Energy Relevant Decisions in Office Buildings (8/1996 - 5/1999)

Project Description

The development of electricity consumption 1986—1996 in 100 Swiss office buildings was empirically analysed in order to determine trends in consumption and to characterise energy-relevant decsion-making. The results empirically build on electricity bills, energy audits and interviews with technical staff and managers in firms. The aims of the study were:

• to determine typical trends in the evolution of electricity consumption,
• to identify crucial changes in technical equipment and installations and evaluate their impact on electricity consumption,
• to identify energy-relevant decision-makers and assess their opportunities to take more sensible decisions,
• to determine the role of energy efficiency in energy-relevant decision-making and evaluate the impact of energy-saving measures,
• to evaluate the impact of organisational prerequisites and management attitudes in firms on energy efficiency.

The average electric energy index amounted to 300 MJ/m²a. It varied considerably according to the equipment installed in the building, e. g. air conditioned buildings consumed three times as much electricity as buildings without electrically-powered ventilation. From 1986 to 1996, the electric energy index decreased by one percent per year. Electricity was mainly consumed by central computing, ventilation, air conditioning and lighting, which took up altogether about 80 percent of the electricity consumption. The share of office equipment was only 10 percent.

The average thermal energy index amounted to 390 MJ/m²a. In new buildings it has decreased by 30 percent over the last twenty years.

The data collected in the study show that, although the management tended to overestimate energy costs by a factor of three, energy efficiency was taken into consideration in less than a quarter of all decisions related to a change in technical infrastructure or maintenance. Such decisions I call energy-relevant decisions. Moreover, only one seventh of the total reduction in electricity consumption resulted from a decision expressly intended to save energy. Most energy savings were a positive side-effect of core business-related activities. The factor found to have the most impact was an increase in computing.

The majority of energy-relevant decisions were about investments. The nominal decision-maker was the management, but in practice decisions were found to be mostly taken by specialists inside the firm, e. g. the maintenance staff. Conservation measures that require an extra investment are unlikely to be taken because of their low priority compared to investments in the core business. Successful conservation measures were mostly initiated, decided and realised by a single person fairly low down in the hierarchy.