Monday, September 26, 2011

How green is Douglas College? Part 1: The green roof

Tana Frie photo
By Tamara Letkeman, doug Editor

 Look out the third floor windows of the New Westminster Campus onto the roof decks and you’ll see something that looks a bit like a park, complete with greenery, benches and walkways – not to mention fine views of New Westminster. This is Douglas College’s green roof system.

As the name suggests, a green roof is a roof that has plants and/or trees growing on it. But while it’s a nice place to take a short stroll or relax on one of the benches, a green roof provides way more than a pleasant spot to hang out.

The green roof helps the College reduce energy costs during the summer. It does this by mitigating the urban heat island effect. With traditional roof systems, the surface materials absorb sunlight and then radiate the energy as heat. With a green roof, grass and other plants absorb sunlight through photosynthesis, so the roof and the adjacent area remain cooler.

The green roof also reduces the amount of sunlight that reflects through the windows. With lower radiant temperatures and less sunlight coming in, the air conditioning does not have to work as hard to cool the building, which results in lower energy usage for the College and neighbouring buildings.

The plants on our green roof are sedums – hardy, drought-resistant succulents that can grow pretty much anywhere – that are planted in two inches of dirt that sits in trays. The sedums can withstand heat and dry spells with minimal irrigation, meaning they basically never need to be watered. That said, when it rains, the rainwater is captured in capsules underneath the trays, which irrigates the plants as well as reducing storm water run-off.

Green roofs can also reduce noise, as the plants act as a filter, as well as clean the air, as they trap smog and dirt.

Another advantage to a green roof is it increases the life of your roof. Covered or shaded by plant material, the roof membrane is not exposed to the elements, adding years to its longevity.

Finally, in some cases – like at Douglas – a green roof allows you to add more usable space, as you’re turning it into a green area where you can add pathways and benches.

There’s just one caveat.

“The one caution we have is the sedums and trays are very sensitive to pedestrian damage,” says Louie Girotto, Manager, Facilities. “They’re not designed to be walked on. You have to keep to the walkways.”

Green tips

There are lots of things that you can do at the office and at home to live a greener life. Here are a few suggestions to get you started:
  • Use blinds and curtains to save on heating and cooling costs. For example, you can close blinds at night to retain heat.
  • Move furniture, rugs and curtains away from air grilles and heating vents to heat an area efficiently.
  • Heat and cool spaces strategically to save energy. For example, don't heat storage areas, and close doors to retain heat.
  • Lower your thermostat after hours or at night to save on energy costs.
  • Use water-efficient fixtures; showers and baths account for about 30 percent of indoor water use and toilets account for about 35 percent.
  • Repair leaks immediately, as a small drip quickly amounts to litres of water wasted. Water metres can help detect a leak.
  • Instead of using city water, capture rainwater in barrels or pails and use it to water your garden.


Check back next week to find out how the College cafeterias have gone green.