Chapter hvac engineering Fundamentals: Part 1 Introduction

8.7
Computer-Based Controls
The use of computers as controllers in HVAC systems began about
1969 with the introduction of computer-based ‘‘supervisory’’ systems.
These systems provided central monitoring and recording of local ac-
Design Procedures: Part 6
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Design Procedures: Part 6
279
Figure 8.60
Electrical ladder diagram.
tivities and, in addition, such control programs as programmed start-
stop and reset of local loop controller set points to decrease energy
use. The systems are given a variety of names, the most common being
EMCS
(energy management and control system), and
BAS
(building
automation system). In industry there is reference to a SCADA system
(supervisory control and data acquisition system). The principal jus-
tification for these systems is the energy savings and system manage-
ment data which may be obtained.