Our fascinating look at building automation history starts in 270 B.C.
Welcome to the brief building automation history page!
emphasis concerning building automation history will be about Direct
Digital Controls for HVAC systems, but a quick study on general
development history is in order:
The earliest documented example
of an automatic control system device happened in the year 270 B.C. In
this example, the device was a water clock, shown below.
(I think the Gentleman is slightly out-of-place for the period, but you get the idea!)
More specifically, if we're talking about HVAC related
systems, during the period of the 1700's, Rene-Antoine Ferchault de
Reaumur (1683-1757, inventor of the Reaumur Scale thermometer) had some
ideas for temperature control of incubators.
(Reaumur shown below)
Reaumur's ideas were based on an invention by Cornelius
Drebbel (1572-1663). Drebbel's invention used a U-shaped vessel
containing mercury, sensing temperature, that operated a lever arm,
controlling the draft to a furnace that controlled heat output.
these early times, there were several things going on at the same time
in different areas of automatic control systems development.
(Drebbel shown below)
Automatic control of the steam engine and the various attempts at
maintaining accurate control of the steam engine helped to lead the way
for improvements on automatic control systems in general (James Clark
Maxwell 1831 -- 1879, and his work titled "On Governors" for example,
that dealt with linear differential equations for governor speed
control). Maxwell also wrote a textbook called "Theory of Heat" in
Most of the automatic control systems during the 1800's
dealt with temperature, pressure, liquid level, and the speed of
rotating machinery. So long as the operators had stability, the folks
that operated the systems were generally happy.
(Maxwell shown below)
improvements began to be made when larger ships, new weapons and
propulsion systems began to appear. The systems used pneumatic power to
operate position control mechanisms. As we neared the 1900's,
electricity also began playing a part in automatic control systems.
of the first examples of PID-type controls that were developed was by
Elmer Sperry. In 1911, this type of system was used for automatic ship
steering (Sperry did a lot of work involving gyroscopic compasses).
Sperry's device compensated for disturbances in the water as sea
In 1914, one of the Foxboro Instrument
Company founders named Edgar Bristol, invented the pneumatic "flapper
nozzle amplifier." The action of this flapper nozzle can be likened to
a flexure lid on the modern pneumatic controller. Early flapper nozzle
systems that attempted to control devices were proportional and because
there was no integral or derivative action, made a controlled device
act like a binary "on-off" instead of modulating.
Elmer Sperry used a type of PID control in 1911, the control law that
we commonly associate with the modern PID loop came from Nicholas
Minorsky (1885-1970). In 1922, he observed a helmsman controlling a
ship and came up with the proportional, integral, and derivative type
of control we know of today:
Proportional is the control required
to steer the ship based on actual ship direction compared to the
desired course setpoint.
Integral is the amount of reset
required to correct an amount of error. For example, if the ship is off
course by a small amount, and correcting it to the left brings it back
on bearing, then turning the wheel all the way to the left is
inappropriate. Only a slight adjustment to the left is required.
is the attempt to see how far a process variable (ship course) has been
from the set point in the past, and anticipating where the course
correction will need to be in the future.
In the 1920s, several instrument companies began making complete boiler control systems.
the 1930s, the Foxboro Instrument Company made improvements to the
flapper nozzle system that incorporated the integral and derivative.
The controllers made during this period were very expensive and also
not very well understood in operation.
(An example of a PID Loop shown below)
In the example above using PID control, if you stop and think about it
-- you can apply this type of control to almost anything in the HVAC
business that requires analog control (i.e. modulating a valve, a set
of dampers, controlling the speed of a variable speed motor, etc.).
1936, the first professional organization that dealt with automatic
control was created and called the Industrial Instruments and
Regulators Committee. Standardizing the automatic control design
methods and terminology were the primary goals of this early
During the 1940s and 1950s, instrumentation
companies continued to improve their products. For example, the Foxboro
Instrument Company featured an improved Stabilog controller that was
field adjustable, and the Taylor Instrument Company did the same for
the Taylor Fulscope. During this time, papers were also published that
describe how to adjust the PID values for optimal settings on the
From the 1930s to the 1950s, some very important
work was done by MIT, the IEE, and by several people, both overseas and
in the United States regarding electrical and electronic automatic
controls. This was a very exciting time period in electricity and
electronics, which led to the early systems of modern weapons
development, communications, and semi conductor circuitry.
systems evolved quickly, such as an example of electric relays, versus
transistor controls. Without the fast and accurate control systems that
were developed during this period, defensive systems used in the free
world would not have been accurate, nor work correctly.
were many spinoffs to the military technologies that were developed
since the 1950s. Small-scale electronics lead to affordable computers,
and those computers constantly evolved from the 1950s to the present.
personal computer that we use today, and the electronics used in
today's digital controllers, make it possible to effectively and easily
control the environment within a modern building.
Okay, now let's take a look at a short history on Direct Digital Controls
1. Stuart Bennett, "A Brief History of Automatic Control," June 1996.
2. Wikipedia, the free online user-generated Encyclopedia.