Environmental Change Institute, University of Oxford

Domestic Equipment and Carbon Dioxide Emissions (DECADE)

DECADE is a two year project to assemble market, behavioural and other information about domestic electric appliances (including lighting) and, using these data, construct a model of electricity use in the UK domestic appliance sector. The intention is to use the model to assess the impact of a range of energy efficiency policies in the UK. The project is funded under the European CommissionÂ’s SAVE programme, with substantial financial support from the Energy Efficiency Office of the Department of the Environment. The project was made possible also by the financial support of the Environmental Change Unit by Nuclear Electric, and Dr Brenda BoardmanÂ’s Fellowship in Energy Efficiency funded by PowerGen. It is hoped that the results of the project will contribute to European Commission policy making, in addition to that of the UK government.

The emphasis in the first year was always on obtaining a model and data and combining the two. This has been achieved, though the variability in the quality of the data and the gaps in knowledge on usage were greater than anticipated. There is now a methodology for getting all data on UK domestic electric appliances into one common, interactive format.

The first iteration of the DECADE model provided a total for domestic electricity consumption in appliances within 3% of the total given to us by the Building Research Establishment. This extremely successful result was based solely on our data, collected or interpolated, and did not involve any fine-tuning of the results. The first year of DECADE, therefore, confirms the previous judgements on the proportion of electricity going into appliances. However, this has focused concern on the remaining consumption of electricity in water and space heating. The interim judgement is that the total consumption in domestic electric appliances, as given in Figure 2.3, demonstrates the correct trend, when the effect of price, weather and other major factors, is smoothed out.

The results show a doubling in electricity consumption in domestic appliances and lighting in Great Britain between 1970 and 1992. In many cases the improvements in technical efficiency of an appliance appear to be being offset by increased standards of service.

In addition to improved standards of energy service, the increase in total demand comes from:

  • The growth in household numbers (in addition to a general increase in the population, the average household size has been falling steadily for many years, and these two trends are predicted to continue such that the total number of households could reach over 27 million by 2020, compared with under 18 million at the beginning of the 1970s).
  • A higher proportion of all households owning individual appliances (although ownership levels of some appliances such as refrigerators are at or close to the maximum they are ever likely to reach, for others such as dishwashers or personal computers there could be a significant increase)
  • New equipment on the market (it is only relatively recently that microwave ovens, and satellite and cable TV equipment have been introduced to the UK domestic market, and there may be many other such innovations over the coming years which could have an impact on domestic electricity use).

If overall electricity use is to be stabilised or reduced, the improvements in energy efficiency would have to be substantial to offset the cumulative effect of these trends.

The DECADE approach is to take account of both technical change and human behaviour, and to look at the impacts of these on:

  • decisions to purchase appliances;
  • the choice of model (both the range available to the consumer and the choice from within this range);
  • usage patterns and trends;
  • responsiveness of both consumers and the supply chain to policies, for instance educational energy efficiency labels or minimum efficiency standards.

All the work in this first year has confirmed the benefits of this approach but has also highlighted the shortage of good research that identifies and quantifies these interactions. One of the main challenges for the second year is to undertake our own research into values and associated behaviour and to develop the model to deal with these factors.

Research carried out during the first year of the project was published in DECADE: First Year Report, 1994, which provides a full background on the project's methodology and achievements over the first twelve months. The main findings were summarised in the first model of electricity consumption in lights and appliances, known as Run 1. This work formed the basis for the modelling carried out in the DECADE: Second Year Report, 1995 which identified the economic and technical potential for savings in electricity consumption of lights and appliances as 39% of the expected consumption by 2020. The suitability of different policy instruments for influencing the energy efficiency of each type of domestic appliance was also investigated, as was the interaction between policy instruments. One of the key conclusions was that if overall electricity use was to be stabilised or reduced, substantial improvements in energy efficiency would be required in order to offset the effect of additional households and higher appliance ownership levels.

Project details