Environmental quality is the fruit of teamwork, starting at the first phases of a building project. The initial choices (i.e. whether to build or renovate, the site, rough layout) determine future performance over the building’s lifetime. Since this lifetime is long, impacts generated during the utilization stage are generally high in comparison to oneoff impacts during construction. This chapter therefore includes recommendations to carefully design buildings to reduce the flows generated during utilization: water and energy consumption (for heating, possibly air conditioning, lighting, hot water, ventilation and other electricity uses such as domestic appliances or computer equipment), transport, waste production, etc.