Bringing bioengineering to architecture, UCBerkeley Professors Luke Lee in Bioengineering and Maria-Paz Guttierez in the architecture department are pioneering a new type of thin film building membrane, creating a material structured at the nano and micro scale that can substitute for energy used for climate control in buildings.
In a project recently proposed to the National Science Foundation, they are working on a “skin” that works like nature’s skins to control humidity, light and heat in buildings the same way that nature does in our skin, without the use of electricity or mechanical elements.
Their prototype lense for use in their biomimic Self-Activated Building Envelope Regulation (SABER), reacts to changes in the building’s atmosphere by triggering microscopic openings in the membrane.
The film has two alternating rows of cells providing openings that are actuated by either light from the outside or humidity from the inside. Both types of cells are passive devices that work by material properties, not mechanical or energetic devices.
The first row of cells has micro-lenses embedded in the film that direct light to tiny pockets of photo-activated hydrogels which contract with the light and open up elastomeric microventuri tubes, bringing more airflow into the building when the film is in sunlight.
The second row of cells has a hygroreactive polymer that expands with increased moisture and opens up microvalves to allow more air, like hydraulic mechanisms in nature such as the turgor pressure in the guard cells of stomata in plants.
Wrapping it up on the outside is an external moisture barrier with a hydrophobic nano structure which works like the surface of the lotus leaf to wick water off. On the inside, a layer of desiccant silica gels absorbs moisture from the air inside and is integrated with the self-regulated ventilation system.
Energy used for climate control in buildings is responsible for about a third of the nation’s fossil fuel use. This project could prove a significant pioneering breakthrough that would eliminate the need for mechanical structures – run on electricity – to supply heating, cooling and humidity control.