Early examples of large scale building electrification projects plot out a learning curve with some rewarding discoveries along the way. Notably, there are cost savings to be reaped when efficient new technologies enable the downsizing of HVAC systems from original specifications. That can further bolster the business case if the building’s existing electrical capacity can then handle the added heating load without need for expansion.
However, project proponents stress that the numbers will crunch most effectively when switchovers are synced with the end-of-life of existing mechanical equipment and/or asset repositioning plans. Sharing their experiences during a December webinar sponsored by the Collective for Advancement of Connected Buildings (an offshoot of the Proptech Collective), they sketched out both project details and the broader decarbonization mandates of their corporate employers or government clients.
“Our philosophy is that every time you have the opportunity to touch a system, if you’re spending money on it, replacing it or upgrading it, that is the best time to align it with a net-zero roadmap,” advised Lee Hodgkinson, head of sustainability and technical services with Dream Unlimited, which is targeting net-zero greenhouse gas (GHG) emissions in its portfolio by 2035.
One such example is 67 Richmond Street West, an 80-year-old, 50,000-square-foot mid-rise that Dream asset managers envision as a “net-zero-ready luxury boutique office building”. The in-progress transformation includes: a new variable refrigerant flow (VRF) heat pump system for heating and cooling; an energy recovery ventilator (ERV) for ventilation and managing outdoor air intake; and building envelope upgrades that underpin a 10 per cent reduction in HVAC system size. Collectively, retrofit measures are calculated to deliver a 61-tonne annual reduction in emissions, representing a 55 per cent cut to the building’s previous tally, along with a 30 per cent reduction in energy use.
Similarly, co-presenter, Joe Brown, vice president, building technology, and decarbonization lead with KingSett Capital is tasked with executing his company’s goal for a 67 per cent reduction in GHG emissions by 2035. He underscored that the recent $65-million overhaul at Toronto’s venerable Royal York Hotel, which has merited CAGBC zero carbon certification for the 94-year-old facility, entailed about $55 million worth of upgrades that would have been required anyway.
“The additional $10 million to go zero-carbon was a very small uptick,” Brown said. “All these projects that we’ve done have really been driven by end-of-life mechanical equipment. Then you can come up with a long-term plan and the numbers start to make a lot more sense.”
In this case, the hotel was opportunely located to adopt deep lake water cooling (DLWC) with connections already in place to the district energy provider’s (Enwave) pipe. DLWC has supplanted three 800-ton chillers, cutting the building’s electrical load. Water pulled from the return side of the heat exchange also supplies the energy source for the heat pumps that provide domestic hot water and space heating. Project commissioning was still in progress as of the mid-December presentation, but it’s expected to deliver a 7,700-tonne annual reduction in emissions.
Toronto climate welcoming to heat pumps and added wintertime electricity loads
Both the Royal York and 67 Richmond previously relied on steam from Enwave’s district energy system for heating, and the building owners will continue to keep it as a backup option. In contrast, another KingSett project at 100 Yonge Street in Toronto, is now solely reliant on VRF air-source heat pumps that do not function in temperatures below -30 degrees Celsius. Since the initial start-up in November 2022, temperatures have dropped as low as -20 C on just one day, in February 2023.
“We have the capability of adding electric boilers; we just haven’t seen the need yet,” Brown observed. “They (heat pumps) cut out at -30 real temperature, but Toronto rarely, if ever, sees that temperature.”
Also related to Toronto’s climate, buildings are typically equipped for summertime peak demand, giving them surplus electrical capacity for their needs in colder months. This already provides manoeuvrability to take on an electric heating load, which can be stretched even further with other efficiencies a retrofit can introduce. When replacing end-of-life boilers and chillers at 100 Yonge Street, for example, decision-makers drew on historic consumption data to justify a 30 per cent reduction in system size.
“I didn’t have to call Toronto Hydro because we didn’t increase our line,” Brown affirmed. “Our peaks have actually reduced in this building overall. We have more efficient cooling equipment now and our heating equipment doesn’t pull what the old equipment pulled.”
Hodgkinson described VRF heat pumps as “the most energy-efficient, GHG-efficient option that we looked at” — also calling its ability to provide precise temperature control within a number of different contiguous thermal zones a good fit for the needs of an office occupancy. Even so, the technology was chosen for 67 Richmond Street after a thorough exploration of other possibilities and with integrated technical expertise on hand.
“Engaging heat pump manufacturers, energy consultants and mechanical-electrical consultants early on in a collaborative manner was very important,” Hodgkinson reported. “There are a lot of products out there, many of which are not tested for our climate. Also, there are a lot of products out there that don’t have real-world testing or data, and we need that data in order to form our energy models accurately as well as our HVAC design.”
Federal “flagship” retrofit features geoexchange infill
Heating for the government of Canada’s 442,000-square-foot office building at 25 St. Clair Avenue East in midtown Toronto is supplied via a new geoexchange system drilled in the underground parking garage. It’s one component of a whole-building retrofit — a newly completed five-year project expected to achieve an 80 per cent reduction in GHG emissions — that also includes a full envelope upgrade and installation of rooftop solar photovoltaic (PV) panels to power about 15 per cent of the building’s electrical needs.
The deep retrofit aligns with both required mid-life refurbishment of the 1950s-era building and the Canadian government’s pledge to pursue net-zero carbon within its own property portfolio. The project is considered one of the “flagship” undertakings, but is occurring along with a number of smaller-scale interventions to reduce emissions and offset peak demand through equipment replacement and operational adjustments within federal buildings.
At 25 St. Clair, major project components were devised to be mutually supportive with air-tightness and energy efficiency improvements deemed key to reduce the heating and electrical load. Adding to the challenge, the site is locked in on all sides with no exterior space to drill a geoexchange well.
“Using the envelope aspect has allowed us to make a manageable-sized geothermal system where we just had the space under the building, and that was it,” advised Paul Barton, director of energy and sustainability with the project manager, BGIS. “It was a very complicated drill session where we had more than 50 bore holes all at slightly different angles to spread out to be able to deal with the height restrictions in the parking garage.”
The system has now been operational for more than a year, providing heating throughout the winter of 2023 while other construction continued, and rendering the backup electrical boiler and emergency gas-fired boiler unnecessary. “We have had construction challenges throughout, but we’ve managed to get through and keep that gas turned off so we hope to use this as an example going forward for many other retrofits like this,” Barton recounted.
Meanwhile, synergies with energy efficiency are prioritized no matter what the project scale. BGIS has also managed a range of more scoped electrification projects in the government’s portfolio — switching out humidification or boilers without necessitating a complete system overhaul.
“We’re trying to keep flexible as we go forward and not presume we have to renovate everything. We can still do things with what we have and optimize that with controls and strategies to offset many peak demand charges and offset larger amounts of emissions,” Barton said. “The efficiency aspect in buildings is going to be hugely considered with this. We’re not doubling our demand at a building, simply jamming a heat pump onto an existing building.”
Technology is the easier part
Looking to the private sector, Hodgkinson and Brown concur that their companies’ emissions reduction targets are achievable, but other uncertainties complicate planning and budgeting. Unknowns include the future costs of electricity versus natural gas, particularly if there is a step back from the current carbon pricing schedule, while net-zero strategies in general are predicated on comprehensive and relatively rapid expansion of supporting infrastructure.
“The solutions are pretty available. I don’t really see a lot of buildings where I can’t come up with a combination of solutions to get there (net zero). I think the concerns over the longer term are around the grid, the cost of electricity and the carbon tax,” Hodgkinson reflected. “That does make it challenging to forecast out, as an asset manager, where we can afford to do things.”
“The technology is there. The business case is tougher than the technology, trying to make the numbers work, but it’s doable as well,” Brown maintained. “You need to really push the engineering; you need the information; you need to make the decisions, but I’m picking them off based on when there’s capital work due. That makes the business case.”