UBC lab finds a way to bring daylight inside
On the outside of a building at Burnaby's B.C. Institute of Technology, a rectangular box filled with tiny mirrors is doing something extraordinary. It’s lighting offices deep inside the building by efficiently transferring energy that’s available outdoors for free.
“The light is right there. All you have to do is bring it inside,” says Michele Mossman, manager of the University of B.C.'s Structured Surface Physics Laboratory. The lab has pioneered the new lighting technology, which it calls a “solar canopy.”
The solar canopy collects ambient sunlight outside the building, concentrates it into a beam that is 10 times brighter than the light outdoors, then pipes it through a small window to ceiling fixtures where it is dispersed as overhead lighting. The fixtures are also fitted with fluorescent tubes which kick in when it’s too gray outdoors to provide adequate light.
“It’s lighting the offices and desks inside the building with real sunlight,” says Mossman.
Mossman says that provides a number of advantages over traditional lighting – and even some newer eco-alternatives. For example, while solar panels can collect free energy from the sun, Michele says that doesn’t make much sense when it’s light that you really want.
“With solar panels, you’re using the sun to create electricity, then using the electricity to power electric lights. You lose in two ways: the light isn’t natural because it’s electrically generated, and you lose a lot of energy on both of those conversions, so it’s not very efficient.” (The solar canopy system is seven times more efficient than photovoltaic cells.)
Daylight beats artificial light
The quality of light is a definite plus to the solar canopy system, says Alex Rosemann, a BC Hydro engineer who has been supporting the UBC project.
“The eyes of humans have had several million years to adapt to natural light, but only about 150 years to adapt to electric light,” he says. “The solar canopy system offers a very good quality of light in addition to its energy efficiency.”
Mossman agrees. “It’s hard to describe, but things look like they do outdoors in sunshine, more natural,” she says. “We know there are people who are studying the impact of natural light on how people feel and how productive they are, though we’re not doing that work ourselves. Anecdotally, though, people would rather have sunlight than fluorescent light.”
Glare and energy costs
The solar canopy can pipe light up to 60 metres (and possibly as far as 80 metres) into a building from its sunny south side, giving it the potential to cover most of the floor space in all but the very largest office buildings. In comparison, natural light streaming in from average-sized office windows only penetrates three metres into the room, and Michele says the sideways angle is problematic.
“Windows make you feel good but they’re not useful for work,” she says. “How the light is distributed is important. When it comes in sideways, it produces glare. One study showed that people tend to turn electric lights up even brighter to compensate for the glare, so in some offices, the more sunlight there is, the higher the energy costs!”
Notwithstanding the solar canopy’s other benefits, saving energy is the primary reason the technology is gaining interest. Michele says the development team estimates that using the system in B.C.’s Lower Mainland (a region not known for its excess of sun!) will provide a 25% reduction in energy usage for lighting over the course of a year (dark days in December included).
The demonstration currently installed at BCIT is just starting to collect data to test this estimate. Given that 30% of the energy used in buildings is used for lighting, the energy costs savings could be significant.
More projects in the works
Five more solar canopy installations across Canada are now being planned, thanks to funding just received from Sustainable Technology Development Canada and support from other partners including BC Hydro, which has provided funding, technical advice, and valuable introductions. These additional sites will allow testing in different climates and on different building types.
Mossman says the goal of the project all along has been to develop a system that can be commercially viable – appropriate for mass production at a marketable price. This is made newly possible, she says, by a highly-reflective polymer film invented by 3M, a solar canopy project partner. The film allows light to be piped a much longer distance that was previously possible, and it is now commercially available.
“We’re focused on making an inexpensive system so people can afford to do this,” Mossman says. “But the idea of bringing in the sunlight is not new.”
Daylighting for homes and businesses
Bchydro.com offers tips for daylighting – harnessing the power of natural light – both at home and in your business. And at least one organization – the Daylighting Collaborative – exists solely to promote the concept of daylighting for energy efficiency.
Getting in touch with UBC
Interested in becoming a solar canopy project partner? If you own a commercial building that you’d like to offer for a demonstration installation, email Michele Mossman to see if your site would suit the researchers’ needs. And you too might harness the power of the only energy source that’s available for free.
Nina Winham is a Vancouver-based writer and sustainability consultant.
Source: BC Hydro News