A multilayer photonic structure is described that strongly reflects incident sunlight while emitting heat selectively through an atmospheric transparency window to outer space; this leads to passive cooling under direct sunlight of 5 degrees Celsius below ambient air temperature, which has potential applications in air-conditioning and energy efficiency.

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Passive radiative cooling below ambient air temperature under direct sunlight

Brian Thompson is a Senior Nutrition Officer at the Food and Agriculture Organization of the United Nations (FAO). FAO is an intergovernmental organization, it has 191 Member Nations, two associate members and one member organization, the European Union. As a knowledge organization, FAO creates and shares critical information about food, agriculture and natural resources in the form of global public goods. FAO plays a connector role, through identifying and working with different partners with established expertise, and facilitating a dialogue between those who have the knowledge and those who need it. By turning knowledge into action, FAO links the field to national, regional and global initiatives in a mutually reinforcing cycle. Its mandate is to raise levels of nutrition and standards of living. What is the size of the malnutrition problem and what regions are most affected? There are persistently high levels of undernutrition. Nearly 870 million people in the world go to bed hungry (1 in 8 people) according to the recently released report of The State of Food Insecurity in the World 2012 (SOFI) and 2 billion have some form of micronutrient malnutrition – this constitutes a crime against humanity and is a responsibility for all of us. Prevalence of undernourishment in developing countries has declined over the past two decades, from 23 to 15 percent. In terms of total numbers in 1990– 92, around 980 million individuals were estimated to be undernourished. The number dropped to 901 million in 1999– 2001, to 885 million in 2006–06 and to 852 million in 2007–09. The financial crisis, economic downturn, persistent food price volatility, drought and other repercussions of climate change since 2006–08 may have prevented any further significant improvements in the number of people who are undernourished in developing countries since then. Africa has by far the highest prevalence, at around 23 percent in 2010–12 but though it is down from what it was in 1990–92 (27 percent) the numbers have risen from 175 million to 239 million with nearly 20 million added in the past four years. In subSaharan Africa, the modest progress achieved in recent years up to 2007 was reversed, with hunger rising 2 percent per year since then. In Asia, both prevalence and numbers dropped over the same period from 24 percent (739 million) to 14 percent (563 million). Latin America and the Caribbean (LAC) boasts the lowest rate of undernourishment (8 percent) among developing country regions but the rate of progress has slowed recently. Countries considered as leastdeveloped countries and lowincome economies have the highest prevalence rates of all around 30 percent but down from the 40 percent levels of twenty years ago.

Interview ラン・ラン

To bridge the gaps between traditional mesoscale modelling and microscale modelling, the National Center for Atmospheric Research, in collaboration with other agencies and research groups, has developed an integrated urban modelling system coupled to the weather research and forecasting (WRF) model as a community tool to address urban environmental issues. The core of this WRF/urban modelling system consists of the following: (1) three methods with different degrees of freedom to parameterize urban surface processes, ranging from a simple bulk parameterization to a sophisticated multi-layer urban canopy model with an indoor–outdoor exchange sub-model that directly interacts with the atmospheric boundary layer, (2) coupling to fine-scale computational fluid dynamic Reynolds-averaged Navier–Stokes and Large-Eddy simulation models for transport and dispersion (TD addresses the daunting challenges of initializing the coupled WRF/urban model and of specifying the potentially vast number of parameters required to execute the WRF/urban model; explores the model sensitivity to these urban parameters; and evaluates the ability of WRF/urban to capture urban heat islands, complex boundary-layer structures aloft, and urban plume T&D for several major metropolitan regions. Recent applications of this modelling system illustrate its promising utility, as a regional climate-modelling tool, to investigate impacts of future urbanization on regional meteorological conditions and on air quality under future climate change scenarios. Copyright © 2010 Royal Meteorological Society

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The integrated WRF/urban modelling system: development, evaluation, and applications to urban environmental problems

Zero Energy Building: A Review of Definitions and Calculation Methodologies

Building energy-consumption status worldwide and the state-of-the-art technologies for zero-energy buildings during the past decade

The U.S. Department of Energy (DOE) Building Technologies Program has set the aggressive goal of producing marketable net-zero energy buildings by 2025. This goal will require collaboration between the DOE laboratories and the building industry. We developed standard or reference energy models for the most common commercial buildings to serve as starting points for energy efficiency research. These models represent fairly realistic buildings and typical construction practices. Fifteen commercial building types and one multifamily residential building were determined by consensus between DOE, the National Renewable Energy Laboratory, Pacific Northwest National Laboratory, and Lawrence Berkeley National Laboratory, and represent approximately two-thirds of the commercial building stock.

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U.S. Department of Energy Commercial Reference Building Models of the National Building Stock

A net zero-energy building (ZEB) is a residential or commercial building with greatly reduced energy needs through efficiency gains such that the balance of energy needs can be supplied with renewable technologies. Despite the excitement over the phrase “zero energy,” we lack a common definition, or even a common understanding, of what it means. In this paper, we use a sample of current generation low-energy buildings to explore the concept of zero energy: what it means, why a clear and measurable definition is needed, and how we have progressed toward the ZEB goal. The way the zero energy goal is defined affects the choices designers make to achieve this goal and whether they can claim success. The ZEB definition can emphasize demand-side or supply strategies and whether fuel switching and conversion accounting are appropriate to meet a ZEB goal. Four well-documented definitions—net-zero site energy, net-zero source energy, net-zero energy costs, and net-zero energy emissions—are studied; pluses and minuses of each are discussed. These definitions are applied to a set of low-energy buildings for which extensive energy data are available. This study shows the design impacts of the definition used for ZEB and the large difference between definitions. It also looks at sample utility rate structures and their impact on the zero energy scenarios.

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Zero Energy Buildings: A Critical Look at the Definition

The excitement surrounding the drive to build and renovate commercial buildings to achieve exemplary and even “net zero performance,” coupled with the realization that complex systems engineering is usually required to achieve such levels, has led to a broader use of computer energy simulations. To provide a consistent baseline of comparison and save time conducting such simulations, the U.S. Department of Energy (DOE) – through three of its national laboratories – has developed a set of standard benchmark building models for new and existing buildings. These models represent a complete revision of the DOE benchmark buildings originally developed in 2006. The shapes, thermal zoning, and operation of the models are more indicative of real buildings than in the previous versions. DOE has developed 15 benchmark buildings that represent most of the commercial building stock, across 16 locations (representing all U.S. climate zones) and with three vintages (new, pre-1980, and post-1980 construction). This paper will provide an executive summary overview of these benchmark buildings, and how they can save building analysts valuable time. Fully documented and implemented to use with the EnergyPlus energy simulation program, the benchmark models are publicly available and new versions will be created to maintain compatibility with new releases of EnergyPlus. The benchmark buildings will form the basis for research on specific building technologies, energy code development, appliance standards, and measurement of progress toward DOE energy goals. Having a common starting point allows us to better share and compare research results and move forward to make more energy efficient buildings.

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DOE Commercial Building Benchmark Models

Commercial buildings have a significant impact on energy use and the environment. They account for approximately 18% (17.9 quads) of the total primary energy consumption in the United States (DOE 2005). The energy used by the building sector continues to increase, primarily because new buildings are added to the national building stock faster than old buildings are retired. Energy consumption by commercial buildings will continue to increase until buildings can be designed to produce more energy than they consume. As a result, the U.S. Department of Energy's (DOE) Building Technologies Program has established a goal to create the technology and knowledge base for marketable zero-energy commercial buildings (ZEBs) by 2025.

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Lessons Learned from Case Studies of Six High-Performance Buildings

A net zero-energy building (ZEB) is a residential or commercial building with greatly reduced energy needs through efficiency gains such that the balance of energy needs can be supplied with renewable technologies. Despite the excitement over the phrase ''zero energy'', we lack a common definition, or even a common understanding, of what it means. In this paper, we use a sample of current generation low-energy buildings to explore the concept of zero energy: what it means, why a clear and measurable definition is needed, and how we have progressed toward the ZEB goal.

Michael Deru

Papers

U.S. Department of Energy Commercial Reference Building Models of the National Building Stock

Zero Energy Buildings: A Critical Look at the Definition

DOE Commercial Building Benchmark Models

Lessons Learned from Case Studies of Six High-Performance Buildings

Zero Energy Buildings: A Critical Look at the Definition; Preprint