Civil Engineering Reference
In-Depth Information
Chapter 9
Building Automatic Controls
9.1
Importance of Building Automatic Controls
Along with proper system selection, a well-planned control system is one of the
most effective design elements that can contribute to proper functioning and also
saving energy during the building operations. A well-planned control system can
make all the building system elements to function close to their highest possible
effi ciency level when they are supposed to, and preserve energy when there is an
opportunity for energy saving in the system throughout the time. If the building
control system is designed properly it acts as a knowledgeable and strong brain and
nerve network that receives messages, thinks through them, and selects the proper
responses and informs the targeted muscles (element) to act properly and in a timely
manner according to the selected response. Therefore understanding the structure of
the building control system and also recognizing the important role that automatic
control and proper use of this effective tool can have, will be essential for satisfying
the building energy saving goals. In this section after a short introduction about how
a communication network is structured and works, I will briefl y describe the neces-
sary elements and duties of the building automatic control system components. I
will also discuss the importance of a properly written sequence of operation for the
building equipment later in this chapter. For a thorough discussion about specifying
direct digital control system refer to ASHRAE Guideline—Specifying Direct
Digital Control Systems.
9.2
A Brief Overview of Communication Systems
In networking environment, an open system interconnection (OSI) model is a frame
that is used for standardization of functions of communication systems. Therefore
to understand how a network communication works, it is necessary to understand
