A climate cascade is a vertical shaft inside a building in which water is sprayed from the top; the falling droplets cool, warm and clean the ventilation air and at the same time drag it downwards. The solar chimney is its counterpart on the extract side: a tall shaft in which the sun heats the return air so that it rises and pulls the building empty.
Together with the Venturi-effect roof, a roof shape that uses wind to create positive and negative pressure, they form the concept Earth, Wind & Fire, on which Ben Bronsema took his doctorate at Delft University of Technology in 2013. The idea is air conditioning with no — or minimal — mechanical ventilation: gravity, sun and wind do the transport work that fans would otherwise do.
How it works
The falling droplets in the cascade do two things at once. They exchange heat with the passing air — cold water cools in summer, tepid water warms in winter — and through their falling speed they transfer momentum to that air, creating a downward flow without a fan. As a side effect the droplets wash dust out of the air.
Where it applies
- Commercial and high-rise buildings — the concept needs structural shafts, so it suits offices, hotels and education buildings, not a terraced house
- Built examples in the Netherlands — a hotel in Amsterdam and the Langeveld building of Erasmus University Rotterdam use this principle
- Combined with ground-source storage — the water in the cascade can be fed from a borehole system
- Solar chimney on its own — even without a cascade, solar chimneys are used to drive natural ventilation in atria and stairwells
Points to watch
- Space take — shafts for the cascade and the chimney cost lettable floor area; that has to be in the concept design, not added later
- Water quality and hygiene — a system with open water demands attention to legionella control and cleaning
- Controllability — natural driving forces vary with weather and season; in practice a supplementary control strategy or assist fan is nearly always needed
- Not a DIY solution — this is services engineering at design level, where the building fabric and the climate system belong in one hand
Related terms
- Climate façade
- Indoor climate
- Climate-adaptive building
- Balanced ventilation
- Stack effect
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