Reducing CO2 emissions could be achieved by maximising heat recovery and increasing the share of renewables in the primary energy mix. Process Integration has developed over the years into a credible process system engineering tool. One of its important developments has been Total Site Heat Integration, which has combined the heating and cooling requirements of individual processes unlocking, allowing better integration. The current paper presents an extension of the Total Site methodology covering industrial, residential, service, business and agricultural customers and the incorporation of renewable energy sources (solar, wind, biomass, and some types of waste), accounting for the often substantial variability on the supply and demand sides and for the use of non-isothermal utilities. It further applies the extension of the heat cascade principle with inclusion of heat storage and minimises the heat waste and carbon footprint of the considered sites. This is illustrated with a comprehensive case study. (C) 2011 Elsevier Ltd. All rights reserved.