Tips for Efficient Lab Design and Operation

By Hans Plichta, PE

Laboratory facilities exist to meet the occupants' needs and provide a functional space to safely conduct research.?This research could focus on advancing the development of a drug to combat a disease for profit, or it could be a more basic effort aimed at fostering further research and gaining additional funding.?Private companies, clinics and hospitals, and research and higher education institutions want cutting-edge labs to help them recruit top talent and allow those individuals to develop and produce.?This objective comes at a cost, including both capital costs and ongoing operational costs.

Historically, laboratory facilities have been some of the largest energy users of all building types.?Labs can require five to ten times as much energy to operate per square foot as a typical office building.?The single largest contributor to this energy demand is the general ventilation load: a parameter that is significantly influenced by the lab designers.?"Dilution ventilation" is another way of thinking about this airflow.?The design process begins by working with the users to address the hazard/risk within the proposed lab and to determine what support equipment the operators require.

In that process, the designers (and I’ll focus on the mechanical aspects) must understand the type of lab being designed based on the users' research needs and the equipment to support that mission.

A few lab design basics:

• Labs are generally negatively pressurized, meaning they exhaust more air than is supplied to the room.
• When fume hoods are used to contain the contaminants, the air is exhausted without any recirculation. (This is called a "once-through" ventilation strategy.)
• Air introduced to labs needs to be suitably conditioned: heated and humidified, or cooled and dehumidified.?This conditioning is provided by a central air-handling unit or system.
• Often, for occupant comfort, the dehumidified air must be reheated to make the space habitable.
• In some cases, the lab’s temperature and humidity can be dictated by the process or research being completed.

To start the ventilation-rate exercise, the design team needs to determine the driver(s) of a lab’s airflow rate. One or more of the following drivers may apply:

• The required lab airflow is driven by exhaust make-up (hood-driven).
• The required lab airflow is driven by a specific air change minimum (air changes per hour, or ACH).
• The required lab airflow is driven by thermal equipment (space cooling).

At a minimum, owners should consider the design’s baseline efficiency parameters and specify the most energy-efficient laboratory equipment and lighting fixtures.?This could also include daylighting opportunities in combination with occupancy sensors to reduce the lighting energy.?The most important factor still needs to be examined: the ventilation requirements.

Fume hoods have been modernized with safe low-flow options, helping reduce make-up air requirements.?Reducing the exhaust airflow reduces the make-up airflow until a minimum lab ACH is reached.?Sometimes the ACH minimum is prescribed by the owner or operator; this number may not be negotiable, even if it is higher than industry norms.?In this situation, and also for thermally driven labs, I encourage a design that decouples the cooling load from the ventilation air, incorporating a fan-coil unit or chilled beam.?Here's why.

If the minimum required ACH and exhaust air aren't enough to condition the space for user comfort, then more cooling will be needed.?In an air-only facility, delivering more air (and thus exhausting more air) is the only solution.?Accordingly, the central supply and exhaust systems are upsized, raising initial capital costs and burdening the facility with large continuing utility bills to preheat, cool/dehumidify, and eventually reheat the air used to condition the lab.

With a chilled water fan-coil unit (or chilled beam) serving the lab, the exhaust and supply air only need to cover the minimums: minimum make-up air to replace the exhaust air, and minimum supply to attain the client’s stipulated ACH and no more.?The remaining lab cooling can be done with the fan-coil unit, provided chilled water is available year-round.

It isn't easy to retrofit a chilled beam or fan-coil unit into an existing lab facility.?Such units require power, water piping, and controls and programming.?This type of retrofit also places a device requiring maintenance somewhere the original facility designers hadn't anticipated.?These kinds of retrofits have benefits, but not without some compromises.

Our firm has successfully completed retrofits that improve labs' energy efficiency and thus reduce their greenhouse gas emissions.?This post only touches on the thought process facility managers may go through as they consider lowering their labs' energy footprint.?Early buy-in from owners and operators is essential in achieving this reduction.

Historically, laboratories have been major consumers of energy. Developments and technologies available in the past several years demonstrate that reducing labs' energy burden is an increasingly attainable goal.?Laboratory designers should be educating owners and project teams regarding these possibilities.

Hans Plichta, PE, is an Associate Vice President in GBA’s Wauwatosa, WI office.?Click here?to contact GBA about your laboratory operations and projects.