Chapter Winner
Category: Public Assembly for an Existing Facility.
Submitted by, Cassidy Taylor, P.Eng., CPHD, LEED AP
AME Consulting Group Ltd. (AME)
Strathcona Gardens Recreation Complex
Energy Recovery Project
Project Summary:
The Strathcona Gardens Recreation Complex (SGRC) originally consisted of an arena and lap pool, which were built in the 1970’s. In 1995, the SGRC underwent an expansion project, which connected the two buildings and added a second arena, a leisure pool, as well as fitness, administration and multi-purpose spaces. The majority of the existing air handling units (AHUs), with the exception of the main pool AHU, were mid-efficiency gas-fired units. The existing boilers and domestic hot water heaters were also midefficiency models.
In 2019, as part of a separate project, the existing ammonia refrigeration plant was replaced with a CO2 plant. This new plant produces approximately 600 MBH of high-grade heat (140° F) and 2,000 MBH of low-grade heat (95° F).
The primary goal of the Energy Recovery Project (ERP) was to capture 100% of the waste heat from this new ice plant and transfer it to where it can be used to satisfy the building’s domestic hot water and building heating demands. A secondary goal of the project was to reduce the greenhouse gas (GHG) emissions from the facility.
The ERP was implemented over two phases. Phase 1 replaced the existing boilers and domestic hot
water heaters with higher efficiency equipment, while introducing a recovery system that uses the highgrade heat as domestic hot water preheat. Phase 2 connected an existing, abandoned loop of pipe, routed over the roof of the building, to the low-grade heat available from the ice plant as well as to four new hydronic air handling units (AHUs).
Project Criteria:
The system in Phase 2 was designed as a low temperature heat pump loop in a cascade configuration that delivers the hydronic fluid to the refrigeration plant at the lowest temperature possible, in order to maximize heat recovery. After picking up the waste heat, the hydronic fluid is topped up by the boiler plant to the minimum temperature required to satisfy the spaces, before connecting to the four air handling units.
The design effectively centralized the gas input to the majority of the building by replacing all of the
existing mid-efficiency gas-fired AHUs and boilers with a new central boiler plant that uses condensing models. Only two existing AHUs remain unconnected to the new hydronic loop, but the loop is sized such that they can be added in the future. Currently the spaces that are served by these remaining units, the pool natatorium and original arena, are being considered for substantial upgrades, so it was decided to replace the AHUs serving these spaces in that future project.
The new AHUs consisted of two packaged heat pumps serving the administration and pool change room spaces, providing heating and cooling to those spaces. Heat pulled from the building to provide cooling is rejected to the hydronic loop, where it can be used by other equipment. Heat exchangers were provided at the pools to make use of this recovered heat during the summer when the other equipment may not be requiring heat.
AHU-5, serving the arena change rooms, is a heat recovery ventilator, which reduces the heat input required as it recovers heat from the exhaust airstream.
IAQ, existing ductwork connecting to any new equipment was cleaned as part of this project. According to information available, this had not previously been done in the building.
Additionally, AHU-5 supplies 100% outside air to the arena change rooms.
Innovation:
The majority of existing ice plants currently reject their waste heat to the exterior through various types of heat rejection equipment. At the time of the original design, heat pump and heat recovery technology and techniques perhaps were not at a place where they could be implemented effectively. However, this represents a significant missed opportunity for the rest of the building as more fuel (gas or electricity) must be consumed to provide heat to the building that could have been recovered. The recovery from the ice plant accounts for 50% of the current heating demand on the boiler plant of approximately 4,000 MBH and will eventually account for approximately 30% of the future heating demand of the boilers after the new natatorium and arena renovations, currently estimated at approximately 6,000 MBH.
Operation & Maintenance:
All of the work done in both phases of the project is fully accessible, either in mechanical rooms or on the roof itself. Nothing was routed through the existing ceilings that could make access more challenging.
The project also included an upgrade to the existing Building Management System that will allow the entire system to be monitored more effectively and consistently.
Cost Effectiveness:
Both phases of this project have been completed on budget. Equipment was selected after consideration of first costs, operating costs, maintenance costs, equipment build quality and expected lifespan.
Environmental Impact:
The project was not able to switch completely from natural gas to electricity as the primary fuel source due to existing infrastructure constraints. However, both phases of the project were conducted keeping the project’s secondary goal of GHG reduction, both now, through centralization and upgrading of the fuelfired equipment, but also for the future, when additional opportunities for heat recovery into the low temperature loop will be available. When the new pool AHU is designed, it will be provided with hydronic coils that will recover heat from either the dehumidification process or from the exhaust air stream.