Estimating the impacts of climate change and urbanization on building performance

Over the past 15 years, much scientific work has been published on the potential human impacts on climates. For their Third Assessment Report in 2001, the United Nations International Programme on Climate Change developed a set of economic development scenarios, which were then run with the four major general circulation models (GCM) to estimate the anthropogenesis-forced climate change. These GCMs produce worldwide grids of predicted monthly temperature, cloud, and precipitation deviations from the period 1961–1990. As this period is the same used for several major typical meteorological year data sets, these typical data sets can be used as a starting point for modifying weather files to represent predicted climate change. Over the past 50 years, studies of urban heat islands (UHI) or urbanization have provided detailed measurements of the diurnal and seasonal patterns and differences between urban and rural climatic conditions. While heat islands have been shown to be a function of both population and microclimatic and site conditions, they can be generalized into a predictable diurnal and seasonal pattern. Although the scientific literature is full of studies looking at the impact of climate change driven by human activity, there is very little research on the impact of climate change or urban heat islands on building operation and performance across the world. This article presents the methodology used to create weather files which represent climate change scenarios in 2100 and heat island impacts today. For this study, typical and extreme meteorological weather data were created for 25 locations (20 climate regions) to represent a range of predicted climate change and heat island scenarios for building simulation. Then prototypical small office buildings were created to represent typical, good, and low-energy practices around the world. The simulation results for these prototype buildings provide a snapshot view of the potential impacts of the set of climate scenarios on building performance. This includes location-specific building response, such as fuel swapping as heating and cooling ratios change, impacts on environmental emissions, impacts on equipment use and longevity comfort issues, and how low-energy building design incorporating renewables can significantly mitigate any potential climate variation. In this article, examples of how heat island and climate change scenarios affect diurnal patterns are presented as well as the annual energy performance impacts for three of the 25 locations. In cold climates, the net change to annual energy use due to climate change will be positive – reducing energy use on the order of 10% or more. For tropical climates, buildings will see an increase in overall energy use due to climate change, with some months increasing by more than 20% from current conditions. Temperate, mid-latitude climates will see the largest change but it will be a swapping from heating to cooling, including a significant reduction of 25% or more in heating energy and up to 15% increase in cooling energy. Buildings which are built to current standards such as ASHRAE/IESNA Standard 90.1-2004 will still see significant increases in energy demand over the twenty-first century. Low-energy buildings designed to minimize energy use will be the least affected, with impacts in the range of 5–10%. Unless the way buildings are designed, built, and operated changes significantly over the next decades, buildings will see substantial operating cost increases and possible disruptions in an already strained energy supply system.     

Carrots and sticks: A comprehensive business model for the successful achievement of energy efficiency resource standards

U.S. utilities face significant financial disincentives under traditional regulation in aggressively pursuing cost-effective energy efficiency. Regulators are considering some combination of mandated goals and alternative utility business model components to align the utility’s business and financial interests with state and federal energy efficiency public policy goals. We analyze the financial impacts of an Energy Efficiency Resource Standard on an Arizona electric utility using a pro-forma utility financial model, including impacts on utility earnings, ROE, customer bills and rates. We demonstrate how a viable business model can be designed to improve the business case while retaining sizable benefits for utility customers.     

Effect of fatigue loading-confining stress unloading rate on marble mechanical behaviors: An insight into fracture evolution analyses

Rocks in underground works usually experience rather complex stress disturbance. For this, their fracture mechanism is significantly different from rocks subjected to conventional triaxial compression conditions. The effects of stress disturbances on rock geomechanical behaviors under fatigue loading conditions and triaxial unloading conditions have been reported in previous studies. However, little is known about the dependence of the unloading rate on fatigue loading and confining stress unloading (FL-CSU) conditions that influence rock failure. In this paper, we aimed at investigating the fracture behaviors of marble under FL-CSU conditions using the post-test X-ray computed tomography (CT) scanning technique and the GCTS RTR 2000 rock mechanics system. Results show that damage accumulation at the fatigue stage can influence the final fracture behaviors of marble. The stored elastic energy for rock samples under FL-CSU tests is relatively larger compared to those under conventional triaxial tests, and the dissipated energy used to drive damage evolution and crack propagation is larger for FL-CSU tests. In FL-CSU tests, as the unloading rate increases, the dissipated energy grows and elastic energy reduces. CT scanning after the test reveals the impacts of the unloading rate on the crack pattern and a fracture degree index is therein defined in this context to represent the crack dimension. It shows that the crack pattern after FL-CSU tests depends on the unloading rate, and the fracture degree is in agreement with the analysis of both the energy dissipation and the amount of energy released. The effect of unloading rate on fracture evolution characteristics of marble is revealed by a series of FL-CSU tests.     

Knowledge,sustainability and corporate strategies in the European energy sector

The paper analyses the apparent position of the European Union and the largest European energy corporations concerning the energy future of Europe and the environmental impacts of their business activities. In contrast to growing public concern at the long-term environmental, economic and social consequences of the reliance on non-renewable energy sources, official words about sustainable development are copious, but ineffective in producing investment in public and private research and development expenditures in the energy sector. Apart from the economic and social problems of the innovation deficit of the European Union, the stagnant and shrinking expenditures also raise ethical dilemmas linked to the questions of intergenerational equity. If we believe that there are technological solutions to our environmental problems we should redefine the corporate responsibility in terms of knowledge production, use and dissemination, too.     

Residential cooling loads and the urban heat island—the effects of albedo

The urban heat island has become the target of recent research aiming at improving urban climates and energy efficiency of cities. In the warm, mid- and low-latitude cities, the typical heat island intensity averages up to 3–5°C on a summer day, adding to discomfort and increasing the air-conditioning loads, whereas in some temperate and cold, high-latitude cities a 2°C heat island is considered as a mild asset in winter. Some of these cities have been built to retain the urban heat. The objective of our ongoing research is to identify ways to mitigate summer heat islands in hot climates, for example by increasing the urban albedo, expanding evaporative surfaces and vegetation covers, and increasing urban thermal mass. From the energy consumption point of view, simple techniques such as these can be effective in reducing air-conditioning costs by modifying and improving the urban micro- and meso-climates.

In this work, we have correlated the residential cooling energy and power consumption in Sacramento, California, with the urban heat island intensity. The effects of selected strategies, such as the ones mentioned above, upon changing the urban micro-climate and reducing the heat island induced cooling loads were simulated. The main focus in this paper is placed on albedo. The simulations were performed using the DOE-2.1C building energy analysis program in conjunction with micro-climate and planetary boundary layer models that predict the effects of albedo modifications on ambient conditions and micro-climates. The simulations indicate that there exists significant potential energy and peak power savings by using such simple conservation strategies. Simulations for Sacramento indicate that whitewashing the buildings can result in direct savings of up to 14% and 19% on cooling peak power and electrical cooling energy, respectively. Modifying the overall urban albedo, in addition to whitewashing, can result in total savings of up to 35% and 62% respectively.     

Impacts of airtightening retrofits on ventilation rates and energy consumption in a manufactured home

A retrofit study was conducted in an unoccupied manufactured house to investigate the impacts of airtightening on ventilation rates and energy consumption. This paper describes the retrofits and the results of the pre- and post-retrofit assessment of building airtightness, ventilation, and energy use. Building envelope and air distribution systems airtightness were measured using fan pressurization. Air change rates were measured continuously using the tracer gas decay technique. Energy consumption associated with heating and cooling was monitored through measurement of gas consumption by the forced-air furnace for heating and electricity use by the air-conditioning system for cooling. The results of the study show that the retrofits reduced building envelope leakage by about 18% and duct leakage by about 80%. The reduction in the house infiltration rates depended on weather conditions and the manner in which the heating and cooling system was controlled, but in general these rates were reduced by about one third. The energy consumption of the house for heating and cooling was reduced by only about 10%, which is relatively small but not totally unexpected given that infiltration only accounts for a portion of the heating and cooling load.     

The reality and future scenarios of commercial building energy consumption in China

While China's 11th Five-Year Plan called for a reduction of energy intensity by 2010, whether and how the energy consumption trend can be changed in a short time has been hotly debated. This research intends to evaluate the impact of a variety of scenarios of gross domestic product (GDP) growth, energy elasticity and energy-efficiency improvement on energy consumption in commercial buildings in China using a detailed China End-Use Energy Model.China's official energy statistics have limited information on energy demand by end-use. This is a particularly pertinent issue for building energy consumption. The authors have applied reasoned judgments, based on experience of working on Chinese efficiency standards and energy-related programs, to present a realistic interpretation of the current energy data. The bottom-up approach allows detailed consideration of end-use intensity, equipment efficiency, etc., thus facilitating assessment of potential impacts of specific policy and technology changes on building energy use.The results suggest that: (1) commercial energy consumption in China's current statistics is underestimated by about 44%, and the fuel mix is misleading; (2) energy-efficiency improvements will not be sufficient to offset the strong increase in end-use penetration and intensity in commercial buildings; (3) energy intensity (particularly electricity) in commercial buildings will increase; (4) different GDP growth and elasticity scenarios could lead to a wide range of floor area growth trajectories, and therefore, significantly impact energy consumption in commercial buildings.     

Mitigating temperature increases in high lot density sub-tropical residential developments

Residential developments built with houses that use passive design features can have significantly reduced energy requirements for thermal comfort. In the context of global warming, this can reduce greenhouse gas emissions. The current trend towards higher lot density in residential developments and the resulting increase in thermal mass increases the associated heat island effect. Designers of future residential developments face the dual challenges of heat island impacts and any future global warming. Resource efficient house designs combined with approaches that mitigate the outdoor heat load must be considered and addressed from the design of the initial subdivision layout. Some land sub-division and house design initiatives are proposed for sub-tropical climatic conditions as prevailing in south-east Queensland, Australia. Computer simulations that account for heat island and global warming effects are used to estimate the indoor thermal performance of display houses constructed by a large scale property developer for current climate conditions and scenarios that may occur in the future. The use of north–south orientation of narrow building lots combined with high albedo house surfaces and the increased strategic use of shade trees for reducing the heat island effect of high density residential developments are presented. The cooling requirements of houses with high-energy rating (5 star or more) are found to be significantly superior to those with low rating (3.5 star) in scenarios of global warming.     

Efficiency of energy recovery ventilator with various weathers and its energy saving performance in a residential apartment

The energy recovery ventilator (ERV) is an effective method, which can transfer heat and moisture from the exhaust air into the outdoor fresh air to save energy in buildings. Nowadays, ERV has been widely used in the commercial, industrial and residential buildings in China. Its energy saving performance depends on a lot of factors, such as the outdoor environmental conditions, the enthalpy efficiency of the exchanger, and so on. Based on the relationship among sensible heat, latent heat and enthalpy efficiency, we analyzed the weighted coefficient equations for describing the performance of ERV in different climatic zones in China. According to China weather data, enthalpy efficiency of the exchanger mainly depends on sensible heat efficiency in winter and latent heat efficiency in summer. The energy simulations of a sample apartment in a residential building were made under different operation conditions to study the performance of ERV. The energy saving performances of the ERV were studied with five different outdoor climatic conditions, the enthalpy efficiency, fan power consumption of ERV and fresh air change rate. To improve energy saving performance, better efficient enthalpy exchange material and higher effiencient fans must be explored, while reasonable fresh air change rate as well as proper operation period according to local climate should also be carefully considered.     

Integrated research on subsurface environments in Asian urban areas

The RIHN project "Human impacts on urban subsurface environments" aims to suggest improved development plans of urban centers for human well-being. This will be done by examining reconstructed past changes in urban environments, and by developing integrated nature-social models. Subsurface environmental indicators are developed from the points of view of: (1) human activities; (2) climate change; and (3) character of urban development and social policies. Water, heat, and material environments and transport vectors are being evaluated by a number of different approaches. Some of these include investigating changes in groundwater resources using satellite observations, reconstructing effects of climate change and urbanization using subsurface thermal regimes, and evaluating past contamination patterns from preserved subsurface records. In this overview paper, we describe the current status of urbanization in Asia, subsurface water conditions, material and contaminant transport to surface waters by groundwater, and subsurface thermal anomalies due to the heat island effect. The rapid pace of urbanization in Asia requires that we develop a better understanding of how to deal with environmental impacts, both above and below ground.     

Erratum to “Integrated research on subsurface environments in Asian urban areas”

The RIHN project “Human impacts on urban subsurface environments” aims to suggest improved development plans of urban centers for human well-being. This will be done by examining reconstructed past changes in urban environments, and by developing integrated nature-social models. Subsurface environmental indicators are developed from the points of view of: (1) human activities; (2) climate change; and (3) character of urban development and social policies. Water, heat, and material environments and transport vectors are being evaluated by a number of different approaches. Some of these include investigating changes in groundwater resources using satellite observations, reconstructing effects of climate change and urbanization using subsurface thermal regimes, and evaluating past contamination patterns from preserved subsurface records. In this overview paper, we describe the current status of urbanization in Asia, subsurface water conditions, material and contaminant transport to surface waters by groundwater, and subsurface thermal anomalies due to the heat island effect. The rapid pace of urbanization in Asia requires that we develop a better understanding of how to deal with environmental impacts, both above and below ground.     

Sustainable energy policy for small-island developing state: Mauritius

Small-island states face a unique challenge. Their natural beauty, an asset as a tourist attraction, hides the fact that they have fragile ecosystems, vulnerable to climate change. They often rely on imported fossil fuel, even if they may have a potential for renewable energy. High population density may be an additional burden. A new paradigm for their development is necessary. The case of Mauritius as a sustainable island (Maurice Ile Durable or MID) is analyzed with focus on energy, considering intrinsically-related engineering, economic, environmental and ethico-socio-political dimensions. A holistic action plan is proposed for a transition towards a sustainable future.     

Energy consumption and refugee migration in Turkey

This study investigates the effects of refugee migration on energy consumption in Turkey. Our results reveal that: (i) the total number of refugees and the number of people in refugee-like situations reduce per-capita energy consumption in Turkey, (ii) changes in total refugees and people in refugee-like situations lead to significant changes in total energy consumption in Turkey. Hence, policymakers should consider the environmental and energy impacts along with social and economic impacts of refugee migration in the context of sustainable development.     

A simulation of the energy consumption monitoring in Mediterranean hotels: Application in Greece

Due to the competitiveness the importance of reducing cost and the growing sensitivity to environmental factors in the hotel design, is leading to the introduction of environmental friendly elements; if will be added the considerable increase in the cost of fossil fuel, it is obvious that all these factors create conditions favorable to the optimization of energy resources.     

Improving energy efficiency through the design of the building envelope

Buildings, their surroundings and related enterprises produce more CO₂, generate more pollution, consume more energy, and waste more natural resources than any other human enterprise or industry. Moreover, considerable parts of these environmental impacts are the results of the lodging industry [1].     

长壁孤岛工作面冲击失稳能量释放激增机制研究

煤矿开采中跳采形成的孤岛工作面由于容易产生应力集中，来压强度高，极容易发生冲击地压。基于唐山矿孤岛工作面的地质条件和周期来压步距的监测结果，通过数值分析的方法，研究孤岛工作面煤岩体能量释放的动态特征，揭示工作面前方能量释放激增机制，对比普通工作面和孤岛工作面能量场的区别，介绍冲击地压预警防治措施。数值模拟结果显示，长壁孤岛工作面回采时随着直接顶的随采随冒，采空区悬空面积的不断增大，使得老顶积聚大量的弹性能。若老顶发生周期性垮落，弹性能将瞬间释放，此时工作面和顺槽巷道极易冲击失稳。由研究结果可知，孤岛工作面周期来压时顶底板和煤层的能量激增可做为判断冲击失稳的前兆信息之一。因此，微震监测等手段可以根据此结论预测潜在的矿山动力灾害。针对老顶周期性断裂时积聚能量的突然释放规律，运用强制放顶、超前卸压孔、开切卸压槽和卸压爆破、煤层注水等技术可以提前释放煤层内积聚的弹性能，达到良好的冲击地压防治效果。     

Basic building life cycle calculations to decrease contribution to climate change – Case study on an office building in Sweden

This study examined whether simplified life cycle-based calculations of climate change contributions can provide better decision support for building design. Contributions to climate change from a newly built office building in Gävle, Sweden, were studied from a life cycle perspective as a basis for improvements. A basic climate and energy calculation tool for buildings developed in the European project ENSLIC was used. The study also examined the relative impacts from building material production and building operation, as well as the relative importance of the impact contributions from these two life cycle stages at various conditions.     

Automatic generation of energy conservation measures in buildings using genetic algorithms

Building energy simulations are key to studying energy efficiency in buildings. The state-of-the art building energy simulation tools requires a high level of multi disciplinary domain expertise from the user and many technical data inputs that curb the usability of such programs. In this paper an IT tool is presented, which has the capability of predicting a building's energy utilization configuration based on the reported annual energy and a few non-technical inputs from the user; and correspondingly generates cost effective energy conservation measures for the intended savings.The approach first identifies the system variables that are critical to a building's energy consumption and searches for the combination of these parameters that would give rise to the annual energy consumption as reported by the facility. Genetic algorithms are utilized to generate this database. A statistical fit is formulated between the system variables and the annual energy consumption from the database. Using this correlation, system configuration for the target energy efficiency is determined with corresponding energy conservation measures. A cost analysis is carried out to prescribe the most cost effective energy conservation measures. Competency of the tool is demonstrated in the paper through case studies on three geographies with different climate conditions.     

Do green roofs really provide significant energy saving in a Mediterranean climate?Critical evaluation based on different case studies

Green roofs represent a growing technology that is spreading increasingly and rapidly throughout the building sector. The latest national and international regulations are promoting their application for refurbishments and new buildings to increase the energy efficiency of the building stock. In recent years, vegetative coverings have been studied to demonstrate their multiple benefits, such as the reduction of the urban heat island phenomenon and the increase in the albedo of cities. On the contrary, this study aims to verify the actual benefit of applying a green roof on a sloped cover compared with installing a highly insulated tiled roof. The EnergyPlus tool has been used to perform dynamic analyses, which has allowed to understand the behavior of two different stratigraphies in accordance with weather conditions, rain, and irrigation profiles. Results have shown that the installation of a green roof cannot always be considered the best solution for reducing building energy consumption, especially if compared with a classic highly insulated clay tile roof. In terms of summer air conditioning, the maximum saving is 0.72 kWh/m2. The presence of water in the soil has also been proven a crucial factor.     

Policy options towards an energy efficient residential building stock in the EU-27

The EU-27 residential building stock offers high potential for energy efficiency gains. The policies already in place or proposed to improve the energy efficiency and thus the environmental performance focus on new buildings and major renovations of existing buildings. However, there might be additional measures that could lead to further energy efficiency improvements. In particular, the installation of roofs or windows that show a high thermal efficiency outside major renovations offer a large improvement potential. In this study, the potential environmental and economic impacts of two types of such policy options were analysed: first, measures that require high energy efficiency standards when roofs or windows have to be replaced; and, second, measures that accelerate the replacement of building elements. The results suggest that the two policies offer the potential for substantial additional energy savings. In addition, the installation of energy efficient building elements comes at negative net cost. When the replacement of building elements is accelerated, however, the additional costs do not outweigh the energy cost savings.