Conversation: Engineering net-zero libraries

Photo courtesy mcCallumSather.

Mary Georgious, P.Eng., is principal and mechanical lead for mcCallumSather, which has been working on Waterloo Region’s first net-zero/carbon-neutral municipal facility, Kitchener Public Library’s (KPL’s) Community Branch. As one of the first buildings in the planned Rosenberg neighbourhood, this new 14,000-sf, all-electric building will incorporate a variety of measures to reach its sustainability goals, including solar panels, a geothermal field, a high-efficiency envelope, insulated flooring and special glazing to capture solar heat. We spoke with Georgious about the process.

Where did the net-zero carbon target come from for this project?

We proposed the idea and worked through the budgeting to help KPL understand the cost. This is not our first net-zero rodeo; we worked on the Joyce Centre for Partnership and Innovation at Hamilton’s Mohawk College and Endress+Hauser Canada’s customer experience (CX) centre in Burlington, Ont., and Toronto Public Library’s (TPL’s) new Centennial Branch.

KPL was open to pursuing net-zero and the public was excited about it. Once we proposed how we would achieve it, we got the green light.

Have there been any specific challenges?

The groundwater in the area was protected, so we couldn’t drill boreholes vertically for a geothermal field. Instead, we worked closely with our geotechnical consultant on a horizontal field. From there, it was just a matter of optimizing the building’s energy use.

What were the stages of that optimization process?

The first is to set an energy use intensity (EUI) goal. Normally, we would look at old data as a baseline for how libraries perform, but libraries are different nowadays. They’re not just a place to borrow a book; they’re interactive, with multi-use spaces. In this case, one challenge was electrifying a kitchen. We started by targeting an EUI of 70 kWhr/m² per year.

Once you set a target, the next thing to tackle is the building envelope, trying to achieve high-efficiency performance through insulation and reducing thermal bridging, leakage and the window-to-wall ratio.

Then you get into custom heating, ventilation and air-conditioning (HVAC) systems and renewables, which go hand-in-hand. Heat pumps and isolating outdoor air from internal loads have been very successful in libraries, so that’s what we did here. We’re using the geo field both for renewable energy and to save space for mechanical systems, as the boiler and chiller are in the ground.

Then you look at occupant behaviour, e.g. how long will that kitchen area be running? We can set a schedule with the client for the consumption of energy.

Once that’s set in stone, you program it in energy modelling and run iterations for optimization. We do build in a buffer for future expansion and uses of the building; while our EUI is 70, we’re confident we’re now running at 63. We’ll watch that closely and make sure we can still hit it.

The process is a lot more collaborative than linear. You start in stages, but always go back and keep an eye on the bigger picture.

It requires a lot of creativity to strike a balance between a sustainable solution and a system that will make the space functional, comfortable and flexible for users to do what they want to do there without realizing they’re off the grid.

What’s going to help get more buildings to net-zero?

Governments are urging reductions in carbon footprints and we are starting to see a lot of deep-energy retrofits for the decarbonization of existing buildings. They’re an exciting challenge, particularly in phasing work for a building that’s already running.

Staying on top of technology is key, as it changes so quickly, particularly in HVAC with dehumidification, new refrigerants, etc. It’s about putting together the pieces of a puzzle; it’s never a cookie-cutter design.