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Utility systems that support forensic science need to hit the mark and be, as Goldilocks said, just right. Design systems that are too big and you’ve invested money that could have been used elsewhere. Too complex and you’ll spend more money maintaining them. Skip the energy conserving features and you’ll spend more on utility bills indefinitely.

This lab is too hot.
Visit an older lab facility and almost without exception, you’ll find the existing utility system having difficulties supporting the direct equipment needs as well as struggling to maintain the environmental conditions necessary for proper instrument function. One of the largest strains on the building electrical and cooling systems is instrument rooms packed full of equipment with extensive electrical demands and cooling requirements. Undoubtedly fume hoods and biological safety cabinets have been added and somehow have been made to work, and most often only sort of made to work compromising the safety of the workspace. In general, in older laboratory facilities the lab utility systems are inadequate; quite often substantially inadequate.

This lab is too cold.
Examine many new lab facilities and you’ll find that the pendulum has swung too far in the opposite direction. Don’t be surprised if you find that the actual peak electrical or cooling requirements are one-third to one-half of what was installed. Buying the infrastructure which supplies two to three times more than what you need to support your building is expensive and an investment that could have been better directed to improving energy efficiency. The systems that you will see in many new laboratory facilities are also unduly complicated. Forensic labs are some of the most complex buildings that a city, county, and/or state government facility staff will need to maintain, so it is important to have systems that are not overly complicated. It is important to keep it as simple as possible.

Figure 1: An LED exam light at the Johnson County facility. © Joe Atchity  These labs are just right.
Here are a few concepts from two recently completed facilities, the Tucson Police Department Crime Laboratory and the Johnson County Kansas Sheriff’s Office Criminalistics Laboratory. Both buildings are about 60,000 square feet and house full service forensics laboratories. (Read more about both of these stunning new facilities in the feature article in this issue, “The New Face of Forensic Science.”) There are many ways in which the systems in these two new facilities are just right.

Figure 1: An LED exam light at the Johnson County facility. © Joe Atchity

Hybrid Ventilation Systems
For decades lab designs have called for the installation of separate ventilation systems for offices and laboratories. If you would like a just right facility, combine them into a single system. A single hybrid ventilation system is easier to build, saves significantly on initial cost, simplifies maintenance, reduces energy consumption, and provides better ventilation in the office areas. Design a hybrid properly and you’ll also build in greater standby capabilities without adding additional expense.

Chemical Fume Hoods
Carefully select the type of fume hood you will use for your project. Old technology fume hoods are highly inefficient. To make such hoods more efficient, designs routinely incorporated elaborate systems of controls to throttle back unnecessary air flows bringing both added expense and maintenance issues to the table. Newly designed chemical fume hoods offer many containment performance improvements. By using either restricted sash opening or low face velocity (60 fpm) designs the amount of exhaust in hood systems can be reduced by up to 75% of older hood designs. With these lower flow rates, complicated variable volume controls may not be needed adding an additional perk to the use of such hoods.

Energy Capture
Capture and reuse as much energy as possible from the exhaust air stream. Even in the most efficient laboratory facilities, energy is being wasted by the evacuation of conditioned air out of the building. The most effective system available for capturing this lost energy uses a “total energy (enthalpy) wheel” that transfers both sensible and latent energy in both heating and cooling modes between the air being brought into the building and the conditioned air being exhausted. (It is important to evaluate chemical usage since enthalpy wheels may not be compatible with all chemicals.) A detailed review of chemicals used at the Johnson County facility confirmed that the use of an enthalpy wheel was appropriate and it became a key component in an overall energy saving strategy of the building, which netted a 48% overall energy reduction in heating and cooling costs.

Heat Pumps
If you’re in a region that has balanced heating and cooling seasons you may want to consider ground source heat pumps, often also referred to as a geothermal system. At the Johnson County Criminalistics Laboratory, a well field of 118 five-hundred-foot-deep wells is connected through recirculating piping to central heat pump units that produce chilled water, heating hot water and hot domestic water. Using the well field improves energy efficiency and also eliminates the use of over 1,000,000 gallons of water annually when compared to conventional cooling towers.

Figure 2: Sensors automatically turn off lights when there is enough daylight that they are not needed.

Figure 2: Sensors automatically turn off lights when there is enough daylight that they are not needed.Sun Energy and Day Lighting
Take advantage of the sun. While the use of photovoltaics may or may not be economical depending on where you are located and what you pay for electricity, controlling, capturing, and using the sun’s energy for day lighting is always important. A good example is the Tucson Police Department Crime Lab. Tucson’s desert location benefits from over 350 sunny days a year. Control and capture of the sun’s energy is an important part of the design of this facility, allowing for day lighting of even central core areas of the building. Day lighting strategies that combine high performance windows with shading and light shelves which bounce daylight further back into the building were used on both the Tucson and Johnson County projects. This strategy was combined with lighting controls to turn off fluorescent lighting when not needed providing additional value in the cost savings realized by decreased dependence on electrical lighting.

The type of lighting is also an opportunity to both improve the work environment and to reduce energy consumption. High efficiency pendant mounted fluorescent light fixtures provide a highly effective way to light a space, but also create an environment with a bright ceiling and a more open feel. LED task and exam lights are great ways to provide higher localized light levels without using a lot of power. Last, the simple forethought of siting a building appropriately to take advantage of natural light should be a key component to your initial design thoughts.

While a laboratory isn’t a bowl of porridge, like in the story of Goldilocks and the Three Bears, laboratories can be too hot (lacking infrastructure), too cold (over-engineered), or just right. Just right labs, such as the Tucson Police Department Crime Laboratory and the Johnson County Sheriff’s Office Criminalistics Laboratory find the right balance. They include such elements as correctly designed and sized heating and cooling systems, energy capture devices, and harness the energy of natural day lighting. And then they all lived happily ever after.

Lou Hartman is a Principal and Sr. Mechanical Engineer with Crime Lab Design, which provides full A/E services for forensic and medical examiner facilities around the world.

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