Planning for Optimum IAQ

Planning for Optimum IAQ

Addressing key issues during planning and design enables building owners to provide the optimum HVAC and the resulting indoor environment.

Janet Wiens

Good looks aren’t everything. A building with a grand architectural design but with poor indoor air quality (IAQ) doesn’t pass the test today. The growing focus on IAQ and its importance to the health of building occupants is rightly a cause of great focus for any design team. And, as with any building component, designing an HVAC system that ensures good IAQ doesn’t happen without a great deal of thought.

Target Points

Richard Bursi, P.E., president and chief executive officer of OGCB, Inc., a mechanical and electrical consulting engineering firm located in Memphis, has worked with numerous college and university clients. He maintains that a number of critical areas must be thoroughly addressed during a project’s planning stage in order to install the most appropriate HVAC system.

“There are many types of systems available,” said Bursi. “Our discussions with an institution’s administrators, facility managers, and operations and maintenance personnel during the planning stage help us to find the answers to some very important questions.” According to Bursi, his team wants answers to the following questions or target points:

  • What is the building’s projected average occupancy?
  • What is the building’s area and orientation?
  • What is the building used for and what functions take place within its walls?
  • How many temperature zones (areas of control) are desired?
  • What is the skill level and experience of the operations and maintenance staff that will run the HVAC system?
  • What is the anticipated budget and/or financial investment philosophy for both initial and life-cycle costs?

Handling Outside Air

How a system handles outside air is very important, and both local codes and American Society of Heating, Refrigeration and Air-Conditioning Engineers (ASHRAE) standards must be followed. The number of building occupants drives outside air requirements. A system that does not properly handle this component can lead to undesirable circumstances — such as a building that is too humid — which can foster the growth of mold while also being very uncomfortable.

Bursi says that some types of systems can be customized, so determining what a college or university wants to invest is important. For example, a building owner may be satisfied with a system with a single throw-away filter, which is typical in a standard HVAC equipment package. For various reasons, the owner may want a system with a throw-away filter followed by filter banks of greater air-cleaning capability, humidifiers, or ultraviolet sensors. Both the initial and the life-cycle costs of the first approach are obviously lower, but the second approach would provide better IAQ and some operating cost savings, due to longer equipment life and lower energy use.

Other control issues influence initial costs but also have long-term operating and maintenance implications. A building with a high number of thermostats gives more temperature control to building occupants. However, having more control zones usually translates to needing a more sophisticated HVAC system, which costs more. Some colleges and universities want to install carbon dioxide and/or Volatile Organic Compound (VOC) sensors as part of their IAQ program. The cost for these system components must be calculated and weighed against the project’s overall budget and other building requirements.

 

Planning at Wesleyan University

The restoration of the historic Memorial Chapel and Patricelli ’92 Theater at Wesleyan University in Middletown, CT, illustrates the challenges of designing the most appropriate HVAC systems for historic buildings, a task that was complicated by the age and condition of the two buildings. Robert Olson, principal of Robert Olson + Associates, Boston, agrees with Bursi that a project must be thoroughly analyzed during the planning stage.

“Our design joined and restored two hallmark buildings on the campus,” Olson said. “We truly didn’t have any space on the interior for the HVAC system based on other project requirements. Our discussions with all members of the design team enabled us to craft the best HVAC solution, which involved locating the HVAC system outside the historic buildings and underneath the pavilion that joins the two structures.

Olson also agrees that greater detail up front results in a better outcome for everyone. Initial targets and concepts should be discussed and then revisited, perhaps multiple times, to produce the optimum design solution.

Building with BIM

The use of Building Information Modeling (BIM) was an integral part of the award-winning Wesleyan project, and is a tool advocated by Olson. “BIM enables us and our clients to visualize an environment or system in three dimensions before anything is built and, among other things, to quantify the impact of design options early in the design process. Much of the work that we do with BIM was formerly done by hand, so there is an important efficiency factor for us as well.”

The $22M project united two historic buildings with a new transparent pavilion to create a center for theater, music, worship, and teaching. Among other efforts, Olson and members of the team used BIM to complete sun studies on their design. This enabled the team to accurately determine the impact of the extensive amount of glass on HVAC requirements, as well as to refine the design of the pavilion to capitalize on the shading provided by the historic buildings on either side of the structure.

“There are many factors related to HVAC performance and IAQ that are critical for performance spaces and the preservation of historic buildings,” said Olson. “Providing exterior air intakes that are clean and quiet, adequate volumes of fresh air, equipment locations where noise can be controlled and isolated, and a distribution system that provides accurate and quiet delivery of conditioned air, all play a part in the architectural and the HVAC design, and are key to creating a high quality indoor environment.”

Olson also notes other important elements. Early discussions with facilities staff are important to ensure that control systems and equipment selections will be appropriate. The ability to adjust system performance for different occupancies through the control system results in a system that can be operated more quietly and efficiently while saving energy. Extensive and open communication early in the process among the entire team is needed to integrate these buildings systems with the architecture, and to provide efficient HVAC systems and a safe IAQ environment for all building occupants.

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