Changes in HVAC systems of the manufacturing, industrial building market
Several changes to the design of HVAC and plumbing systems of manufacturing and industrial buildings are covered here by the experts
- David L. Cooper, PMP, Principal, Smith Seckman Reid Inc. (SSR), Memphis, TN
- Andrew David Hager, BASMA, PE, LEED AP, Senior Mechanical Design Lead, CRB, St. Louis
- Darren Rogge, Senior Associate, Jordan & Skala Engineers Inc., Norcross, Georgia
- Joe Schadt, Construction Executive, Industrial, Harris, St. Paul, Minnesota
What unique cooling systems have you specified into such projects? Describe a difficult climate in which you designed an HVAC system for an industrial or manufacturing facility.
Andrew David Hager: For our clients with high cooling demands, we use ammonia and carbon dioxide cooling systems for their flexibility, range and efficiency at high and low demands. An example of an extreme user is a 45°F/75% relative humidity manufacturing facility outside of Dallas, where air temperatures can rise to over 105°F quite frequently. Our challenge was to provide 35°F supply air for manufacturing process. Ammonia as the refrigerant allowed us to hit those 25°F coil temperatures and the flexibility to modulate under low load conditions in the winter.
Darren Rogge: We are seeing most industrial facilities incorporating cooling systems to provide a more comfortable environment for the employees. While to most cost-effective solutions include rooftop package direct exchange equipment, some clients opt for a more robust chilled water system. The desire is typically to either temper the entire space or spot cool where the employees are located. The hot humid climate zones are the most challenging areas.
What unusual or infrequently specified products or systems did you use to meet challenging cooling needs?
Darren Rogge: We had a project in Miami where the client had specific humidity level requirements. To meet this criterion in this climate, we specified a dehumidification unit for the space. This unit was provided in addition to DX packaged cooling equipment having internal dehumidification components.
How have you worked with HVAC system or equipment design to increase a building’s energy efficiency?
Darren Rogge: A number of our industrial projects have achieved U.S. Green Building Council LEED certification. With this, the HVAC systems have been designed to increase the overall building energy efficiency.
Andrew David Hager: We use heat reclaim from the process systems and high-efficiency systems.
Describe an industrial or manufacturing project in which process piping was required. What were the challenges and solutions?
Joe Schadt: We recently completed a project with a large amount of sanitary stainless-steel piping for the production of a pharmaceutical product. It was necessary for the piping to be sloped either back to its source or to the end use point in almost every case. The competition for space in the building was quite challenging. To ensure all of the necessary piping, duct work and other equipment could be designed in the available space, we focused heavily on BIM and coordinated all systems so the process piping had a pathway at the required slope. The work on the BIM model did allow for a majority of the process piping to be fabricated off-site where clean conditions were much easier to maintain.
Andrew David Hager: Today, material costs and material acquisition are big issues. However, that should change back to a more new normal with somewhat predictable costs and schedules. Material costs are always a big concern in using the correct material for the process. Long runs of piping/tubing require a lot of planning and coordination of routing, support and ability to accommodate expansion and contraction. This is very challenging when we are dealing with a lot of pipes for long runs at varying temperatures.
What best practices should be followed to ensure an efficient HVAC system is designed for this kind of building?
Darren Rogge: To design an efficient HVAC system for industrial buildings, you must work in harmony with the architect to develop a good building envelope first. Working closely with the architect on the building envelope elements and how they impact the HVAC equipment sizing will help provide the most efficient and cost-effective overall design. Also understanding the buildings internal load components (equipment, people, lights, etc.) will factor into your equipment selections.
Andrew David Hager: Weigh the best efficiency available with the return on investment. Both require a cost perspective. Even when a client wants to meet a LEED goal, the costs must be looked at to be able to establish what is the best efficiency available and what is the return on the investment. Best efficiency available is not just limited by what manufacturers offer, it is limited by the client’s budget and it can lead to some very interesting discussions.
What type of specialty piping, plumbing or other systems have you specified recently?
Andrew David Hager: We typically design stainless steel tubing and piping for process and manufacturing, where the piping is exposed in the same room as the process and/or the stainless steel is necessary for its resistance to correction either from the fluids inside or the environment outside the pipe. In special cases, high-grade alloy metals are used such as a Hastelloy, primarily in the pharmaceutical industry.
Darren Rogge: Some of our projects pursuing LEED certification have incorporated rainwater harvesting for toilet flushing and/or irrigation. This typically includes a collection piping system, storage tank, pump and controls. Sizing of the storage tank is key to making sure the system will provide some reasonable payback. Using the local rainfall rates and the anticipated water usage will allow the designer to size the storage tank to meet the water usage demand.
What are some of the challenges or issues when designing for water use in such facilities?
Darren Rogge: For large industrial buildings, one design challenge is to ensure that you have consistent water pressure throughout the facility. Long pipe lengths create increased friction losses. A booster pump system with pressure reducing valved zones can be designed to deliver required pressures. Another challenge is expansion and contraction of longer pipe lengths. Expansion loops are typically implemented to account for the anticipated pipe movement.
Andrew David Hager: Where the water should be and where the water should not be. Sometimes those areas are next to each other. Other challenges are maintaining the water temperatures for a process in an environment that is not complementary to the water temperatures. Water conditioning and maintaining the water condition especially for long runs or piping. Water demand and pressure are also concerns with multiple processes requiring variable flows of water and at different pressures.
Describe a facility in which there were specialty air movement requirements, such as unique air pressure needs or high-velocity low-speed fans.
Andrew David Hager: Many of our clients require a pressurization scheme that either attempts to keep air out of space or keep air within a space depending upon the process involved. Clean areas require clean supply air and typically are pressurized positively to adjacent spaces to keep the air from those spaces out of the clean area. Air movement can be critical with processes that have high latent loads. Air movement on surfaces can help keep condensation from its forming on walls, ceilings and equipment, however, caution is required to keep from overcooling surface especially where high latent loads are an issue.
Darren Rogge: We had a building design that required air supply in close proximity to employees. In addition to providing ducted supply to the employee areas, we designed air circulation fans and HVLS fans to implement more air movement for employee comfort. This design included small circulation fans at employee workstation areas and large HVLS fans in open areas. The end result was the employees perceived the environment to be cooler with the additional air movement.