 An SEU is focused on permanently lowering overall energy use and limiting supply to renewable energy sources.Rather than slowing the rate of energy market expansion or improving the efficiency of energy services, the SEU cuts energy requirements based on sustainability defined constraints; notably, the need to adhere to an annual 3.3 ton per capita emission budget for greenhouse gases released, expressed in a CO2 equivalent.An SEU functions as a 'community utility' directly accountable to the local community it serves as it seeks to deliver sustainable energy services.