Issue 5, Aug/Sep 2009
FOCUS COOLING
STEP 3 Air quality analysis begins by assessing qualitative parameters of the ambient air. The depth of this analysis can vary greatly from laboratory sample testing to informal observations and fundamental questions and answers.
Does ambient air carry smog or particulate matter? Are there any unusual or excessive corrosive effects observed? What would be the impact to IT equipment if it was exposed to these environmental conditions? Even high-level investigation can often yield revealing information (see figure 6.)
Beyond what may already be in the air, it is useful to evaluate the activities, industries or natural events that may affect the quality of the ambient air.
Figure 1: Air or water cooling the load Figure 2: Air or water cooling the cooling equipment
Can pollen count be excessive for short periods of time? Are there any agricultural, construction or industrial activities that will affect the environment? Is there a major transportation hub or intermittent pollution source that may be difficult to predict? Understanding how air quality impacts and how it may need to be rectified could greatly impact the assessments made in step four.
STEP 4 High-level TCO analysis will need to be performed, so ultimately it will become necessary for each variable and impact to be monetised. The goal of the analysis is to generate a baseline for evaluation so that meaningful decisions on a path forward can be assessed. It is not meant to be an exhaustive or comprehensive financial model of a given option.
Figure 3: Potential data center locations
Even though this step is a type of scoping study, fundamental financial and cost-dependent variables will need to be assessed. These would include the cost of implementation, annualised operations and maintenance costs and associated energy costs.
Figure 4: Typical data distribution for climate analysis
Each assessment needs to be grounded so it is important to qualify the payback parameters. An industry metric that may be useful is that the typical IT refresh rate in a data center is three to five years. Using this data point, a meaningful comparison can be made to understand whether or not the high-level TCO is economically viable (see figure 7.)
WATER ANALYSIS The boundaries of practicality for using water as the heat transfer medium can also be established by using the same four-step process. The approach will use similar lines of questioning but will be grounded in using water for the cooling processes.
• Step 1 - Establish the basics • Step 2 - Climate analysis • Step 3 - Water quality analysis • Step 4 - High-level TCO analysis
STEP 1 In establishing the basics, an initial consideration should be assessing the proposed IT equipment type and configuration to understand whether or not water can be used as a cooling medium. Once understood, qualitative issues such as available temperatures, pressures and volumes are considered so that the viability of a water- based system can be assessed.
Practical limits of access, temperature and volume are equally apparent with water as they are for air. Water, unlike air, can present significant variability in access, even after its source has been established. It is not sufficient to simply understand the water volume required for a design cooling load at any point in time. A determination of water volumes per minute, per day and per year for your IT equipment is necessary.
Future planning for upgrades, expansions or even limitations of service can significantly change present day versus future planning associated with a water-cooling scenario. Consideration should also be given to non- traditional (NPW) water sources using a similar analysis that addresses their life-term availability and volume.
STEP 2 Climate analysis requires a broad interpretation of statistical climactic data. Similar to climactic data for air, a grounded multi-year data set should be used for analysis. Consideration of the boundary (lifetime) values would include the never-exceed minimums and maximums for temperature and whether or not the data is seasonally influenced. Related seasonal information may include drought conditions, utility company failures and how issues were addressed. This data will help establish an availability matrix for different sources of water and whether or not they are of sufficient capacity for consideration.
STEP 3 Water quality analysis is again a qualitative assessment of the chemical parameters in the water. While empirical analysis can play a role in water sample
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