Showing papers in "Ashrae Journal in 2000"

EnergyPlus: Energy simulation program

Abstract: Various building energy simulation programs developed around the world are reaching maturity. Many use simulation methods (and even code) that originated in the 1960s. Without substantial redesign and restructuring of the programs, continuing to expand their capabilities has become difficult, time-consuming, and prohibitively expensive. However, phenomenal advances in analysis methods and computational power have increased the opportunity for significant improvements in the flexibility and comprehensiveness of these tools.

A Standard for Natural Ventilation

Abstract: Architecture and engineering journals have been increasingly attentive to innovative non-residential buildings designed with operable windows. Such buildings may rely exclusively on natural ventilation for cooling, or may operate as mixed-mode, or hybrid buildings that integrate both natural and mechanical cooling. Architects who want to incorporate natural ventilation as an energy-efficient feature need to collaborate closely with mechanical engineers. Unfortunately, engineers often need to veto such natural approaches, citing their professional obligation to adhere to thermal comfort standards such as ASHRAE Standard 55 or ISO 7730. In their current form, these standards establish relatively tight limits on recommended indoor thermal environments, and do not distinguish between what would be considered thermally acceptable in buildings conditioned with natural ventilation vs. air conditioning. In other words, engineers have not had a suitable tool to help decide when and where full HVAC is required in a building, and under what circumstances they can incorporate more energy-conserving strategies without sacrificing comfort.

Guidelines for Comfort

Abstract: A Standard 55-1992, Thermal Environmental Conditions for Human Occupancy, is mainly a prescriptive standard intended for occupants with primarily sedentary activity. This article discusses some of the issues being addressed during the proposed revision. The proposed revision will include an analytical method based on the PMV-PPD method, where different levels of comfort may be specified. Using the analytical method requires better dialog between the client (builder, owner) and the designer.

Air-to-Air Energy Recovery

Abstract: Indoor air quality, ventilation airflow rates and HVAC capital and operating costs usually are closely related. Auxiliary energy loads for supply air heating or cooling sometimes can substantially reduce the need for dehumidifying or humidifying by using air-to-ait heat or energy exchangers. The most important factors in reducing HVAC capital and operating costs are ventilation airflow requirements, climatic parameters, exchanger recovery system performance factors and duration of operation.

Heat Gain From Office Equipment

Abstract: About the Authors M.H. Hosni, Ph.D., is professor of mechanical engineering and the director of the Institute for Environmental Research at Kansas State University. He has been the principal investigator (PI) and Co-PI for RP-822 and RP-1055. He is the chair of the Handbook Committee for ASHRAE Technical Committee (TC) 5.3, Room Air Distribution. Christopher Wilkins, P.E., is group leader for Hallam Associates in Burlington, Vt. He is a member of TC 4.1, Load Calculation Data and Procedures, and TC 4.12, Integrated Building Design. Heat Gain From Office Equipment

Refrigerant use in Europe

Abstract: The environmental issues of ozone depletion and global warming have considerably affected the refrigeration, air-conditioning and heat pump industry over the last 10 years. The Montreal Protocol has caused the refrigeration industry to introduce newly developed hydrofluorocarbons (HFCs) as substitutes for the chlorine-containing, ozone-depleting chlorofluorocarbons (CFCs). This process for new systems has been finalized in industrialized countries and is ongoing in developing countries. Hydrochlorofluorocarbons (HCFCs), such as R-22, have much lower ozone-depleting potential (ODP) and will be phased out within the next 20 years worldwide. However, national regulations require a much earlier phase-out date, especially in Europe. Therefore, chlorine-free HFCs will replace chlorine-containing refrigerants in the marketplace.

Smart Maintenance For Rooftop Units

Abstract: Packaged HVAC equipment is the most common source for HVAC in small and medium commercial buildings, including retail stores, supermarkets, and restaurants. The U.S. Department of Energy estimates that rooftop and unitary air-conditioning equipment accounts for about 1.03 out of a total of 1.66 quads (62%) of total energy consumption for cooling the current building stock of commercial buildings in the United States. Generally, packaged equipment is smaller, more numerous, and not as well maintained as large built-up systems. Because ofthe large numbers, service technicians cannot afford to spend much time on each unit. In addition, the units are not located in highly visible equipment rooms where it is convenient for onsite technicians to visit daily.

Comparing Economizer Relief Systems

Abstract: An outdoor air economizer is a damper arrangement and automatic control system that allows a cooling air handler to supply outdoor air instead of recirculated air to reduce or eliminate the need for mechanical cooling during mild or cold weather. One ofthe key elements of an economizer is a system to relieve the excess outdoor air supplied to the building when the economizer is enabled. Without an adequate relief system, the building can become over-pressurized, causing exterior doors to stand open (a potential security issue) and air to whistle through exterior doors and elevator doors. For very tight buildings, the pressure buildup can reduce supply air rates. Maximum building pressure to avoid these problems is typically about 0.05 in. w.g. to 0.10 in. w.g. (12 Pa to 25 Pa).

Efficacy of Antimicrobial filter treatments

Abstract: In response to the ongoing debate as to the appropriateness of incorporating antimicrobial,agents into fibrous air filter media, ASHRAE funded research project 909-RP, Determine the Efficacy of Antimicrobial Treatments of Fibrous Air Filters. This article summarizes the project and results.

Primary chilled water loop retrofit

Abstract: The University of California at Irvine (UCI) near Los Angeles has a mild Mediterranean climate, with a summer design temperature of 90°F (32°C) and winter design temperature of 38°F (3°C). The 1,500 acre (607 ha) campus has approximately 6.5 million ft 2 (604 000 m 2 ) of developed facilities (3.5 million ft 2 [325 000 m 2 ] is served chilled water from the central plant). Many of the campus facility buildings are 100% outside-air science buildings.

Control Valve Selection for Hydronic Systems

Abstract: Water is one of the primary distribution media for heating or cooling energy in large buildings. This energy is imparted through heat exchangers (coils), normally part of an air-handling unit. The traditional method of control is to throttle the flow of water, air or both in proportion to space or air-handler discharge air temperature. When water flow is throttled, a control valve performs the function. This article discusses some of the effects of the valve in operation and ideas for proper valve selection. Understanding control valve performance is required to operate the system efficiently, tune temperature controllers, minimize interaction effects on other parts of the HVAC system, reduce operating cost and keep people comfortable.

DDC and the Web

Abstract: Wide-spread access to the world wide web (www) opens up new opportunities for owner-operators and service providers to use the web to manage and control facilities more effectively. This paper examines the intersection of the web with direct digital controls and the opportunities it presents. The paper describes the technology available today for using the web for facility control and management and the benefits this can provide. It also identifies weaknesses in how we can use the web today and what is emerging to eliminate these problems. The paper then takes a look at what the future likely holds in terms of technology to improve building operation even further by the use of wireless technology, hand held devices, and other technologies emerging from the fields of information technology and communications.

Ice storage project

Abstract: Combustion turbine peaking units typically are used to meet peak power demands for short periods of time when system demands are highets. For summer-peaking utilities, these conditions occur during hot, humid weather periods. The hot weather conditions that increase the peak demand also degrade the combustion turbine output and heat rate. The thermal storage inlet cooling system that was installed on the MS7001B gas turbine at the Rokeby Peaking Unit Site was designed to increase the output of the turbine during these periods.

Vibration tests for bearing wear

Abstract: This article discusses an example of an outer race-bearing defect on a 1,250 ton (4400 kW) air-conditioning chiller. The defect was detected using off-the-shelf portable vibration analysis hardware and software. The machine is a single-stage centrifugal compressor with a rolling element thrust bearing on the motor free end and a sleeve bearing on the motor drive end. This article discusses methods used to diagnose and trend the bearing defect using vibration spectra as an indicator of the bearing condition. The diagnostic methods covered are universally applicable to other types of machines (pumps, fans, gears) with rolling contact bearings.

Local Pumping System

Abstract: In a hydronic piping system, centrifugal pumps provide the primary force to distribute and recirculate process water by overcoming water pressure drops and power losses in the system All distributing pumps are centrally located with balancing valves and control valves installed at cooling coils, heating coils, and heat exchangers to restrict and regulate water flow by creating water pressure drops and power losses across the valves In a system with a large number of balancing valves and control valves, total water power and energy losses across the valves can be significant This wasted pump power and energy would be eliminated if the balancing valves and control valves were removed from the piping system This article introduces a pumping system where pumps are locally located at the coils The local pumps circulate and regulate water through the cooling coils, heating coils, and heat exchangers without balancing valves and control valves

Improving humidity control for commercial buildings

Abstract: For more than 100 years, temperature control has been the principal concern of our industry. That focus and our collective efforts have achieved immense improvements in the human condition --- improvements so fundamental that they are usually overlooked and unappreciated, even by ourselves. We seldom reflect on what the world was like before the refrigeration of food and medicine, or before the availability of low-cost, reliable heat in the winter and cooling in the summer. However, in spite of- or because of - those achievements, the expectations of the public have moved higher. Now, we face the challenge of providing cost-effective control of humidity.

Fundamentals of DDC

Abstract: This article provides an introduction to direct digital control (DDC) by discussing direct and control in their own sections.

Determining Equipment Service Life

Abstract: Where does one find accurate equipment service life data? That question has long been the focus of ASHRAE's Technical Committee (TC) 1.8, Owning and Operating Costs. Thorough examination of available equipment life data, including most of the data in the ASHRAE Handbook-HVAC Applications chapter on Owning and Operating Costs, reveals that most data reported to be equipment service life, is not scientifically derived, and is in reality not service life information at all. That is not to say, however, that the available information is not useful. Rather, it is important to understand the limitations of that information, and what it really represents.

Expanding the Use of Ammonia

Abstract: Discussing new developments for ammonia sounds like a paradox, as ammonia is one of the oldest industrial refrigerants. As emphasized by J.W. Pillis, it never stopped being a leading refrigerant for large systems used in food industry and for other industrial applications. After losing matket share to R-22 in recent decades, it is making a strong comeback due to the pressure to phase out R-22. Some major food industry companies have a clear strategy of using only ammonia for their new investments, and to retrofit existing plants worldwide.

Minimizing fungal defacement

Abstract: Fungal defacement in dwellings is a widespread problem and has been extensively studied in cool and cold climates. In Canada, 10% of the housing stock in the 1980s was reported to have dampness and mold (Marshall et al. 1983). In the United Kingdom, inquiries conducted by the Building Research Establishment indicate that 27% of the housing stock is affected (Sanders et al. 1982, IEA, 1991c). In a study for the national housing society, the Belgian Building Research Institute mentions that 20% to 30% of the low-income houses have mold problems (Wouters et al. 1987). In a 300-dwellings survey, the Fraunhofer Institut fur Bauphysik, Germany, reported that 40% of the dwellings visited suffered from mold (Erhom 1988).

Operation and Maintenance Of Evaporative Coolers

Abstract: Evaporative cooling (air conditioning) was used long before the advent of mechanical refrigeration and its application to comfort cooling. Equipment and systems are available for residential, commercial, agricultural, and industrial markets. Within each market, a wide range of configurations and applications are available. Direct evaporative cooling most often is thought of and used to provide temperature reduction. However, it is also a humidifier. Consequently, it is applied to provide year-round cooling and/or humidification.

Energy Efficient O&M for Airport

Abstract: Three years ago at the Greater Rochester International Airport, the county's aviation director was dissatisfied with the rising cost of services and the poor service quality. The aviation director asked the county's director of facilities management to take over the operations, improve the service quality, revise staffing within a 4,000-hour limit, and reduce costs as that unit had done in the other county facilities under its management. The challenge was to accomplish the same or better level of service at a lower cost.

Selecting Valves and Piping Coils

Abstract: hen the design of variable flow hydronic systems was initiated 30 to 40 years ago, little emphasis was placed on the selection of the modulating two-way coil control valves. The existing valve specifications that were used for constant flow were often applied to variable flow systems. In many instances the valves that were used were not constructed to meet the high differential pressures encountered in variable flow systems. As a result many variable flow chilled water systems experience Delta T’s that are below design and have chillers that operate inefficiently. This low Delta T is often caused by valves leaking due to either insufficient close off capabilities or erosion (often referred to as “wire drawing”) of the seat or plug.