Cooling clothing
“The Earth is getting warmer, and humans are feeling the effects,” begins thermal physiologist Hein Daanen, who likes applying his scientific knowledge to practical solutions for a variety of problems. “For instance, we’re researching personal cooling systems. These are much more energy-efficient than air conditioning, which requires a lot of energy to cool an entire space.”
Especially for people working outdoors in extreme heat, a cooling system in their clothing could be a solution. Daanen explains that there are several ways to achieve this: “Think about cooling systems integrated into clothing, for instance, such as underwear connected to a pump system that circulates cold liquid. That’s very effective.” In addition, there’s air cooling, Daanen explains: “In hot countries, people often choose loose-fitting clothing, allowing sweat to evaporate. By moving in loose clothing, air circulates in the space between the skin and the fabric, helping sweat evaporate and cooling the body.”
Last but not least, there are so-called “phase-change materials”: material that’s initially cooled in a solid form, but melts at a certain temperature and absorbs heat. The material is available at various melting points. When worn on the body, it absorbs body heat as it melts. “But cooling these elements requires energy,” says Daanen. “So we thought, why not use the sun for that?”
Sun4Cooling
All this led to the Sun4Cooling project. The interdisciplinary team designed a cooling vest (picture) with phase-change material elements (picture) that melt at 18°C. Alongside water bottles for further cooling, these elements are stored in a cooler (picture) that receives energy directly from solar panels. Daanen explains: “The more the sun shines, the better the cooler works. So when you need cooling the most, the system provides the most cooling.” The team submitted the idea to the Amsterdam Sustainability Institute, who were enthusiastic and decided to support the project through their innovation programme.
Daanen worked on the project with Master’s student in Science and Business Innovations Luuk Schermerhorn, who researched the cooling efficiency, costs, and feasibility of the system. Technician Hashim Quraishi made the system possible, and knitwear designer Carolien Evers designed the cooling vest. The cooling elements were created by IZI body cooling, and the energy calculations for the solar panel were performed by EigenEnergie.Net.
Improved productivity through cooling
The system was tested in the climate chamber, a unique research facility at VU Amsterdam where human performance is studied under extreme conditions (such as low oxygen levels, or low and high temperatures). These tests showed that workers wearing the vest could perform 3% more work, on average, and that their body temperature dropped by an average of 0.8 degrees Celsius. The cooling vest works, but there’s also room for improvement.
Master’s student Schermerhorn concludes in his thesis: “The next steps are to test the vest on workers accustomed to the hot Indian climate, to improve the cooler, and to collaborate with stakeholders – including local users and product manufacturers – to further substantiate the value of the product.” Schermerhorn also writes that for continuous use, the cooler needs to work faster so that users have a steady supply of cooling elements. Applied scientist Daanen hopes to further refine this product in the future, so it can be implemented to provide workers with the necessary cooling in practice.