What will indoor climate systems of the future look like?

News - 25 October 2022 - Communication BK

The corona pandemic, summer heat, high gas prices... the indoor climate has been getting a lot of attention in recent years. Atze Boerstra, Professor of Building Services Innovation at TU Delft, specialises in technologies that control the indoor climate. On 11 November, he will deliver his inaugural speech on the topic: Indoor Climate Systems Design in Times of Uncertainty.

While the importance of adequate ventilation and clean air in buildings was emphasised the last two years to prevent the spread of corona, and last summer overheated houses once again raised concerns about increasingly harsh living conditions, today the focus is all on energy prices and insulation. What are the wise choices to make? “Not long ago, schools had to keep their windows open all day because of a new virus. Two winters later, they have to keep everything closed to reduce heating costs. This is a good time to reflect on how we manage the climate in our buildings and to find more structural solutions,” concludes Boerstra. On top of this, there is a growing shortage of high-grade raw materials for mechanical and electrical engineering systems, and personnel for the installation sector is getting harder and harder to find. “We really need to reconsider how we go about achieving a comfortable and healthy indoor climate with our building service systems.”

Non-residential construction

Some needs can be met ‘passively’ says Boerstra, such as cooling during summer. This requires well thought-out building physics, smart facade design and a carefully designed indoor environments. “Smaller windows, effective sun blinds and deciduous trees with a substantial canopy planted around a building can have a huge impact on the overheating risk. Like that the mechanical cooling system’s capacity can be kept limited or can be avoided all together.”

We really need to reconsider how we go about achieving a comfortable and healthy indoor climate with our building service systems.

Boerstra believes that a healthy, comfortable, energy efficient building often won’t be possible without adequate building technology. “Of course, the function of a building strongly determines the specific climate requirements.” In other words, healthy air and thermal comfort are more important in a hospital than in for example a sports club canteen. “In non-residential construction, controlling physical conditions is usually a bit more complicated than in residential construction. That means, you are more likely to find sophisticated systems for ventilation, air treatment and temperature control there. My knowledge and experience mainly relate to non-residential construction, but advanced HVAC technologies are also used in residential construction these days.”

Air treatment unit

Lowering the temperature

Designing climate systems is a bit of a balancing act. On the one hand, there are the client’s wishes and performance requirements for comfort and well-being in health and safety regulations, for example. On the other hand, there are the costs and energy consumption of the systems. How does a systems designer find a balance? “Fortunately, we are getting better and better at coming up with sustainable solutions,” says Boerstra. “For example, in the wintertime we can now recover heat from the return air in the mechanical ventilation system. By preheating the supply air with this return air, we can save 80 to 90% of the energy required for heating, while still providing ample ventilation.”

Boerstra says there are more clever ways to save energy. “In recent decades, we have become accustomed to relatively cheap energy, and keeping all kinds of spaces warm or cool, often right up to the ceiling, while these spaces are not or only partially used.” But there are smarter ways. Simple technologies make it possible to create individual comfort zones right there were people sit or lie. “In two projects I am involved in, we are cooling and heating workplaces using technology that is integrated into the office chairs or tabletops.” Sensors detect whether the workplace is occupied and if not, the systems are automatically switched off. “The beauty of such microclimate management solutions is that the surrounding space does not need to be heated or cooled as much.”

Increasing prices and delays in the deliveries of building materials also require reconsidering traditional practices, thinks Boerstra. “Can we design smarter components that last longer or can be more easily reused? For example, a student of mine is looking at ways to replace air ventilation ducts, usually made from sheet metal or virgin plastics, with a bio-based alternative.” Circularity is still in its infancy in his field, says Boerstra. “I want to collaborate with colleagues active within the Circular Built Environment Hub, like professor Tillmann Klein, to change that.”

Da Vinci: First "air conditioning" system in early 16th century


Boerstra’s appointment at the Faculty of Architecture and the Built Environment is for 1,5 day a week. As Professor of Building Services Innovation, he is engaged in both research and teaching. His primary teaching goal is to challenge students of construction engineering to design sustainable buildings and systems that meet the perceptions and requirements of the intended users. “It is simple enough to put together an intelligent system, but you also need to tailor the conditions to individual needs. This is particularly important in spaces where people spend extended periods of time.” This means that the control panel on the wall of a home, school or office, and the app on a mobile phone, should be functional and easy to use. “This also requires the insights of industrial designers and environmental psychologists, for example.”

Boerstra is also the director of a consultancy firm, and as such his teaching and research are firmly rooted in practice. His preferred method of teaching is to let his students sink their teeth into currently relevant design challenges. Research projects in response to the corona crisis revealed how talking, singing, and coughing all cause aerosols (tiny droplets in exhaled air) that transmit viruses in indoor spaces. “So I ask my students for example to redesign festival tents and bars so that they are less of a (COVID) health risk, even when they are packed full.”

Boerstra is convinced, the challenges of climate change and the increasing uncertainty about our energy mean that his industry needs to change its course. “Starting with the question: what will more crisis-proof climate systems – ready for the societal problems of tomorrow - look like?”

Further information

Professor Atze Boerstra (Department of Architectural Engineering and Technology) will deliver his inaugural address on Friday 11 November, which will be preceded by a symposium on Innovative Climate Systems.

Visit Atze Boerstra’s professor page for more information.

Header photo outdoor air intake grill | Credits: Pawel Czerwinski - Unsplash