Exploring energy integration between new and existing developments

The UK government has ambitious goals to reduce national carbon dioxide (CO2) emissions and has targeted the new and existing built stock with measures to improve building performance and provide more local and centralized renewable energy. New dwellings are proposed to be 'net-zero carbon' by 2016, which includes proposals to offset CO2 by integrating new and existing development. To what extent can new zero-carbon communities be more readily achieved through increasing the integration between new and existing domestic developments? A methodology is presented for determining the ratio of on-site renewable energy supply to energy demand for a series of densities using a simplified model. Options that increase the proportion of existing dwellings served by a new development to balance further energy demands are presented. The practical opportunities and constraints are considered for integrating new and existing domestic development to achieve net-zero carbon. Meeting net-zero on-site annual energy requirements through on-site energy resources is possible even at high urban densities, with annual average supply/demand ratios of approximately 2.3. Also, integrating existing dwellings may offer an opportunity to improve supply/demand ratios for further CO2 reductions; low densities are shown to have annual supply/demand ratios of approximately 9.5. Although a finer temporal scale illustrates the limitations of an annual average and the variable nature of on-site energy resources; this straightforward method can act as a catalyst in achieving net-zero-carbon communities.