Vol.3 No.3 2010
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Research paper : An optimum design method utilizing a strategic system design concept (J. Fukuda et al.)−190−Synthesiology - English edition Vol.3 No.3 (2010) many datacenters, there is a temperature difference of about 5~10 °C per yearNote 3). It is projected that the power consumption of air conditioning can be reduced about 8 % by constructing the datacenter in cold climate areas such as Sapporo (Table 2). Conversely, the power consumption of air conditioning increases about 8 % in warm areas such as Naha. However, since the power consumption of air conditioning is about 30 % of the total power consumption of a datacenter, only about 2 % total reduction can be expected between Tokyo and Sapporo (Table 2).Another method for improving air conditioning efficiency is a method called “capping” where the racks are surrounded by panels to prevent the mixing of waste heat from servers and cold air from air conditioners (Fig. 2)Note 4). While this allows reduction of about 20 % of the power consumption of air conditioning, it is projected that the reduction will be about 5 % of the total power consumption of the datacenter (Table 2).As it can be seen, there are limitations in achieving energy consumption efficiency for a single stand-alone datacenter, and a radical technological innovation or some new design approach is necessary to achieve significant CO2 reduction.3 Proposal of the strategic system design3.1 Physical system and value systemWe propose a new design approach through “strategic system design”, a concept that transcends the conventional approach to optimizing stand-alone datacenters (a single system).Figure 3 shows the concept of the strategic system design. In conventional system design, evaluation and optimization were conducted from the perspective mainly of physical performance of a single system. However, a system has a stakeholder who has a vested interest in that system, and therefore, evaluation of a system is based on what is valuable for the stakeholder. The value is dependent on the psychological values of the stakeholder, and while monetary matter is not the only concern, using the monetary scale allows generalization and quantification.The system exists in two spaces: the physical system that exists in the physical space, and the value system that exists in the psychological space of the stakeholder.The datacenter is composed of the “physical system” including the building, power supply, air conditioner, racks, and others, and the “value system” for the company in the form of sales generated by the physical system.In this case, the optimization of the physical system and the optimization of the value system do not necessarily coincide. In case of the datacenter, the optimization of the physical system means minimizing the power consumption, while the optimization of the value system means maximizing the profit by minimizing the cost. While the minimization of power consumption and minimization of cost run in the same direction, the two may not match. For example, the introduction of a highly efficient facility will reduce power consumption, but the cost may increase due to the high facility cost. If the value decreases, the company will not introduce the new facility even if it is highly efficient.Panels prevent mixingof waste heat fromserver and cool airAirconditionerAirconditionerServerServerFig. 2 Example in achieving efficiency of air conditioner by cappingPower consumption of serverPower consumption of air conditionerPower supply facility, uninterruptible power supplyLighting etc. 2 %13 %27 %58 %Table 1 Details of energy consumption at the datacenterTable 2 Location of the datacenter and CO2 emissionNahaSapporoTokyoTokyoAislecappingSapporoAislecapping11,51412,47916,81014,39315,59973.8 %80.0 %107.8 %92.3 %100.0 %53,73354,69759,02956,61157,81792.9 %94.6 %102.1 %97.9 %100.0 %1.601.631.761.691.7264465670867969492.8 %94.5 %102.0 %97.8 %100.0 %0.4790.3390.9340.4790.33925,73818,54255,13327,11719,600131.3 %94.6 %281.3 %138.4 %100.0 %*1 *2 CO2 emission(t/year)CO2 emission coefficient*2kg-CO2/kWhPower cost(million yen/year)PUE*1Power consumptionof entire datacenter(MWh/year)Power consumptionof air conditioner(MWh/year)PUE (power use effectiveness) = power consumption of entire datacenter / power consumption of server. Figures for FY 2006 are according to the source from the Ministry of Environment (figures for Naha are for FY 2007). Numbers below the dashed line are comparisons when Tokyo is set as 100 %.Fig. 3 Concept of strategic system designStakeholderExample: DatacenterValuesystemPhysicalsystemStakeholderExample: Greenhouse farmingDomain of conventional system designDomain of total physical system designDomain of total value system designDomain of strategic system designExchange ofvalueExchange ofmaterialSupersystem(Other stakeholders, social systems, global environment, etc.)PhysicalspacePsychologicalspaceOptimization by single systemOptimization by composite systemValuesystemPhysicalsystem

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