Many office buildings rely on double-glazed facades. That gives a lot of light, but also requires a lot of energy. These facades create heat that needs to be regulated. Architects of the Technical University of Munich have developed a ventilation system in which buildings regulate themselves. A role model is the human being.
By Bernd Schlupeck
"My name is Philipp Molter, and we at the Chair of Design and Building Envelope of the Technical University of Munich have set ourselves the goal of simplifying facades so that they work self-regulating."
Currently, the architect is dealing with double-glazed facades of modern buildings. Because in these buildings, the individual windows can not even open. The result: The air space between the panes heats up quickly. Against the formation of moisture on facades of the latest generation, the space between the glass fronts even sealed. To solve both problems, today sophisticated control technology is used. Philipp Molter wants buildings with double-glazed façades to be self-regulating in the future. For this he has developed a simple and affordable ventilation system - the autoreactive facade.
"There are changes in both temperature and humidity over the course of the day and throughout the day, and autoreactive facades can capture and adapt to these changes to keep the user comfortable in the building."
It does not take "rocket science"
Philipp Molter's model for autoreactive facades is human skin. The architect wants to transfer the principle of how the pores of the skin automatically open when they are hot and automatically close in the cold, the architect wants to transfer to the outer shell of buildings. And with the help of so-called thermal cylinders, which he builds between the two glass fronts of a façade element. The researcher pulls out a stick, about a finger thick, 20 centimeters long and covered by a spring.
"This thermal cylinder is not a 'rocket science', but a proven element that we know from greenhouse construction, a very robust element that requires very little maintenance, and that at a certain temperature an internal paraffin can expand and thus a This drive pushes out the outer glass pane.
"The principle works like this: If the air between the outer and inner glass facade is warmer than 20 degrees Celsius, the wax-oil mixture inside the cylinder expands and pushes a piston outwards. The outer pane opens and the heated air between the first and second glass front can escape. At temperatures below 15 degrees Celsius, the paraffin solidifies again, the piston collapses and the outer disc is closed. A total of four thermocylinders are necessary to apply enough force for opening. In order to solve the problem of moisture, Philipp Molter also plans to install a second regulating element - basically a bath ventilator, as he says:
"We've slightly modified that, but in principle, in certain situations, a damper opens and actually vents constantly if we have too high humidity levels in the space between the panes."
In summer there are the first tests
The ventilation system still exists only as a concept. The simulations are completed and first prototypes are being built. In summer, the autoreactive façade on the roof of the TU Munich is to be tested extensively. Philipp Molter hopes to soon be able to install his system in real buildings. In addition to new buildings, it is also conceivable to retrofit old administration buildings. The advantage: Autoreactive facades are technically simpler and require significantly less energy to cool and dehumidify glazed buildings than systems used today.
"An unoptimized administration building from the seventies can generate energy consumption of up to 600 kilowatt hours per square meter per year, and what an optimized building can do today is about 100. That means you can save a relatively large amount of energy here In our case studies, we have determined these autoreactive components to save about 50 percent of the energy compared to a non-autoreactive facade. "