ASHRAE Journal - October 2023 - 31

HONORABLE MENTION 2023 ASHRAE TECHNOLOGY AWARDS
In 2015, the City of Vancouver (COV) began retrocommissioning
(RCx) investigation studies for
their top greenhouse gas emitters. The RCx study
at Kitsilano Community Centre revealed potential
control measures to enhance HVAC efficiency and
optimize operation. It also identified capital upgrades
that had the potential to reduce more than 80% of the
site's emissions, which aligned with COV's aggressive
emission reduction targets.
The HVAC system consisted of the original
construction hydronic system, three oversized boiler
systems and supplemental gas-fired air-handling units
that had been added in previous retrofits. The systems
installed during previous retrofits overlapped with
the original system, in terms of the service area and
heating capacity, making the HVAC system oversized
and inefficient. With major components past their
service life, there was an opportunity to perform a
deep retrofit that integrated the whole facility into
a single system and to take advantage of the ice rink
waste heat. With a strong business case, the City
was able to present the project's benefits and get
stakeholders' buy-in.
Through the review process, a total of 18 RCx
measures and major capital energy conservation
measures were identified and analyzed, including:
 HVAC control improvements;
 Boiler plant re-piping to enhance condensing
efficiency;
 Ice plant control improvements;
 Heating plant integration with heat recovery
chillers (ammonia plant heat recovery),
recovering heat to the building HVAC system,
DHW and snow pit;
 Replacing fitness center condensing units with
variable refrigerant flow system that can recover
heat.
In 2017, the engineering firm prepared a detailed
design for the identified measures to retrofit the HVAC
systems in both the rink and the community center
facilities. The project was constructed in 2018 and fully
commissioned by October 2018.
To minimize the impact on electrical consumption,
the building control system was upgraded to provide
optimal operation of the HVAC system, including
Iram Green, P.Eng., is principal, energy engineer at Prism Engineering Limited in Burnaby, Canada.
O CTO B ER 2023 ashrae.org ASHRAE JOURNAL
31
CASE STUDY
weekly schedules adjusted based on occupancy
and desired thermal conditions. Following the
implementation, the electrical energy use indicates the
efficiency improvements offset the increased electrical
load from the new electric heat pumps, which
now provide heating to all the buildings. Through
optimized control sequencing, the electrical energy
increase accounts for only about 15% of the heating
energy provided to the building.
Understanding that gas boilers will provide
supplementary heating during peak loads and
equipment maintenance, the inefficient heating plant
was removed, and a high-efficiency domestic hot water
heating system was installed. The domestic heaters
are connected directly to the city cold water, achieving
maximum condensing performance due to cold
entering the water.
The rink facility had high-efficiency boilers that
were oversized and were operating outside condensing
efficiency. Through piping modifications, the hightemperature
and low-temperature loads were
separated and supplied to the boilers through their
dual return ports. This allows the boilers to operate
at their highest efficiency, even when high supply
temperatures are required for the arena's domestic
hot water. In addition, the boilers were reconfigured
to operate with variable primary flow to maximize
supply/return water differential temperature and
maximize condensing performance. Finally, with the
two-building plant integration, the potential heating
load on the boilers was increased, further improving
their efficiency.
Heat recovery chillers were selected to operate with
variable primary flow, maximizing pumping efficiency
and improving supply temperature control.
The implemented upgrades resulted in a total of
4000 GJ in natural gas savings annually. Natural gas
use for space heating was eliminated during the ice
season. This is more than an 80% reduction in GHG
emissions for the site.
All systems were designed to exceed ASHRAE
Standard 90.1, including variable source and heating
primary pumping (no chiller or boiler pumps are used
in main plants).
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ASHRAE Journal - October 2023

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