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preventive (or even predictive) maintenance based on automatic equipment monitoring and service
hour metering are possible.
Moreover, collecting (and allocating) energy consumption data with high resolution would not be
feasible without central data acquisition. The resulting increase in cost transparency finally allows
more precise controlling measures to be put in place.
This is not limited to HVAC and lighting. While other systems often stay stand-alone from a auto-
matic control point of view, they can be integrated into a single building management system (BMS).
Recognizing the head start of BAS with regard to central data acquisition, control, and presentation,
theyprovidethenaturalbaseforthesuccessiveintegrationofothersystems.
A common way of accessing all systems, supported by tailor made user controls, allows changes
during regular operation to be applied without special training, despite the controlled equipment
being technically complex.
29.3.1 Integration
“System integration” is an everyday reality (and necessity) even for BAS that solely target the HVAC
domain. System parts must be combined to form the HVAC control system, and devices must be
configured to interact properly. Oten, cabling, sensors/actuators (field devices), cabinets, controllers
(for those pieces of equipment that do not have their own), and management infrastructure are
tendered separately and provided by different specialist contractors (as is, of course, the HVAC
equipment itself).
This division is even more pronounced between building disciplines, since they have evolved
separately. Consequently, their respective automation systems are as well still entirely separate in
most buildings today. However, information exchange between systems of different domains unde-
niably provides benefits. Actually, such cross-domain integration is indispensable for intelligent
buildings [].
For example, in case of a fire alarm, the HVAC system could enter a special mode for smoke extrac-
tion, elevators could automatically stop loaded cabins at the next floor level and shut down, and the
flextime system could print out a list of all people having checked in. Another scenario would be
lighting a pathway through the building and controlling elevators based on card access control at
the gate.
A key area of cross-domain integration is room automation. For example, window blinds have
considerable impact on HVAC control strategy, as incident solar radiation causes an increase in air
temperature as well as in immediate human thermal sensation. Automatically shutting the blinds on
the sunlit side of a building can significantly decrease the energy consumption for cooling purposes.
A (computer aided) facility management system that has direct access to data from the BAS
becomes an even more efficient tool for, among others, accounting and controlling purposes. For
example, consider cost allocation for climate control and lighting using live metering data.
As another example of BAS integration with IT systems, consider conference rooms to be air-
conditioned only (and automatically) when booked. Also, hotel management systems can automati-
cally adjust HVAC operation depending on whether a room is currently rented or vacant.
Yet, in all cases, the benefits reached by tighter integration come with a drawback. In an integrated
system, examining subsets of system functionality in an isolated manner becomes more difficult.
This introduces additional challenges in fault analysis and debugging as well as functionality assess-
ment. Additionally, if multiple contractors are working on a single integrated system, problems in
determining liability may arise.
This assessment problem is of special concern where life safety is involved. For this reason, fire
alarm systems traditionally have been kept completely separate from other building control sys-
tems. Although a considerable degree of integration has been achieved in some projects, building
codes still often disallow BAS to assume the function of life safety systems. his of course does not
