Ontario Power Generation set out to unite its various corporate offices into a single, modern facility that embodies collaboration, efficiency, and long-term sustainability. Repurposing the former GM headquarters brought new life to an iconic site. The project was recognized with a 2026 Award of Distinction from the Association of Consulting Engineering Companies - Ontario Chapter.

OPG selected Oshawa as its new corporate headquarters, purchasing and redeveloping a well-known building - the former General Motors (GM) administration building — a 285,000 ft2 facility with five levels (four storeys plus a lower concourse).

The project brought together OPG’s non-station staff from across the Greater Toronto area and Durham Region under one roof, transforming the existing structure through extensive interior and exterior renovations. Upgrades encompassed all major building systems, focusing on enhancing performance, comfort, and environmental responsibility.

HH Angus and Associates played a pivotal role as mechanical and electrical engineers, IMIT and lighting consultants, owner’s engineer, plumbing/fire protection/life safety designer, and commissioning authority.

The overarching goal was to create a future-ready workplace capable of supporting OPG’s operational and cultural needs for the next 40 years — targeting a net-zero carbon footprint and integrating leading sustainable design strategies throughout.

Meeting the objectives
HH Angus’ design solution had high sustainability and energy aspirations and involved the adaptive re-use and re-development of the GM administration building in Oshawa. HH Angus’ Commercial and Angus Connect teams came together for this project.

The project team successfully navigated a series of challenges that tested both creativity and collaboration, ultimately demonstrating their ability to deliver excellence under demanding conditions.

Materials and equipment
The unique use of materials was in fact the ‘re-use of materials’, significantly reducing deconstruction waste and embodied carbon. Much of the existing HVAC equipment was optimized (e.g., terminal heating and cooling devices) to enhance performance and capacity, rather than replacing the distribution network.

Internal resources, experience and expertise
To meet the demands of the accelerated schedule, the project team of mobilized a robust internal team, drawing on resources from across the firm. This collaborative effort, made possible by the firm’s size and depth of expertise, allowed us to maintain quality and precision while delivering on time.

Apart from strategic reuse of existing infrastructure, to accommodate increased occupancy, the design team included the use of energy recovery and thermal storage to allow system capacities to be sized below the peak demands to get the most out of the cost and embodied carbon of the equipment provided.

Outcome
Through ingenuity, collaboration, and technical excellence, the team successfully overcame these challenges—delivering a high-performance, cost-effective design that met the client’s objectives and ambitious goals, and reinforced their trust in the team’s ability to deliver innovative solutions under pressure.