Energy use is a key environmental impact of office buildings. It can represent a significant share of the costs associated with running the buildings. Energy management, a systematic approach to managing energy use, offers the opportunity to public administrations to reduce environmental impact and costs related to energy.
Good energy management should be integrated into wider management systems and have support at the top level of management and dedicated staff resources. It must include a policy (action plan and regular reviews) and performance measurement, and it must be embedded at all levels in the organisation along with internal and external communication and staff training.
Energy management follows the principles of PDCA (plan, do, check, act) (IEMA, 2014) in accordance with leading environmental management systems, e.g. EMAS and ISO 14001. This is an iterative sequence that facilitates continuous improvement and allows those responsible to be proactive.
Parts of the PDCA cycle that are specific to energy management are:
- Identification of benchmarks.
Benchmarks are useful for comparing actual energy use performance to standardised performance—whether that is best practice, good practice or typical performance.
- Data collection and ongoing monitoring (in the ‘check’ part of the cycle).
Energy consumption data should be collected at the building level and ideally also by building area, particularly if the building envelope has different characteristics in different zones (such as a lobby that has more air changes or two wings built in different decades). The data should be collected by fuel type and, if possible, by end-use category, such as space heating, water heating, catering, lighting and equipment, ideally through automatic meter readings (AMR) and the building management system (BMS) where available.
- Data analysis, target setting, establishing a strategy/action plan (in the ‘plan’ part of the cycle).
Data must be analysed to detect inefficiencies and establish priorities for action. Space heating and space cooling energy use needs to be normalised for weather variations to allow meaningful comparison, e.g. with benchmarks, targets or previous years. Thanks to the ‘climate correction’, fluctuations caused by external weather changes can be eliminated, allowing energy figures to be meaningfully compared year to year and changes to reflect the results from actual actions taken rather than external factors such as a milder or cooler winter. Moreover, regression analysis and cumulative sum of deviation (cusum) can quickly help energy managers spot waste.
Based on the data collection and analysis, the organisation can define targets, i.e. a quantified goal to be reached within a specified timeframe and an energy strategy that outlines how energy is managed in a building or portfolio of buildings and which actions will be taken to reduce energy use. Actions would typically include both energy efficiency (reducing the amount of energy used) through technical solutions and staff engagement/behavioural change, as well as switching to a low- or zero-carbon energy source by e.g. installing on-site renewable energy.