Labs for the 21st Century -

		Sustainable Strategies
		Frequently Asked Questions

This Frequently Asked Questions (FAQ) list includes questions and answers from various sources, including Labs21 partner projects, Labs21 supporters, laboratory design experts, and others. The questions are categorized by strategy. This list is continually updated. If you would like to contribute to it, please contact us.

Energy Recovery

Q. What are the typical O&M procedures for run-around glycol loops? Are there particular design strategies to minimize O&M requirements?

Q. Can energy recovery wheels be used in chemistry labs?

Optimize Ventilation Requirements

Q. Our university campus standard is 10 ACH ventilation rate for laboratories. How do I address safety concerns when lowering the required minimum ventilation rate to 8 ACH or even 6 ACH?

Efficient Fume hoods

Q. You claim improved safety and performance of lower velocity fume hoods such as the Berkeley Hood. Our Safety Office is not convinced about the benefits of speeds below the standard 100 fpm. Can you provide any technical papers to support the lower velocity designs?

Q. Our lab needs a small stand-alone hood for storing H2S (and other toxic gas) cylinders. What you recommend?

Rightsizing Laboratory Equipment Load

Q. The Labs21 EPC Energy Credit 9 requires that electrical panels be designed to allow for portable or permanent check metering of equipment loads. How much space is required in the panel to allow for clamp on meters? What type of meters can be used?

Q. What are the typical O&M procedures for run-around glycol loops? Are there particular design strategies to minimize O&M requirements?

A. The O&M is typical to any hydronic and coil system - glycol needs to be annually checked and periodically replaced, pumps need minimal maintenance, system performance needs to be checked and optimized, and coils need to be cleaned if pressure drop starts to increase across coils.

Filters should be installed before supply and exhaust coils. If corrosive conditions are expected use a coil coating to minimize corrosion on the exhaust coil. The filters can be low efficiency - they are there mostly to catch things like wipes that get sucked into the exhaust system. Be sure to design to allow filer replacement without having to enter the exhaust stream.

Q. Can energy recovery wheels be used in chemistry labs?

A. The concern is always cross-contamination, although it can be minimized with advanced
membranes, seal design, and seal pressurization.

Enthalpy wheels have been used in many bio labs (see Labs21 case studies of NIH, Pharmacia and Nidus Center) and some chemistry labs. The reason they are considered better for bio labs is that bacteria and viruses are relatively big - the smallest virus is about 3000 angstroms and the pore size on an enthalpy wheel is 3 A, so they cannot be transferred in the pore. Also biology work is typically done in a BSC that has a HEPA filter on the exhaust, so in theory no biologicals ever leave the lab. If for some reason biologicals did leave the BSC and did somehow get transferred on the wheel, the supply air to a bio lab is usually also HEPA filtered, so they would get caught there.

Enthalpy wheels have been used in chemistry labs. The best example is Johns Hopkins Ross Research building. They have 164 fume hoods, 150 BSCs and general exhaust. All exhaust goes through the wheels. However, in most cases, EHS officers will not allow fume hood exhaust to go through the wheel. In such cases, it may not be effective to use a wheel, since chemistry lab exhausts are often fume hood driven.

Q. Our university campus standard is 10 ACH ventilation rate for laboratories. How do I address safety concerns when lowering the required minimum ventilation rate to 8 ACH or even 6 ACH?

A. Ask your EHS professional for the scenario when 10 air changes are safe and 6 air changes are not. Generally the concern is a major release such as a spill. In such a situation, neither air change rates are safe - the occupants should leave. So if they have the opportunity to push a panic switch, five benefits can arise:

1. The control system can increase the airflow significantly (say to 20+ air changes)
2. An alarm can signal your EHS staff that there is a problem
3. An alarm can signal others that may enter the lab that they should not
4. Huge amounts of energy and capital costs are not wasted
5. Lower quantities of air supply reduce the negative effects supply air can have on fume hoods

This option with lower capital and operating cost may actually significantly improve safety.

Many labs are not classified as hazardous (most university labs). H-6 occupancy (a hazardous classification) only requires six air changes. Note that standards are not codes, and judgment is required in their application. For example, ASHRAE's recommendation of 6 to 12 air changes does not mean 6 is marginal and 12 is better. There are many examples when more air is not better (e.g. fume hood face velocity).

It is when a systems approach is not used that air change rates may be driven up. Poor design may lead to more airflow. For example, if the room airflow patterns are not well designed, undesirable dead air spaces may occur. Increasing airflow and turbulence solves that design problem, but can significantly undermine the safety of the fume hoods. A systems approach optimizes all aspects (no dead air, and safe hoods) and is a win-win approach.

If a 200,000 square foot lab saves 4 air changes that would be in the ball park of $800K per year (perhaps more in colder/warmer climates). That could pay for a full time energy manager and a full time EHS manager to optimize and assure long term performance while still putting hundreds of thousands of dollars back into research or teaching.

A. 100 fpm is the optimum face velocity for most hoods (conventional design). However, there are a number of manufacturers developing high performance hoods that require less air flow and maintain or enhance containment/safety. Such is the case with the Berkeley push-pull hood (http://ateam.lbl.gov/hightech/fume hood/fhood.html)
These two recent reports compare a very high performing conventional hood to the Berkeley Hood using both a standard testing protocol and a new dynamic test.
- Comparison with standard protocol
- Comparison with dynamic test
As can be seen, the Berkeley hood running at 50% of the air volume performed significantly better than the conventional hood (running at 100 fpm) in side by side tests.

There are some in the industry who do not favor high performance hoods (e.g. manufacturers without competitive products, and hood control vendors worried that high performance, constant volume hoods may become competition to their products), so you should be skeptical of the nay- sayers. However, you should be equally cautious about "high performance" hoods that aren't high performance. The bottom line is that hood performance should be judged using industry standard tests on hoods as-installed (not as manufactured in an ideal test chamber). Containment is far more important than face velocity. We strongly advocate automated hood controls (e.g. VAV), room pressure controls, monitoring and alarms (for any hood/lab).

A growing number of experts believe that face velocity is not a good indicator of containment or safety. 12.5% to 17% of installed hoods with 100 fpm face velocity fail more robust tracer gas testing (ASHRAE 110 using ANSI/AIHA thresholds). Therefore there is growing consensus that to assure safety, containment testing must be performed (i.e. ASHRAE 110).

The Berkeley Hood is in the field testing and demonstration phase. We are running these tests at 50% of conventional air flow. Our ultimate goal is a safer hood running at 25 to 30 percent of the airflow used in conventional hoods. Other high performance hoods are on the market. Generally they operate at 60 to 80 percent of the traditional air volume. These, often safer hoods, should be considered for projects now. Some can be combined with VAV and other control strategies and, if required, they can be run at higher flows to satisfy arbitrarily set standards. If lower flows are accepted, the savings in the HVAC system can more than pay for the higher cost of the hood and the testing. The end result is lower first cost, lower operating costs, and improved safety.

Reducing the face velocity does reduce turbulence and eddies in front of the user. The Berkeley Hood actually introduces air at the face of the hood (in front of the user), thus further eliminating such problems. The reduction of turbulence and eddies near the face of a hood is a side benefit of high performance hoods and may be most beneficial in high density fume hood situations, such as teaching labs, where it is very difficult to design the supply/make-up air system to not interfere with the performance of the hoods. Unfortunately cross currents can have a greater impact on some low flow hoods, especially more conventional hoods running at low face velocities. This underscores the benefit of as-installed testing of the hoods within the context of an overall system.

Q. Our lab needs a small stand-alone hood for storing H2S (and other toxic gas) cylinders. What you recommend?

A. We recommend not using a lab hood to store gas cylinders. You should use a gas cabinet. They will use less energy and provide a higher degree of safety.

A. The usual configuration puts the current transformers and voltage connections inside the panel, and the actual logger is outside the panel. This requires the wires to run out through a partially closed door. Most authorities allow this configuration for temporary connections, and typically no
special provision needs to be made for it (the CTs and voltage connections coexist with what's in the panels already). If one insists on having the panel cover completely secured, then the logger needs to be inside, and it either needs to run on its batteries or the low-voltage power supply needs to somehow be provided inside the panel. Most panels have enough extra room for the latter configuration, but a really packed panel might not.

Examples of loggers which are commonly used these days for energy logging field work are the Elite Pro units with split-core CTs (technically a clamp-on is a hand-held device). See these logger specifications and CT specifications.