Project description by jury
The Hydroculus is an organic-shaped prototype for building cooling that uses hydroscopic materials and radiant heat transfer geometries. Its elongated structure is constituted by waffle ribs covered with a photonic membrane that reflects shortwave solar heat and emits longwave radiant cooling stored in the embedded thermal mass. A hydrogel membrane positioned at the top of the system stores water at a specific percentage to induce a proportional evaporative cooling and downdraft rate. It is connected to water supply tanks at the base that are linked to a desiccant water vapor recovery system at the edges. Water is supplied with small tubing and peristaltic pumps powered by photovoltaics.
Through these evaporative and radiant mechanisms, the Hydroculus reduces cooling energy ten-fold, while increasing comfort and health. Evaporative cooling provides constant cool temperatures within the pavilion during the day. During the night, the thermal mass encapsulated in the modules of the pavilion’s skin is radiated upwards, creating a cold radiant envelope for additional cooling during the day.
The global energy demand for the cooling of buildings is projected to surpass that of heating by mid-century. The over-cooling of homes and offices is a diffuse cause of discomfort for occupants, and also constitutes a major contribution to building energy consumption worldwide. This is the reason why providing new sustainable cooling modes can be revolutionary. The Holcim Awards jury North America particularly commended the manner in which the authors successfully combined engineering and an interesting design. While results from the research underpinning the project were very promising, the jury recommended further extrapolation of the methodology for integrating the system into a building. The authors are on track to achieve a functioning prototype and to test a system that has a great potential to be patented.See more
As a Main category prize winner in the regional Holcim Awards 2020, Hydroculus Cooling from Arizona automatically qualified as a finalist in the Global Holcim Awards 2021.
An organically shaped pavilion was built as a prototype. The shape of the light wood frame ideally channels the downdraft. The shell of the structure reflects shortwave solar radiation during the day. At night, longwave radiant cooling is effected, coupled with embedded thermal mass storage. The evaporation and radiation mechanism reduces necessary cooling energy by a factor of ten over conventional systems. The jury particularly commended the manner in which the authors successfully combined engineering and an interesting design. “The concept demonstrates new possibilities for envelope design and rethinks the way that sustainable cooling can be achieved through combined architectural and engineering engagement,” says project author Forrest Meggers of the Princeton University, NJ, USA. “Thanks to the Award, we will now be able to test the concept in the hot, arid desert of Arizona.”Read more »
Planet and Place: addressing the cooling crunch without an energy/emissions crunch
Cooling and heating are more than half of energy used in buildings, and with the rapid growth of the global south it is projected that cooling will surpass heating as the dominant demand by mid-century. We must counteract this spiral of increasing electricity demand. Designing new systems that demonstrate alternative cooling solutions is critical to address global warming caused by global cooling. Building on several years of collaboration we developed the Hydroculus for Tuscon in the arid Southwest of the US as demonstrator of several advances. The dry climate enables evaporative cooling, which we leverage using a new hydrogel system with desiccant water recovery to minimize water losses. This is combined new systems of photonic materials and thermal mass to maximize radiant sky cooling.
People and Prosperity: cooling for people, not giant sealed buildings
The form of the Hydroculus strategically guides the flow of cool downdraft and orients cool radiant surfaces to create an interior, not separate from the outside, but that provides cooling to the occupant radiantly and evaporatively. The form is supported by an inexpensive wooden frame custom CNC'd out of wood, which has already been prototyped and tested this year. The spatial thermal programming provides new paradigms for access to cooling. Heat stress is a major environmental justice concern with the vast majority of victims being low income and/or from disadvantaged communities. Leveraging radiant heat transfer, which is more than half of heat experienced in the hot outdoors, the Hydroculus combines evaporative cooling with radiant surfaces to activate new accessible cooling modes.
Progress: thermal design for new expanding architectural experiences and education
The planned demonstration can easily be scaled and replicated. The first demonstration will take place adjacent to the architecture school at Arizona University, and we will use the pavilion as both technical and teaching tool. The Holcim Award would certainly enable further development and opportunities to scale up and explore other locations. There is no cost of facade insulation, glazing or sealing, and only minor pumping and basic controls to operate. This creates a whole new model for what it means to have "conditioned" space. As designers and technical researchers this project is an evolving concept in development, and with additional support we hope to translate these novel thermal designs to real experiences that help both designers and people accept new thermal paradigms.See more
AC units for a large (or glassy) room in a hot arid climate use about 1 ton of cooling - equal to melting 1 ton of ice. A typical AC machine has COP ~3.5 so uses ~1 kW of electricity to do that. A typical engineering improvement would improve COP to 4-8 for efficiency, and a typical architectural solution would be to remove the air conditioner and allow natural ventilation. Incremental progress fails to really address the scale of the problem with 50 million units/year being installed, and climate variability makes the architectural solution unreliable. Our comfort system will use <0.1 kW of electricity, have >10x less CO2, and easily be powered by PV. In addition, the materials used are lightweight and low carbon, plus no walls/glass/insulation are needed.
A new approach for engaging with the thermal environment to minimize energy consumption and improve comfort in buildings.
Author comment by Forrest Meggers, Princeton University; Aletheia Ida, Arizona University; and Dorit Aviv, UPenn School …
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