Analysis of electricity consumption for lighting and small power in office buildings

There is significant evidence to suggest that buildings do not perform as well as expected, and this is commonly referred to as the "performance gap". Energy compliance calculations for Building Regulations in England and Wales do not include sources of energy consumption in buildings such as small power, catering, external lighting and vertical transportation (i.e. lifts and escalators). These so called "unregulated" loads are therefore rarely included in building energy models, and the lack of feedback regarding the in-use performance of buildings makes it harder for designers to quantify their impact on the overall energy consumption of a building. Aiming to address these issues, this paper provides an analysis of monitored electricity consumption in two multi-tenanted office buildings, with one tenant in common in both buildings. This paper focuses on tenant electricity consumption, including lighting and small power. Detailed analysis of the monitored data demonstrates significant variation between the electricity consumption of different tenants occupying the same building whilst performing similar activities. Elements such as lighting controls, hours of occupancy and management decisions are observed to have a significant impact on such variations. Further analysis of half-hourly energy consumption data is also provided, in addition to a detailed breakdown of small power energy consumption due to individual office equipment. Future work will build on this study and aim to develop evidence based benchmarks for energy consumption in office buildings. It will include a "tailoring" component allowing the benchmarks to be adjusted according to profiles of occupancy and management behaviour, as well as workstation density and the specification of energy consuming equipment. It is expected that such benchmarks will inform designers about the impact of each of these parameters on the measured energy consumption of buildings.