Indoor environment control

CONTROL's Around the Loop columnist Terry K. McMahan has been following building automation technology since the '70s and concludes that the evolution of this industry has been dramatic.

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By Terry K. McMahon, CONTROL Columnist

INDOOR ENVIRONMENT control for laboratories and manufacturing processes is increasingly critical in regulated industries such as pharmaceuticals, cosmetics and food processing. Indoor environment control (building energy management & automation) has historically been a poor stepchild to its industrial counterpart (process control & automation) in terms of accuracy and reliability as well as capital investment. With signature projects like NIST’s new Advanced Measurement Laboratory (see Around The Loop Nov. 2004), indoor environment control may be stepping up to a higher level of technical challenges. At ISPE’s (New Jersey Section) annual Chapter Day Symposium, Richard Nowak of Siemens Building Technologies presented a discussion of how building automation technology interacts with R&D and manufacturing functions in the bioscience industries.

The Symposium was jointly sponsored by the Central N.J. Section of ISA. Alex Habib – ISA Standards & the PAT Iniatative, Ken Clevett – On-Line Analyzers, and other speakers presented one-hour lectures on technical topics of interest to pharmaceutical engineers. When I met him 11 years ago (see Around The Loop Sept 1994), Habib was chief automation specialist for Rhone-Poulenc’s U.S. operations. He has been a major factor in sustaining the Central N.J. Section’s quality speaker program held monthly at the Washington Group’s offices in Princeton. Clevett, based on his long tenure with Exxon in analyzer technology development, is a widely recognized expert in this field and author of perhaps the most authoritative text on the subject (see Bob Sherman’s comments in Around The Loop Feb. 2002). Clevett provided technical guidance in the formation of the International Forum on Process Analytical Chemistry (IFPAC) in the 1980s (see Around The Loop March 2005). For further information on ISPE or the Chapter Day Symposium contact Lorraine Gallo (manager@ispenj.org).

According to data presented by Nowak, electrical energy consumption in a typical pharmaceutical laboratory is:

ENERGY FUNCTION

% TOTAL

Ventilation

52%

Cooling

24%

Boilers, Pumps, Misc.

4%

Lighting

7%

Lab Equipment

13%

      

THE UNUSUALLY large energy expenditures on ventilation are required to meet the applicable regulations on allowable concentrations of biologics and contaminants. Ventilation savings opportunities derive from the airflow strategy, fume hood strategy, laboratory occupancy scheduling & sensing, and fan energy optimization.

Airflow and fume hood strategies include constant volume based on the anticipated maximum loading, variable volume based on feed-back primarily from fume hood sash position sensors, and multi-stage constant volume based on different usage patterns (primarily occupancy). Fan energy optimization is an important economic variable. Variable Volume Variable Pressure (VVVP) is a control strategy for providing optimal performance by varying air volume and static pressure in a coordinated manner.

At the Fred Hutchinson Cancer Research Center (Seattle, WA), VVVP control was first implemented in December 2001. This installation includes 13 air handling units connected to 770 terminal units.  Average fan size was 50hp. Typically, VVVP algorithms can save $200-500 annually per fan hp.  Projected annual savings at FHCRC were 1.6 million kwh but realized savings exceeded 2 million kwh per year representing 35-40% of fan energy for an overall ventilation energy reduction of about 30%.

Ventilation regulations for laboratories, particularly those concerned with biohazards, is a very complex subject with many professional and governmental bodies involved. These include ASHRAE, NFPA, OSHA, American Industrial Hygiene Association and others. Siemens has prepared a 42-page summary of these regulations: Laboratory Ventilation Codes and Standards (Rev 4 January 2002).

Chiller plant optimization is another major economic benefit. Chillers operate at partial load 95% of the time and become progressively less efficient at decreasing load levels. Optimal sequencing of multiple chillers, optimal condenser water temperature and optimal cooling tower fan sequencing can help to minimize these lower efficiencies. Chiller plant optimization has also advanced to include global setpoint strategies. These minimize the total energy by dynamically calculating optimal chilled water differential temperature and discharge air temperature setpoints that minimize the combined energy of the chiller plant, pumping system and air-handling units to meet the required load.

I have been following building automation technology since the mid 1970s. The evolution of this industry has been dramatic as these systems have become ever more robust and precise and, just in time, keeping pace with the requirements of industry regulators.


  About the Author
Terrence K. McMahon of McMahon Technology Associates, Leonia, NJ is the "Around the Loop" columnist for CONTROL magazine and ControlGlobal.com. He can be reached at Mcmahontec135@aol.com.
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