Org / Contact Title Green O t h e r Calculation Description R o o f s W a l l s City of Portland Dan Vizzini Zoning Code for the Downtown District's • x • Because of the complex nature of the Portland Green Roof policy, please click here to see a fully illustrated graphic description of the policy.  For a complete description of the Portland Green Roof policy, please click here.      Green Roof policy development has been the driving force behind green roof industry development around the world, and North America is no exception. Policies vary greatly from city to city around the world.  An example of Osaka's Green bonus policy for all new private development is illustrated to the right.  For every 1m² of only Green Roof added, 0.2m² floor area is awarded.  When publicly-accessible open-space and Green Roof space is added together, the bonus becomes 1:0.3m².  When it comes to private residences, the city will pay half of the construction cost of a Green Roof or Wall (up to $20,000).  Forward-thinking, simple and profitable policies propel the Green Roof industry forward.