August 30, 2022
There was a time that facility managers focused on the need for air exchange without having a working knowledge of the impact on optimal comfort and safety levels for all building occupants. The ORFA has raised awareness of the importance of building operators tracking outside weather conditions to maximize facility air handling equipment and to ensure the best conditions for aquatic water, wood design and furniture as well as ice conditions. While air exchange may remove toxic air levels, precision humidity control will help increase building comfort while also providing a safer environment to breathe.
In all aspects of recreation facility management and operations, the building team needs to focus on understanding relative humidity (RH), HVAC and filtration innovations. In a post pandemic world, there is an increased awareness to what health benefits are associated with these operational focal points. The ORFA Ice Making and Painting Technologies (IMPT) course first introduced the science of building air management and how inadequate indoor air would impact ice making, paint application and ultimately ice conditions. ORFA aquatic courses continue to explore how humidity levels impact user comfort, as well as air quality.
Humidity is the amount of water vapour present in the air expressed as a percentage. When RH is at 100 percent outside, it is raining. When RH is at 10 percent outside, the environment is very dry. But where do we need to keep the RH values inside a building? The general design parameters of RH control are between 40 and 60 percent. This range is designated as “comfort zone” for humans. When HVAC systems have a difficult time meeting these parameters, this introduces unnecessary risk into buildings. A facility’s indoor air quality will drop quickly if the RH values are allowed to fluctuate outside these boundaries. The more fluctuation, or the more hours per year a building operates outside of these parameters, the more likely there will be an indoor air quality (IAQ) issue and unnecessary risk of poor air quality and ice conditions. Long-term impact could include moisture damage or mold, which would reduce the projected lifecycle of the structure.
The coronavirus pandemic forced the HVAC industry to become more creative and innovative. Overall HVAC air handling unit (AHU) design and optimizing off the shelf filtration. These two focus points are allowing facility managers to increase their IAQ, save energy annually, and reduce their overall risk of poor indoor air quality. The industry quickly identified that to combat the growth and spread of viruses, bacteria and other pathogens, the traditional AHU design has to be altered. The first innovative design change is the maximization of coil surface area. Traditional HVAC AHU designs use small four or six row coils. These coils allow the heat to be removed from the building. The more rows of coils there are, the more heat that can be efficiently removed. This process dries the air out and allows any moisture in the air to be properly captured and ejected from the facility safely. Using larger 10-row coils allows for more precision in efficiently obtaining RH goals of 40 to 60 percent. However, larger coils are just the start. It is also advantageous to slow down the face velocity of air through the system. Traditional design AHU face velocity is around 450 to 550 feet per minute (fpm). Newer innovative designs are using face velocities from 250 to 350 fpm. This allows the air to slow down through the unit and spend more contact time with the larger coils that are working hard to dehumidify the air. A traditional four to six row coil design at 500 fpm blows across the coil in 0.06 to 0.09 seconds which is much faster than a blink of an eye (.30 seconds). When air is slowed down through the system and the coil size is increased, the system improves. There is now the opportunity for fan savings, compressor savings, pumping savings and higher IAQ inside the building.
To maximize the filtration in an AHU, a pre-filter system and after-filter system are needed. The pre-filter system needs to be a set of two filters. The first filter is typically a Minimum Efficiency Rating Value (MERV) of 8 to 11. The second filter in the pre-filter system is a MERV 16, or in some cases a HEPA filter. The reason for the two filters is to remove the “filter loading” on the filter that is able to do more filtering. In this case the MERV 16 can now filter more, finer, particles because the MERV 8, or MERV 11, is capturing the larger particles up front allowing the MERV 16 filter to last longer, reducing maintenance times and costs. According to a NASA study, filter efficiency is highly dependent on the velocity of the air in the system. The lower the air velocity, the more effective the high-end filters become. This also means that the innovative pre-filter systems and after-filter systems receive another “jump” in filter effectiveness.
There are always silver linings to the obstacles and challenges we face as a society and there have been many throughout history. However, the most recent challenge has pushed HVAC design to newer and better heights. As these innovations become more mainstream and more broadly accepted in facilities around the world, occupants will be happier and more productive.
ORFA training courses continue to evolve to include all forms of advancements within our industry. The objective of ORFA training is always to focus on awareness of topics that are important to human safety and maximum performance or enjoyment of the investment. Members often need to identify which elements are impacting operations and seek higher learning and/or professional advice. Recreation management and operation is a complicated responsibility that requires ongoing investment. Together, we will continue to improve our industry.
Comments and/or Questions may be directed to Terry Piche, CRFP, CIT and Technical Director, Ontario Recreation Facilities Association
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