Engineer Ben Bronsema built his career around working on machines he knew people didn’t like: air conditioning systems for big buildings. Air conditioning units are loud, big, expensive, not pretty to look at and consume a lot of energy, he says in a talk at TEDxDelft. Yet, they get the job done.
After struggling with the pitfalls of modern air conditioning for years, Bronsema had an idea — look to nature.
“[I'd seen] lots of termite hills in Africa, in Kenya,” he says in his talk. “[Their mounds] are very large buildings they build for themselves. Inside that building, that mound, they grow a fungus. The fungus is their primary food source. The fungus grows best at a temperature of 30 degrees Celsius, so the temperature in the mound has to be kept at 30 degrees, while outside it’s 50 degrees in daytime and the sun is shining on the hill, and at nighttime, the temperature can go down to about zero.”
So, Bronsema set out to study how termites regulate the temperature of their dwellings in order to design a better air conditioning system for the (human) built environment. “Could we,” he asked himself, “by [mimicking nature], probably, maybe, hopefully, make a zero energy building and a building where the endoclimate is more like the outdoor climate and people are more satisfied with it?”
After years of research and some devastating life events, Bronsema and a team of researchers from the Delft University of Technology and the University of Eindhoven as well as a group of advisers from the construction industry worked to create a system — like that of termites — makes use of the natural world to cool and heat a building.
This system works through several processes powered by sun, soil, wind and water, Bronsema explains. An overhang called a climate cascade captures, cools, warms and redirects wind while a solar chimney captures heat energy to power the system. The climate cascade overhang catches outside wind and directs it towards the building, Bronsema says, and as the wind enters the building, water at a temperature of 13 degrees Celsius is sprayed from the top of the climate cascade, which cools air in the summer and pre-heats it in the winter.
“The temperature of 13° C, we can get that from [the] cold [of] the soil,” Bronsema says. “The soil is about 11 to 12° C, so we don’t need chillers, we can get the cold from the soil to cool the air. Then the air is cooled, for instance, in summer from 28 degrees outside to 18 degrees.”
“At the foot of the climate cascade, pressure is built up,” he says, “We need some pressure to distribute the air into the building. Because of the weight difference between the water air mixture inside the climate cascade and the surroundings, there is a negative thermal draught, so we have positive pressure at the foot.”
As for the system’s solar chimney, “the sun shines into the chimney, the air is heated up, is rising, it’s thermal draught,” Bronsema says, “and at the foot of the solar chimney, there’s an underpressure. That underpressure exhausts the fresh air that is distributed by the climate cascade… All that heat is recovered by water, that water is heated and stored into the soil beneath the building. We can use that in winter to heat the building … Then the air is going up through what is called a venturi ejector … When wind blows through the roof, the wind speed is accelerated and there is an underpressure in the heart of the roof. By that underpressure, the wind, the air is removed from the building.
“This works all naturally,” Bronsema says. “We only need one small pump to pump the water up to the sprayers.”
Bronsema and his team are excited about the potential for this new system, which is currently in beta mode and is being virtually tested on an existing building in Amsterdam.
To learn more about how the system works, watch Bronsema’s whole talk below:
Insight from the TEDx office — why we like this talk:
The speaker is an engineer who completed original research with the help of researchers associated with several universities and well as professionals from related fields. This work is evidence-based and being tested. He presents his idea — a novel way to heat and cool buildings — in a way that is engaging, interesting and comprehensive, without being so technical that it alienates viewers from outside his field.