What the thermal management of parking heaters can learn from clothing - and vice versa

They heat, cool and regulate the temperature - but in different places and with different methods: clothing and stationary heaters. What differences and similarities are there in the thermal management of these two different worlds? We wanted to find out and put Monika Rausch, a material specialist and engineer for technical sportswear from mrd studios, in conversation with Jörg Hornung, VP Business Line Thermal Management from Webasto. Whether in construction, material science, recycling or circular economy: there are far more similarities than expected and some impulses for both areas. 

Easy Way: Let's start with the perhaps smallest common denominator. What does comfort mean to you, and what does it mean in a professional context? 

Monika Rausch: I associate the term comfort with an emotional well-being. In technical sportswear we use the term 'comfort' more, which describes the state when the parameters for the wearer's body are optimal but also a feeling of well-being exists. In clothing, the decisive factors for comfort are temperature and humidity - their management is the 'climate regulation' of the clothing. So one could also describe the perception of well-being or comfort with the absence of disruptive factors that allow an athlete to access his full performance. In extreme cases, the right clothing in extreme temperatures and weather conditions can even save the wearer's life. For example, on expeditions or even ultramarathons. 

Jörg Hornung: When I think of comfort in combination with a stationary heater, I think of a cold morning when I get into my warm vehicle, don't have to scrape the window and can start driving right away. Performance is also important to us. Because the engine is preheated, the vehicle is at temperature from the start. That spares the engine and the environment. Thinking a little further, the topic of performance becomes even more important with electric vehicles. Because then the question arises how to keep the vehicle occupants efficiently, but also the battery, at a comfortable temperature in cold days. 

Easy Way: How is the comfortable temperature maintained in clothing? 

Monika Rausch: For thermal management in clothing, both air intakes for heat retention and the avoidance of heat conduction and heat flow are used to keep warm air on the body. To prevent overheating, the human body can act like a buffer system to balance excess heat through the extremities to keep the torso - the body core - at the ideal temperature. A critical aspect of insulating clothing is also to vent excess heat but also body moisture/sweat from the system. Moisture that accumulates in the system creates refrigeration cold. 

But in sportswear, we have 'artificial' heat sources that very much compare with parking heaters. In cold situations, in which one is not active, the body shuts down and the self-heating is throttled, one must reheat. We have Lithium-ion battery powered heat panels that are strategically placed in the garment. I think, a decisive difference and advantage to thermal management in stationary heaters is that the body can take over a decisive part of the regulation itself during sports and movement - to support the garment. 

Jörg Hornung: You are mentioning a very interesting feature of a good thermal management system there: the exchange of heat and cooling. In the past, the areas of heating and cooling were considered independently of each other. There was the classic area of stationary heating and the area of air conditioning, for example for buses. With electrification, we now have to take care of both at the same time. When there is high power draw and low outside temperatures, the batteries must be cooled, and the passenger compartment heated at the same time. At Webasto, we have developed a coordinated E-Thermal Management system with which we can use the heat, which was previously a waste product and would actually have to be removed, positively at another point. In this way, we create a cycle in which one can heat and cool at the same time. 

Easy Way: How important are the materials used for thermal management for both of you? 

Jörg Hornung: When it comes to materials with us, we are embedded in a system that is specified by the vehicle manufacturer. We move with our products within tight framework conditions and have to fit in with our stationary heaters into the system. 

Monika Rausch: The selection of materials is often key for us, depending on the target purpose of the garment, and it is specific to either a summer or winter product. We achieve the thermal insulation of the materials either by trapping air as with lofty fleece fabrics, by lower thermal conductivity as with polypropylene fibers in underwear, or with wind proofing by the use of membranes. For particularly high insulation values, we use down or synthetic fiber fillings, which offer maximum thermal insulation at low weight. 

Easy Way: What similarities do you see in terms of thermal management? 

Monika Rausch: At the widest level, the interior of our clothing outer layer with membrane is very similar to the interior of a vehicle. In our case, the body is the heater, and in yours it's the heater. And we both work to optimize the systems of material and function and their tuning. The wearer of the clothing takes on the task of regulation with us: through venting or adjusting the layers. 

Jörg Hornung: In our case, the energy supply takes on the heater. An example of this is the conversion of logistics companies to electric vehicles. When the vehicles are parked and the packages are delivered, the interior can quickly cool down in the winter. We have developed a solution for this. We operate the air heater with an external tank with biofuel. That's sustainable and efficient. For electric vehicles, we are also working on intelligent control systems that, for example, only let cold fresh air into the vehicle when the air quality requires it. 

Monika Rausch: Are there any performance losses with biofuels? 

Jörg Hornung: On the contrary. This fuel even has better combustion characteristics than diesel or gasoline.  

Easy Way: We have now talked a lot about the materials and concepts of the products. How is it in the clothing industry and in heaters with recycling and a circular economy? 

Monika Rausch: Recycling and circular economy - that is probably different from us in the automotive industry. Nowadays, every company uses recycled materials. In the long run, it is more important to implement a real circular economy. In the 'mono-polyester' area, the industry is probably closest to large-scale implementation for the royal discipline 'circular economy'. The biggest challenges are in collecting and retrieving a product at 'end-of-life' and in developing a truly single-material product for later contamination-free spinning mass for fiber processing. In the automotive industry, it is probably even more difficult. With the old cars you can still get to the components. But with the new vehicles, large components have to be exchanged. Is that necessary? 

Jörg Hornung: If the car gets older, repair concepts are in demand. In our area, the heater is then removed and restored by a trained company. In any case, it is worth making the decision for a high-quality product and for a company that enables such repairs. In addition to repair friendliness, we must not forget the high technical recycling rate of old cars. It is now far above 80 percent, the utilization rate including the combustion of some materials is even 98 percent. This also applies to our products such as heaters and air conditioners. The reason for this is the high metal content of over 70 percent and the extensive legal regulations for vehicle recycling. In the future, it will be even more important to pay attention to the three topics of repair friendliness, single-component dismountability and recycling-friendly materials and operating fluids. 

Monika Rausch: In the textile sector, customers are becoming more and more sensitive to this topic. They expect the manufacturer to make and implement sustainable concepts as well as repair ideas. This starts with simple concepts, in which you can exchange the zip slider yourself and don't have to throw away the jacket, to topics such as the use of 'biodegradable materials' or materials from renewable raw materials. All these topics are already a great sales argument. In apparel, this is rapidly gaining momentum. The market and the customer demand this. 

Jörg Hornung: Sustainability is becoming increasingly important and we should constantly ask ourselves what we can do to make our individual components repairable. 

Monika Rausch: We see in our industry that one is dependent on the participation of everyone else. The entire industry must rethink and join forces. 

Jörg Hornung: This is a social movement and it is important to adjust to it. 

Easy Way: Thank you very much for the interview, Ms. Rausch and Mr. Hornung!