Ashrae Journal

Published by American Society of Heating, Refrigerating and Air-Conditioning Engineers
Discusses the new classroom acoustics standard, ANSI Standard S12.60, which specifies maximum sound level limits that are significantly lower than currently typical for classrooms. Addresses guidelines for unducted HVAC systems, ducted single-zone systems, and central VAV or multizone systems. (EV)
A simple design procedure for single and multiple borehole configurations for designing vertical geothermal systems based on the borehole sizing equation given in ASHRAE Handbook is presented. Sizing equation proposed by S.P. Kavanaugh and K. Rafferty and recast by M. Bernier is used that is derived by assuming that heat transfer in the ground occurs only by conduction and that moisture evaporation and underground water movement are not significant. For single borehole, it is found that on an annual basis, the net amount of heat rejected into the ground is equivalent to a heat pump operating one-eighth of the time, which corresponds to 1.5 kW. Iterative method is used for multiple boreholes, and it is found that in this case borefield length is 10 150 m with a corresponding borehole depth of 84.6 m and temperature penalty T p is -0.24°C after 10 years of operation.
A new cooling load calculation procedure, the transfer function method, has been incorporated in the 1972 ASHRAE HANDBOOK OF FUNDAMENTALS. This article presents a short discussion of the calculation procedure based on the transfer function method, and demonstrates the extended capability of this new, computer-oriented, method. Une nouvelle méthode de calcul de l'effort de refroidissement, la méthode de fonction de transfert, a été introduite dans l'édition de 1972 du Handbook of Fundamentals. Le présent article est une brève étude des modalités de calcul de cette méthode, mais il s'agit surtout de montrer que celle-ci possède un champ d'application plus vaste que l'"ancienne" méthode. On compare l'"ancienne" mé thode et la méthode élargie quant au calcul des profils d' effort de refroidissement. Les résultats d'un calcul-é chantillon montrent graphiquement les applications élargies de cette méthode relativement à un programme d'exploitation variable, au calcul de l'enlèvement de la chaleur à une tempé rature ambiante variable de l'air et aux caractéristiques d' enlèvement de la chaleur d'une borne de conditionnement de l' air (y compris les organes de commande). RES
Presents guidelines for designing classroom HVAC systems that will be able to achieve lower background noise levels that conform to the NC-30 background noise rating level. Guidelines for both central and dedicated systems are offered revealing that the use of conventional HVAC system components can be used to achieve sound levels comparable to NC-30. (GR)
The need to estimate accurately the heat and moisture flow through openings arises increasingly in the design of special purpose refrigerated and air-conditioned spaces. There is the associated problem of inhibiting such heat and moisture transfer. In this paper, relationships which are applicable to many of these problems are presented, along with charts to facilitate the calculations. The application of the charts to various types of problems is demonstrated. RES
Scatter plot of experimental and calculated CO 2 concentrations.
Scatter plot of experimental and CFD CO 2 concentrations in smoke layer.
Atria have become popular in commercial, office and residential buildings because they provide attractive, environmentally controlled, and naturally lit spaces. Such spaces, however, present a challenge for fire-protection engineers because of their height and the lack of floor-to-floor compartmentalization that, in other buildings, limits the likelihood of fire and smoke spreading from the floor of fire origin to other areas of the building. Evacuation routes in atria are of concern because they become vulnerable to spreading smoke unless smoke management measures are used. Les atriums sont maintenant très appréciés dans les bâtiments commerciaux et résidentiels et les immeubles à bureaux; ils procurent des espaces attrayants, à ambiance contrôlée et à éclairage naturel. De tels espaces présentent toutefois un défi aux ingénieurs de sécurité incendie en raison de leur hauteur et de l'absence de compartimentage de niveau à niveau, lequel, dans les autres types de bâtiments, restreint le risque de propagation de la flamme et de la fumée du niveau du foyer de l'incendie à d'autres aires du bâtiment. Les parcours d'évacuation dans les atriums sont un sujet de préoccupation car ils deviennent vulnérables à l'enfumage, à moins que l'on n?applique des mesures de gestion de la fumée. PRAC
This paper presents a brief review of existing smoke control models. The review includes each model's concepts, numerical technique, capabilities, limitations and assumptions. Potential applications of the model are also discussed. Cet article présente un apercu des modèles de limitation des fumées existants. L'auteur indique, pour chaque modèle, le concept de base, la technique numérique employée, les capacités, les limitations et les hypothèses. Il examine aussi les applications possibles de ces modèles. RES
Joseph W. Lstiburek, Ph.D., P.Eng., fellow ASHRAE, shared his views on the role played by pressurized units in hospitals in the growth of molds that infected patients leading to their death. He visited one such hospital to investigate the death of a patient who had been infected by such a mold inside one of the pressurized patient units that had several defects. Investigations revealed that the hospital building enclosure was a brick veneer with a masonry block backup wall that lacked water control layer on the exterior of the block backup wall. Another defect was that a foil-faced vapor barrier was installed on the interior of the semi-rigid fiberglass insulation. The existing conditions encouraged the growth of molds, such as aspergillus fumigatus, on the paper reinforcing of the foil vapor barrier. It was observed that the air-handling unit was depressurizing the interstitial cavity sucking the mold out the exterior wall and injecting it into the breathing zone of the occupied space.
We are still thinking about the role of water in refrigeration, so we turn to the old-style absorption refrigerators. I was asked the question recently "why is the hydrogen pressure in a refrigerator so high?" If you are thinking "what hydrogen?", then what follows may come as a surprise.
An effective design review process should be the highest priority of designers and owners when design documents are returned for revision and resubmission. Design review provides an opportunity for the owner to confirm the finished product meets the requirements. The elements of a successful design review process are checklist items of responsibility for either the owner or the design professional. An improved coordination between the work of the designer and the expectations of the reviewer is helpful in preventing time-consuming problems when the documents are later reviewed. Many design review comments may involve coordination between disciplines, coordination within a discipline, and general items such as illegible text or incorrect drawing cross-references. Computer-aided drafting has provided many improvements to the drafting process and has made possible new potential document deficiencies as conveying technical information and operating the drafting program.
The psychometric chart is a convenient and useful tool for determining moist air psychometric properties, and visualizing the changes of properties in a sequence of psychometric processes. Prior to the advent of personal computer psychometric software, the psychometric chart was also used extensively as an extremely useful graphical tool for solving and diagnosing and then visualizing psychometric processes. This paper looks at the state-of-the-art of psychometrics prior to 1904 when Willis H. Carrier produced the first chart and then traces the developments from 1904 to 2004.
The first documented hydronic cooling systems were connected to the Roman aqueducts, in which water was routed through brick walls of homes of the affluent. Hydronic heating became prevalent in buildings as the source of hot water expanded. The first commercial hot water boilers became available in the 1700s. Gravity hot water or steam heating systems were the norm in buildings until the mid-1900s.
What is cloud computing? For a term that has seen a significant rise in popularity, it remains one that is difficult to clearly define...or perhaps that in itself is an indication of the inherent abstraction that is cloud computing. The context of cloud computing is the attempt to marry information technology (IT) strategies and overall business strategies. The rapid advancements of the former combined with the infinite variability of the latter make for a myriad of possibilities of how to achieve an aligned outcome. This is the driver behind why there are so many variants for the types and models of cloud computing.
Hydronic heating and cooling systems are popular in situations where designers and owners are conscious of space and system operating efficiency. Common components installed in hydronic systems to enable their operation include heat source or sink (boiler, chiller, water-source heat pump, heat exchanger), pump(s), flow control devices, and water treatment (air separation, antifreeze, chemical additives, and biocides).
This article offers more suggestions to increase the operating efficiency of R-717 (ammonia) and R-22 industrial refrigeration systems. Not every suggestion applies to every plant. The owner must decide which suggestions best suit the plant.
Developers of Standard 189.1—with its provisions for renewable energy, peak load reduction, and other efficiency improvements—were ambitious in setting the bar for energy performance. Their goal: an average 30% increase in site energy efficiency (i.e., a 30% decrease in site energy consumption) in comparison with Standard 90.1-2007. Does Standard 189.1 hit the mark? That was the question evaluated by the U.S. Department of Energy and researchers at the National Renewable Energy Laboratory.
Colonial Williamsburg, located midway between Richmond and Norfolk, Va., is the nation's largest and oldest outdoor living history museum and has set the standard for historical restoration around the world. The Colonial Williamsburg Foundation is a not-for-profit, tax-exempt educational institution that oversees and operates the restored 18(th)-century town of Williamsburg. The Historic Area comprises 173 acres (70 ha) with 88 original 18(th)-century buildings and hundreds of structures that have been reconstructed on their original foundations. The Foundation also owns and exhibits Carter's Grove, a historic plantation site with its 18th century mansion on the nearby James River. In addition, the complex includes multiple hotels, restaurants, three golf courses, hundreds of residences, offices, support facilities and an upscale shopping area. A 3,000-acre (1,214 ha) greenbelt softens modern intrusions.
A project was undertaken by the design engineers to decreased the energy use intensity (EUI) of the 30 year old 712,930 ft2 National Bank of Canada building to the original design EUI without replacing major equipment. The goal was met by writing a modernization guideline that dealt with the increased indoor air quantity requirements, office densification, computer equipment loads, and a new floor use. It was decided to optimize the operation of existing equipment and limit the replacement of major equipment. The solution was to remove the water content at the source with the new dedicated outdoor air systems (DOAS) and combine it with the existing dedicated outdoor air systems. Reducing air temperature and humidity with the existing cooling coils in the dedicated systems on each floor is also a preferred solution.
Société Immobilière du Québec (SIQ), in a bid to restore the Cowansville Courthouse to its original function, designed an energy-efficient HVAC system with a low-performance building envelope. The project's goal was to recover as much energy as possible before tapping into geothermal energy. It was found that cooling and lighting systems can be progressively reduced to keep electrical peak demand below a critical setpoint. By sizing the ground loop to fit the building's cooling capacity, engineers sidestepped the need for extra cooling equipment. Designers made a detailed model of the geothermal system with the help of TRNSYS simulation software. By plugging in the hourly loads from the EE4 simulation model, designers could map out the appropriate number, depth and configuration of the geothermal boreholes to guarantee the system's stability.
The Air-Conditioning and Refrigeration Institute (ARI) gives it appreciation to the effort and expertise that the Accredited Standards Committee, S12 (Noise)/Working Group 42 and its Secretariat, the Acoustical Society of America, has applied to the classroom acoustics initiative which resulted in ANSI S12.60-2002. For an optimum learning environment in schools, adequate clearance is needed between a teacher's voice level and the background noise level in the room; that is, an adequate signal-to-noise ratio (SNR). Given various alternatives, it will make attaining the objective of conductive learning environments feasible for the rennovation of existing schools as well as for the construction of new schools.
Seventeen years ago, the ventilation rates established by ANSI/ASHRAE Standard 62-1989, Ventilation for Acceptable Indoor Air Quality, increased substantially over those previously required by the 1981 version of the standard. Fifteen years later, Standard 62.1-2004 (Standard 62.1) prescribed new minimum breathing zone ventilation rates and a new calculation procedure to find the minimum intake airflow needed for different ventilation systems. Described in previous articles,1-4 these new rates and procedures must be used to find the required capacity of mechanical system equipment. In this article, we turn from ventilation system design to operation.
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