This project is the first Quebec’s multi-rental office building with a recognized ecological performance, that is, LEED certification. This new four-storey building of 54 000 sq. ft. is a high energy effectiveness building. HVAC systems were conceived to separate the internal zone from the external zone for a total of five systems; for each side and for the central zone. We had also the mandate to help develop of the design criteria in order to obtain mention LEED GOLD. Regarding the heating of this building, a solar wall was designed on the southern side, allowing to recover the equivalent of approximately 56 000 kWh per year, that is to say approximately 20% of the energy consumption of heating of this building.