Mechanical and Control System Consideration for Lab Buildings with High Performance Fume Hoods

Victor Neuman, Tek-Air Systems, Inc.

Objectives:

Laboratory building designers have extensive experience with designing around chemical fume hoods that have face velocities of 100 feet per minute. The recent development of high performance fume hoods which have face velocities of 60 feet per minute or below change the parameters on which the laboratory control systems and mechanical systems are based.

Design alternatives will be discussed for right sizing systems to take advantage of the new High Performance Hoods. Most laboratories of the past have been designed around or dominated by their exhaust requirements. With the new hood designs, internal heat gain driving cooling loads and minimum ventilation loads will become much more important. The interaction of fume hood loading, cooling loads, and minimum ventilation requirements must be considered in the lab with high performance hoods.

The decrease in cfm/square foot made possible by the new fume hood designs will also provide more opportunities for the use of process cooling systems to handle high head load rooms.

Properly designing cost effective control and monitoring systems will have different costs and paybacks when coupled with high performance fume hoods. This presentation will outline some of the costs and paybacks of different control system options.

Findings:

New users of high performance hoods want to know the effect on the first cost of the building. This key economic question along with the associated factors of energy use and operating cost will be presented for lab buildings with High Performance Hoods.

In addition to new laboratory buildings, the same cost parameters will be presented for several examples of renovated laboratories. How the high performance fume hoods work, their aerodynamics and design features should be covered in one or more additional presentations. For example, Geoff Bell should be encouraged to talk.

Control options for high performance hoods will be discussed for two types of hoods:
- the 50-60 feet per minute face velocity fume hood
- the 30 feet per minute face velocity fume hood

For 30 feet per minute hoods, constant volume is the option. For 50 feet per minute hoods, the control options are as follows:
- Constant Volume
- Two Position Constant Volume/Night Setback
- Full Variable Volume

The design and use of process cooling systems for high heat load laboratories will be covered as an adjunct to the use of high performance fume hoods. The safeguarding of the exhaust systems for use with reduced flow hoods will also be covered both for duct transport velocity and for the design of the roof exhaust stacks. As much as possible, all the pieces of the laboratory affected by the new High Performance Hoods will be covered and integrated into a cohesive design philosophy.

Labs21 Connection:

This presentation stresses right sizing of the lab ventilation system. Improving safety with high performance hoods while minimizing first costs and operating costs of the building are all goals of the Labs21 Approach. The reduction of cfm/square foot by using the new hood technologies holds more promise than any other single technology for reducing laboratory energy use.

The emphasis of this presentation will be on an integrated, holistic design. When a new technology is first used, too often it is plugged into existing design frameworks without exploring how all elements of the design can be changed to integrate the new technology into a new whole. An example would be the combination of High Performance Fume Hoods with Variable Volume Technology. The early adopters of new technologies typically have large budgets and the best fume hood, Low Velocity, might be combined with the best control systems, i.e. variable volume. However, there is a case to be made for constant volume controls for the hoods and variable volume for the room supply and general exhaust system.

The design methodology to correctly size the ventilation and control systems and how to reintegrate them into a new whole will be presented in this presentation.

Biography:

Victor Neuman is a professional engineer specializing in fume hood control systems and laboratory ventilation systems. He is a Senior Director with Tek-Air Systems, Inc. and is based in San Diego, California. Victor has experience as a principal in 1999-2000 with the lab planning firm of GPR Planners Collaborative, a division of Jacobs Engineering and worked through most of the 1980's for the lab planning firm of Earl Walls Associates. He is a recipient of ASHRAE's Distinguished Service Aware for his work in laboratory ventilation and is past chairman of their Laboratory Technical Committee. Victor is an original and continuing co-author of ANSI Z9.5 on Laboratory Ventilation and a recipient of an award from the American Industrial Hygiene Association in 2002 for Outstanding Contributions to the Field for Laboratory Safety.