Part 2: Tips for sizing
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Fig. 1. Lab aisles should be at least 5 ft within the module. This allows someone to
pass behind another person standing at a fume hood or sitting at a bench. All illustrations
courtesy of HOK.
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In the October issue, we examined trends in lab module sizing over time. To define the right
size module for a lab being planned, the planner and client should review all the elements that
will make up a flexible, energy-efficient lab module over time. This begins with the width and
depth of the module and continues into lab neighborhoods and blocks.
Sizing: The correct width
There are various approaches to sizing a lab module. Key factors to be considered in generating
the recommended width for a module include the following (see Fig. 1):
- During early programming, while the building size is still being defined, calculate the
dimensions required to accommodate the size of equipment and features the client will need in the
future.
- Benchtops for casework typically are either 30 or 33 in. deep. The 33-in. benchtops often are
proposed around perimeter walls to accommodate deeper equipment and more space for log-in of
samples. A 33-in.-deep benchtop allows for a 1-in.-deep overhang for the benchtop, a 22-in.-deep
cabinet, and a 9-in.-deep plumbing chase.
- Lab aisles should be at least 5 ft within the module. This allows someone to pass behind
another person standing at a fume hood or sitting at a bench.
- Lab aisles should not exceed 6 ft wide. When they do, users often begin to store equipment,
boxes and other obstacles in the aisle, cluttering an otherwise efficient lab. A 6-ft aisle starts
to be too wide for ergonomic use of the module. Users ideally want to work at one side of the
aisle, then pivot and move something to the other side without having to walk there.
- Mobile casework and tables are available in an array of sizes, but typically are 30-in. deep.
Locating back-to-back mobile casework at an island, therefore, would require an island depth of
only 5 ft. Mobile tables and other stand-alone equipment will vary in size, with a 3-ft depth
being common. The open island configuration allows users to comfortably locate anything from 30
in. to 6 ft in depth in this area. The issue is whether there may need to be a 6-ft clearance for
future equipment or fume hoods.
- If the lab building includes chemistry labs, it most likely will require a generic density
level of one or more fume hoods per module. If the high-efficiency fume hoods are desired for
energy reduction reasons, depth will be even more of an issue. Again, 34 to 40 in. depth for a
high-efficiency fume hood is becoming a planning rule of thumb.
- Configuring fume hoods back-to-back helps minimize the profile of an otherwise substantial
visual obstruction, especially in a chemistry lab where there are many fume hoods to block the
view. Hoods can be backto-back but never front-to-front because of the resulting air flow
patterns. Fume hoods require adequate distance from other airflow generators in order to function
properly. A side-by-side configuration could be acceptable if the distance apart is far enough. It
is ideal to locate fume hoods away from the traffic, near the back of the labs, if possible.
- Some modules are deeper than 11 ft. Larger equipment, nanotechnology labs or some laser labs,
to name a few, would warrant additional depth.
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Fig. 2. Some academic and clinical labs prefer a “cul-de-sac” layout. The lab work
area becomes a personal space, undisturbed by others who may share the overall lab.
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The goal is to size the module to accommodate what will be needed without sacrificing
flexibility by cutting costs. Fig. 1 is characteristic of today’s planning modules, with
consideration for a deeper fume hood or equipment integrated into the line of casework or the
process within the module.
Sizing: The correct length
Determining the right length of a lab module takes into account a variety of factors. The nature
of the ultimate use should be the primary influence on the layout.
Academic and clinical labs have traditionally preferred the layout that provides a “cul-de-sac”
condition. This allows a highly defined, relatively private area with no traffic through the work
areas for each principal investigator and, potentially, their graduate assistants or lab
techs.
Fig. 2 depicts this type of “culde-sac” layout. The lab work area becomes a personal space,
undisturbed by others who may share the overall lab. This type and size of layout plays a critical
role in lab design and should be based on the linear ft of space required for the typical users to
do their work properly—currently and in the future.
Though research labs also make use of the “cul-de-sac” layout, they are increasingly being
designed with a dual (or more) cross corridor layout as shown in Fig. 3. Because research labs
often attempt to promote interaction and collaboration, it is more consistent with the
dual-circulation corridor layout. This is often a more flexible and efficient layout option.
Key design considerations for determining the best lab module depth while improving efficiency,
safety and flexibility include:
- The length of the space allocated to each user should be added for the entire lab room and
divided into logical groupings. This will help define a working bench length.
- Shared functions such as equipment or services can be conveniently located outside the cross
corridors with greater ease of access in this location.
- Providing room for a cross corridor along the two ends of the islands provides the future
ability to expand the space of individual scientists around the corner of each island and permits
ease of flow for all occupants. The open-ended island makes it harder for indi viduals to
establish a “territory.”
- Allowing room for a cross corridor along the two ends of the islands provides two means of
egress from any point within the lab. Variations on this theme are possible. If columns are placed
on every other row at the end of the island blocking the full circulation along one end of the
labs, for example, there are still two means of egress through the second module in groupings of
two modules.
- More linear ft of bench space are possible when the casework is run perpendicular to the
islands along either end of the lab, as shown in Fig. 3. On average, you gain 12 linear ft of
bench space per module when both ends of the lab are used for casework rather than for
circulation. Potential tradeoffs that should be considered include how much daylight can be
brought into the labs and how much visibility can be provided into adjoining portions of the
building when the potential window area is reduced to only the area above the casework.
- To increase building flexibility, consider making the overall length of the module a multiple
of the width. Fig. 4 shows an example of these dimensional relationships. This way, when there is
a desire to locate a lab support or smaller, related labs immediately adjacent to feed into the
larger main lab, the adjoining lab layout that is perpendicular is as efficient and usable as the
layout of the main lab, with the same depth of benches as the main lab.
- From an efficiency standpoint, a “rule of thumb” ideal bench length has ranged from 18 ft to
24 ft. This gives maximum length as might be usable for one, two or three users per side of bench,
depending on the functions. (If the lab bench length gets longer than 24 ft, the tendency is to
introduce another cross corridor, which reduces overall efficiency until the second bench length
starts to approach ~18 ft.)
- Rules of thumb should be rigorously questioned, because this issue is affected by the
functions performed and the specific users. In many research labs, the single module is often
dedicated to two people. Therefore, if there are two exit paths, no one needs to walk past any
other scientist who is working at the bench. On the other hand, in a product testing lab where
there may be as many as six research technicians, three on each side of the bench, it is expected
that they will cross behind other technicians when coming and going. It is even more important
under these circumstances to maintain a second circulation corridor.
- Some lab planners start with a corridor no less than 6 ft so that it comfortably accommodates
two-way traffic. A second ghost corridor can be as narrow as 4 ft.
We can conclude that the length of a proposed lab module should be calculated based on the
series of elements that are expected to be located within the module.
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Fig. 3. More linear feet of bench space are possible when the casework is run
perpendicular to the islands along either end of the lab, as shown here.
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Neighborhood “blocks”
Sometimes the size of the research group a client is accommodating makes it is clear how large a
lab “neighborhood” should be. In most cases, however, the organization that is building the
facility is changing. Clients need to consider the longterm implications and determine how to
achieve the right size for a lab neighborhood that will give them flexibility and energy
efficiency while meeting all their program requirements.
The technical requirements and key issues to consider when defining the size of an individual
lab neighborhood include:
- Identify the total amount of lab and lab support space required by each group in the
organization so that each full group can be co-located, if possible.
- If the program is not set up into logical groupings, the total net assignable ft2
of lab and lab support can be summarized as an overall group of lab space. This total can be
divided by the total number of floors and evaluated for other key considerations.
- An efficient run length for mechanical systems should be discussed with the mechanical
engineer. For example, it may be most efficient to set up blocks of eight modules with utility
shafts and cross corridors between each block of lab and lab support.
- Code implications must be considered. 2004 NFPA 45 limits the overall laboratory unit size for
Class A or B labs to 10,000 ft2. A bigger factor will limit the size if the lab
neighborhood needs to maintain a higher quantity of hazardous materials than allowed per control
area (IBC) or laboratory unit (NFPA). This more often becomes an issue in a heavy chemistry lab,
or in a lab that deals with other more hazardous materials in larger quantities, especially on
higher floors.
- An architectural challenge is to provide daylight as deep into the labs as possible to
minimize the amount of energy necessary for lighting the lab and to provide a better quality
environment for investigators. This is mainly a factor at the exterior walls of the lab building.
It can also be possible at the interior of the building if an atrium, light well or other means of
daylight penetration is introduced. This may suggest that locating labs at the exterior window and
placing lab support, which often doesn’t require daylight, either at the interior or at the sides
if interior daylighting is possible.
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Fig. 4. To increase building flexibility, consider making the overall length of the
module a multiple of the width. The illustration shows an example of these dimensional
relationships.
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Guidelines for success
In conclusion, to accomplish the most reasonable level of flexibility and energy efficiency at
minimal cost to the owner, calculate the optimum size of the lab module as a key first step:
- Use a lab module width of approximately 11 ft. Try to get as much lab module width as the
budget can bear for the greatest flexibility. This is likely to be an 11-ft module if you plan to
incorporate a new energy-efficient chemistry lab with low-velocity fume hoods into your mix.
- Try to get between 18 and 23 ft of bench length for the greatest efficiency. This is likely to
result in an overall module length of approximately 33 ft.
- Consider a multiple of the width to be used as the length to enhance the flexibility and
efficiency of support rooms and future subdivisions of the lab—the “bidirectional module.” For
more discussion of this important concept, see the section "The 'bidirectional module'."
- Consider the tradeoffs between the efficiency of casework along the perimeter walls at the
exterior and at the interior corridor vs. the daylighting and views afforded without
casework.
- Plan lab “neighborhoods” that make sense for a range of reasons, including size of the user
functions, optimum serviceability for utilities, minimizing the distance to researcher offices,
optimizing interaction, minimizing noise and confusion, providing relationships of lab to lab
support that work for the user, and accommodating the maximum allowable quantity of hazardous
materials.
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Fig. 5. Service corridors may be external to the lab neighborhood, as shown here in
darker green.
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If lab planners can focus more rigor on sizing the lab module, we can deliver flexible and
energy-efficient spaces that accommodate our clients' changing needs.
The “bidirectional module”
One way of considering future flexibility is by thinking of the lab module as a set of squares
that are 11- x 11-ft (or whatever the size of the lab module is). This type of future flexibility
must be developed in conjunction with the engineers who will lay out the utility services in the
ceilings. These services then are more capable of being accessed and modified in the future when
changes are made to the layout of labs. The main issues relate to gaining access to the services
to be modified without disrupting existing labs that are outside the renovation area.
One way to ensure flexibility in labs and to maintain the distribution of utilities is to
follow a set of basic “rules”:
- Respect the rated walls, if any, and construction surrounding the neighborhood. The rated
walls generally are driven by the code-dictated “control area” (if it is IBC-based) or “laboratory
unit” (if it is NFPA-driven).
- Respect the utility access corridor, which is usually the interior service corridor or ghost
corridor in which the pipe and IT raceways, as well as the access terminals for mechanical
systems, are located. (It is shown in darker green in Fig.5.) If you don't maintain the same
location for this corridor, the costs will increase exponentially.
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Fig. 6. Service corridors may also be centrally located within the neighborhood, as in
this plan for the Wisconsin Energy Institute labs.
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- Locate walls along the 11 x 11 lines.
- Locate casework on either side of these 11 x 11 module lines.
- Locate aisles between the casework in the center of the 11 x 11 modules.
- Keep permanent elements that penetrate the floors. such as drains, piping and columns.
within a “virtual” 6-ft intersection of each 11 x 11 grid. This allows the permanent elements not
to interfere with future changes and still maintain efficiency.
Note that the utility access corridor may be external to the lab neighborhood as shown in
darker green in the very large lab configurations at King Abdullah University of Science and
Technology (KAUST) labs (Fig. 5), or it could run through the center of the lab neighborhood as it
does in the design of the Wisconsin Energy Institute (WEI) labs (Fig. 6). Other configurations
also are possible.
Kathryn Tyson, AIA, LEED AP, is VP/senior lab planner for the Science + Technology group at
Hellmuth, Obata + Kassabaum (www.hok.com). The author extends thanks to Joseph Ostafi and Paul
Wilhelms for editing and illustration support.
Published in Laboratory Design newsletter: Vol. 15, No. 11, November,
2010
