The condensate trap perhaps is the most overlooked item in the design and installation of fan coils and air handlers with cooling coils. In this October 2001 article, Ronald F. Brusha clears up widespread misconceptions about the workings and sizing of condensate traps and provides simple advice intended to make condensate traps much easier to inspect and maintain.
In this highly detailed December 2010 article, Alexander L. Burd, PhD, PE, and Galina S. Burd, MS, compare the operational modes and performance of primary/secondary-loop and primary-loop-only-variable-flow chilled-water-plant systems.
The Adam Joseph Lewis Center (AJLC) for Environmental Studies on the campus of Oberlin College in Oberlin, Ohio, is one of the nation’s most widely publicized green buildings. Showcasing a variety of energy-efficient strategies and technologies, the 13,600-sq-ft building is the winner of numerous architecture awards and was named the most important green building constructed since 1980 in a poll of green-building experts and advocates. In this January 2013 article, John H. Scofield discusses how the AJLC failed to meet a key design goal for years and calls into question the scientific value of high-performance-building case studies.
Many variable-air-volume systems are designed with incompatible and/or incomplete control strategies that undermine the performance of outdoor-air economizers. In this March 2013 article, Craig F. Hofferber, CxA, CSI, discusses how, through proper application of modern tools, such as direct digital control and highly accurate, low-cost instruments, a much higher level of success can be achieved. Many of the methods discussed in the article are not industry-standard practice, but nonetheless worth considering in the name of controllability, performance, and energy efficiency.
Chilled beams are cooling (and optionally heating) units located in or above a conditioned space that utilize a ventilation-only primary air stream from a remote air handler to induce larger recirculating room flows, effectively heating, cooling, and ventilating the space without the use of an in-room fan and with reduced overall airflow from the central air-handling unit. In this November 2013 article, Craig R. Buck, PE, LEED AP, HFDP, discusses benefits and challenges related to the use of active chilled beams in health-care settings.
In this April 2013 article, the Global Field Devices Business of Honeywell Inc. provides tips for selecting globe, ball, butterfly, two-way, quick-opening, linear, equal-percentage, three-way, mixing, and diverting valves.
Air-cooled chiller systems usually are less expensive to install and easier to maintain than other systems, such as water-cooled. On the other hand, these advantages typically have come at the expense of efficiency. In this August 2012 article, Eddie Rodriguez explains how manufacturers of air-cooled chillers have overcome this efficiency disadvantage by incorporating variable-frequency drives on compressors.
As air-conditioning equipment ages, its ability to maintain adequate space temperatures and humidity levels declines. Often, the culprit is reduced coil heat-transfer effectiveness. Typically, reduced heat-transfer effectiveness results from the buildup of contaminants on coil surfaces. In this July 2013 Managing Your Facilities column, Forrest Fencl explains how ultraviolet-C energy can be used to reduce mold and biofilm, coil pressure drop, and coil-cleaning functions without the use of chemicals while increasing airflow and heat-transfer coefficient and reducing fan- and refrigeration-system energy use.
Since the deadly outbreak of what came to be known as Legionnaires' disease during an American Legion convention in Philadelphia in 1976, our knowledge of the illness and its causes has grown dramatically, and state-of-the-art prevention has become practical and affordable. Any water source can serve as a source of Legionella bacteria. In this July 2011 article, Frank Rosa discusses the prevention of Legionnaires' disease from cooling towers.
In this November 2013 article, Arvind Akela, PE, CEM, LEED AP BD+C, details the sizing and selection of a replacement chiller based on sustainability considerations for a high-base-load cooling application.
The first step in most HVAC design projects is to calculate heating and cooling loads. These calculations become the basis for sizing equipment and, when required, projecting energy use. While energy-use projections can be data- and calculation-intensive, even the most sophisticated procedures consist of little more than calculating the heating or cooling load at each outdoor temperature of interest, multiplying by the number of hours of each outdoor-temperature occurrence in a year, and summing. In this September 2013 article, Kenneth M. Elovitz, PE, Esq., explains how engineers can apply the process in reverse: use historical energy-use and weather data to infer building heating or cooling loads and understand how a building uses energy.
The third edition of ASHRAE's "Thermal Guidelines for Data Processing Environments" contains new data intended to improve data-center energy efficiency without voiding information-technology-equipment warranties. In this January 2013 article, longtime HPAC Engineering Editorial Advisory Board member Don Beaty, PE, FASHRAE, co-founder and first chair of ASHRAE Technical Committee 9.9, Mission Critical Facilities, Technology Spaces and Electronic Equipment, summarizes the third edition of "Thermal Guidelines for Data Processing Environments" and discusses ways to save energy while minimizing risk to tightly controlled environments for sensitive and valuable equipment.
Some years ago, two young and inexperienced technicians were called to work on a large refrigerant system. In their attempt to fix the system, the technicians caused a leak in the piping at the tank, which contained several hundred pounds of refrigerant. Being heavier than air, the refrigerant gas began displacing oxygen in the mechanical room. Little did they know—refrigerant cannot be seen or smelled—the technicians were starting to suffocate. In this December 2013 article, Greg Cunniff, PE, explains how to administer limits for the amount of refrigerant that can be discharged into a space in the event of a leak.
An alternative to conventional variable-air-volume systems, chilled beams circulate chilled water through tubing embedded in a metal ceiling fixture to wick away heat. In this July 2011 article, John Vastyan helps readers get better acquainted with this type of convection HVAC system designed to heat or cool nonresidential buildings.
When it comes to deciding whether to repair or replace an older rooftop unit, it is important to consider a number of factors, including current condition, age, efficiency, maintenance/repair history, and associated utility costs. In this February 2014 article, David Negrey discusses the process of making an informed decision.
Traditionally, sizing UV-C lamps for the purpose of irradiating HVAC cooling coils depended on trial and error and rules of thumb. That changed with the publication of the 2011 edition of ASHRAE Handbook—HVAC Applications, which provides a quantitative approach to lamp sizing resulting in systems meeting performance requirements at the lowest initial and long-term operating costs. In this article, Forrest Fencl summarizes that guidance and offers a method to simplify future designs.
A cooling tower is only as good as the details of its design and the specification of its supporting components. Details such as pump net positive suction head, strainers, and pipe size can have a major impact on performance and energy bills. In this May 2005 article, a companion to "Finer Points of Specifying Cooling Towers," Keith Rinaldi, CEM, discusses ways to ensure the impact is positive.
In this August 2011 article, Fred W. Dougherty, PE, BAE, MME, examines the effect of economizer operation on the comfort of spaces served by constant-volume air-conditioning systems. The ideas presented are applicable primarily to direct-expansion systems with limited unloading capability; however, many also apply to chilled-water systems. The hypothetical case of an office building is presented.
Air infiltration long has been a little-understood or even ignored factor when it comes to energy efficiency in commercial buildings. Engineers understand it exists, but tolerate its existence by simply accounting for it in heating- and cooling-system design. Fixing the problem at its source can be complicated and span beyond a designer’s scope of work. In this April 2013 Engineering Green Buildings column, Nate Gillette, AIA, LEED AP, CEM, says addressing air infiltration no doubt will become a best practice in the green-buildings industry.
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 author Mirza M. Shah, PhD, PE, says he has come across in recent years use dry coils only. These include 13 hospitals in California that won awards for energy efficiency. As Shah shows in this January 2011 article, energy recovery in the hospitals would be several times greater if exhaust air were evaporatively cooled.
With a nominal efficiency of 0.2 kw per ton, evaporative cooling towers are among the most energy-efficient and cost-effective technologies for rejecting waste heat from air conditioning and other heat-exchange processes to the atmosphere. In the process, however, they use significant volumes of water. In this February 2008 article, Kent Sovocool discusses practical water-conservation opportunities for cooling towers.
Within large industrial corporations, facility maintenance often is viewed as no more than an operating expense. In northern Colorado, however, one manufacturer is working hard to change the way the economic benefits of energy efficiency are perceived and accounted for, recognizing facility energy-cost savings as a key contributor to the overall profitability of an organization. In this February 2014 article, Peter D’Antonio, PE, CEM, LEED AP, details a public-private partnership between the manufacturer, a commissioning provider, and local utilities to reduce HVAC energy costs.
If you liked this gallery, you may want to check out:
• Most Popular HPAC Engineering Heating Content.
• In Case You Missed It: The Best of HPAC Engineering 2013.
• Innovative HVACR Solutions, January 2014.
• 2014 AHR Expo Report.
Looking to broaden your knowledge about nonresidential-building air conditioning? Here is your guide to HPAC Engineering's most-viewed air-conditioning-related content.
Most Popular HPAC Engineering Building-Controls Content
Most Popular HPAC Engineering Heating Content
Most Popular HPAC Engineering IAQ & Ventilation Content
Most Popular HPAC Engineering HVAC Motors and Drives Content
HPAC Engineering Magazine
Sponsored Introduction Continue on to (or wait seconds) ×