Community energy management (GEM) (also called community energy planning) combines planning concepts - neo-traditional design, complete communities, green cities - with energy management concepts - energy cascading, demand-side management, integrated resource planning. It can be applied at the level of neighborhoods, cities and even small regions in order to exploit the synergies between urban design objectives for livable cities and energy management objectives of minimizing energy use and its associated environmental effects for a given standard of living. CER I encompasses (i) land use planning, (ii) transportation management, (iii) site design, and (iv) local energy supply and delivery planning. While traditional energy management focuses on energy using equipment and buildings, CEM also considers the urban land use and infrastructure level. This study applies CEM to four representative communities in British Columbia, Canada, over the period 1995 to 2010, and compares the results to a business-as-usual (BAU) scenario. The aggregate effect is a decrease in energy service costs and energy consumption of 15-30%, and in air emissions (CO2 and NOx) of 30-45%. The methodology and results, with respect to one aspect of CEM -land use planning - are extrapolated to the provincial level in order to estimate total CO2 emission reduction potential. CO2 emissions are reduced by 17% from BAU. Additional approximate calculations (restricted to land use planning) suggest that on a global scale CEM can be an important element in the greenhouse gas emission reduction strategy, especially given the dramatic urban growth anticipated in developing countries in the coming decades. Implementation of CEM requires an array of policy initiatives from governments at all levels, as the following examples illustrate. National and provincial (state) governments can (i) change the legislation governing regional and municipal land use planning, (ii) tie infrastructure grants to CEM type municipal investments, and (iii) provide information support and fiscal incentives for developers. Regional and municipal governments can (i) change zoning objectives, (ii) encourage specific types of developments through development charges and tax incentives to developers, and (iii) work with energy and other utilities to encourage particular energy forms and delivery systems.