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1.
Engineering models of the physical processes of energy use in individual houses are quite complex. We investigate simple statistical models of summer electricity use and compare them to engineering models. Our data include interviews, energy audits, and utility billings for a random sample of residences in Davis, California. We predict summer kWh using appliance and cooling-load models. The appliance model is based on manufacturers' or published data on average annual kWh used by major appliances; refinements for appliance location, seasonality and frequency of use have mixed success. The cooling-load model includes the major variables used in the DOE 2.1A simulation; coefficients estimated by a multiple regression model closely resemble interpolation parameters derived from DOE 2.1A. The appliance and cooling-load models explain over 50% of the variation in summer kWh in single-family detached houses. Using the appliance model and only two variables from the cooling-load model, house area and self-reported frequency of air-conditioner use, we explain nearly 60% of summer kWh in houses. The simple interview question on frequency of air-conditioner use captures most of the effects of structural features such as insulation and glazing. Finally, the appliance and cooling-load models are applied successfully to other house types (common-wall houses and apartments).  相似文献   

2.
In this paper different window energy rating systems (WERS) are evaluated and compared. The comparisons are made for different European climates, types of buildings and orientations. The purpose of the paper is to evaluate how complex a WERS needs to be in order to be able to provide a reliable energy rating which can be applied to different buildings in different climates and orientations. The results indicate that Europe needs to be separated into several different climate zones. A simple linear heating energy-rating model of the form AgBU (where g is the total solar energy transmittance, U is the thermal transmittance of the window, and A and B are empirical coefficients), may be sufficient within certain regulations. For warm locations a linear cooling energy rating, depending only on the g factor may also yield an acceptable rating. More advanced models that take the building type into account and that use hourly climate files showgood fit with building simulation programs.  相似文献   

3.
The skytherm system, a roof covered with water filled plastic bags equipped with moveable insulation, is studied and a model is presented to predict its thermal behavior. A computer program is written to calculate hourly cooling and heating load requirements of a building and is validated by comparison with field data taken from an actual house in Shiraz, Iran. This program is then used to simulate metal and concrete skytherms. It is shown that for a 140.55 m2 one story house, the skytherm system is capable of reducing heating demands by 86% and cooling loads by 52%.  相似文献   

4.
5.
In this paper an experimental research is presented on a new use of Phase Change Materials (PCMs) in concrete floors, in which thermal energy provided by the sun is stored in a mix of concrete and PCMs. When this thermal energy is being released - in moderate sea climates during the evening and early night - it is aimed to reduce the need for thermal energy of conventional heating in houses. The temperatures of four concrete floors in closed environments were monitored to reflect on the influence of PCMs and type of insulation in relation to ambient temperatures and solar irradiation. The application of PCMs in concrete floors resulted in a reduction of maximum floor temperatures up to 16 ± 2% and an increase of minimum temperatures up to 7 ± 3%. The results show the relevance of an integral design in which the thermal resistance of the building shell, the sensible heat capacity of the building and the latent heat capacity of the PCMs are considered simultaneously.  相似文献   

6.
Energy retrofitting of existing buildings is a central challenge for local, national, and international climate policies, and in several countries, single-family houses represent a major energy-saving potential. Although many municipalities are implementing local climate policies with initiatives to promote energy retrofitting of buildings, little research has been done regarding the role of single-family houses in local climate policies. Thus, we have little knowledge about specific initiatives to promote energy retrofitting amongst owners of single-family houses, we know little about experience from such initiatives, and we lack knowledge about the extent to which national and EU policies support local initiatives directed at homeowners. This article provides insights into these issues from an explorative study on local climate strategies in Danish front-runner municipalities where single-family housing is the dominating building segment. Based on a study of local governance strategies in 12 municipalities targeting homeowners’ engagement in energy retrofitting, the paper finds that these municipalities have developed promising local network-based ways to engage homeowners in energy retrofitting, but finds simultaneously that the national policy mix is only partly supporting these local initiatives. The paper also points out that the local and regional context for the programmes, including the local economic situation, is of great importance, and this context creates both potentials and challenges for the local programmes.  相似文献   

7.
This paper presents a method for the estimation of potential impact of climate change on the heating energy use of existing houses. The proposed method is based on the house energy signature that is developed from historical energy use data. The method can be applied to any individual house, by using the utility bills from the owner, or can be used by utility companies, which have databases of recorded energy use for large number of houses. The second case can lead to accurate estimates of potential impact of climate change within a city, a province or a country. A case study of a house in Montreal (Canada) is presented, and the results obtained with different sampling rates of data are discussed. The method is also applied to a sample of 11 existing houses, and the results show the reduction of heating energy use between 7.9% and 16.9% due to climate change between the present period (1961–1990) and the future period (2040–2069).  相似文献   

8.
Improved energy efficiency is a key policy goal of all International Energy Agency (IEA) member countries, but tracking energy efficiency gains is not straightforward. As part of its contribution to the G8 Gleneagles Plan of Action, the IEA has been developing in-depth indicators—tools that provide data and analysis of energy use and efficiency trends. This paper gives an overview of the IEA indicator methodology and presents examples of how disaggregated indicators can be used to identify the factors that drive and restrain energy demand at the end-use level. A decomposition approach is also used to separate efficiency effects from the impacts of structure and activity. The results clearly show the important role that energy efficiency has played in shaping trends in final energy use in IEA countries for more than 30 years. However, the analysis also reveals that recent gains in energy efficiency have been much lower than in earlier decades. Accelerating energy efficiency improvements is therefore a crucial challenge for IEA governments and indicators have an important role to play in helping to develop and evaluate the policies that will be required.  相似文献   

9.
The high cost of lithium ion batteries is a major impediment to the increased market share of plug-in hybrid electric vehicles (PHEVs) and full electric vehicles (EVs). The reuse of PHEV/EV propulsion batteries in second use applications following the end of their automotive service life may have the potential to offset the high initial cost of these batteries today. Accurately assessing the value of such a strategy is exceedingly complex and entails many uncertainties. This paper takes a first step toward such an assessment by estimating the impact of battery second use on the initial cost of PHEV/EV batteries to automotive consumers and exploring the potential for grid-based energy storage applications to serve as a market for used PHEV/EV batteries. It is found that although battery second use is not expected to significantly affect today's PHEV/EV prices, it has the potential to become a common component of future automotive battery life cycles and potentially to transform markets in need of cost-effective energy storage. Based on these findings, the authors advise further investigation focused on forecasting long-term battery degradation and analyzing second-use applications in more detail.  相似文献   

10.
The efficient use of energy is a key component of current efforts to reduce carbon emissions. There are two factors which are important when assessing the potential gains from energy efficiency technologies: the scale of energy flow and the technical potential for improvement. However, most efficiency analyses consider only the potential gains from known efficiency technologies, while ignoring the complex flow of energy through the chains of conversion devices. In response, this paper traces the global flow of energy, from fuels through to the final services, and focuses on the technical conversion devices and passive systems in each energy chain. By mapping the scale and complexity of global energy flow, the technical areas which are likely to deliver the largest efficiency gains can be identified. The result is a more consistent basis for directing future research and policy decisions in the area of energy efficiency.  相似文献   

11.
Sugarcane energy use: The Cuban case   总被引:1,自引:0,他引:1  
This paper examines the history, methods, costs, and future prospects of Cuba's attempts to develop the energy potential of sugarcane. An overview of the main factors affecting the current sugarcane agro-industry in Cuba is provided, along with an analysis of why, despite attempts by the Cuban government to revive the country's sugarcane agro-industry, the industry continues to decline.

The prevailing conditions and degree of modernization in Cuban sugar factories are evaluated. The sugar-agro industry's main production bottlenecks are studied. The fall in sugarcane yield from 57.5 ton/ha in 1991 to 22.4 ton/ha in 2005 and its relation to land use is explained. The socio-economic impact of the sugarcane agro-industry's downsizing is assessed. The governmental and quasi-governmental entities in charge of sugarcane energy use development and the country's legal framework are analyzed. The Cuban sugarcane agro-industry's opportunities in the growing international biofuels and bioenergy market are evaluated. To situate Cuba within the global bioenergy market, international best practices relating to the production and commercialization of biofuels are examined to determine the degree to which these experiences can be transferred to Cuba.

The analysis of the Cuba sugar industry's biofuel potential is based on a comparative technical–economic assessment of three possible production scenarios: (1) the current situation, where only sugar is produced; (2) simultaneous production of sugar–anhydrous ethanol; and (3) production of sugar–ethanol and simultaneous generation of surplus electricity exported to a public grid.

Some of the key assumptions underlying these analyses are as follows: Ethanol production and operation costs for a 7000 ton/day-sugar mill are estimated to be 0.25 and 0.23 USD/l, respectively. The influence of gasoline prices on sugar–ethanol production is also assessed. The kWh production and operation costs starting from sugarcane bagasse are estimated at 0.06 and 0.04 USD, respectively. Cuba's potential sugarcane cogeneration capacity is estimated to be 9006 GWh/year. Investment–profit analyses are offered for two scenarios: annexing a 300,000 l/day distillery to a sugar mill, and enlarging the cogeneration capacity of a 7000 ton/day mill. Added production cost/added-value analysis was carried out. The main environmental issues associated with sugarcane-based fuel production are also analyzed.  相似文献   


12.
介绍了适于北方农村地区应用的低能耗住宅的设计方案,阐述了其工作原理及其使用效果.设计方案充分利用了生物质能和太阳能等可再生能源,设置了利用秸秆进行冬季采暖的地下燃池和太阳能空气集热器.该方案在农村应用,既解决了多余的农作物秸秆利用问题,也节省了采暖费用,在一个采暖期平均每户节约采暖费用1000元.  相似文献   

13.
Vehicle trials with the first sodium/nickel chloride ZEBRA batteries indicated that the pulse power capability of the battery needed to be improved towards the end of the discharge. A research programme led to several design changes to improve the cell which, in combination, have improved the power of the battery to greater than 150 W kg−1 at 80% depth of discharge. Bench and vehicle tests have established the stability of the high power battery over several years of cycling. The gravimetric energy density of the first generation of cells was less than 100 Wh kg−1. Optimisation of the design has led to a cell with a specific energy of 120 Wh kg−1 or 86 Wh kg−1 for a 30 kWh battery. Recently, the cell chemistry has been altered to improve the useful capacity. The cell is assembled in the over-discharged state and during the first charge the following reactions occur: at 1.6 V: Al+4NaCl=NaAlCl4+3Na; at 2.35 V: Fe+2NaCl=FeCl2+2Na; at 2.58 V: Ni+2NaCl=NiCl2+2 Na. The first reaction serves to prime the negative sodium electrode but occurs at too low a voltage to be of use in providing useful capacity. By minimising the aluminium content more NaCl is released for the main reactions to improve the capacity of the cell. This, and further composition optimisation, have resulted in cells with specific energies in excess of 140 Wh kg−1, which equates to battery energies>100 Wh kg−1. The present production battery, as installed in a Mercedes Benz A class electric vehicle, gives a driving range of 205 km (128 miles) in city and hill climbing. The cells with improved capacity will extend the practical driving range to beyond 240 km (150 miles).  相似文献   

14.
This paper estimates models of electricity and gas consumption for individual households using the Miracle 4 to 6 data sets collected by San Diego Gas and Electricity Company. Two types of model were constructed: the first involves typical end-use models with consumption explained by appliance ownership, household demographic characteristics, house dimensions and household income; the second class uses these variables plus consumption data for the previous year. The latter models consistently fitted better, while the end-use variables afforded little explanatory power. The results thus suggest that simple end-use models are of little value, at least for short-run forecasting. Their use for long-run forecasting has yet to be evaluated.  相似文献   

15.
The main purpose of this article is to highlight the problems inherent in some basic mathematical assumptions used in the formulation of models, and to show how these assumptions influence the results derived from the models. The author analyses and criticizes three energy policy models; the World Oil Model; the MIT Energy Self- Sufficiency Study; and Project Independence. The author also aims to show that failure to consider non-quantifiable factors when assessing the models' results can lead to misleading conclusions.  相似文献   

16.
王默晗 《节能》2005,(5):36-39
太阳能光伏发电是利用太阳能电池这种半导体电子器件有效地吸收太阳光辐射能,并使之转换成电能的直接发电方式。开发利用太阳能这种可再生的清洁能源发电是解决能源短缺、保护环境的重要途径。本文概述了太阳能光伏发电技术的研究情况,根据传热学及相关知识建立数学模型,并运用Lab VIEW软件对该系统进行动态模拟与仿真。  相似文献   

17.
Richard Mogg 《Refocus》2001,2(9):12-17
For Indonesia's myriad smaller islands, as well as for rural locations that cannot be economically connected to the grid, electric power development strategy is increasingly seen more in terms of the country's abundant renewable energy resources. Hydro, biomass, solar and wind energy are being explored for their potential to generate power, to lessen national dependence on fossil fuels. Expert attention today is focused on exploiting the huge geothermal potential of the spectacular mountain ranges in Java and Sumatra, volcanic Indonesia's so-called “Ring of Fire”. Richard Mogg, Lanna Blue Bangkok reports on geothermal energy production and use in the region.  相似文献   

18.
方毅立 《节能》2003,(12):16-18
本文从变压器选择、配电系统和绿色照明等三个方面讨论了住宅小区节能设计的方法及实现的途径。  相似文献   

19.
An adhesion map provides quantitative criteria for the appropriate selection of adhesion models applicable to a specific adhesive contact problem of fine particles in complex particulate flows. In this paper, three different general adhesion models are used to construct adhesion maps. The applicable regimes on the adhesion map for different approximate adhesion models are determined according to their underlying limitations. It is found that the choice of general model has limited influence on the structure of a constructed adhesion map. On the contrary, the regime of application for each approximate model is sensitive to the approximation level. A three-dimensional, more intuitive adhesion map based on physical parameters of particles is also built. Finally, recent applications of adhesion models in discrete element method (DEM) investigations of fine-particle flow dynamics are briefly discussed.  相似文献   

20.
M.A. Rosen 《Solar Energy》1998,63(2):69-78
The results are reported of an energy-economic analysis of the use of berms in thermal energy storage (TES) systems. The analysis compares the initial cost savings derived from using a bermed tank instead of an in-ground tank, with the additional costs associated with the greater heat losses for the bermed tank over the life of the installation. The main factors considered include: (1) the increased excavation associated with an in-ground tank, (2) the increased wall structural support required for an in-ground tank, (3) the haulage and disposal of excavated soil for an in-ground tank, compared with the haulage and disposal or acquisition of soil for a bermed tank, (4) the forming of soil into a berm, and (5) the increased heat loss associated with a bermed tank. In evaluating the last factor, the findings of previous studies are used by the author into the effects of berms on TES heat losses. As space for the berm is assumed available, the cost associated with any land additionally required for the berm is neglected. The results indicate that tanks having berms are, in most practical instances, economically superior to other tank configurations.  相似文献   

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