The primary design goals were to provide a welcoming home for the Elementary Teachers’ Federation of Ontario; create a highly sustainable and efficient green building; use architecture as an educational opportunity; and achieve effective neighborhood integration and signature architecture. The building's design prioritizes a contextual response to knit together the divergent set of conditions that characterize the neighborhood and its edge conditions. Siting strategies involved preserving the existing tree canopy to provide a natural shading device. The building is massed to respond to the rhythm and scale of Victorian residences to the west. A large black walnut tree was retained by creating a west-facing tree court cutting into the building. A façade of vision glazing, fibre-cement panels and vertical sunshade fins reduces solar gains. For south and west façades, late-day solar gains are countered by a fully automated exterior shading blind system — one of the only large-scale applications in Canada. As the greenest, and most energy-efficient, purpose-built office building in the Toronto region, the new ETFO headquarters will be a model for other organizations to take action and confront energy-climate challenges.