City Hall’s green roof is cutting down on city’s energy consumption

City Hall’s award-winning green roof is saving the city thousands of dollars a year in energy costs.

City Hall’s award-winning green roof is saving the city thousands of dollars a year in energy costs.

The roof provides energy savings in part because of its vegetative layer that protects the waterproof membrane from UV damage, temperature variations, and physical damage, says Amber Zirnhelt, the city’s sustainability manager.

“Overall energy consumption at City Hall is on a downward trend, resulting in approximately 25 per cent reduction and savings of almost $15,000 per year at today’s electricity rates based on analysis of data from 2007 to 2011,” Zirnhelt said in a report to council.

Both numbers exceed original savings estimates.

“Prior to installation of the green roof, staff conservatively forecast a 12.5 per cent reduction in the energy required to heat and cool the building, resulting in approximately $2,100 in cost savings per year,” Zirnhelt said.

“Energy savings are the result of increased insulation provided by the growing medium (soil) and vegetation layer on the roof.”

Zirnhelt notes that since the green roof was installed, the city has transitioned to using more efficient lights and turning lights off when not being used but neither of those actions alone would have provided the level of energy savings the city is seeing.

Zirnhelt said the best way to measure the energy savings attributable to the green roof is to look at the months between November and March, when there is the highest demand for heating.

“When the average winter consumption before and after the green roof installation is compared, the results indicate an energy savings of approximately 15 per cent or 53,000 kilowatts per hour, which translates to $4,240 per season at today’s electricity rates,” Zirnhelt said.

The city’s green roof was completed in 2009 and Campbell River became the first municipality in B.C. to install such a roof on an existing civic building.

Last year, the roof won the National FCM Sustainable Community Awards in the Building Category, from among 40 municipalities, and received Honourable Mention in the B.C. Climate and Energy Awards.

The roof cost $489,039 to build and  was funded through federal gas tax funding earmarked for environmental sustainability projects.

The green roof falls in line with the city’s 2009-2011 Strategic Plan aimed at environmental sustainability and reducing greenhouse gas emissions.

City Hall’s roof consists of a combined upper roof and landscaped courtyard area.

The upper roof is modeled after rocky bluffs in the coastal range.

The courtyard area is designed to look like a Japanese style garden in recognition of Campbell River’s sister city of Ishikari, Japan.

The area is used by city staff as a gathering place.

City council reviewed Zirnhelt’s report outlining City Hall’s energy savings at Tuesday night’s meeting after the Mirror went to press.