Ottawa businesses are opting to set up in environmentally friendly offices with hopes of cutting down on electricity and employee sick days.

Vacancy rates in certified "green" office buildings have dropped below six per cent in Ottawa, while their "brown" counterparts have vacancy rates over seven per cent, said James McNeil, a vice president with Cushman and Wakefield, an Ottawa-area broker that helps clients find green buildings.

McNeil said it's a positive trend that's being driven by tenant demand.

"Tenants are starting to demand better quality space," McNeil said.

"Tenants are starting to understand the advantages to green buildings."

Amidst the rise of green buildings in Ottawa is 180 Kent Street, a 19-storey office tower run by the Minto Group that has applied for the highest possible third-party green certification.

The building features toilets that use rainwater, access to rooftop gardens, lighting fixed to motion controls and "regenerative elevators" that generate electricity while they're going down.

"We bring in more fresh air so people have a better feeling, no more dry eyes, no more scratchy throats," Robert Smith, head of Minto's green team said.

"Fresh air increased productivity, and if people work in a building that has lots of fresh air and air changes, it is a better place to work."

More green offices planned for Ottawa

An estimated 20 per cent of Ottawa's office space is considered green, double what it was a year ago, McNeil said.

Green office space still comes at a premium price. Space in 180 Kent costs between $45 and $50 per square foot, approximately double what a regular building might charge.

McNeil said savings in water, energy and employee sick days make up for the cost.

Cushman and Wakefield expects 25 per cent of Ottawa's office space to be green by the end of the next year.