ID#1920 made on
EAp2 - Minimum energy efficiency performance
LEED O+M: Existing Buildings
Our 151,744 square foot building has a 9,782 square foot computer data center. The data is not a typical single office building small data center; it supports the company's local headquarters four-bui...
Our 151,744 square foot building has a 9,782 square foot computer data center. The data is not a typical single office building small data center; it supports the company's local headquarters four-building campus as well as national needs, and thus has significant power requirements. Based on metering data obtained over the last month, the data center is using approximately 26watts per square foot. This figure includes power used by the server equipment as well as server room air conditioning equipment. As a comparison, in a benchmarking study performed by Lawrence Berkley National Labs , the minimum power densities for data centers were 8-10 watts per square foot and average power densities were 25 watts per square foot. Our problem is that the Energy Star Portfolio Manager program does not adequately account for the data center power use. Consequently, our Energy Star score across the building is quite low since the data center power density is not correctly represented. We have installed a sub-meter on the data center to accurately capture the energy used by the data center and would like to pull the data center out of the Energy Star Portfolio Manager scoring system. Energy Star will allow you to pull out the square footage of the data center and the total energy used by the data center for Energy Star Certification if you have 12 months of actual metering data. This is allowed so that an accurate picture of the energy use of the office building can be seen without being skewed by the energy use of a data center. Our hurdle is the sub-meter was installed in August so we will have three months worth of sub-metering data (not 12). We are highly committed to submitting for certification by the end of the year. This facility has been working extremely hard and is on track to submit for Gold certification and potentially Platinum by 12/31/07. However, we need to be able to pull the data center out in order to meet the Energy Star Score prerequisite requirements. The facility is aggressively targeting energy conservation projects to increase the score as well. We plan on using the 3 full months of metered data to estimate the remaining 9 months energy use, and then use this number to estimate the total energy use for the data center over the 12 month period as required by Energy Star. In other words, from the 3 months of gathered data, a Professional Engineer (mechanical) will calculate the average monthly use and apply that figure to each of the nine months for which we do not have separate metering data. The 3 months of our performance period occur during late summer (mid-August) and early winter (mid-December), which will give us a good picture of energy use during typical heating and cooling seasons. By using this method, we will be able to obtain a reasonable estimate of annual energy use for the data center. We would like to know if the USGBC will accept an energy star score that is calculated using this method. Worthy of note, we have also looked into the other methods of identifying your Energy Star score discussed in the reference guide, but since this is a typical office building (outside of the data center), none of those options apply.
LEED-EB v2.0 EA p2 and c1 recommend using the US EPA's Energy Star Benchmarking Tool. The U.S. EPA Energy Star program does permit exceptions for facilities such as described above where the data center is less than 10% of the total floor spaces, but a much larger percent of the energy use. When there are high energy loads associated with computer data centers it is acceptable to install sub-meters to capture the data center energy use. As correctly stated, the U.S EPA requires 12 months of data to officially obtain an Energy Star rating. However, for the purposes of meeting EA prerequisite 2 and EA credit 1 by obtaining a score using the Portfolio Manager Tool, the USGBC allows the extrapolation of annual data from a minimum of 3 months of data for initial LEED-EB applications. Three months aligns with the minimum length of the permitted performance period. The sub-metering should be a continual metering of the energy use for the piece of the building of interest, in order to quantify the total energy consumption for the period of interested. The sub-meter does not need to be a utility-installed meter. Applicable Internationally.
Related Addenda (Corrections & Interpretations)