited. Essentially what it showed us was that different people have very different priorities – which was not much of a surprise.
When you are busy negotiating a compromise the design tends to take a backseat. That is because industrial companies do not care so much about the design, meaning that the reasons for good design tend to be brushed off as personal and imprecise. Getting journalists and architects on board for the market research session was something that worked really well here; surprisingly there was a lot of consensus between them and they were frank in pointing out potential shortcomings. I don’t think anybody at Bosch expected that.

What were the major challenges during the design process?

One challenge was to implement the results of market research, in particular the reasoning of the architects and our own, such that the product would still be affordable. In achieving this we once again teamed up with an engineering firm based near Munich, which will produce parts of the series. Examples like this demonstrate why we are so happy with the infrastructure we have here in Germany.

Are today’s wood burning stoves expected to be multi-talents in that they have the added ability to feed into a building’s heating circuit?

When talking about “stoves” many people still regard the open fireplace as their ideal. By contrast, “LogaStyle” is a device that has come a long way from the traditional fireplace. Many aspects such as efficiency, emission protection, cleanliness in operation, and safety for kids swiftly dilute that unadulterated product experience. You need to take the bad with the good, an old saying goes. I believe we have found a good compromise; that said, reconciling a bunch of widely diverging expectations is clearly not an easy task. So I am calling for a greater sense of responsibility when it comes to introducing more and more rules allegedly designed to make our world better and safer.

Thank you for talking to us.

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