Data Center Energy Efficiency

     So, what is a "Data Center"? And, how can Mechanical Engineering help increase the efficiency of data centers?

     I recall being introduced to the concept of a data center while working in the Telecommunications industry. When I started, I was given a tour of a local phone company's "Central Office". At the time, the "clickidy-clack" sounds of actual switches (yes, mechanical switches used to exist) permeated the air - as opposed to the din of the "whhhrrrrrrrrrrrrrrrrrrrrrrr" from the small fans cooling the high-tech [and VERY high heat-density] rack equipment of today's buildings. Soon, the term "Server Farm" arose...and then...the data center!

     To a Mechanical Engineer, there is only the flow of heat regardless of building use. Whether you're trying to get rid of it, store it, or transfer it somewhere else. Your mind is constantly occupied with Temperatures & flows (and COP, EER, ASHRAE 90.1, etc.). 

     That's not to say that you're not mindful of the Systems Engineering coordination with IT, other A/E, the GC, subs, and especially the bottom-line '$' for the customer. Because I'm talking purely ME here, I'm also not talking about building use, permitting, and other municipality regulation - All of these factors come into play in the Project Management space.

     Back to efficiency. For the better part of the last two decades, I've seen industries transform from dinosaur-like relics following Standard Operating Procedure "by the book" (that was written centuries ago) to Dynamic Agile organizations that strive to continually reduce cost & increase efficiency. According to a recent ASHRAE Article written by M. Hastbacka, M. Rutberg, and A. Bouza; about 385 kWh per year can be shaved off of a 62 MWh per year office building. This is done by using laptops & desktops that are "ENERGY STAR" certified. Of course, this example seems tiny but imagine "tweeking" ALL of the energy-consuming equipment.

     While these concepts are not new (I saved an estimated $100k after the first few years of a multi-story lighting retrofit long ago), there is an exponential increase in the urgency to execute these types of projects. This drive comes from the impact on high-energy use buildings like data centers plus the multiplicative effect these savings have on the supporting power infrastructure. This multiplicative effect comes from the fact that the electrical load being saved no longer traverses down-stream from the house service, through the power-loss-inducing wires, transformers, through the batteries, and finally to the floor equipment etc.

     So how can Mechanical Engineering help increase Data Center Energy Efficiency? Well, newer HVAC technologies allow greater efficiencies though the use of "heat wheels" (aka "enthalpy wheels" aka "Sensible / Desiccant & Total Energy Wheels") that temper the outside air. Also, an ME can design a transfer of waste heat into areas where the heat can be consumed and where this waste meets certain quality criteria. The ME can analyze and redirect data center floor space heat flow with Computational Fluid Dynamics (CFD), and she/he can collect actionable metrics from the data center equipment along the entire Energy Value Chain.

     ["Value Chain" = corporate-speak for "System"]

     The well known ASHRAE Guideline 14-2002 was written to help determine how to measure energy and demand savings in pre- and post-retrofit applications.

     Not to mention the calibration of existing chiller/AHU/Cooling Tower equipment by the Building Technician whose job it is to live with whatever is designed. [Lesson #1, NEVER have design meetings without the Building Tech buy-in]. He/She may adjust the Chiller compressor guide vanes, ensure the chiller operation at optimal Temperatures/Pressures, and flows, and do a host of other maintenance adjustment tasks (VFDs, etc.) geared toward high efficiency.

     It's important to note that leveraging AutoCAD with BIM, CFD, SolidWorks, and even Mobile Apps [eg. Android - as The Disney Imagineering Team does] is a foregone conclusion in that the Professional Engineer should leverage the currently available tools to increase accuracy and Agility :)