The Hartman Company Newsletter

Issue: January 2004
Topic: Control Your New Year's Resolution

Dear Hartman Company Newsletter subscriber,

New Year's Resolutions can be an important way to make necessary
changes in one's life or work. If you are looking to make a change
for the better in your activities within your Building Design or
Operations career, we have a suggestion  -  Resolve that this year
you will try to implement new more effective control strategies!

The Hartman Company has worked with and participated in various
activities sponsored by The Iowa Energy Center focusing on improving
building controls. In round table discussions and Web based
discussions, a wide cross section of practicing engineers generally
agree that poor control today is a major obstacle to better building
operating reliability, comfort and energy performance. However, many
engineers appear to believe that the root causes of this problem are
poor quality control systems, and poorly trained controls designers
and building operators.

There may be another explanation, however. It is possible that the
control strategies themselves we have been applying are not well
suited for modern building control application. It may be that PID,
an analog method of control developed long ago is inherently difficult
to apply to the more complex equipment configurations and the digital
control platforms now used in modern buildings.

This is the premise that has guided our firm throughout the last
decade. In that time we have tried to challenge ourselves to find and
try new approaches to achieve more energy efficient and effective
control. This challenge led us to The Equal Marginal Performance
Principle, a truly powerful and useful principle of optimization for
systems employing variable speed motors and drives. The Equal Marginal
Performance Principle has led us to a new method of "power based"
control called "Demand Based Control."

1. You can learn more about the Equal Marginal Performance Principle
and Demand Based Control from an on-line article Mr. Hartman wrote on
Demand Based Control for Automatedbuildings.com. This article is
available at:

http://www.automatedbuildings.com/news/may02/articles/hrtmn/hrtmn.htm

2. There is more on Demand Based Control available from a recent HPAC
Engineering Magazine Control Freaks column Mr. Hartman wrote on the
subject. This article is available at:

http://www.hartmanco.com/pdf/a38.pdf

Demand Based Control is an important element on the replacement of
outdated PID controls with newer, simpler and more effective control
strategies. Because Demand Based Control does not employ temperature
or pressure setpoint control, it is usually much easier to setup and
rarely requires the type of loop tuning associated with PID control.
However, there are many applications in building control in which
setpoint control is required (to maintain a supply air or room
temperature setpoint, for example). For these applications, We
developed a network enabled digital control replacement for PID control
based on the iterative problem solving techniques used for many years.
Intelligent Iterative Control (IIC) is a very useful "drop-in"
replacement for PID control loops when non-linear responding loops need
precise control. Tom Hartman explains IIC in a three part series that
appear in HPAC Magazine as follows:

1. In the first segment of this three part column series, Mr. Hartman
explains how energy efficiency and equipment longevity is improved by
the application of Intelligent Iterative Control when setpoint control
is required. This article is available at:

http://hartmanco.com/pdf/a40.pdf

2. In the second column segment, Mr. Hartman shows how such an IIC
control loop is set up. This article is available at:

http://hartmanco.com/pdf/a41.pdf

3. Finally, in the final column on Intelligent Iterative Control,
Mr. Hartman explains how the limitations of more efficient non-linear
control loops can be accommodated in the design of the system and
related components. This article can be found at:

http://hartmanco.com/pdf/a42.pdf

By using a combination of Demand Based Control and Intelligent
Iterative Control to replace PID in building controls, building
operation can be made much more effective and reliable, energy
efficiency of these systems will be improved by 30% to 50%, and
comfort improvements can be expected as well. These kinds of
improvements are worth the effort, especially if one is resolved
this year to make such improvements in their work!


If you have questions, suggestions or comments regarding this topic,
please do not hesitate to contact The Hartman Company

Please use "January 2004  Newsletter" as the subject of your email.

If you have suggestions for a topic you would like to see covered in
a future newsletter please contact The Hartman Company.


To search the Hartman Resource Library yourself for additional articles
on this topic, go to:

http://www.hartmanco.com/cgi-bin/dbman/db.cgi?db=resource&uid=default&view_search=1


Linda, Editor
THC News
The Hartman Company



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                                The Hartman Company
                        An HVAC Technology Development Firm
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