SURVEY RESULTS: DATA CENTER ECONOMIZER USE

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1 WHITE PAPER #41 SURVEY RESULTS: DATA CENTER ECONOMIZER USE EDITOR: Jessica Kaiser, Emerson Network Power CONTRIBUTORS: John Bean, Schneider Electric Tom Harvey, Emerson Network Power Michael Patterson, Intel Jessica Winiecki, Emerson Network Power

2 PAGE 2 Executive Summary In early 2011, The Green Grid (TGG) an international, non-profit consortium working to enhance data center resource efficiency conducted a survey to learn more about current economizer awareness, perceptions, and use in the data center industry. The survey s results indicate that economizers are well-known throughout the data center industry and that adoption is becoming fairly widespread. Economizers represent an effective means of increasing energy efficiency and reducing costs in data centers, and TGG expects this survey s findings to spur further economizer research, education, and adoption efforts. The following paper highlights some of the most interesting results from TGG s survey.

3 PAGE 3 Table of Contents I. Introduction... 3 II. Survey Respondents and Their Data Centers... 4 III. Current Economizer Landscape... 6 IV. Hours of Economizer Use... 8 V. Challenges to Economizer Adoption and Use VI. Satisfaction with Economizers VII. Cost Impact of Economizer Use VIII. No Correlation Between PUE and Economizer Use IX. Next Steps X. Summary XI. References XII. About The Green Grid I. Introduction In keeping with its aim to improve the resource efficiency of data centers and business computing ecosystems around the world, The Green Grid (TGG) sought to gain a clearer picture of the attitudes toward, and use of, economizers within data centers. To do so, it launched an online survey in January TGG s goal was to better understand what compels economizer use in data centers, the implementation and operational challenges associated with economizers, their effects on data centers overall operating costs, decision makers reasons for not using them, and so on. The knowledge gained from the survey is intended to support industry efforts to boost adoption of these energy-saving systems. WHAT IS AN ECONOMIZER? Economizers are cooling technologies that take advantage of favorable outdoor conditions to provide partial or full cooling without using the energy of a refrigeration cycle. There are two fundamental economizer categories: Air-side systems. These are systems that may use direct, fresh air blown into the data center with hot air extracted and discharged back outdoors, or they may use an air-to-air heat exchanger. With the airto-air heat exchanger, cooler outdoor air is used to partially or fully cool the interior data center air. Airside systems may be enhanced with either direct or indirect evaporative cooling, extending their operating range.

4 PAGE 4 Water-side systems. These systems remove heat from the chilled water loop by a heat exchange process with outdoor air. Typically, there may be a heat exchanger that is piped in series with the chilled water return and chiller as well as piped either in series or in parallel with the cooling tower and chiller condenser water circuit. When the cooling tower water loop is cooler than the return chilled water, it is used to partially or fully cool the chilled water, thus reducing or eliminating demand on the chiller refrigeration cycle. The American Society of Heating, Refrigeration, and Air Conditioning Engineers (ASHRAE) standard 90.1 on energy efficiency is adopted by many of the states and municipalities in the United States as their building energy efficiency code. The recent 2010 version of this standard now includes applicability to data centers and requires economizers as a baseline installation for a large portion of the U.S. Beyond their ability to save energy, economizers are becoming a regulatory requirement and their use will see an increase. The Green Grid is committed to exploring how best to spread the word and educate the IT community about economizers advantages as well as their challenges. II. Survey Respondents and Their Data Centers The online survey included approximately 36 questions and was fully completed by 115 participants (a 9.11% margin of error at a 95% confidence level). Respondents had to be somewhat familiar (22%) or very familiar (78%) with their data centers cooling and operation systems to participate in the survey. Half of the respondents identified themselves as either facilities managers or holding both IT and facilities responsibilities. The other participants represented a mix of those in engineering, IT management and IT operations, consulting, executive management, and project management. Due to the low likelihood of economization use in data centers that are less than 2,500 square feet, only those with data centers 2,500 square feet or larger were asked to participate in the survey. Approximately half of the respondents had data centers that were 2,500 to 24,999 square feet, and the other half had data centers larger than 25,000 square feet. The facilities in question were primarily located in the United States (90%) and Europe (6%). The survey also received one response each from Australia, Canada, India, and South America. Respondents average utility cost was U.S.$.09/kWh, and the total average power load of their primary data centers was 3,737 kw. A large majority of respondents (87%) manage humidity inside their data centers, with the most popular type of humidifier reported as infrared (27%), followed by canister (18%), adiabatic (17%), and building steam (10%).

5 PAGE 5 One-fifth of respondentss who indicated that they manage humidification were not aware of the type of humidifier used in their data centers. When measuring humidity, more than half of the survey participants use return air to the cooling unit as their control criterion, and their average range for target humidity was 39% to 53% relative humidity (RH). To measure temperature, 43% of the respondents use return air to the cooling unit as their control criterion; at that location, their average target temperature was 72.8 F. The Green Grid analyzed the survey results by data center size and organizational role and compared economizer use with data center location. It is important to take location into consideration because the climate in which a data center is located affects the number of hours during which it is possible to effectively use it. Dry, cool climates are the best for economization, whereass hours of application may be limited in hotter, more humid areas. Figure 1 below shows where the majority of the data centers surveyed were located and whether they used economizers (blue markers) or did not use economizers (red markers). No respondentss in the southernmost tier of the United States used economizers. Figure 1. Locations of U.S. survey respondents data centers, with blue markers indicating economizer use and red markers denoting data centers that do not use economizers

6 PAGE 6 III. Current Economizer Landscape The central question to ask in a data center survey about economizers is, Do you use economizers in your primary data center? The responses showed a nearly even split between data centers that employ economizers and facilities that do not. (See Figure 2.) Use of Economizers Do you use economizers in your primary data center? No 50% Yes 49% Don't know 2% 0% 10% 20% 30% 40% 50% 60% Figure 2. Data center economizer use among survey respondents Figure 3 below shows that the incidence of use is slightly higher in the largest facilities (50,000 square feet or more) and lower in the smallest facilities (2,500 to 4,999 square feet).

7 PAGE 7 Economizer Use by Data Center Size Do you use economizers in your primary data center? Yes No Don't know 50,000 sq ft or more 63.89% 33.33% 2.78% 25,000 49,999 sq ft 43.48% 56.52% 10,000 24,999 sq ft 50.00% 50.00% 5,000 9,999 sq ft 45.83% 54.17% 2,500 4,999 sq ft 10.00% 80.00% 10.00% 0% 20% 40% 60% 80% 100% Figure 3. Responses about economizer use, grouped by data center size Of those who currently use economizers, almost three-quarters implemented their economizers during new construction, as opposed to retrofitting existing facilities to accommodate them. Of that same group, 91% reported that they had adopted economizers to increase energy efficiency and reduce costs. (These same two reasons were cited by 89% of those considering economizer use.) Other reasons cited by respondents included code compliance and recommendation from consultants or engineers. As for the type of economizers implemented, Figure 4 reveals that the most popular are direct outside air (39%) and chilled water with a water-cooled chiller (27%).

8 PAGE 8 Types of Economizers Used What type of economizer system is used in your data center? Direct outside air Chilled water with water-cooled chiller Other, please specify Chilled water with air-cooled chiller DX with fluid economizer coil Indirect outside air with heat wheel Don t know 2% 0% 12% 11% 9% 27% 39% 0% 5% 10% 15% 20% 25% 30% 35% 40% 45% Figure 4. Kinds of economizers used in survey respondents data centers IV. Hours of Economizer Use As mentioned in the Introduction, it is important to remember the nature of economizers and the conditions under which they can function. When asked to provide the average number of hours per year during which outside temperatures and humidity levels are suitable for economizer use, survey participants answers ranged from 1,000 hours per year to 8,000 or more hours per year. Together, the group averaged 4,724 hours per year during which economizers could be used effectively. Having asked for the possible number of hours respondents could be using their economizers, the survey next asked the actual time that the economizers were in use. (See Figure 5 below.) It turned out that, of the average 4,724 hours available, the respondents data centers used economizers an average of 3,943 hours per year, or 80% of the time.

9 PAGE 9 Actual Number of Hours Economizers are Used On average, how many hours per year is the economizer actually used? 8,000 or more hours per year 4% 7,000 7,999 hours per year 2% 6,000 6,999 hours per year 5% 5,000 5,999 hours per year 12% 4,000 4,999 hours per year 16% 3,000 3,999 hours per year 12% 2,000 2,999 hours per year 21% 1,000 1,999 hours per year 4% Less than 1,000 hours per year 4% None economizer disabled after installation 2% Don t know 18% 0% 5% 10% 15% 20% 25% Figure 5. Average annual number of hours economizers are used in survey respondents data centers If the economizers are fully installed and the temperature and humidity conditions fall within the appropriate ranges, then why are the economizers idle 20% of the time? As shown in Figure 6 below, about one-third of the survey participants responded to this particular question that they believe their economizers are always used when it is possible to do so. Among those respondents whose data centers are not making full use of their economizers during available hours, their main reason is that their corporate standards for acceptable set points are more strict than the published standards. Others have concerns about the switchover process, high costs of maintenance and humidification/dehumidification, and the presence of air pollutants.

10 PAGE 10 Reasons Economizers are Not Used During Applicable Hours During applicable hours for economizer use, why are they not used? Select all that apply. N/A Economizer is always used Set point tolerance for temperature and humidity is lower than advised standard Concerns with switchover between economizer and mechanical cooling Maintenance Other, please specify 9% 11% 13% 25% 31% Operating costs for humidification / dehumidification Air pollutants Don t know 5% 5% 5% Noise 0% 0% 5% 10% 15% 20% 25% 30% 35% Figure 6. Survey responses as to why economizers are not used during all applicable hours ASHRAE has established standards for temperature (upper and lower limits), RH (upper), and dew point (upper and lower limits) to optimize computer equipment reliability and energy efficiency for the IT components inside the data center. When asked whether they would be willing to exceed any ASHRAE recommended limits to gain extra economizer hours and, if so, which ones, almost 70% of the survey respondents noted that they were willing to exceed ASHRAE s 2008 upper temperature or lower temperature recommendation. (This is in accordance with economizer best practices and temporary excursions outside of the recommended range but inside the allowable range). Approximately 24% were unwilling to exceed any parameter of the ASHRAErecommended range. ASHRAE actually encourages data centers to operate within the allowable range for some time. In fact, ASHRAE further widened its environmental ranges recently in 2011, underscoring the key role economizers can play in improving data center energy efficiency. (See References for links to more information.)

11 PAGE 11 V. Challenges to Economizer Adoption and Use Part of understanding the economizer landscape includes gaining insight into the obstacles perceived and/or encountered by data center decision makers. When economizer users were asked about challenges, approximately one-third of the survey participants responded that they have had no problems with their economizers. For those respondents who have experienced difficulties, another third identified initial costs as posing the greatest challenge to economizer adoption and use. (See Figure 7 below for more detail.) Challenges Have you faced any challenges with using an economizer? Select all that apply. Initial cost No challenges with economizer 34% 34% Actual usage time is less than expected 20% Reliability of economizer Other, please specify 11% 11% Architectural impact due to cooling air routing or add'l liquid heat exchangers 7% Maintenance costs Financial savings is difficult to calculate Don t know Financial savings is less than expected 5% 5% 5% 4% Decreased server reliability 2% 0% 5% 10% 15% 20% 25% 30% 35% 40% Figure 7. Survey participants responses regarding obstacles to economizer adoption and use Figure 8 below shows the responses of those survey participants who had considered economizers but opted not to move forward with their implementation. Approximately 38% cited the difficulty of retrofitting an existing facility as the deciding factor against implementing economizers. Reliability concerns caused 23% of respondents not to pursue economizer use.

12 PAGE 12 Primary Reason for Not Using Economizers What was your primary reason for not using economizers? Retrofit too difficult 38% Reliability concerns 23% Climate is not suitable Return on investment did not justify costs 15% 15% Other, please specify 8% Initial costs Not recommended by engineer/ contractor/consultant Executive management did not approve Data center manager (IT or Facilities) did not approve Don t know 0% 0% 0% 0% 0% 0% 10% 20% 30% 40% Figure 8. Respondents answers as to why they had considered economizers but decided not to use them In the survey, TGG sought to determine not only why respondents were not using economizers, but also why some respondents had not even seriously considered pursuing them. As Figure 9 below reveals, for those who have not considered using economizers, the primary obstacles are climate unsuitability and economizers initial costs.

13 PAGE 13 Primary Reasons for Not Considering Economizers What is the primary reason for not considering economizers? Climate is not suitable Initial cost 17% 17% Not familiar with technology Reliability concerns Haven t built or retrofitted data center Don t know Other, please specify 11% 11% 11% 11% 11% Unsure of return on investment Has not been recommended 6% 6% High maintenance costs 0% 0% 5% 10% 15% 20% n = 18 Figure 9. Survey participants reasons for not even considering the use of economizers in their data centers VI. Satisfaction with Economizers As for those respondents who do employ economizers in their primary data centers, TGG wanted to understand how happy they are with various elements of economizer use. The survey asked respondents about their levels of satisfaction regarding economizers reliability, financial savings, coordination with mechanical cooling mechanisms, maintenance costs, and actual time in use. Figure 10 below shows that all responses were positive, with economizer reliability receiving the highest average satisfaction level at 8.38 out of 10.

14 PAGE 14 Satisfaction with Economizers How satisfied are you with the following economizer aspects of the on a scale from 1 (not at all satisfied) to 10 (extremely satisfied)? Average satisfaction rating (out of possible 10) Reliability 8.38 Financial savings Coordination between economizer and mechanical cooling Maintenance costs 7.55 Actual usage time 7.46 Figure 10. Respondents satisfaction ratings regarding various aspects of economizer use Through a follow-up question in the survey, respondents made it clear that they were satisfied with their economizers, and nearly 3 out of 4 reported that they are very likely to recommend their specific type of economizer to others (8 or higher out of 10). In addition, 65% responded that they would be very likely to repurchase the same type of economizer that they currently employ. The results were lower for likelihood to purchase a different kind of economizer, with only 35% indicating they would be very likely to do so. Respondents reluctance to try a different type of economizer presumably stems from their high satisfaction with what they presently use. VII. Cost Impact of Economizer Use As mentioned in Section III, a significant percentage of survey participants identified cost savings as one of the two main motivators for considering and/or implementing economizers. Therefore, the survey asked whether those data centers had indeed achieved reductions in their operating costs. Figure 11 illustrates that, on average, respondents have seen a 20% decrease in energy costs since deploying their economizers and a 7%

15 PAGE 15 decrease in maintenance costs. As seen in Section VI, this has resulted in high satisfaction levels relative to financial savings and maintenance costs. Economizer Impact How has the economizer affected data center operating costs? Energy Costs Maintenance Costs 7% 4% 7% 21% 20% 39% 50% 5% 2% 2% 18% Increased less than 25% 0% 20% 40% 60% 80% 100% 2% 23% Decreased 50% or more Decreased 25% - 49% Decreased less than 25% No change Figure 11. Impact of economizers on respondents data center operating costs VIII. No Correlation Between PUE and Economizer Use Over 70% of respondents reported their power usage effectiveness (PUE ) value, which was an average of There was no statistically significant difference between the PUE reported by those who use economizers and by those who do not. TGG subdivided the data to compare reported PUE values against economizer use for the 68 survey respondents who reported PUE values. Below, the Figure 12 box plot of PUE values versus economizer use shows that there is no clear advantage reported for using economizers.

16 PAGE 16 Figure 12. Power usage effectiveness (PUE) values of respondents who do and do not use economizers Location does not seem to be a factor in this result. Analyzing only responses for data centers located in the San Francisco Bay area still did not produce evidence of a difference in PUE between the data centers that used economizers and those that did not. (See Figure 13 below.)

17 PAGE 17 Figure 13. Power usage effectiveness (PUE) values of San Francisco Bay area respondents who do and do not use economizers The United States Environmental Protection Agency (EPA) Energy Star program noted a similar lack of correlation between reported PUE and economizer use in its 2009 ENERGY STAR Data Center Infrastructure Rating Development Update. (See References #5 for more information.) The lack of correlation does not seem to affect owners satisfaction with economizers or the perceived savings in an individual application of economizers. IX. Next Steps This survey represents one component of The Green Grid s efforts to determine the situation today regarding economizers and to identify and resolve the barriers to their adoption. TGG is conducting ongoing investigations and analyses to help equipment manufacturers, data center owners/operators, and others in the industry understand and overcome both the real and perceived hurdles that currently hinder widespread

18 PAGE 18 use of economizers and other such tools. For example, TGG plans to examine in more detail the impact of economizers on PUE. Having learned that half of those surveyed presently use economizers, one of the most compelling questions to answer has to do with how the industry should go about encouraging the other half to adopt them. It is interesting to note that the majority of the survey respondents identified the facilities manager as the primary decision maker regarding economizers, while only 12% pointed to executive management as responsible for economizer adoption. Therefore, determining what kinds of information, education, incentives, and improvements would most resonate with data center facilities managers may be helpful in encouraging them to take advantage of economizers. X. Summary Overall, TGG s survey results suggest that economizer use is likely to increase with time; 49% of respondents already use them and another 24% are considering their implementation. In fact, almost half of those respondents without an economizer are currently considering using one. In addition, many of those who do not have economizers responded that they would definitely consider installing them during their next data center construction project. According to the survey results, respondents adopted economizers chiefly to increase efficiency and save money; those considering economizer use gave the same two reasons for that consideration. Since implementation, respondents have saved an average 20% on energy costs and 7% on maintenance costs. With regard to economizer-related difficulties, the results seem to indicate that the greater challenge lies in learning about and implementing economizers rather than operating them. Familiarity with economizers among non-economizer users could be improved, and respondents who are not considering their use identified climate issues, the difficulty of retrofitting existing facilities to accommodate economizers, reliability concerns, and initial costs as factors that keep those respondents from pursuing them. Yet respondents whose data centers use economizers are satisfied with them and are highly likely to recommend their specific type of economizer. Certain obstacles to economizer adoption such as climate unsuitability cannot easily be addressed, but it may be possible to address others. In fact, economizer users satisfaction with the reliability, financial savings, interoperability with data center systems, and other aspects of economizer use implies that reluctance to

19 PAGE 19 adopt economizers may be overcome if data center decision makers were to learn more about economizers dependability, return on investment, and ease of operation from satisfied industry peers. The Green Grid will continue its research and reporting efforts to help strengthen both the real and perceived efficacy of economizers so that data centers around the globe can benefit from increased resource efficiency and reduced costs. XI. References 1. ASHRAE, 2011 Thermal Guidelines for Data Processing Environments Expanded Data Center Classes and Usage Guidance %202011%20Thermal%20Guidelines%20for%20Data%20Processing%20Environments.pdf. 2. ASHRAE, 2008 ASHRAE Environmental Guidelines for Datacom Equipment 08.pdf. 3. The Green Grid, Recommendations for Measuring and Reporting Overall Data Center Efficiency (May 2011) 20Recommendations%20V2% pdf?lang=en. 4. The Green Grid, Qualitative Analysis of Cooling Architectures for Data Centers White Paper #30 (2011) hitectures_final.pdf?lang=en. 5. United States Environmental Protection Agency, 2009 ENERGY STAR Data Center Infrastructure Rating Development Update (Web Conference, September 29, 2009) _Prelim_Results_92909.pdf. XII. About The Green Grid The Green Grid is a non-profit, open industry consortium of end users, policy makers, technology providers, facility architects, and utility companies collaborating to improve the resource efficiency of data centers and business computing ecosystems. With more than 170 member companies around the world, The Green Grid seeks to unite global industry efforts, create a common set of metrics, and develop technical resources and educational tools to further its goals. Additional information is available at