Green Room: A Giant Leap in Development of Green Datacenters

Abstract: In a world that is slipping towards a global energy crisis as a result of a heavy dependence on depleting fossil-based fuels, investment in projects that promote energy efficiency will have a strong return on investment not only economically but also socially & environmentally. Firms will directly save significant amounts of money on their energy bills and besides, contribute to slowing down the environmental degradation & global warming by diminishing their carbon footprint. In the global contest to achieve high levels of energy efficiency, IT sector is no exception and telecommunication companies have developed new approaches on how to develop more efficient data centers and cooling systems in the past decades. This paper describes an ambitious project carried out by TeliaSonera to develop a highly-energy-efficient cooling approach for data centers called "Green Room". It is important to realize that Green Room approach is not specifically limited to data centers. It is designed to support any sort of “technical site” in need of an efficient cooling system. As a result, the word “datacenter” repeatedly used in this paper is expandable to a huger category of technical sites. As the hypothesis, Green Room was expected to generate appropriate temperature level accompanied with effectual steady air flow inside the room while using considerably lower amount of electricity compared with other cooling methods in the market. To begin with, an introduction is given to familiarize the readers with the concept of "data center" and immediately preceded a concise discussion in Chapter 2 providing convincing reasons to promote energy-efficient projects like Green Room from economic, social and environmental points of view. The chapter is complemented by a comprehensive part attached to this paper as Appendix I. In Chapter 3, the different cooling approaches currently available for datacenters is looked into. Chapter 4 describes how it is possible to assess the efficiency of a data center cooling system by introducing critical values such as PUE (power usage effectiveness) and COP (Coefficient of performance). Understandably, it is of great significance to determine how accurate the measurements carried out in this project are. Chapter 5 provides useful information on measurements and describes uncertainty estimation of the obtained results. Chapter 6 explains the test methodology and continues by touching on the components of Green Room and their technical specifications. Subsequently, it compares the Green Room approach to other cooling systems and identifies five major differences making the Green Room a distinctive cooling method. Chapter 7 explains the measurement requirements from the point of view of sensors, discusses the calibration process and finally represents the uncertainty calculations and their results. Chapter 8 broadly describes the five different categories of 25 independent tests carried out within a period of almost two weeks. It provides the readers with all the necessary details for each test and includes thorough description of conditions, numerical results, calculations, tables, charts, graphs, pictures and some thermal images. Ultimately, the last two chapters summarize the results of this project and assess its degree of success based on the hypothesis of this paper. Consequently, a number of questions have been raised and relevant suggestions made to modify this approach and improve the results. Surprisingly, the values obtained for efficiency of this cooling system are as expected. However, some part of calculations to achieve the total power load of the whole cooling production system is based on estimations acquired from software simulations. Overall, this is considered as a successful project fulfilling the primary expectations of the founders.