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.

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.

View Global Holcim Awards Entry – Hydroculus Cooling from Arizona

The built environment has a significant role to play in addressing climate change and enabling the transition to a net-zero and more inclusive future. The Holcim Awards for Sustainable Construction global winners showcase the cutting edge of approaches to sustainable design, green architecture, and materials innovation. In the 6th competition cycle, the predominant focus of the entries in the North America region was the sustainable improvement of quality of life. The global prizes were presented at a handover ceremony at the International Architecture Biennale in Venice, Italy. The regional Holcim Awards Main category winners for North America were recognized at the same event.

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.

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.