**3.1 Environmental synergy**

The original construction of obsolete buildings, including disused or underused historic buildings, expended a large amount of embodied energy through material extraction, production and transportation. Reuse of such structures is also the reuse of embodied energy and hence, avoiding demolition waste and reducing the amount of energy consumption [10]. Adaptation of obsolete historic buildings is also an opportunity to incorporate energy-efficient features to bring old structures in line with current building legislation in terms of safety and sustainability. The environmental synergy between the two sectors not only conserves energy as the 'greenest building is the one already built'

The social housing is adjacent to the boardwalk in the Beaches, one of the most attractive historic neighbourhoods in downtown Toronto, and is itself a historic resource. The building contributes to the character of the place and provides an opportunity to integrate social housing tenants in a high-income area. During the reconstruction, only the original façade of the 3-story, the 27-unit property was preserved. In addition to the installation of an elevator and other accessibility features, the primary goal of the regeneration was to meet a 40% energy efficiency improvement. The total cost of the regeneration was \$5,894,340, and it provided 27 apartments of mixed-income housing. Funding from energy efficiency retrofit and neighbourhood environmental programs covered project costs. Half of the original tenants were able to come back to Hubbard Boulevard and live in rent-geared-to-income units where their pay 25% of their income in rent [16].

## **Box 1.**
