Specifications

84 Control and Automation Solutions Guide
Building Automation Systems (BASs)
A building is much like a factory in
that it is expected to be ecient,
and, as in factories, a more ecient
building is both more productive
and less costly to operate.
Aside from electric lighting, the most
dramatic example of automation
aecting the design of a building is the
humble elevator. In fact, without the
elevator, today’s modern cities would
have a distinctively dierent look. The
elevator has made it practical to stack
story upon story, enabling modern
skyscrapers. While we take the operation
and availability of the elevator for
granted today, and while it is a relatively
simple device (it really only goes up
and down), the elevator has been made
increasingly productive over time
through the development of complex
control algorithms that maximize the
ability of an elevator to both ll and
empty a large building in a short time.
As time progresses, and as the relative
costs for labor, materials, and energy
have changed, buildings too have
changed to be more economical.
Today, for example, buildings can be
economically constructed with relatively
low-cost materials like steel, concrete,
and glass. This combination allows the
construction of large towers that are
strong and stable, even in earthquake-
prone areas. But to make these buildings
economical for use, attention must
be paid to ongoing expenses like
energy and water usage, especially
when the cost of energy is outpacing
ination and new renewable energy
resources become available. To continue
to meet occupants’ expectations of
comfortable and productive work
environments, optimizing energy
usage, which leads to savings, is
essential. This optimization requires
more sophisticated environmental
controls and monitoring systems.
In the past, building automation
centered on eciently moving people,
freight, and other items like mail. Today
building automation focuses on energy
management and communications.
Because energy management and
communications are based on sensors
and computer control, the use of
semiconductor technology within
buildings for the purpose of reducing
and controlling costs has rapidly
escalated. For technology providers
today, building automation is a large,
growing, and relatively untapped market.
BASs have evolved along with factory
automation systems to now use
distributed processing elements
networked together; they are truly
distributed control systems (DCSs).
BASs provide similar advantages as DCSs
in factory automation systems such
as reduced cabling, faster response to
sensor inputs, improved data gathering,
comprehensive communications
resulting in enhanced operations, and
easier upgrades and modications.
These systems enable building energy
measurement and management, water
supply monitoring and processing, HVAC
and refrigeration (HVAC&R), lighting
systems, security and access control
systems, occupancy response systems,
elevators, escalators, moving walkways,
and re safety systems. In hotels, the
hospitality systems (room reservations),
Internet access, food services, and
conference room automation systems
are based on similarly constructed
distributed processing systems linked
by communications channels that either
ow via rewalled LANs or wireless
connections. BASs connections to
system controllers use few wireless
links and mostly rely on physical
cabling, sometimes including powerline
communications. This is due to the
long distances involved, the high
data loads, and the high criticality
of the data communications.
The primary dierences between a
factory automation system and a BAS
are in the types of equipment, network
protocols, and terminologies used.
Control systems are very similar to PLCs.
Often standard industrial PLCs are used
in BASs. Because the networks used
must be robust, as in factories, and the
human machine interfaces must provide
timely and comprehensive information,
many of Maxim’s products suited for
the factory environment are also suited
for BASs. Usually in BASs data rates can
be slower and the environments are
often not as harsh as in high-speed
production factories. But, as mentioned
in the introduction, a BAS and its related
equipment can be critical to occupants’
safety and well-being, so robust
equipment design and dependable
fail-safe operation is required.
Technical floor of a smart building HVAC system.