Constant-volume air-conditioning systems control space air temperature directly and humidity indirectly by modulating or cycling the cooling apparatus. This article examines the effect of economizer operation on the comfort of spaces served by constant-volume air-conditioning systems....More
An alternative to conventional variable-air-volume (VAV) systems, chilled beams circulate chilled water through tubing embedded in a metal ceiling fixture to wick away heat. The business end of a chilled beam is made of copper tubing bonded to aluminum fins. The beam is housed in a sheet-metal enclosure typically placed at ceiling level...More
Most of the articles on building information modeling (BIM) published in recent years focus on the generation of buildings and the design of the systems within. The creation of the components that make up those systems is all but ignored. As a result, finding, judging, and improving the quality of existing BIM content quickly is becoming a valuable skill. This article is intended to help you gain that skill....More
Energy recovery with runaround coils can be greatly enhanced with evaporative cooling of exhaust air, a long-established fact that seems largely forgotten by design engineers and building owners, as all of the applications the author has come across in recent years use dry coils only....More
Melvin Cohen and Associates Inc. was chosen by the State of Illinois Capital Development Board to prepare design documents for bid and construction, and Primera Engineers in Chicago was chosen to provide commissioning for hydronic update on the Michael A. Bilandic Building....More
Subdividing various systems into a primary/secondary (P/S) loop via a hydraulically dependant interconnection long has been a standard solution for central chilled-water plants in the United States and Europe. This achieves, at a relatively low cost, reasonably good hydraulic separation of central-water-plant cooling-generation systems (primary loop) from distribution piping and terminal units (secondary loop). Primary-loop flow is relatively constant, while secondary-loop flow varies based on load demand. Primary- and secondary-loop water flows are interchangeable....More
At Allina Medical Clinic in Forest Lake, Minn., temperatures in the 10-ft-by-12-ft data room, which houses network switches and other computer and telecommunications equipment the clinic depends on for day-to-day operation, were high, but acceptable. That changed with the installation of additional switchgear and computer equipment and a larger uninterruptible power supply....More
What can the HVAC industry learn from hybrid-vehicle design? Can a hybrid cooling system provide similar performance with less horsepower? Can it provide lower operating costs or extra power when it’s needed—when loads or energy costs are high? How does a hybrid cooling system compare with conventional systems in terms of life-cycle costs?...More
Many data centers are "mission-critical," meaning essential to the core function of an organization. As such, they must remain operational at all times. However, that does not mean significant improvements in energy efficiency and sustainability cannot be made....More
Not long ago, Warren Brader brought his 25 years of experience in HVAC service and maintenance to a major military contractor. His responsibility: maintaining the HVAC equipment at military bases around the world....More
Several factors need to be addressed prior to determining the appropriate cooling-tower system for a facility with critical demands. Locations, such as data centers, medical centers, airports, and electronic-chip manufacturers, require special considerations in addition to the requirements of an average cooling-tower system....More
This article will present an alternative central-chiller-plant model, one that is consistent with the laws of thermodynamics and can be executed with a laptop computer. The model will be demonstrated based on an assumed chiller plant operating at design weather conditions in Salt Lake City....More
It's summer, a time when overworked HVAC systems become prone to failure and portable air conditioners are pressed into emergency service. But portable air conditioners are not just for use in hot weather. They can provide solutions to a range of heat-related and comfort challenges year-round. This article will review what facility owners and managers need to know about portable cooling equipment for the summer season and beyond....More
In the world of facility management, no one can afford to be caught unprepared in the event of an emergency. Yet the uncertainty of today’s economy is forcing many facility managers to tempt fate. Organizations of all sizes are under increasing pressure to cut capital expenses and focus on revenue-generating core competencies. As a result, substantial facility investments are being put on hold, with limited or aging equipment forced to operate for as long as possible in what commonly is referred to as “run-to-fail” mode. For facility managers in such predicaments, there is the cooling contingency plan, an affordable, flexible, and reliable way to prepare for the unexpected....More
Looking to meet its growing cooling needs using less power, UT recently embarked on a district-cooling-optimization project that has seen gas-use quantities return to 1970s levels....More
At its plant in Charleston, S.C., the Bosch Group, global supplier of automotive, industrial, and building technology, was having trouble maintaining sufficiently low temperatures in each of seven 1,000- and 1,250-ton chillers. One chiller in particular was underperforming....More
In 2007, a partnership was formed by the city of Lansing, Mich.; the state of Michigan; Accident Fund Insurance Co. of America and its parent company, Blue Cross Blue Shield of Michigan; developer and construction manager The Christman Co.; Lansing Economic Development Corp.; and Lansing Board of Water & Light (LBWL) to renovate the decommissioned Ottawa Street Power Station in Lansing into Accident Fund’s new world headquarters. The partnership required LBWL to construct a separate plant to provide chilled water, which previously was supplied by equipment in the Ottawa Street Power Station’s basement....More
An engineer is calculating the cooling load for each room to be served by a new rooftop unit. Solar and transmission heat gains through the windows, walls,...More
It is no secret that R-22 refrigerant is going away. What members of the refrigeration and air-conditioning industry may not be aware of is that the U.S. Environmental Protection Agency's (EPA's) hydrochlorofluorocarbon- (HCFC-) allocation final rule, signed Dec. 7, 2009, further reduced R-22 supply by 150 million lb....More
Built in 1938, Waterloo High School in Waterloo, Ill., part of Waterloo Community Unit School District No. 5, had become seriously overcrowded. In 2006,...More
Though vital to maintaining good indoor-air quality, outdoor air can be expensive to temper and, if not conditioned properly, cause humidity problems...More
Three facilities a warehouse, forge plant, and paint-preparation area had complaints about excessive heat in working areas. I recommended that air be...More
