Researchers from Washington State University (WSU) have created a test chamber within a shipping container to trial passive cooling systems.
The project aims to help researchers and builders test carbon-free systems in a controlled environment, such as using wind towers or water evaporation instead of electricity to cool spaces.
Lead author of the study and assistant professor in WSU’s School of Design and Construction Omar Al-Hassawi believes cooling is increasingly in demand in buildings, especially as the climate gets hotter.
“Finding cooling methods that don’t require putting more greenhouse gases into the air is crucial to helping a growing population adapt to climate change,” he says.
The test chamber is independent of grid power, using solar power with battery storage. It measures the temperature, humidity and air velocity within and around a cooling system. The chamber was constructed based on the results from a full-scale experiment of a passive, downdraft cooling system tested in Phoenix, Arizona.
“The chamber can recreate hot climate conditions regardless of the outdoor humidity conditions,” says Al-Hassawi.
He says the temperatures and humidity levels they can create are in alignment with extreme summer conditions in Washington State and common summer conditions in the south-west USA (approximately 40–45°C and 10–20 per cent relative humidity).
Al-Hassawi notes that the chamber is useful for getting results quickly, rather than having to wait on large-scale prototype construction.
The project will help test passive systems that require less energy and produce less carbon emissions. Some of the concepts are thousands of years old, and were used in ancient Egypt to capture breezes from towers. Using a layer of moisture at the top of the tower, evaporation cools the air, which then becomes heavier and sinks by gravity into a living space below.
According to Al-Hassawi, the prototype systems they have tested so far are comparable to the passive evaporative shower towers used for the Interactive Learning Centre at Charles Sturt University’s Dubbo campus in western New South Wales. But the new prototypes incorporate multiple cooling technologies in the tower, not only standard direct evaporative cooling.
Al-Hassawi says there’s been an attempt to innovate and use a mix of new and existing technologies to improve performance in different systems.
“There’s a lot of new construction with the rising global population that is going to happen in the coming years, and a lot of it is going to be in the developing world,” he says.
“If we build like we’ve been building and continue to rely on mechanical systems to meet cooling demands, that’s going to be an issue. These alternative systems can be used in upgrading existing buildings as an attachment or by repurposing existing shafts, as well as in new construction by considering this system early in the design process.”
Testing passive cooling systems takes considerable investment and training, but the team hopes this smaller testing environment will ease some of the strain.
“How can we address building design, revive some of these more ancient strategies, and include them in contemporary building construction?” asks Al-Hassawi. “The test chamber becomes a platform to do this.”
Students will start testing some of their prototype cooling systems next semester, and there are hopes that industry partners will also be interested in testing passive system designs in the chamber.
Feature image courtesy of WSU shows battery rack in doghouse, perforated access panel for mini-split indoor unit, air straightener placed in chamber test side, fan array fixed in place, weather-proof port connecting doghouse to chamber, and door-side corner fairings.