by Sarah Badger

VIDEO: Wood Turner, Stonyfield’s VP of Sustainability Innovation, discusses how Stonyfield approaches environment issues through the company’s Mission Action Plan (MAP) teams.

In this first installation of our Mission Action Plan (MAP) blog series, Mary Fischer, Stonyfield’s Carbon Master, filled me in on a recent project she headed up – installing “light tubes” in the roof of our warehouse.

Mary is a member of the Stonyfield Facility GHG Emissions MAP Team (aka, the Energy Team) which is charged with eliminating greenhouse gas emissions associated with energy use at our production facility through efficiency and using renewable sources of power. In addition to making sure Stonyfield’s yogurt making facility is increasingly efficient, the team also looks at different ways to utilize alternative energy sources.

For example, we capture biogas from our on-site wastewater treatment facility – an anaerobic digester which generates very little waste – and use it to create both heat and electricity to keep the digester running. That way, we don’t have to use as much fossil energy to power it.


Let there be light (tubes, that is)! The light tubes in the warehouse, bright enough to keep the light fixtures turned off.

Harnessing the Power of the Sun with Light Tubes

As Carbon Master, Mary manages the ongoing life-cycle assessment (carbon footprint) of our products, as well as other projects such as renewable energy, energy efficiency and energy analysis. While some work was being done on the roof, it opened another opportunity to install “light tubes.”

Light tubes are similar to skylights, except they do something very special: the inside of each tube is coated with a highly reflective material that concentrates sunlight as it travels down the tube.

That means even when it’s cloudy (as it often is here in New Hampshire), and even though the lights have only a 22″ diameter, the light will still beam sunlight into the building.

Alongside the tubes, we’ve installed “smart” electric light fixtures that can communicate with a photosensor, which measures how much sunlight is in the room. When sun is shining plenty of daylight in the room, the lights will automatically shut off – saving both electricity and money.

Carbon Master Mary Fischer beams with pride over the light tube domes on the roof.

Sure, saving electricity and money are great reasons for installing light tubes, but the benefits of this project extend beyond these savings. As Mary explains, “We’re taking advantage of the free energy of the sun, which happens to be the best light for visibility and mood.”

“It’s amazing how much we adapt to environments that are completely void of natural light. That’s the case in many warehouses, and it took some getting used to when I went there for the first time. It was a dim environment. It’s completely unnatural, and there’s no reason it has to be that way.”

What does the future hold?

Having more light in the warehouse from light tubes has made it a brighter environment, and employees are happier because of it. The Facility GHG Emissions Team is also happy because the light tubes have the ability to reduce some electricity usage. The addition of the light tubes has been such a success that a second installation is already underway in the roof of another Stonyfield warehouse.

Like a crystal ball, Mary looks into the future of light tubes at Stonyfield

Mary feels strongly that light tubes like ours should have a place in warehouses everywhere. “We don’t have to build buildings that shut out the sun and ignore the greatest light source we have just because we’re afraid of a leak or the financial payback is too long. There’s a different way of doing things, and that’s what Stonyfield is about.”

Light tubes, like the ones we’ve installed in our warehouse, are available for residential use as well, which means you could easily have them installed in your own home! What do you think? Are light tubes going be the lights of the future?


Solar light tubes in a private residence.
Solar light tubes can be installed in residential homes, too.