Image courtesy The Atmospheric Fund
Modulating the domestic water booster pumps to match the demand
Another energy conservation measure implemented was the installation of VFDs on domestic water booster pumps for the low- and mid-rise buildings. Previously, the pumps ran continuously, regardless of the domestic water demand from the units—thus wasting energy. Coupled with pressure sensors in the network, the VFDs now allow pumps to reduce their speed and energy consumption to perfectly match the actual pressure needs in the building.
Giving tenants control over comfort
Aside from the ongoing centralized control sequence optimization, one of the last measures implemented was the installation of smart thermostats in suites across four of the seven buildings. Each thermostat controls a new valve that was installed in each unit, controlling water flow to the radiators.
Pre-retrofit, the lack of heating control in each unit as well as oversized mechanical systems with poor modulation capability often resulted in high indoor temperatures, resulting in residents opening their windows even in winter.
Post-retrofit, the thermostats helped maximize space heating efficiency improvements by allowing residents to control their own interior temperatures. Resident surveys conducted in March 2018 showed a reported decrease of (39 per cent) windows opening during the winter, indicating this measure is improving tenant comfort and reducing energy waste. Additionally, interior temperatures in units decreased by approximately 2 C (3.7 F) on average, while extreme overheating (with units exceeding 28 C [84 F]) decreased by 31 per cent. Overall this thermostat measure has not only maximized the expected space heating savings, but also improved tenant comfort and satisfaction.
Having specific heating controls in these units also enables the decrease of the return hot water network temperatures. This helps to maximize the amount of time the new boilers are within the condensing range, ultimately increasing the overall efficiency of the heating network.
Extensive recommissioning
One of the two high-rise buildings recently received an upgrade of its heating and domestic boilers, but needed recommissioning to operate these systems effectively. Ecosystem optimized the boiler room controls logic to make sure the new boilers could condense whenever possible and pumps could be shut off when not needed. This ultimately improved the thermal comfort and the resident satisfaction.
The end of the project placed emphasis on providing proper training to the facilities maintenance team as well as the buildings’ superintendents. The comprehensive training program was tailored to address each group’s particular considerations. A reference manual, complete with all the final specs and drawings, operation and maintenance procedures, required replacement parts to stock, and equipment guarantees was provided for each site.
Achieved outcomes
This project has achieved more than $492,000 in utility cost savings over the first performance year—22 per cent greater than the expected savings. This is mostly due to higher-than-expected water and electricity savings. Ecosystem also designed the project to maximize financial incentives, which reached $332,000.
Water consumption was reduced by 53.6-million L (14.2 million gal) over the last year (a 27 per cent reduction), while electricity consumption was reduced by 1190 MWh (a 64 per cent reduction for common areas), and natural gas consumption by 370,000 m3 (13 million cf), a 22 per cent reduction. Further, carbon emissions have been reduced by 920 tCO2eq per year (a 26 per cent reduction).
Thanks to an integrated approach to the project, TCH was able to operate the buildings throughout the implementation process. With the design-build firm accountable for providing comfortable indoor environmental conditions, proper control of the systems was performed throughout the entire construction period. These efforts were also maintained during the measurement and verification process, enabling the team to keep optimizing the systems after project completion, and exceed expected results.
| INTEGRATED PROJECT DELIVERY APPROACH |
 Image courtesy Ecosystem A whole building, integrated project delivery approach was key in achieving the goals of the TowerWise project. This outcomes-based approach allows the design-build firm to spend more time in the detailed study phase, seeking more information from both the building and the people operating it, to come up with the best optimized solutions for meeting the client’s desired outcomes. For the low-rise buildings, this translated in building improvements covering most of the HVAC systems, including the addition of new, properly sized space heating boilers and domestic hot water gas absorption heat pumps, new air handling unit (AHU) with heat recovery and variable frequency drivers (VFDs), conversion to light-emitting diode (LED) light fixtures, new valves on radiators along with electronic thermostats, optimized control sequencing, and new high efficiency water closets |
Engaging residents
Aside from the technical challenges posed by such a project, co-ordination with residents required additional skills and flexibility. Proper communication was key to ensure residents were on board with the in-suite measures. Communication initiatives informed tenants about the upcoming improvements as well as the benefits that could be realized. Lobby posters, easy to understand measure notices, and translated materials were all used to educate residents about the type of work happening in their buildings as well as the comfort improvements they could expect. A key engagement piece focused on the in-suite smart thermostats where residents were taught not only how to use the thermostat, but also energy saving behaviour that will improve their comfort.
Olivier Matte is development manager at Ecosystem. After receiving a bachelor of mechanical engineering degree in 1999, Matte joined the Ecosystem team in 2003 as a project development engineer. An excellent communicator, Matte is responsible for staff training and occupant awareness. To date, Matte has trained staff in four colleges, 17 school boards, and 24 hospitals. He has also created and co-ordinated 18 awareness campaigns for Ecosystem’s health and education clients, reaching nearly 35,000 people. Matte also educates the market about energy efficiency solutions by contributing to articles and videos. He can be reached by e-mail at olivier.matte@ecosystem.ca.
Ekaterina Tzekova, PhD, is the low carbon buildings manager at The Atmospheric Fund (TAF), overseeing the energy efficiency demonstration work. Tzekova has published widely on topics related to sustainability, building energy performance, material durability, and indoor environmental comfort. She is a voting member on the National Research Council’s (NRC’s) Canadian Commission on Construction Material. Tzekova can be reached at etzekova@taf.ca.
Keith Burrows, LEED AP, is the energy and indoor environmental quality (IEQ) research co-ordinator at The Atmospheric Fund (TAF), responsible for analyzing building performance and indoor environmental quality data for the TowerWise retrofit program. Burrows holds master’s degrees in computer science from Boston University and sustainable design studies from Boston Architectural College. He can be reached at kburrows@taf.ca.
