New Empirically-Based Models of Energy Use in the Building Stock

National plans for CO2 reduction and security of energy supply depend on very significant and rapid reductions in the building sector. Delivering this transformation will require a raft of effective technology and policy interventions. These in turn will depend on much better knowledge of the present patterns of energy use in the building stock, and the incorporation of this understanding into new predictive models. The project will seek to contribute to developing this knowledge for the national stocks of both domestic and non-domestic buildings (i.e. all buildings other than houses and flats). Greater emphasis will be placed on non-domestic buildings, since here the state of current knowledge is weaker.

The Department of Energy and Climate Change (DECC) is in the process of constructing a National Energy Efficiency Database (NEED) in which information about dwellings and non-domestic premises is being linked to their actual gas and electricity consumption, at the level of individual properties. The present project is intended to run alongside and support the development of NEED. Work is well advanced on a domestic stock database, the Household Energy Efficiency Database (HEED), which currently contains information on some 13 million dwellings, their types and construction, their use of energy, and what energy-saving measures have been installed. HEED will in due course, in effect, be linked into NEED.

Work on the non-domestic part of NEED is not so far advanced. In anticipation of the further development of NEED, this project proposes several strands of work. An existing database and model of the non-domestic stock at the level of individual premises, developed by the applicants, will be elaborated and strengthened with the incorporation of new data from a variety of sources. Meanwhile a separate new model will be built, working with aggregated data, to follow trends in energy consumption over recent years and to try to determine the various effects of climate, economic activity, growth in floor area, changes in fuel price, and efficiency improvements.

These models operate just with floor areas and rates of energy use per unit of floor area (as will the non-domestic part of NEED). They do not deal with buildings as units, even though the geometry and construction of buildings are important for energy use. The project will explore new methods for relating non-domestic floor areas to buildings and their construction, using information from digital maps, 3D digital models of cities, and photographic databases such as Google StreetView.

In a previous EPSRC-funded project the team has already carried out extensive analyses of the HEED database to study current patterns of domestic energy use. The plan in the present project is to build on that work, and to study some new issues. There can be significant differences between the levels of energy savings predicted from different measures by theoretical models, and actual savings as observed from empirical measurements (as in HEED). There are likely to be several causes, including so-called 'rebound' or 'take-back' effects, where the occupants react to energy improvements by for example enjoying higher temperatures, heating more rooms, or using appliances more frequently. Conversely it is possible that householders may reduce their consumption of energy if they have better information about exactly how and where that energy is being used in the home. Such behavioural effects can be observed to an extent through analysis of much more frequent metering data, derived from so-called 'smart meters'. The project proposes to compare data for the same dwellings from smart meters with data from normal 'dumb' meters (as in HEED), in order to try to better understand these feedback phenomena. These can then be allowed for in improved predictive models, which can be used to support the government's programme of refurbishment of the housing stock over the coming decades.

The government in its strategy for achieving substantial reductions in CO2 emissions from the UK building stock, has been developing a National Energy Efficiency Database (NEED) with which to monitor the effects of intervention programmes and plan for reductions in energy demand and emissions, for example under the Green Deal. The investment in both public and private initiatives in delivering these programmes will amount to many billions of pounds. Achieving the necessary improvements in the stock in a difficult economic environment requires that investment must be targeted in the most cost-efficient way, which will mean that the policies and regulations introduced to support these measures must be based on robust, empirically-derived evidence of building performance. For this, data must be collected and analysed in a much shorter timeframe than previously. The costs of collecting and maintaining data that can be used to validate and shape government policies for refurbishment will be modest by comparison with the size of the total investment.

The Impact Plan for this project seeks to underpin these general goals in three ways: with support for research and policy, with stakeholder engagement, and through the dissemination of data and results. The project will seek to contribute to the development of NEED and government policy with new methods for the classification and analysis of the non-domestic stock. An existing bottom-up model of consumption in the stock will be enhanced with the addition of energy data on tens of thousands of premises, and with the explicit representation of building geometry and construction; and a new top-down time-series model will be built with which to study trends and factors affecting consumption. The models and their associated data will be made publicly available. Previous analyses of consumption in the domestic stock will be linked to new smart meter data, to determine take-back and other behavioural effects in the use of energy. The project involves collaboration with several organisations - DECC, the Energy Saving Trust, the Ministry of Defence and energy suppliers - and aims to provide benefits to all these partners in the form of data processing, analytical results and advice.

Two workshops are planned, one for industry and government, the other for government and the academic community. The first will seek to engage stakeholders in the non-domestic stock, and draw out their concerns in relation to the constraints and coverage of existing data, and the refurbishment agenda. The second will concentrate on the issue of widening access to data, and on questions of accuracy, bias and validation. The project is intended to have a role as a 'data facilitator', in disseminating data, analyses and the results from new models to a wide audience of users in research and application. These will include workers in adjacent areas of building research, whose findings can in turn be linked back into national building stock databases. Results will also be disseminated via conferences, seminars, reports and papers.