“The PBL analyzes the options of green gas, fully electrical, heat grids at high and low temperatures, a combination of gas and electricity, and a mix of all of the above. An update that includes hydrogen and aquathermia as well as the costs for the public, is planned for March 2020. After that, I would advise the municipality of Eindhoven to look at how we as a university can help in each individual residential area.”

Gas as an option

Smeulders emphasizes that the PBL includes the option of gas as a heat source in its analysis. The government, he says, is becoming more and more aware that it’s simply far too expensive to completely disconnect from gas - which is exactly what the professor argued last year in an article on Cursor’s website that was read many times.

Incidentally, Smeulders says that TU/e got involved with a ‘CO₂ reduction Agreement’ between the municipality and the housing corporations in the city a few years ago already. “I’m the contact person on behalf of TU/e for that, and I also maintained regular contact with the predecessor of current alderman Rik Thijs.”

Making buildings sustainable

His own group regularly explores options for making specific buildings or projects sustainable, Smeulders says. A few years ago, for example, Smeulders and two of his students looked into the possibilities of CO₂ emission reduction in the Ir. Otten swimming center in Eindhoven (see panel). “That, too, was in collaboration with the municipality, so they probably still have that report.”

Such projects were always carried out with graduate students, says the professor of Energy Technology. “That doesn’t cost the municipality anything. I would appreciate it if they were to show a bit more ambition when it comes to financing projects in collaboration with TU/e.  It could be useful to have a PDEng student look into ways to make the ice rink, sports park or the new swimming center Tongelreep more CO₂ efficient, for example. That engineering trainee should be partially financed by the municipality.”

“On the very first cold day, the peak demand caused by all those heat pumps will result in an electricity grid failure. We need a much smarter system, one that will have to be calculated in its entirety. We are currently working on this within the Renovation accelerator initiative of the Ministry of the Interior with several groups at the department of the Built Environment, based on our computational models for building physics. These groups will now be fused into a team that advises the government on this issue.”

Heat in stone

The second line involves local energy production and storage. At the Department of the Built Environment, for example, researchers are looking into ways how to integrate solar panels in dormers. “There is a large testing facility on Vertigo’s low rise for that purpose,” Salet says. “We are also thinking about how to retain heat in the house itself, in the building materials. Heat can be retained in stone, but also in so-called phase-changing materials, such as salt that can melt and solidify again. We want our research to be in line with research conducted at IRES, TU/e’s new institute for renewable energy storage. Obviously, it’s important that newly developed materials are circular: they need to be reusable.”

His department’s third area of attention is transportation, Salet says. “Clearly, we aren’t working on fuel-efficient cars, but we do focus on urban planning. How do you design cities where transportation’s contribution to CO₂ emission is as small as possible? Where should you locate a shopping mall or sports park with that in mind? And what will change with the increase in the number of electrical cars and bikes? In order to answer these questions, we use so-called digital twins of the city, models that are fed with data from sensors. That’s in line with EAISI, TU/e’s institute for artificial intelligence.”

Printed concrete

Salet gained recognition in recent years with 3D printed concrete that can be used as building material. That method can also make a considerable contribution to the reduction of CO₂ emission, he says. “The production process of cement in concrete produces a lot of CO₂, no less than five percent of overall emissions worldwide. Sixty percent of the concrete in buildings is located in the floors, and by printing these instead of pouring concrete into a formwork, you need half as much concrete.”

In addition, concrete in buildings also absorbs CO₂ from the air. As a result, paradoxically, buildings with an artificially large concrete surface - which is relatively easy to achieve with a concrete printer - can actually make a contribution to meeting climate targets. Whether this will have a serious impact still remains unclear, Salet emphasizes. “That’s what we’re trying to figure out now.”

“Ultimately, we want to develop concrete without cement as a binding agent, but until we get there, using concrete printers is a good deal more efficient already,” the expert says. Even before 2030, he believes. This field is growing at a very fast rate. “I can’t even keep up who’s working on this anymore. TU/e will organize a large conference on concrete printing next summer, and at least half of the participants will represent the industry. The government believes in it as well, and the scientific community is coming together by sharing results, that’s exciting to see. The construction sector has really been mobilized.”