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Mechanical / HVACaka: BASaka: BMSaka: building management systemaka: DDC system

Building Automation System

In Plain English

A computer system that automatically controls and monitors a building's HVAC, lighting, and other systems to save energy.

Definition

A computer-based control system that monitors and manages a building's mechanical, electrical, and plumbing equipment, including HVAC, lighting, and fire safety systems. Building automation systems improve energy efficiency by optimizing equipment operation based on occupancy, weather, and time schedules. They provide centralized monitoring and fault detection through a graphical interface.

Why It Matters in Bidding

A building automation system is a high-value, integration-heavy scope that crosses mechanical, electrical, and controls trades, so the estimator must pin down exactly where the controls scope starts and stops to avoid gaps with the HVAC and electrical subs. Points counts, programming, and commissioning labor are easy to underprice and are frequent sources of post-award change orders.

Example

During scope review, the estimator confirms the controls contractor's bid covers the BAS head-end, sensors, and DDC programming but excludes line-voltage power to the panels, so she carries that wiring in the electrical sub's number to close the gap.

Related Terms

HVACVariable Air VolumeVariable Frequency DriveThermostat

Frequently Asked Questions

A specialized controls or temperature-controls contractor usually furnishes and programs the BAS, often as a subcontractor to the mechanical sub. Coordination is critical because the electrical sub typically provides line-voltage power and conduit while the controls contractor handles low-voltage wiring, sensors, and software. Clear scope splits prevent gaps at bid time.
Pricing is driven by the points count, the number and type of sensors and controllers, the head-end software and graphics, programming labor, and commissioning. More monitored and controlled points mean more wiring, hardware, and engineering. Estimators should verify the sequence of operations and points list against the controls contractor's proposal.
Common omissions include commissioning and functional testing labor, integration with fire alarm and lighting systems, line-voltage power to control panels, network infrastructure, and owner training. Graphics development and as-built documentation are also frequently underpriced. Reviewing the controls specification and sequence of operations closely helps capture these costs before submitting the bid.

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