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SAN FRANCISCO, Nov. 9, 2016 /PRNewswire/ -- Robert Bolin, PE, LEED Fellow, ASHRAE HBDP, Senior Principal with Syska Hennessy Group, Inc. a global consulting, engineering and commissioning firm, has relocated to the firm's San Francisco location where he will continue to serve in a...


Quirk D.,Verizon Wireless | Sorell V.,Syska Hennessy Group
ASHRAE Transactions | Year: 2010

ASHRAE Technical Committee (TC) 9.9 "Mission Critical Facilities, Technology Spaces and Electronic Equipment" was established to create guidance on the environmental protection of such environments in an energy conscious manner. It's extremely important to note the first word in the quotes of the preceding sentence - Mission. Mission must always precede energy in terms of priorities. Energy consciousness does not mean that energy savings should be pursued at the expense of mission. Unfortunately, understanding where this line is drawn is not very easy and it takes delving into many finer details to distinguish the difference. One particular area of great energy savings, but equally great challenges to the mission, is the use of economizers. This paper attempts to arm the reader with an increased understanding of several aspects of the application of both airside and waterside economizers to datacom facilities so that the right decisions and considerations can be made to serve BOTH mission and energy. ©2010 ASHRAE.


Nall D.H.,Syska Hennessy Group
ASHRAE Journal | Year: 2014

Achieving and documenting compliance with Standard 90.1-2013 with respect to waterside economizers requires a process that provides information for the selection of a number of components that impact waterside economizer performance. The first step is to establish the room sensible part-load fraction at waterside economizer conditions. Reduced window solar control requirements and increased envelope thermal performance requirements in colder climate zones will tend to increase that part-load fraction. After room sensible part-load fraction has been established, along with the potential for supply air temperature reset, the total coil part-load fraction can be calculated. Selection of the cooling coil comes next, and this selection can be done in concert with the heat exchanger selection and the cooling tower selection. The strategy for the cooling coil is to increase the thermal coupling between the coil and the airstream, minimizing the approach of the leaving supply air temperature to the entering cooling water temperature.


Nall D.H.,Syska Hennessy Group
ASHRAE Journal | Year: 2015

Although the term "resilience" has become a hot button in the high performance building community, it seems to have different meanings in different contexts. This column will try to identify these differences and discuss the issues the concept raises for MEP engineers. Copyright 2015 ASHRAE.


Nall D.H.,Syska Hennessy Group
ASHRAE Journal | Year: 2015

Underfloor air-distribution (UFAD) systems have been designed and built in the United States for more than 20 years with various degrees of success. The system remains controversial, with both advocates and detractors, but has experienced significant penetration in some markets. The most common complaint with these systems, however, is that spaces are chronically over-cooled.1 Many critical factors have been identified for avoiding this pitfall, but the implementation of effective control strategies is arguably the most important step. Copyright 2015 ASHRAE.


Khankari K.,Syska Hennessy Group
ASHRAE Transactions | Year: 2011

During power outages servers in the data centers are generally powered by uninterruptible power supplies (UPS). At the same time the sources for active cooling such as CRACs, CRAHs, and chillers stop operating for a period until powered by alternate power sources. During this period servers continue to generate heat without any active cooling. This results in increase in the room air temperature within a short period that can be detrimental to the servers. This paper, with the help of a mathematical model, indicates that the rate of heating of a data center can start initially at a certain maximum level, and can then gradually reduce to a certain minimum level, which is the lowest possible rate of heating that a data center can attain. The rate of such exponential decay is a function of the time constant, which is the characteristic of a data center design and layout. The time constant depends on the heat capacity ratio and the specific surface area of racks in a data center. This paper analyzes various factors that affect these parameters and demonstrates how the time constant can be employed as a matrix to compare the thermal performance of data centers during the power outage period. © 2011 ASHRAE.


Nall D.H.,Syska Hennessy Group
ASHRAE Journal | Year: 2016

Electric motors are the universal drivers of HVAC components. With a few exceptions, such as steam turbine-driven chillers and combustion engine driven chillers, electric motors, ranging in size from fractional horsepower to thousands of horsepower, provide the driving forces for HVAC systems. Many different types of motors are suitable for many conditions such as high and low temperature, moisture, high humidity, and/or corrosive or explosive environment.


Nall D.H.,Syska Hennessy Group
ASHRAE Journal | Year: 2016

ANSI/ASHRAE/IES Standard 90.1, Energy Standard for Buildings Except Low-Rise Residential Buildings, has evolved rapidly over the years. As it has evolved, the requirements have changed, and some of these requirements have been overlooked by the engineering community. Some of these requirements are mandatory, meaning they must be incorporated on all projects for which they are applicable, and others are prescriptive. Copyright 2016 ASHRAE.


Nall D.H.,Syska Hennessy Group
ASHRAE Journal | Year: 2016

Direct-expansion (DX) cooling and heat pump systems have often been the less- respected alternative for building conditioning compared with hydronic systems. In general, they are considered to be a "cheaper" system, with higher maintenance cost, shorter lifespan, limited controllability and lower energy efficiency. On the other hand, they are often more convenient, more amenable to design-build procurement, and less demanding of operator expertise.


Khankari K.,Syska Hennessy GrouP
ASHRAE Transactions | Year: 2010

During power outage servers in the data centers are powered by uninterrupted power supply (UPS). At the same time, the cooling system components such as CRACs, AHUs, and chillers stop operating for a short period until powered by alternate power sources. During this period servers continue generating heat in the data center room without active cooling. It is common notion that data centers contain large thermal mass, and hence, large heat capacity in the steel rack enclosures to protect servers from the thermal shock due to rising room air temperatures. However, the rate of air temperature rise and the availability of rack thermal mass depend on several factors including the height of the data center room, number of rack enclosures and their size, number of rack rows and their layout, and heat load density of a data center. It is crucial for design engineers and facility managers to know how much time can be available for restarting the active cooling systems before servers reach automatic shutoff temperatures. With the help of a heat transfer model this paper systematically analyzes the effect of various parameters and the impact of rack thermal mass on the time that air requires to reach the thermal shutoff threshold temperature. ©2010 ASHRAE.

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