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ÐÇ¿Õ´«Ã½ management systems that utilise intelligent controllers and sensors have been in use for a considerable amount of time, with the communication between the pc-based system supervisor and the field mounted controllers being largely based on individual manufacturer's proprietary communications protocols over a dedicated network.

The latest technology utilises a web browser-based communications platform to link via the general IT infrastructure within a building. This type of system also has the capability to link multiple buildings. Such systems are based on a pc running Internet Explorer, communicating via a data network using TCP/IP data transportation protocol to field mounted controllers.

The move towards web-based browsers gives the advantages of a widely used, user friendly operating system with multiple entry points, low operating costs, and the utilisation of the existing IT network as the communications 'backbone', with all the benefits and savings this brings.

This approach will hopefully lead to further integration of building control systems, including lighting, fire, public address and security, with potential savings related to both capital and maintenance costs.

ÐÇ¿Õ´«Ã½ management systems packages are typically structured to include the power supply to the main plant. This improves co-ordination and provides a single point of responsibility for the installation and commissioning of the MCPs, and of the system as a whole.

BMS and the revised Part L
The importance of building management systems and associated controls has been extended further by the introduction of the revised ÐÇ¿Õ´«Ã½ Regulations Part L (2002) changes to the building services requirement as summarised below:

• Performance standards for heating and hot water systems to provide energy efficient zoning, timing and temperature control.

• Air conditioning and mechanical ventilation systems are to use 'no more energy than is reasonable'. Refrigeration plant, fans and pumps must be 'reasonably efficient' and are to include the facility to monitor and control the system. This leads, in some instances, to the need for the inclusion of variable speed drives on individual plant items.

• Installation of energy meters that should be capable of measuring at least 90% of each fuel type used in the building. The requirement applies to individual buildings over 500 m² on a multi-building site, or to separately tenanted areas that exceed 500 m² within a building. There are additional metering requirements based on energy threshold levels for equipment as listed in the Regulations.

• The provision of a 'building log book' which will include the details of energy consumption of the building services plant.

• Requirements for the inspection and commissioning of the building services systems which can be monitored via the building management system.

Cost implications of these new requirements (with the exception of multi tenanted buildings requiring energy meters) are largely neutralised by the general reduction in costs of intelligent building controls, due to the increased production and use in recent years, coupled with the increased utilisation of existing system capabilities.

The model building
The detailed costs are based on tender costs for a speculative office development in London awarded in competitive tender during the third quarter of 2003. The building has a gross internal area (gia) of 10 000 m², arranged over six storeys, with a net lettable floor area (nla) of 7200 m².

The building is served by a single roof mounted package boiler plant room and external roof mounted air cooled chiller. Primary fresh air is distributed to the floors via two roof mounted supply and extract air handling units. Local temperature control on the floors is achieved via a series of ceiling mounted four pipe fan coil units with water-side controls. Core toilets are served from a dedicated roof mounted supply and extract air handling unit with twin extract fans.

A single pc drives the building management system installation via a dedicated Ethernet network. In addition to control of the environmental plant, the building management system also monitors the main and tenant electricity meters on each of the building's six floor.