Designing labs, research buildings
CSE: What are some common missteps that engineers might make on a laboratory project?
Michael Chow: Cleaning up power should be considered as many laboratory instruments have sensitive power parameters. Consideration should be given also to using uninterruptible power supply (UPS) systems.
Crutchfield: We sometimes run into lab projects where the old 12 air changes per hour (ACH) rules are still being enforced by the environmental health and safety folks at the various institutions. Couple that with the desire for constant volume hoods, which seem to be favored by maintenance staff, and it’s a recipe for an underperforming building. When we discuss this with the owners and suggest alternate compliance and safety methods, they often recognize that there are better ways to accommodate lab airflows, but many owners are still reluctant to change from their institutionally set policies. We aren’t always able to convince them that alternate methods should be used for their projects, but we feel that it is our responsibility to show them the alternatives, and the economics of the alternatives, so that they can be more informed as owners. The goal is to help them ultimately understand their internal policy, and compare that to current state-of-the-art procedures, so that if they want to make policy changes, they have full understanding of the issues involved.
Ramirez: Design for flexibility in control strategies, input/output expandability, and provide for plenty of instrumentation. Laboratory users are constantly changing, particularly in R&D facilities. Specifying the proper control architecture for achieving functional changes a laboratory space may see over the course of its life, specifying proper material for application (metals, gasket seals, temperature and pressure scales, etc.) to achieve functional changes in the laboratory. Of course, this must be balanced with project budget.
Linamen: One common mistake is in thinking that offices, labs, and classrooms/lecture rooms in lab buildings all need to be served from separate HVAC systems. Segregating these spaces on separate systems requires added space for equipment and supply/return/exhaust risers. For a physical sciences building we worked in, there were sophisticated research and teaching labs, as well as classrooms/lecture halls and offices. There is one HVAC system for the entire building, and one main supply air riser, return air riser, and exhaust air riser. Laboratory air is 100% exhausted. What is frequently not recognized is that for most mixed-use lab buildings, the lab air requirement is usually a major part of the total HVAC air requirement for the entire building, usually 70% or more. If multiple HVAC systems are provided, a percentage of the return air from the offices and classroom spaces must be rejected, so that a corresponding percentage of ventilation air can be provided to maintain air quality. However, if one common HVAC system serves all spaces and if the lab air requirement is a high percentage of the total air requirement, 100% of the air from the offices and classroom spaces can be returned. This reduces the total air requirement for the building. This usually results in fewer air handling units for the building, so it saves first cost, it improves overall flexibility because labs can be converted to non-lab functions and vice versa without major changes to the HVAC, and the non-lab spaces have excellent air quality because they receive higher than normal percentage outside air. This usually makes it more convenient to provide redundancy, because redundancy is only required for the one system.
CSE: When working in labs outside the United States, what differences, challenges, or best practices have you observed?
Crutchfield: Our experience has confirmed that laboratory standards outside the U.S. have not evolved to the extent they have in the U.S. Standards outside of the U.S. have remained unchanged largely because the international markets have not developed as many new state-of-the-art lab facilities as we have in the U.S. Many of the criteria points such as load densities, air change rates, and fume hood face velocities have not been challenged because the need simply has not occurred. However, with the globalization of industry groups, this is beginning to change. In the European market, attention to overall health and safety within the lab environment requires focused risk assessment by the project team. The project team routinely consists of owners, design professionals, lab operators, and maintenance staff. We have found this refreshing, as clients now understand the critical role appropriate operating procedures serve for laboratory health and safety.
Ramirez: In the United States, it is general practice to assign about 25% of a fee to construction administration. This is generally in the standard design/bid/build project delivery model. Delivery of a similar project abroad is generally a design/assist or design/build delivery model. This will require significantly more on-site support, and commonly we can see the fee structure being more like 55% design and 45% construction administration and/or on-site support, if not an even split. Depending on the project schedule, this is probably the best way for design professionals to manage their risk.