Ontario Power Generation (OPG) HQ – Net-Zero Retrofit
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Project Overview
In a major sustainability initiative, Ontario Power Generation (OPG) committed to transforming an existing corporate headquarters into a modern, net-zero energy building. Originally planned as a new build, OPG pivoted to retrofit an existing structure in Oshawa, Ontario to meet its long-term carbon and operational goals. This aligns with its broader commitment to net-zero carbon operations by 2040 which fit perfectly with solutions that Siwa offers.
This project involved a complete mechanical system upgrade from the building’s 20 year old high temperature system to a new highly efficient system, optimized for thermal management. This is critical for occupant comfort and peak performance in an energy-optimized environment.
Existing System (Legacy Design)
High-temperature gas boilers (180–200°F)
Conventional chiller plant (44°F CHW)
Aging 2–3 row fan coils
Constant-speed PSC motors
Limited turndown & poor part-load efficiency
No load shifting capability
New Net-Zero Mechanical Design
Central Plant
Air-to-Water Heat Pumps (reversible)
Ice Thermal Storage (off-peak load shifting)
Fully electrified heating & cooling
Hydronic Design Temperatures
Cooling
LAT: 55°F
Optimized chilled water loop
Designed for part-load efficiency
Heating
105°F EWT, 95°F LAT. Can only be done with modern 6 Row coils with long circuits
Low-temp loop to maximize heat pump COP
Result
Elimination of fossil fuel heating
Lower distribution temperatures
Peak demand reduction via ice storage
High-efficiency, low-carbon operation
Net-zero aligned performance
Infrastructure Ontario
Toronto, Ontario
PDWA - Horizontal Ducted Fan Coil Units
PDWA - Horizontal Ducted Fan Coil Units by Polar Air
Q4 2025
