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Building (Automation) Managament Systems ,BMS or BAS

Building Automation Systems (BAS) use computer-based monitoring to coordinate, organize and optimize building control sub-systems such as security, fire/life safety, elevators, etc. Common applications include equipment scheduling (turning equipment off and on as required)
optimum start/stop (turning heating and cooling equipment on in advance to ensure the building is at the required temperature during occupancy)
operator adjustment (accessing operator set-points that tune system to changing conditions)
monitoring (logging of temperature, energy use, equipment start times, operator logon, etc)
alarm reporting (notifying the operator of failed equipment, out of limit temperature/pressure conditions or need for maintenance

Tremendous advances in computer technology are reflected in the sophistication and falling costs of Direct Digital Control (DDC) systems for buildings. DDC systems are now affordable for all but the smallest and simplest of buildings, and allow much finer control and energy savings than pneumatic controls. Besides flexible control of lighting and HVAC systems, DDC can also integrate fire and intruder alarms, security and access systems and local and wide area computer networks.

Even in retrofit situations with existing pneumatic controls, it is usually worth examining the use of zone or central digital controllers. Continued use of pneumatic actuators and sensors is sometimes cost-effective, but requires periodic compressor maintenance and more ongoing attention to calibration and adjustment.

Central DDC systems are typically too expensive for buildings with 10 or fewer HVAC or lighting zones, unless they collect renewable energy using photovoltaic arrays. However, even in these smaller buildings, digital controls and equipment should be specified that: Cost:
Computerized DDC control has evolved rapidly in the last few years with costs dropping significantly. It is difficult to determine the "per point" cost of BAS because bundled points included with HVAC equipment are inherited when common network connections are made.

A range of C$50 to $300 per point is common, depending on the mix of included points. This estimated range includes real or physical points only and does not include the large number of virtual points included in most systems. These estimates include remote communication to a networked personal computer and operating software.

Computerized control is usually the lowest cost option and will be provided as an integral part of all sub-systems.

The cost to manage and integrate, or have the future potential to integrate, is extremely low, or in most cases no cost, if included in the original design request

offer optimal start and stop controls for HVAC plant equipment.
provide occupant-accessible local overrides for temporary off-schedule use.
have BACNet-compatible sensors, actuators and controllers.
Often DDC zone controllers are suitable and economic for small applications with fewer than 16 inputs and outputs.

ISO 16484-3:2005 specifies the requirements for the overall functionality and engineering services to achieve building automation and control systems. It defines terms, which shall be used for specifications and it gives guidelines for the functional documentation of project/application specific systems. It provides a sample template for documentation of plant/application specific functions, called BACS points list. The informative function block examples explain a method to display the referenced functions in system documentation; they do not standardize the method for programming functions and applications. ISO 16484-3:2005 covers requirements and definitions regarding BACS and application software, generic functions for plant/project specific applications and engineering functions for building controls and operations. It provides communication functions for the integration of other dedicated special system processes. ISO 16484-3:2005 defines a method for specifying the procurement specifications containing all essential elements required for the operational functioning of a BACS. The successful installation and operation of a BACS requires that its procurement be based on a complete and accurate functional specification.

For larger and more complex buildings, central controllers or centrally supervised zone controllers connected with a network offer the most flexibility and potential for energy savings. These systems should:

provide a graphic interface for building operators that shows:
floor plans of all areas of the building, locating all controlled equipment.
schematic drawings of each controlled device, with on/off status, current sensor readings, setpoints, operator positions, control constants, and a link that shows the operating control program code.
graphic trend logs of inputs, outputs and control points selected by the operator.
graphs and tables of building energy and demand history for all fuel types.
have BACNet-compatible sensors, actuators, controllers and communications.
use optimal start and temperature-predictor programs for cooling and heating plant equipment.
offer provide storage for at least 12 months of hourly trend-logging of flows, temperatures, pressures and other important data for all plant equipment.
secure dial-up modem access for remote monitoring, supervision and trouble-shooting by building service companies contracted by the owner
A good sample specification and protocol for control point names and equipment control algorithms can be found at the British Columbia Buildings Corporation website (see Further Information).

DDC systems capabilities should be considered when designing mechanical and electrical systems. Often, savings can result from using control software to supplement equipment limitations. For example, the traditional rule-of-thumb has been to select control valves with linear process output / control input relationships. Intelligent DDC programming can automatically compensate for non-linear valves, reducing costs. Similarly, programs that use the fast dynamic response of DDC systems can optimally control pump and fan flows, so pressure drops are lower under non-peak loads. This saves energy, and can often reduce the number and size of motors, especially when variable-speed motor controllers are used.

Where natural ventilation and cooling strategies are supplemented by mechanical systems, their control must be carefully thought through. Sensors for windows and air inlets and outlets should signal their opening by occupants, and lockout or reduce mechanically supplied cooling and ventilation. Automatic systems intended to close windows and air openings must ensure that occupants are not endangered.

Good design documentation for each controlled device should include schematic drawings, listings of control points, expected operating readings and acceptable range, and sequences of operation. Field review and commissioning should check to ensure compliance with documented design intentions, and any changes made should be recorded for future reference by building operators.


Good communications and documentation are essential to a trouble-free control system.
Sensors, actuators and controllers must be carefully commissioned.
Building operators must be trained in control system use.

Building Managament Systems Online Demo's

Building Managament Systems Example Point list

Building Managament SystemsTypical Ahu Control Screen



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