Carbon Co-op is delivering OpenEnEffS, a project seeking to adapt and extend the US-based CalTRACK Methods for use in a possible UK pay-for-performance retrofit programme. The project began in July and, with the summer drawing to a close, things are getting started on this exciting project.
The CalTRACK Methods recommend for the use of OpenEEMeter, a Python-based model that takes external temperature data and smart meter energy consumption data, and uses this to produce a ‘counterfactual baseline’ of energy consumption. Ultimately we are looking to develop an open-source software product for use by retrofit evaluators, network analysts and financial institutions to validate savings from energy efficiency interventions.
Model testing has begun, and preliminary areas of focus have been identified. First among the issues identified is evidence of systematic underprediction in OpenEEMeter. This means that, when compared with actual energy consumption data, modelled energy consumption is almost always lower than it should be.
One reason for underprediction might be an observed structural auto-correlation between errors generated by the model. This usually indicates the omission of key variables, or intertemporal dynamics that are not accounted for. Carbon Co-op will be exploring statistical methods to account for this, and considering what (if any) additional parameters can be measured to improve model outputs. This could include the use of comparison groups, which are increasingly being used in the community.
Another issue Carbon Co-op will be working to resolve is that of a persistent ‘baseload-only’ model selection issue. In cases where it is hard to establish a relationship between external air temperature and energy consumption, OpenEEMeter will often exhibit a ‘baseload only’ model selection issue, which typically corresponds to an average of the consumption data used to inform the model. This can have considerable effects on the accurate prediction of building energy consumption, and is therefore an area that Carbon Co-op will be focusing on going forwards.