The management and control of energy at the design stage of buildings

An essential element of a sustainable building is the amount of operational energy that will be needed to power the engineering services which provide buildings with safe, healthy, comfortable and secure environments. The environmental impact and financial costs associated with energy running costs are factors which are increasing recognised for their importance.At feasibility stages within projects it is necessary to begin to estimate the types and size of building services engineering equipment that will be specified. This process is necessary in order that architects and planners can produce preliminary layouts which also accommodate space requirements for engineering plant. However, because ideas and proposals can have implications for all disciplines designers produce sketch schemes for agreement by all parties so that the project can move from an agreed concept design to a developed design.Within this context, the design of building services plant is an iterative process in which design decisions become progressively more accurate. At the stage when project objectives and sustainability aspirations are not fully defined designers may use benchmarks data for preliminary energy target setting. There are several types of bench-marking systems available for predicting building energy use. Typically, benchmarks are provided in which annual energy use is allocated in terms of annual KWh/square metre of building floor area for various building types. CIBSE has developed a Technical Manual which provides more sophisticated guidance on evaluating energy performance.This paper compares bench marking against actual energy bills for an existing large educational building in Liverpool. The paper considers the accuracy and usefulness of energy bench-marking and discusses its application in the design of a new educational facility.