Design Intent compared with Performance in Practice: Residential Heat Networks with Combined Heat and Power
The GLA’s London Plan includes planning policies that require developers to adopt a range of energy efficient measures and low/zero carbon technologies to reduce CO2 emissions below the Building Regulations baseline. Such polices have consequently formed a new aspect of the planning appraisal process, where the assessment of energy, CO2 and technology is now a material consideration of planning approval. Developers must submit an energy strategy to demonstrate how their design proposals achieve the policy targets. The GLA uses these documents as evidence to evaluate the outcomes of the existing policy and direct future policy decisions. The GLA’s findings suggest that their policies have been successful in reducing CO2 emissions. The vast majority of reductions are attributed to heat networks with CHP. However, there is little evidence of the actual performance of these technologies in practice, including the scale of CO2 emissions reductions delivered. This research adopted a mixed method approach to evaluate if the local energy policies which promote the adoption and implementation of heat networks and CHP are leading to the anticipated reductions in CO2 emissions. This research found that the prescriptive approach to the London Plan policy discourages context specific assessment and can lead to a practice of compliance-over-performance when deciding on the most appropriate technology to adopt. The prescribed assessment methodology was also found to be inadequate to appropriately assess the deliverable performance and would therefore, result in an energy performance gap. The research also found that design assessment measures are available to provide a more reasonable assessment of deliverable performance reducing the gap, but are not used in practice. Furthermore, those responsible for implementing the policy do not expect that the assessed performance of heat networks and CHP or the scale of CO2 emissions saved will be achieved in practice, contrary to the GLA findings.
Energy performance gap, Heat Networks, CHP, The London Plan
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