Laboratory Design Newsletter 2011 Selected Abstract


Reducing Campus Air Change Rates Safely—An Authority Having Jurisdiction and Environmental Health and Safety Approach

Shannon Horn, P.E.
Timothy Lockhart, University of Colorado Boulder



Image of mountains and campus


The University of Colorado (CU) Boulder has approximately 2.1 million square feet of laboratory space, which uses approximately 43 percent of the annual energy consumption of the entire campus.  All of the CU Boulder laboratories were built in different eras, following different philosophies and standards regarding air change rates (ACH) and safety. As such, the CU Boulder Authorities Having Jurisdiction (AHJ) and Environmental Health and Safety (EH&S) departments were challenged with determining what ACH would be acceptable for the campus, seeking an ACH that minimized energy consumption while maintaining a safe laboratory environment, and how this approach could be pragmatically applied to new and existing facilities using limited resources.

First the departments reviewed codes and industry standards adopted by the university and the state of Colorado, as CU Boulder is required to follow codes as a matter of law and enforcement, as well as use standards, guidelines, and best industry practices to make educated decisions in grey areas not covered by code.  After the review, the departments determined that there is no prescribed ACH that determines a safe laboratory. The departments also determined that there are three main drivers for ACH in laboratories: loads, hood ventilation, and hazard type of laboratory activities. 

To calculate the loads the university was maintaining, the departments surveyed all loads in a space; metered a sample of typical laboratories throughout the campus; and determined a diversity value based on metered data compared to surveyed data. The departments then benchmarked this information using the Labs21 Energy Benchmarking Tool. The departments considered options to minimize the load variable. These included working with the laboratory users to use/purchase different equipment, turning off equipment or using setback when not in use, and considering infrastructure changes such as adding fan coil units or chilled beams to decouple the loads from the ventilation. 

The departments determined hood ventilation needs by reviewing hood face velocities, and evaluating if re-balancing, modifying/changing the hood to a high-performance fume hood, or converting to a variable air volume system changed the ACH enough to justify the activity. 

The departments based hazard classifications on National Fire Protection Association guidelines, laboratory activities, laboratory management, risk analysis, and modeling and monitoring techniques to provide a comfort level in the safety of the laboratory.  The departments categorized hazard activities as either high (6 ACH) or low (4 ACH) hazard. Through the hazard evaluation, the departments demonstrated that for high hazard compounds the space was hood driven, while the risk analysis demonstrated that, historically, there is a less than 1 percent chance an event will occur. Through the monitoring/modeling analysis, the departments verified that the lower ACH did not exceed exposure limits based on the compounds reviewed.

By comparing all three variables, CU Boulder could determine which variable was driving the laboratory ACH and, correspondingly, what ACH reduction methodology would be best to pursue.  Through this analysis, the departments determined three main methods to reduce ACH: rebalance the system, modify/replace hoods, or modify major infrastructure.

After applying the above approach to an existing facility, CU Boulder rebalanced a laboratory building from 10 to 64 ACH down to 4 to 6 ACH and solved long-term complaints of temperature and maintenance backlog.  The project also verified the assumptions and extrapolations that went into the load and hazard evaluations and justified itself with a two year payback.

This pragmatic approach will result in substantial energy savings, while establishing a comfort level in the safety of a laboratory. This case study helped establish a model that could be applied campus-wide by leveraging limited resources. CU Boulder is still considering how to continually fine tune the assumptions in the load verification and hazard analysis, how to accurately quantify the energy savings, and how to effectively manage constantly changing and evolving laboratory spaces on campus.

To address these questions, CU Boulder is monitoring/modeling different compounds, using a two-zone model showing generation and decay in near/far field, conducting continuous indoor air quality monitoring and measurement and verification, and establishing a management protocol and commitment from the laboratories to update the departments on laboratory and compound changes, as well as laboratory operation. By applying this approach campus-wide, CU Boulder estimates an approximate 15 percent average energy reduction for the campus.


Shannon Horn is a professional engineer and LEED AP®, with a Bachelor of Science degree from Colorado State University. Ms. Horn is a campus mechanical engineer for CU Boulder, where she holds a diversity of responsibilities from commissioning agent to AHJ to supporting energy conservation projects and initiatives campus-wide. Ms. Horn has more than seven years experience as a consulting engineer for a diversity of clients that primarily focused on industrial, laboratories, data centers, institutional, high-tech, and educational facilities. Ms. Horn has nine years of experience working as a facilities engineer for a semi-conductor/inkjet facility and a higher education learning institute. Regardless of position or job title, Ms. Horn's objective and passion have been oriented towards high-technology environments and how to reduce energy without compromising form, fit, or function.

Timothy Lockhart is a certified industrial hygienist and certified hazardous materials manager with a Bachelor of Science in environmental chemistry and toxicology and a Masters of Science in industrial hygiene from the University of Massachusetts, Amherst. Currently employed as an industrial hygienist for CU Boulder, Mr. Lockhart is responsible for a variety of programs, ranging from indoor air quality to employee exposure assessments, hazardous exhaust ventilation, and employee trainings. Prior to joining the EH&S team at CU Boulder, Mr. Lockhart was a consulting industrial hygienist for seven years and helped manage health and safety risks for various industrial and corporate clients. As a consultant, Mr. Lockhart developed and implemented EH&S programs and corresponding audits, conducted indoor air quality investigations, and implemented various strategies to help protect worker health and safety. Mr. Lockhart's understanding of federal and state regulations and current technology has allowed him to provide cost savings for clients, while ensuring sound health and safety solutions.