Designing industrial, manufacturing, and warehouse facilities: HVAC and plumbing
- Andy Campbell, CEng, MCIBSE Senior Refrigeration Engineer Leo A Daly Minneapolis
- David Crutchfield, PE, LEED AP Principal RMF Engineering Charleston, S.C.
- George Isherwood, PE Vice President Peter Basso Associates Troy, Mich.
- Tommy Lane, PE Department Head, Electrical Engineering Spencer Bristol Peachtree Corners, Ga.
CSE: What unique heating and cooling systems have you specified into industrial, warehouse, and manufacturing projects? Describe a difficult climate in which you designed an HVAC system.
Isherwood: Hermosillo, Mexico, is a hot, dry, desert-like place that also happens to be a hotbed for industrial facilities. Systems that are designed there need to take into account not only the heat, but also the dust that can clog systems and derate equipment. Simple, easy cleaning methods need to be considered to help prevent system failures.
Crutchfield: Charleston, S.C., is always difficult in this regard. Between long periods of high dewpoint, extreme heat, and the occasional snowstorm, the HVAC system must meet a very large variable load. All our equipment must also be compliant with wind loading; Charleston has one of the more seismically active areas on the East Coast. The cost to put an air handling unit (AHU) on the roof is usually higher than in other areas due to the size of the cooling coil, the seismic restraints, and the structure to offset wind loading.
Campbell: One of the unique heating and cooling systems we’re using is trigeneration, or combined cooling, heat, and power (CCHP). A power station is used to generate electricity and useful heat, which is then converted to cooling through adsorption. This is more reliable than absorption systems and allows operators to use sustainable fuels, such as fish oil, wood chips, and recycled fats.
CSE: What unusual or infrequently specified products or systems do you use to meet challenging HVAC needs?
Crutchfield: We often use air-rotation units in warehouse areas to allow for long air throws without using ductwork. This keeps costs down and still does an adequate job of conditioning the spaces.
Campbell: We’ve been specifying ammonia refrigeration for air conditioning in large, nonrefrigerated warehouses. This provides more efficient delivery of cooling to large spaces and helps our clients boost their employee satisfaction and retention by creating a comfortable working environment. We’ve also used geothermal to provide a lower-energy solution for heating and cooling. Geothermal systems use boreholes and pump water out of the ground to cool the building during the summer and boost heating in the winter.
CSE: What types of high-volume, low-speed (HVLS) fans or other strategies are owners and facility managers requesting in industrial, manufacturing, or warehouse facilities?
Campbell: We don’t typically use HVLS fans, which are not as efficient as air-turnover units for large-volume spaces. Why specify 100 packaged AHUs on a 1 million-sq-ft roof, which is then distributed via HVLS fan, when you can install seven air-turnover units and apply ammonia-refrigerant cooling to three to four them? It’s much more effective and efficient to do it with air-turnover units.
Isherwood: The strategy for increasing ventilation effectiveness really depends on three factors:
- The footprint of the area being evaluated (with large, tall storage spaces, HVLS systems can be very effective).
- The process being used (furnace and melt areas are extremely hot so spot-cooling areas is often the process used, which sends a direct stream of cool air to a specific location where the worker can stand).
- The location of the facility. In extremely hot areas (Mexico and Texas, for example) plants try to use the natural stratification of air with cooler air in the occupied zone. HVLS fans would defeat this design strategy, and the system would need more cooling.
CSE: What types of air balancing do you typically include in your designs? Describe the project.
Campbell: We do air balancing as a routine part of designing a fully commissioned system. We always commission under load. If there is no load, we will not commission the system. This takes patience and added effort, but it is really the only way to go. Fully commissioning the system pays huge dividends in efficiency over the life of the facility and is critical to the client getting what they paid for.
CSE: When working on these types of facilities, describe the HVAC ventilation system, which might include hoods, fire suppression systems, or other specialized ventilation systems.
Crutchfield: When we have spaces that have hoods, canopies, or exhaust booths, a portion of the make-up air system is often directly introduced into the hood and not fully conditioned. This allows the cost of the make-up air to be lessened and removes capacity from the HVAC system that conditions the rest of the space.
CSE: How have you worked with HVAC system or equipment design to increase an industrial, manufacturing, or warehouse building’s energy efficiency?
Campbell: We put energy-efficient HVAC systems in our distribution centers as a matter of best practice. Our clients view it as a business necessity to provide a comfortable working environment for employees and to cut down on contamination and product waste. Our clients have consistently reported that installing HVAC systems in their warehouses greatly increases the staff efficiency and reduces turnover. Constant hiring and training will reduce the efficiency of a distribution center and cost a lot of money. We stress energy efficiency as a matter of corporate social responsibility and as a business matter. Warehouses tend to have thin margins, so they can’t afford to be wasteful.