Specifying HVAC systems in manufacturing, warehouse buildings
Warehouse, manufacturing and logistics facilities need engineering experts to specify various HVAC and plumbing systems
- Jarron Gass, PE, CFPS, Fire Protection Discipline Leader, CDM Smith, Pittsburgh
- Mike Morder, PE, CPD, Design Engineer II, Southland Industries, Dulles, Va.
- Bryce Vandas, PE, Mechanical Group Lead, CRB, St. Louis
- John Gregory Williams, PE, CEng, Vice President – Design Studio, Harris, Oakland, Calif.
What unique cooling systems have you specified into such projects?
John Gregory Williams: Our team has looked at many different options for cooling generation. We’ve worked on a number of facilities in the Salt Lake City area. Its dry climate makes it very appropriate for adiabatic cooling, though the hardness of the water needs to be controlled. Where we’ve found this most successful is in projects with large ventilation loads and wide design temperature ranges, which simplifies the controls and design.
Bryce Vandas: This past year has been very interesting. In January, much of the Midwest hit temperatures close to their 10– to 15–year minimums for a few weeks at a time. This prompted many questions about designs of system that heat space or even the operation of cooling equipment. Pharmaceutical manufacturing facilities have very tight temperature and humidity tolerances that they need to maintain as well as very strict process cooling requirements. Systems can be operated with loops that operate at different temperatures and bleed in cold water to maintain that particular loop. This allows you to keep up your return temperatures, specifically when low cooling is required.
What indoor air quality or indoor environmental quality needs have you worked toward on a recent project, as it relates to COVID-19?
Bryce Vandas: Pharma facilities have very strict air quality standards anyway, so process areas have not changed. However, the conversation always comes back to office spaces. Adherence to better filtration as well as maintenance schedules help a lot. While the conversation starts talking about the HVAC system, it inevitably comes down to the main issue. What is your source of contamination? The people who are already in the space. You are not sucking in COVID from your outside air source. In typical office spaces the recirculation of air can spread more than it contains, so if you up your Air changes you end up just spreading faster. You need to understand your space programming. How are people interacting in your spaces, how is that air flowing, where are the most likely areas to increase infectivity and move from that point. Doing large renovations to HVAC systems in most cases is a big waste of time and money.
John Gregory Williams: We have not seen a huge variation on the projects we have been involved with. We always design to ASHRAE 62.1 needs. Though the options for the categories can be limiting within the Standard, we help guide our clients in the direction of what is the best ventilation rate.
What unusual or infrequently specified products or systems did you use to meet challenging cooling needs?
Bryce Vandas: In pharmaceutical manufacturing the heating and cooling needs are all over the map. Form equipment that requires liquid nitrogen to meet cooling needs to systems that have to run heating liquids at high steam temperatures. Using different refrigerants to meet process required set points and finding a cooling medium that can handle that range of temperatures can be challenging. Once those are identified you also have to specify the disposal as many of these types of systems can be simply dumped down the drain.
John Gregory Williams: The use of high-volume, low speed ceiling fans are very popular in the market for local comfort cooling and destratification of heat.
How have you worked with HVAC system or equipment design to increase a building’s energy efficiency?
Bryce Vandas: Owners want their process and their facilities to perform at the end of the day, but there is always one eye on that energy bill at the end of the day. Encouraging clients to understand air change rates in their rooms based on function and risk and really diving deep into why those air change rates are necessary. Air change rates drive massive heating/cooling loads in pharmaceutical facilities and they often set by a quality department or a client standard based on the “it worked in the past” mentality. Lowering air change requirements can have a drastic impact on the energy needs of these facilities
John Gregory Williams: We’ve worked to include water and air side economizers on a number of projects. For a recent project, also in Utah, we’re using free cooling, combining air cooled chillers with air rotation units. This allows us to maximize energy savings while allowing flexibility and minimizing space take from the valuable working space within the facility.
Describe a manufacturing project in which process piping was required. What were the challenges and solutions?
Mike Morder: I have worked on a few projects requiring process piping, including both pharmaceutical and consumer goods manufacturing. Process piping certainly presented a unique challenge compared to more standard utility systems, but designing all of the systems in parallel led to opportunities for prefabrication of multisystem pipe racks and unique solutions to the facilities infrastructure. Process piping typically involves different piping materials, including but not limited to plastics and stainless steel. These systems typically require sanitary style fittings, which means that elbows or bends are longer, which take up more space than typical systems. They may also require systems to be drainable, which means sloping toward a low point throughout the system or having zero static type valves that require looping of services to maintain temperature or flow. Having a deep understanding of not only the requirements of process systems, in my opinion, leads to a deeper understanding of utility systems and how to most cost effectively design and build them on a project.
John Gregory Williams: Many process engineers we are working with do not yet integrate well into a BIM/VDC workflow. This impacts the quick turnaround needed for many jobs when it comes to construction.
Bryce Vandas: Every life science project involves process piping to some degree. Maintaining product conditions and purity is of the utmost importance. Understanding the needs from the USP, EU Annex 1 or whatever jurisdiction a project falls under is very important. ASME BPE also consistently updates recommendations and methods for achieving process piping perfection. As new/ better technologies, valve assemblies, insulation requirements are coming to the market, the cost of these systems is going up too. In addition, it’s important to keep an eye on schedule. Understand actually operating dates because typically the owner has testing and sample runs that need to be performed before that published start date. Engineering turnover packages for these types of systems get very large and it is important that this level of effort is part of your initial estimates.
What best practices should be followed to ensure an efficient HVAC system is designed for this kind of building?
Bryce Vandas: Researching technologies. Many engineers get caught up with the new technologies, but there is often a give and take. It is of the utmost importance to understand what the give is to get this efficiency and especially in life sciences, can you afford that give and still maintain the tight quality standards that are required at the end of the day.
John Gregory Williams: The best practice we would encourage is gaining knowledge about the facility and its proposed use, as soon as possible. This is often in the form of an equipment matrix, which indicates initial needs.
What type of specialty piping, plumbing or other systems have you specified recently?
Mike Morder: Recently, I worked on a project that required process drainage under a slab and routed to a containment area that allowed the building engineer to sample the water to either reclaim and reprocess the chemicals or pump to storm if no chemicals where found. This system, due to water table concerns of nearby neighborhoods, required that the system have fully welded stainless-steel piping. I have also recently worked on systems with large tepid water distribution loops that integrated a skidded tepid water generation system that included the water heater, mixing valves and pump. This enabled the owner to simply “plug and play” once the skid was set and connected to the loop at two locations.
Bryce Vandas: In life sciences, everything is specialty piping and plumbing — from waste neutralization to making sure products and waste streams are appropriately inactivated to systems that perform bio kill for potential live bacteria colonies to ultra-high purity water and product systems. We are constantly involved in the specification, installation and qualifications of high–purity systems and unique waste streams.
John Gregory Williams: We have installed a number of specialty gases and drainage systems.
What are some of the challenges or issues when designing for water use in such facilities?
John Gregory Williams: Ensuring the correct quality and amount of water available where it’s necessary is key. Much like other mechanical requirements, working diligently through the processes helps drive this. Special health and safety items, such as eye washes, must not be overlooked in facilities where water may not be needed otherwise.
Mike Morder: In a lot of the projects I’ve done, there is a variety of water uses. Sometimes it’s made up for part of the process or manufacturing line. Other times it is using domestic water as a backup cooling source for equipment. Understanding backflow prevention and how to serve these situations can lead to an effective domestic water distribution. An example from one project I’ve done is having multiple backflow prevention devices serving four different systems but feeding from one source. I ended up locating these in a common area and skidding them for ease of installation for each of the contractors (both utility and process piping). Also, its likely in these facilities that the length of distribution is vast enough to require a centralized booster pump either at a campus level or building level, so understanding the maximum pressure allowed on the equipment will help determine effective distribution or pressure reduction valving needs.
Bryce Vandas: There is a tremendous amount of waste water in these types of facilities. Water is passed through pretreatment, reverse osmosis skids, distilled and constantly sampled. The amount of water rejected by each individual step adds up to a significant amount of water. Not to mention the water used for cleaning of piping, collected for samples or dumped if water goes out of spec. Reducing the energy burden of this equipment by alternate methods or finding ways to reuse this water are challenges all engineers face.
What types of specialty gases or other similar materials have you specified into a manufacturing facility?
Bryce Vandas: Projects in the life sciences use a plethora of gases. Whether the more general O2, N2, He etc. or gases that pose more of a threat like hydrogen. Gases come in all different quantities and uses. Overcoming the code requirements to find proper ventilation rates as well as the proper methods of detection when using these types of gases.
Describe a facility in which there were specialty air movement requirements, such as unique air pressure needs or high-velocity low-speed fans.
Bryce Vandas: Specialty air movement is what pharma facilities are all about. Cascading pressurizations to move “dirty” air from cleaner rooms to “dirtier” spaces to protect product purity. Or in some cases, making sure that pressurizations ensure no cross contamination between products. Specialty airflow patterns such as uni-directional airflow is used over filling lines to make sure that open product vials only see HEPA filtered air once and that once it bypasses the working surface it never returns where it could bring contaminants from the surrounding areas. A lot of these types of facilities are going to isolators to ensure that airflow pattern at all times. Smoke studies, CFD analysis and rigorous test and balance protocols go into this process to ensure at the end of the day that the product is safe for human injection. In some cases, the airflow patterns are made to protect the operators from the product just as much as protecting the product.
Mike Morder: I have recently worked on projects that had specific requirements for pressurization and air changes per hour. These parameters were in place for clean environments to prevent particulates from infiltration, as well as providing air changes for filtration of the space. The other unique requirement for this facility was maintaining specific humidity levels, both a high end and a low end, due to the product finished condition. We had to humidify in the winter to allow for proper finishing conditions, as well as properly dehumidifying in the summer.
John Gregory Williams: Food and drink facilities have needs to ensure clean spaces throughout their facilities. It’s important for the mechanical team to really understand the operation work flow and design the cfm differentials to encourage air flow in the right direction.
We’re involved in a couple of clean room manufacturing facilities for the advanced manufacturing industries. The requirements of such facilities need detailed inspection as to what level of filtration and air change rate are necessary to ensure the space meets the manufacturing process.