Use Of Energy-efficient Technologies Research Articles

Energy efficiency vs. performance of the numerical solution of PDEs: An application study on a low-power ARM-based cluster

Power consumption and energy efficiency are becoming critical aspects in the design and operation of large scale HPC facilities, and it is unanimously recognised that future exascale supercomputers will be strongly constrained by their power requirements. At current electricity costs, operating an HPC system over its lifetime can already be on par with the initial deployment cost. These power consumption constraints, and the benefits a more energy-efficient HPC platform may have on other societal areas, have motivated the HPC research community to investigate the use of energy-efficient technologies originally developed for the embedded and especially mobile markets. However, lower power does not always mean lower energy consumption, since execution time often also increases. In order to achieve competitive performance, applications then need to efficiently exploit a larger number of processors. In this article, we discuss how applications can efficiently exploit this new class of low-power architectures to achieve competitive performance. We evaluate if they can benefit from the increased energy efficiency that the architecture is supposed to achieve. The applications that we consider cover three different classes of numerical solution methods for partial differential equations, namely a low-order finite element multigrid solver for huge sparse linear systems of equations, a Lattice-Boltzmann code for fluid simulation, and a high-order spectral element method for acoustic or seismic wave propagation modelling. We evaluate weak and strong scalability on a cluster of 96 ARM Cortex-A9 dual-core processors and demonstrate that the ARM-based cluster can be more efficient in terms of energy to solution when executing the three applications compared to an x86-based reference machine.

A demonstration of energy-efficient lighting in residential new construction

,!This field study uses a new model home demonstrating good lighting-design principles with energy-efficient solutions. Surveys showed that builders and the general public accepted and even preferred the appearance and the lighting effects of energy-efficient lighting technologies. Key to the success was integration with architectural features, colour schemes, and user lifestyle. Detailed survey results, energy savings, and illuminance comparisons are presented, as well as a discussion of ongoing barriers to the use of energy-efficient technology. Designers share ‘lessons learned’ from this design case study.

Energy efficiency policies in the OECD countries

Due to several reasons, ranging from environmental concerns to security of energy supplies, almost every country in the OECD implemented a host of energy efficiency policies. Although each government made its choice as to which kind of measures to take in order to deal with this subject, as well as how they would implement them, all of the analyzed programs fit into five basic categories, given below: (1) restrictive regulations, (2) information to the public, (3) creation of market asymmetries, (4) funding/loans programs and (5) state capital/private capital partnerships. Class 1 programs rely on restrictive legislation in order to ensure that manufactured/marketed products are in accordance with energy-efficiency performance standards. Class 2 initiatives aim at raising public awareness of energy-efficiency issues in order to achieve better market penetration of energy-efficient technologies, adoption of demand-side management and other desirable change in lifestyles and consumer behaviour. Class 3 measures work by tipping the scale in favour of energy-efficient technologies and appliances, either by offsetting economic disadvantages they might initially present or by circumventing any other structural barrier to their adoption/purchasing. Class 4 policies refer to purchasers and energy consumers that otherwise would not be able to make use of energy-efficient technologies because of their high initial costs. The Government gives funding or loans in order to offset this cost. Most of the partnerships in class 5 are research partnerships in which governmental departments set research goals and choose private research projects for financial funding through competitive solicitation processes. Other initiatives under this classification are free-of-charge state consultancy services. There are particular programs that fall into more than one of those ‘families’. Actually, initiatives in the third group are frequently a combination of measures from the first and second groups. Additionally, policies in class 5 are sometimes a mix of class 4 (funding) and 2 (information) measures. A comparative table will be assembled, where: (1) Each country will have its energy-efficiency policies classified as a regulatory program, informative campaign, creation of market asymmetry, funding/loan or partnership, with notes regarding overlapping of classes when it happens. Data will be tabulated with basic policy categories as columns; program names being entered in the proper places for their respective countries. (2) Programs will be described in brief, having their present results summarized or prognostics being given where current data only allow for that (data available August 2001). (3) Programs will be comparatively analyzed in each of the five basic policy categories. The overarching goal of this comparative table is to provide an initial basis for an applicability analysis of such policies to South America, being specifically aimed at the Brazilian energetic sector. It is part of a greater effort to achieve efficient energy use in Brazil.

Kyoto and Beyond

By the middle of the next century, the concentration of CO2 in the atmosphere will be twice preindustrial values, if current trends continue. The Intergovernmental Panel on Climate Change has concluded that the balance of evidence is that Earth's climate will warm as a result, although much uncertainty remains, particularly about local and regional effects. The effects of climate change go well beyond increases in temperature. Floods and droughts could become more common and severe. Sea levels are expected to rise by around 50 centimeters (give or take a factor of 2) over the next century. In the longer term, climate change could interfere with the Gulf Stream, which greatly warms the climate of northern Europe. Because of the long residence time of CO2 in the atmosphere, it takes around 100 years for a reduction in emissions to have an effect. The oceans' high heat capacity provides additional inertia. As heat diffuses slowly to the deeper oceans, it will cause further expansion, so even if there were no further change in climate (which would require a 60 decrease in CO2 emissions below current levels), sea levels would continue to rise for hundreds of years. As when turning a large ship, there are long lags between actions aimed at leveling off CO2 concentrations and actual stabilization of those concentrations. This is a strong argument for early action. The economic debate about reducing greenhouse gases tends to be split into two groups. One concludes that strong and early action is essential lest we (in President Clinton's words) burden our children with our failure to act. The other group is concerned that such action will be expensive, costing jobs and adversely affecting economic competitiveness. The naysayers' arguments deserve attention. But experience with environmental action in other areas, such as reducing sulfur emissions, chlorofluorocarbons, and lead in gasoline, suggests that abatement costs will turn out to be lower than initially feared. Several recent studies, including one by the U.S. Department of Energy, have suggested that significant reductions in greenhouse gas emissions are technically possible and can be made economically feasible, in large part by increasing the use of energy-efficient technologies. Many of these actions will bring other benefits, including increased industrial efficiency and thence competitiveness, and environmental gains such as improved air quality. The task of reducing emissions falls very broadly on all sectors of society. For example, the United Kingdom's emissions result about evenly from road transport (22), domestic uses (27), and industry (28); a miscellany of other categories (including other transport and heating and other energy use in shops and offices) makes up the remaining 23. The United Kingdom will hold a national consultation on a climate change program next year. The main features are likely to include more efficient production and use of energy in the main sectors of the economy, further drives to develop combined heat and power schemes and generate more electricity from renewable sources, and measures to create a more sustainable transport system. The United Kingdom already has a policy to increase taxation on road transport fuel at 6 above the rate of inflation each year. Much of the difference between the negotiating positions of the United States and the European Union (EU) derives from the United States' feeling that it will be harder for it to reach ambitious targets. This is largely because the United States is so far behind in addressing the problem of climate change; its emissions are projected to be around 13 higher in 2000 than in 1990. Per capita carbon emissions in the United States are double the EU average. We also need to think long. Whatever emissions target for 2010 is agreed upon at the third Conference of the Parties to the UN Framework Convention on Climate Change in Kyoto, Japan, on 1 through 10 December must only be a first step. Decisions that are effective in the short term must not hinder our options for meeting future reduction targets. The actions needed to address climate change will be impossible to accomplish unless the public is persuaded of the need for them. This is hard, because although the truly serious consequences lie decades in the future, the magnitude of tomorrow's problems depends crucially on today's actions. Our institutions are not well adapted to handling issues such as climate change, on which our long-term fate hinges.

‘No net cost in cutting carbon emissions’

washington A US government report says that the United States could reduce carbon emissions to 1990 levels by 2010 with no net cost to the nation's economy if it increased the use of energy-efficient technology.