Thesis defence Earth, Wind & Fire – Natural Air Conditioning

7 June 2013 | 10:00
location: Aula, Auditorium
by Marketing & Communicatie

Air conditioning doesn’t require fans: natural methods can also be used. PhD candidate Benjamin Bronsema (78) wants to show in a pilot study that cascading water, sun and overpressure can be used to create an energy-positive office environment.

With his concept, the retired building-services consultant and TU Delft PhD candidate wants to bridge the gap between building-services technology and architecture, as a well-designed building can utilise freely available ambient energy, with a helping hand from modern technology. “Architecture that makes climate technology an integral part of buildings provides for air coming into the building and enables nature to inhabit the building.” Ironically, Bronsema’s system could also overturn the building-services industry in which he has earned his living throughout his career. During his research, Bronsema worked closely with TU Delft (Architectural Engineering + Technology department) and Eindhoven University of Technology (Building Physics and Systems unit).

In his PhD thesis Earth, Wind & Fire – Natuurlijke Airconditioning, which he defended on 7 June, Bronsema describes a system that links three innovations: a ‘climate cascade’, a ‘solar chimney’ and a Ventec roof. Together they create a healthy indoor climate and buildings that are, at the very least, energy neutral.
The first component of the system, the climate cascade, is a structural shaft into which water is sprayed from above. The falling droplets, which have a maximum temperature of 13 degrees Celsius, can transfer heat into the air. The cascading motion of the water creates an air flow, without requiring mechanical means. The AE+T department and Eindhoven University of Technology developed computer models for this concept.  Tests showed that even frosty conditions do not hamper the heat transfer.

The solar chimney also contributes to the natural air flow. Peutz set up a test rig in Molenhoek, consisting of an eleven-metre tower that collects heat from incoming sunlight. The heat generated goes to a geothermal installation or is used directly to heat the ventilated air. The dynamic computer model was validated by measurements taken throughout the four seasons.

Finally, the Ventec roof uses underpressure and overpressure to draw in fresh air and expel stale air. Air is drawn in via the climate cascade and expelled via the solar chimney. Promising laboratory results have been achieved with this system. The research also focused on how energy can be generated using wind turbines and photovoltaic foil in and on a Ventec roof. “The principle is that, wherever my system is installed, it can operate entirely on energy that it generates itself,” emphasises Bronsema.

Peter Luscere (AE+T) sees great potential in the Earth, Wind & Fire system. “This research was particularly interesting for us, precisely because it has a purely practical orientation.” A further factor is that, increasingly, mechanical ventilation systems are no longer seen as the ideal solution. Not only because of their high energy consumption, but also because they are unhealthy. Circulating air through buildings spreads bacteria. Often, in practice, air-filtration systems quickly become a source of infection because moulds flourish in them. Luscere: “Therein lies a major challenge, and this idea offers a solution.” Moreover, rapidly changing energy legislation – as of 2020, all new buildings must be energy neutral – underlines the urgent need for Bronsema’s invention, argues Luscere. “Today, the installations in buildings account for 30 to 35 per cent of costs. That has to change.”

A scaled-up trial with Earth, Wind & Fire is therefore the next inevitable step. Bronsema is looking for an existing office building in which he can test the system on a large scale, preferably a disused building of approximately 10,000 square metres that has ten storeys. Ideally this would be a free-standing building, because the Ventec roof and solar chimney obviously need unobstructed sun and wind to function properly.

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