From Data Centers to Pipe Insulation Systems
Engineer’s Notebook Authors Share What They’ve Learned Along the Way
From ASHRAE Journal Newsletter, Jan. 8, 2019
Every month since 2013, an “Engineer’s Notebook” column has appeared in ASHRAE Journal. At every ASHRAE Winter Conference since 2017, the four authors have taken part in a seminar and discussed some of their columns to date.
The authors—Stephen W. Duda, P.E., BEAP, HBDP and HFDP, Fellow ASHRAE; Daniel H. Nall, P.E., BEMP and HBDP, Fellow/Life Member ASHRAE; Kent W. Peterson, P.E., BEAP, Presidential Member/Fellow ASHRAE; and Steven T. Taylor, P.E., Fellow ASHRAE—have worked as senior consulting engineers and share what they have learned, sometimes the hard way, and experience throughout their careers in their recurring columns.
This year’s, “The Best of Engineer’s Notebook 3rd Edition” seminar is scheduled for 11 a.m.-12:30 p.m. on Jan. 13 in room A410 in the Georgia World Congress Center.
Before the conference, the authors discussed the significance of the chosen topics they are presenting.
Data Centers, Cooling Towers and Thermal Storage
Daniel H. Nall, P.E., BEMP and HBDP, Fellow/Life Member ASHRAE
For many data centers, refrigeration compressors are the single largest non-IT electric load for the facility.
This presentation shows how the application of thermal storage could dramatically increase the range of climates in which data centers could be entirely cooled using compressor-less cooling. The analysis revealed maximum overnight wet-bulb temperature is the critical environmental factor toward making the strategy successful rather than the maximum daily dry-bulb temperature. The critical design factors are the cooling towers’ approach temperatures and the phase-change thermal storage device.
Successful application of the system results in a significant decrease in the total cost of ownership (TCO) for the data center.
1. Why did you choose to discuss this topic?
I chose to present this paper because it represents a simple innovative design alternative for a growing issue in this country. I believe this solution could enable data center owners to more cost effectively locate their centers in a wider range of locations.
2. What is the significance of this topic?
With the continuing increase in cloud-based services, the number of data centers is growing. They represent a measurable fraction of the entire national energy consumption.
Increased pressure to reduce the total cost of ownership (TCO) for these installations is encouraging many companies to locate their data centers in cold climates to avoid the need for refrigeration-based cooling for data centers. This avoids the first cost, not only of the refrigeration plant, but also of the generator back-up for the generation plant.
This solution extends the climatic range in which refrigeration-free data centers may be located.
3. What lessons, facts and/or guidance can an engineer working in the field take away from this topic?
Thermal storage can be of value in many different systems, beyond its normal use for peak demand shaving. Its use, furthermore, is not limited to the standard chilled water temperature range. Creative use of storage strategies can enhance many different types of systems.
4. Were there any surprises or unforeseen challenges for you when working with this topic?
Most surprising was how quickly the approach temperature of the thermal storage system fell out as the defining system variable to determine the success of system.
Another surprise was that the overnight low wet-bulb temperature was the defining environmental variable, and that the daytime maximum dry-bulb temperature had little impact on whether or not the system would be useful in a given climate.
Designing Pipe Insulation Systems
Kent W. Peterson, P.E., BEAP, Presidential Member/Fellow ASHRAE
Thermal insulation for piping systems has proven to be a simple and cost-effective means for reducing heat losses and gains in mechanical piping systems. Pipe insulation provides a barrier between the pipe and the environment and can provide many benefits.
Improper insulation installations for HVAC piping can lead to excessive energy loss, safety hazards, condensation, corrosion and mold.
This presentation will help attendees understand the available material options and how to properly select and detail pipe insulation for various applications.
1. Why did you choose to discuss this topic?
A piping insulation system design is only as good as its weakest link. A design for a refrigerant or chilled water system will almost always call out the areas to be insulated, type of insulation and thickness of insulation. But if it does not address the wall and floor penetrations, longitudinal seams, butt joints, pipe supports, termination points, valves and fittings, it is not addressing the most common areas of failure in an insulation system.
2. What is the significance of this topic?
Improper HVAC piping insulation installations can lead to excessive energy loss, safety hazards, condensation, corrosion and mold. It is beneficial for designers to understand the available material options and how to properly select and detail pipe insulation for various applications.
3. What lessons, facts and/or guidance can an engineer working in the field take away from this topic?
Designers need to have information on the local environmental conditions and application requirements for various areas of a project to properly design high-performing pipe insulation systems. All aspects of the systems are important. Attention to detail, following best practices and industry-standard installation techniques can help designers and contractors achieve long-term performance with piping insulation system design.
4. Were there any surprises or unforeseen challenges for you when working with this topic?
Insulation material comparison often involves contrasting the physical properties of available materials as represented on the manufacturer’s data sheets. Many manufacturers do not use the same test method when stating physical properties.
It is important that the physical properties being compared are tested to the same test method and procedure, and the values are expressed in the same units. If not, the comparison is not valid, resulting in an inaccurate analysis of materials.
In order for piping insulation to be effective it also needs to remain as close to its manufactured state as possible, meaning it should remain dry, uncompressed and undamaged.
*Editor’s note: There has been a last-minute change. Kent Peterson will not be presenting at the Winter Conference. However, you can read his article that is the basis of his presentation here.
Making VAV Great Again
Steven T. Taylor, P.E., Fellow ASHRAE
VAV systems have been around since the 1970s. They have been challenged by newer system types but still can have great performance at low cost if “well designed.”
“Well-designed” is in quotes because one significant negative of VAV systems is that they are easily designed poorly, rendering their performance on par with the constant volume systems they replaced.
But two recent ASHRAE publications—ASHRAE Guideline 36-2018, High-Performance Sequences of Operation for HVAC Systems, and Addendum f to ASHRAE Standard 62.1, Ventilation for Acceptable Indoor Air Quality—make it easy to design high-performance VAV systems.
This seminar will describe these new publications and show how using them can make VAV great again.
1. Why did you choose to discuss this topic?
I am a big fan of VAV systems, but they are often poorly designed and controlled, which is why some engineers think the system is not energy-efficient.
But two recent ASHRAE publications, ASHRAE Guideline 36-2018 and Addendum f to ASHRAE Standard 62.1, make it very easy to design high-performance VAV systems with minimal complexity.
2. What is the significance of this topic?
VAV systems are the most popular HVAC systems for commercial buildings in the U.S., so helping them perform optimally can have a significant impact on national energy use.
3. What lessons, facts and/or guidance can an engineer working in the field take away from this topic?
The most important facts are just to be aware of these two new documents and how they can be used to reduce engineering time while maximizing efficiency.
4. Were there any surprises or unforeseen challenges for you when working with this topic?
Not that I can think of.
N+1 HVAC for IT Closets and Server Rooms
Stephen W. Duda, P.E., BEAP, HBDP and HFDP, Fellow ASHRAE
This presentation investigates which system should be your primary cooling source and which should be your back-up when providing more than one cooling source in an IT closet or small server room.
Duda often sees buildings operating a more energy-hungry piece of equipment as the everyday system while a lower energy user sits idle as a back-up.
If you have settled in to using a DX ductless mini-split as your primary source of cooling in an IT closet, while an efficient VAV system with economizer serves only as a backup, this seminar is intended to challenge your thinking.
1. Why did you choose to discuss this topic?
As with many of the columns I write for “Engineer’s Notebook,” this one was prompted by actual installations that I felt could be done better with little to no additional effort.
2. What is the significance of this topic?
It is such a simple topic actually.
It is very common for a small IT closet or server room to be cooled with packaged DX air-cooled equipment because the larger main building air-conditioning system may not operate at nights or on weekends.
And it is also very common to supply the IT closet or server room with building air anyway, in case the packaged DX equipment ever suffers a failure.
So my main point is: use that building air first! It is more energy-efficient over the long-term, especially when the building air-handling system has an economizer and/or energy recovery. Use the packaged DX equipment only for nights, weekends or on building air failure.
3. What lessons, facts and/or guidance can an engineer working in the field take away from this topic?
If you have packaged DX air-cooled equipment serving a small IT closet or server room, and you have air delivery from the larger main building air-conditioning system, use the main building air-conditioning system as primary and use the packaged DX equipment only as backup, nights and weekends.
You will save energy over the course of a year.
4. Were there any surprises or unforeseen challenges for you when working with this topic?
Even after doing the math to show my strategy is more energy-efficient on an annual basis, and even after showing some of my clients the article, as published, one in particular still insisted they were going to use the packaged DX equipment as primary, 24/7 365, because, well, that is what they have always done.