Energy consumption of bioclimatic buildings in Argentina during the period 2001–2008

The energy performance of two bioclimatic buildings located in Santa Rosa city, a temperate semi-arid agricultural region of central Argentina, is analysed. The bioclimatic design included direct solar gain, thermal inertia, natural ventilation, thermal insulation, external shading, building orientation, and dwelling grouping. Each double-story building is aligned on an East–West axis and it has a compact shape with 350 m² of useful floor area (58 m²/apartment). The solar collection area is around 18% of the apartment's useful area on the ground floor and 14% on the upper floor. This paper describes the energy performance of the buildings during the period 2001–2008. The analysis includes: (a) the energy consumption (natural gas and electricity) during 2001–2007 (natural gas: annually, bimonthly; electricity: monthly); (b) the natural gas consumption and the thermal behaviour during the winters of year 2001 (between July 27 and August 3) and 2008 (between August 8 and 13); (c) the daily natural gas consumption and the thermal behaviour during 2001 and 2008 winters; (d) the comparison between the energy consumption for heating in bioclimatic and conventional buildings. The authors concluded that the results confirm the large potential of solar buildings design to reach significant levels of energy saving. The comparison of solar and conventional buildings in terms of natural gas consumption demonstrates the magnitude of such potential.     

Residential energy use in one-family households with natural gas provision in a city of the Patagonian Andean region

Residential energy use was studied in one-family houses in the city of Bariloche, in the Patagonian Andean region of Argentina. A survey was conducted of households connected to the natural gas network to correlate use of gas, living area and number of inhabitants per house. The annual average consumption of gas was found to be 169 GJ, and consumption of electricity 8 GJ. This total energy use per household per year is almost double the average value reported for Stockholm, Sweden, although both locations have similar heating requirements. The difference was mainly due to heating energy consumption per unit living space, which in Bariloche was 1530 MJ/m² per year, while in Stockholm the average is around 570 MJ/m² per year. The high energy consumption in Bariloche is explained primarily by the construction characteristics of the buildings, and secondarily by the efficiency of the heating devices used. We were able to conclude that subsidies on natural gas tariffs given to the residential sector do not promote a rational use of the resource. Furthermore, almost 40% of the population (mostly households in poverty) are not connected to the subsidised gas resource, but pay prices for alternative fuels that are between 10- and 15 times higher. Policies to improve buildings and appliances would reduce emissions and make access to energy more equitable.     

Energy savings of office buildings by the use of semi-transparent solar cells for windows

The study investigated a PV window that consists of a double glazed window with semi-transparent solar cells. The window provides natural light transmission as well as electricity production. The effect of the PV window on energy consumption of office buildings was analyzed in terms of heating and cooling loads, daylighting, and electricity production. The purposes of the study were to find the optimum solar cell transmittance and window to wall ratio (WWR), and to estimate energy savings of the building. A standard floor of an office building was modeled to run computer simulation, and annual energy simulation was performed with EnergyPlus. The results showed that the solar cell transmittance of 40% and WWR of 50% achieved the minimum electricity consumption in the building when artificial lighting was controlled with daylighting. The optimum solar cell transmittance for PV windows in different orientation was also presented. By using the optimum PV window, the electricity consumption was reduced by 55% compared to the single glazed window with WWR of 30% and no lighting control.     

Estimation of energy intensity by end-use for commercial buildings

We describe the results of a study to estimate the energy intensities of major end-uses in commercial buildings in the PG&E service area. These energy intensities are central to commercial sector electricity and natural gas consumption forecasting models that utilize an end-use approach. The use of more accurate energy intensities will result in improved estimates of new power generation needs. To our knowledge, this is one of only three studies using the conditional demand approach for the commercial sector. This technique is less costly than end-use metering a large number of commercial buildings to arrive at energy intensity estimates. We obtained these energy intensity estimates for offices, food stores, restaurants, retail buildings, hotels and motels, hospitals, schools, warehouses, and miscellaneous buildings. We applied the conditional demand technique to monthly energy use, building characteristics, and weather data to produce annual estimates of natural gas and electricity use per square foot of floor space. The consumption estimates are for the following seven end-uses: space heating, cooling, lighting, water heating, cooking, refrigeration, and miscellaneous use.We have compared the results of our study to those of two other conditional demand studies and to other studies where data are available. Presently, there are few metered data available for comparison with our estimates. For most business types and end-uses, the energy intensity estimates appear reasonable. For example, for lighting, the mean energy intensity for each business type is within 20% of all the individual values from all comparable studies. Additionally, for each enduse, the highest energy intensity values occur for those business types that would be expected to show greatest utilization.However, for some end-uses in some business types, there are large discrepancies in energy intensity estimates obtained from various studies. For example, for restaurants, the energy intensity estimates for electric water heating and cooking each vary by more than a factor of seven from minimum to maximum. Additional research is needed to determine if such large variations in estimated energy intensities are real or if they are due to such factors as differences in business types (e.g. liquor stores may be included in retail or food stores), different distributions within a business type (e.g. different ratios of refrigerated to non-refrigerated warehouses), and different floor area definitions.     

Research on improving energy efficiency and the annual distributing structure in electricity and gas consumption by extending use of GEHP

The gas engine-driven heat pump (GEHP), which has been considered as a preferable choice in the heating and air-conditioning scheme can make full use of the waste heat from the engine and achieve a higher primary energy ratio (PER) than other forms of heating/cooling systems. In this paper, the relationship between the capacity characteristic of the GEHP and the heating and cooling loads of buildings has been analyzed. Meanwhile the reasons of the imbalance of the urban electricity and natural gas consumptions between summer and winter have been studied. The running characteristic of a water-to-water GEHP has been investigated experimentally and the PER was measured. Based on the analysis and experimental results, it could be concluded that if both the gas-fired boilers and electric air conditioners are replaced by GEHPs in some percentage, we can narrow the gaps between the requirement and provision of electricity and natural gas and balance the seasonal consumption differences of electricity and natural gas between summer and winter simultaneously. In order to improve energy efficiency, environmental quality and energy consumption structure effectively, the governmental incentive policies for promoting use of GEHPs should be formulated in China and some other developing countries.     

Statistical analysis of residential building energy consumption in Tianjin

To analyze the effect of energy conservation policies on energy consumption of residential buildings, the characteristics of energy consumption and indoor thermal comfort were investigated in detail in Tianjin, China, based on official statistical yearbook and field survey data. A comprehensive survey of 305 households indicates that the mean electricity consumption per household is 3215 kWh/a, in which annual cooling electricity consumption is 344 kWh/a, and the mean natural gas consumption for cooking is 103.2 m³/a. Analysis of 3966 households data shows that space heating average intensity of residential buildings designed before 1996 is 133.7 kWh/(m²·a), that of buildings designed between 1996 and 2004 is 117.2 kWh/(m²·a), and that of buildings designed after 2004 is 105.0 kWh/(m²·a). Apparently, enhancing the performance of envelops is effective in reducing space heating intensity. Furthermore, the results of questionnaires show that 18% of the residents feel slightly warm and hot respectively, while 3% feel slightly cold in winter. Therefore, the electricity consumption in summer will rise for meeting indoor thermal comfort.     

Thermal performance and environmental impact of residential buildings’ heating in Morocco

The seasonal energy requirements and fuel consumption for heating purposes in residential buildings are influenced by the architectural design, construction materials characteristics, meteorological temperature measurements, internal gains and air exchange rate of the building. The goal of this study is to assess the thermal performance and environmental impact of residential buildings’ in Morocco taking into account all these factors and considering two sources of energy: liquefied petroleum gas (LPG) and electricity. The study concludes that the heating energy requirements for the prototype building vary between 2 and 253 kWh/m².year depending on localities, glazing type, glazing area percentage, the internal gains and the air exchange rates. The electricity consumption is 2.6 times greater than that of LPG in terms of kg oil equivalent, and by using LPG instead of electricity the emissions of greenhouse gases can be 3.4 times reduced.     

Monthly natural gas demand forecasting by adjusted seasonal grey forecasting model

ABSTRACT

Natural gas stands out among fossil fuels because it is relatively cleaner. It is also an important energy source type for several fields such as electricity production, industry, and heating, etc. Due to the poor capacity of Turkey in terms of natural gas sources, the demand is supplied by producer countries. Hence, accurate forecasting for the demand is of critical importance for Turkey, which imports 99% of its natural gas consumption. In the current literature about demand forecasting, most studies were conducted on an annual basis. However, the seasonal effect on the demand for natural gas cannot be foreseen through annual studies. Besides, to deal with some situations such as seasonal balancing, peak shaving, and gas supply shortage in monthly demand, forecasting models that capture the seasonal trend are needed. Therefore, in this study, a new grey seasonal forecast model has been presented and Turkey’s monthly natural gas demand was predicted via the proposed model. Performance of that model was compared with SGM(1,1) and SARIMA (p,d,q) x (P,D,Q)^s. The obtained results show the superiority of the proposed model. By using this model, Turkey’s monthly natural gas demand was forecasted up until the year 2025. The proposed model allows us to capture seasonal patterns more successfully. In case this seasonal behavior continues, Turkey’s natural gas demand is expected to increase by %20 until 2025. At this point, the outcomes of the study provide important information to decision-makers to be able to determine reliable and stable energy policies.     

Spatial and temporal analysis of energy use data in Los Angeles public schools

School buildings are significant energy consumers. They are important targets for energy efficiency improvements, which can reduce energy spending and meet energy policy goals for state and federal governments. In the US, few studies have quantified electricity and natural gas consumption patterns in schools. Such information vitally supports energy planning and benchmarking. We present an analysis of high-detail electricity and natural gas consumption for schools in Los Angeles County over an extended period of time. Using a robust database of monthly account-level consumption, we examine electricity and natural gas consumption trends for hundreds of schools in relation to key structural and categorical characteristics, including size, geography, and school type. Results show that school energy use varies greatly across socio-demographic, structural, and climate factors. Correlations between electricity and natural gas consumption are time dependent and seasonally distinct. The analysis provides a useful case study with benchmarks for US public schools and demonstrates challenges with devising large-scale studies of school energy use. We conclude with a discussion of policy implications.     

Stochastic assessment of the energy performance of buildings

A building’s energy performance is a complex multi-dimensional metric consisting of a variety of parameters. Presented herein are the results of a stochastic analysis of the factors affecting a building’s energy performance. The analysis is based on the Dwelling Energy Assessment Procedure (DEAP) (amended for cooling loads) and the general guidelines prescribed by the European Energy Performance of Buildings (EPBD) Directive 2010/31/EU. Modifications to the DEAP model are made for investigating the effect of variable external weather conditions on a building’s energy performance, and to incorporate the additional energy requirement for cooling. Subsequently, a stochastic analysis for three dwelling types is performed to assess the impact of 68 factors on the energy performance of buildings, for 12 different regions in Europe. It is concluded that (1) the factors with the greatest impact on energy use are in descending order, the floor area, external weather conditions, dwelling’s envelope u value (roof, window, walls, and floors), the space heating system, ventilation, windows area and walls area; (2) the energy performance of a building follows a lognormal probability distribution function; (3) buildings in colder EU regions exhibit higher energy profiles and higher variability in their energy profiles than those in warmer regions.     

Response of conventional and energy-saving buildings to design and human dependent factors

During the year 2000, energy-efficient buildings for low-income students at La Pampa University were designed and constructed. Buildings are located at the centre of La Pampa province, in a temperate semi-arid region of central Argentina Socio-economic, educational and environmental reasons have driven the design. Energy conservation devices, passive solar heating, natural ventilation and solar protection were the main strategies. The resulting design comprises two blocks of apartments with a useful floor area of 700 m² and main spaces. Two bedrooms, a dining room and essential services make up each apartment. Solar windows are provided for all main spaces. Northern shading devices and metallic pergolas protect all windows in summer. Once the building was finished, a monitoring plan started on December 2000. This paper shows the results of the thermal and energy behavior of apartments. The evolution of internal temperature was different in each apartment. The consumption of natural gas varied among dwellers, but the volume consumed was lower than that of conventional dwellings. Without extra building cost dwellers live under good higrothermal conditions at 50% of the auxiliary energy consumed by conventional dwellings.     

Opportunities for low carbon sustainability in large commercial buildings in China

China's building sector consumes one quarter of total energy consumption in the country and plays an important role in long-term ability of the country to achieve sustainable development. This paper discusses a comprehensive approach to achieving low carbon sustainability in large commercial buildings in China incorporating both energy and carbon-reduction strategies. The approach concentrates primarily on three complementary aspects: (a) the introduction of an effective energy management system; (b) the incorporation of relevant advanced energy saving technologies and measures and (c) the promotion of awareness among occupants to make changes in their behaviour towards a more environmental-friendly behaviour. However, reference is also made to the role that renewable energy and offsetting may have in the effective management and environmental performance of buildings.Nine examples of large commercial buildings in Beijing and Shanghai were studied and the average electricity consumption of around 153 kWh/m² per annum is about 5 times higher than average electricity use in residential buildings. At the same time the associated green house gas (GHG) emissions are around 158 kg/m² per annum.     

Investigation of photovoltaic-hydrogen power system for a real house in Turkey: Hydrogen blending to natural gas effects on system design

In the study, the effects of hydrogen mixing studies at the rate of 20% to the natural gas system which is an ongoing study in Turkey, on the photovoltaic system (PV) is investigated using a real house consumption. Providing the annual electrical energy consumption (1936,83  kWh) and 20% of natural gas consumption (62,4 m³) of a real house with hydrogen is included in the study. A PV-hydrogen system is theoretically investigated to provide the energy required for hydrogen production from solar panels. Hydrogen blending effects on PV size, capacity usage, and carbon footprint are analyzed. Thus, the contribution was also made to the “green hydrogen” works and reduction of the carbon footprint of the house. It was found that the required hydrogen for electricity can be provided 52,5 m² solar panel area and 14,28% increase in this area and installed power can provide an amount of hydrogen that need for 20% hydrogen blending to the natural gas system. The overall system capacity usage decreased when the system is used for 20% hydrogen blending to the natural gas system. The carbon footprint of the house was decreased by 67,5%. If the hydrogen has not been blended with 20% natural gas, this ratio would have been 59,2%.     

The use of sub-hourly primary meter data to identify electricity savings in municipal buildings

Sub-hourly electricity consumption data is being routinely collected from non-domestic buildings in European countries, yet there is little published guidance on how to analyse this data. A new analysis technique is described that produces electricity load profile indicators to help identify potential electricity savings from 81 municipal buildings of six different types: commercial and public offices, libraries and museums, sport centres, schools, community centres and care homes/hostels. This approach is different from conventional energy management analysis techniques since it uses total electricity consumption data in half-hourly periods rather than annual or monthly data. The analysis enabled the detection of buildings with consumption profiles that differ significantly from the typical profile for that building type. This provided a systematic and rapid procedure to identify potential energy saving opportunities in multiple buildings. The new approach introduces a standard statistical technique, independent of energy manager judgement, to help identify energy saving opportunities in buildings.     

Improving the prediction of UK domestic energy-demand using annual consumption-data

The ability to predict how changes in patterns of usage in different types of dwelling can affect energy consumption is important if efforts to reduce demand and carbon emissions are to be effective. This paper describes an approach using a questionnaire survey, supported by annual gas and electricity meter data and floor-area estimates derived from a GIS. Clusters of higher and lower energy consumers were discovered and these were related to indicators of energy consumption. Simple and multiple regression were used to determine the strength of the relationships and identify the most statistically-significant indicators of differences in gas and electricity consumption. Although significant effects of the built-form type were not observable in the data available, the effects of related measurable and countable aspects of form, such as floor-area and numbers of rooms, were seen. Significant relationships were found with the number of bedrooms and regular home working, which may reflect changes in UK households that are expected to drive future energy-consumption. Implications for zonal domestic energy-models are noted.     

Techno-economic analysis of a hybrid energy system for CCHP and hydrogen production based on solar energy

A typical problem in Northeast China is that a large amount of surplus electricity has arisen owing to the serious photovoltaic power curtailment phenomenon. To effectively utilize the excess photovoltaic power, a hybrid energy system is proposed that uses surplus electricity to produce hydrogen in this paper. It combines solar energy, hydrogen production system, and Combined Cooling Heating and Power (CCHP) system to realize cooling, heating, power, and hydrogen generation. The system supplies energy for three public buildings in Dalian City, Liaoning Province, China, and the system configuration with the lowest unit energy cost (0.0615$/kWh) was obtained via optimization. Two comparison strategies were used to evaluate the hybrid energy system in terms of unit energy cost, annual total cost, fossil energy consumption, and carbon dioxide emissions. Subsequently, the annual total energy supply, typical daily loads, and cost of the optimized system were analyzed. In conclusion, the system is feasible for small area public buildings, and provides a solution to solve the phenomenon of photovoltaic power curtailment.     

Energy performance of residential buildings in Singapore

Energy consumption of buildings takes up about a third of Singapore's total electricity production. In this paper, we present a pioneering study to investigate the energy performance of residential buildings. Beginning with an energy survey of households, we established the air-conditioning usage patterns and modelled residential buildings for computer simulations. An ETTV equation for residential buildings was developed. Employing this equation, we demonstrated how to achieve improved energy efficiency in residential buildings. Two types of residential buildings, namely, point block and slab block, were modelled and parametric runs performed. ETTV impacts the energy consumption of residential buildings and thus lowering the ETTV will result in reduced building heat load. Results from the developed equation showed that a unit decrease in ETTV resulted in 4% and 3.5% reduction in annual cooling energy for point block and slab block residential buildings, respectively. In addition, a set of simple energy and load estimating equations were developed using computer simulation and local climatic data. These equations provided a means of estimating the annual cooling energy consumption of residential buildings in Singapore.     

夏热冬暖地区办公建筑能耗模拟与分析

夏热冬暖地区是我国经济和建筑产业最发达的地区之一,也是建筑能耗最多的地区之一。分析和研究夏热冬暖地区建筑能耗的特点对建筑节能有重要的意义。本文用eQUEST建筑能耗模拟软件模拟了夏热冬暖气候下不同的建筑围护结构的能耗性能,并与实际调查结果进行了比较。结论表明:办公类建筑中的空调是最大的能耗终端,全年的能耗以办公设备和照明的能耗最稳定。有外保温措施和同时具有内、外保温措施最大区别在于节省空调电力消耗31.3%和39.1%。说明建筑外墙保温系统是建筑节能的重要手段。     

Comparing prospective hydrogen pathways with conventional fuels and grid electricity in India through well-to-tank assessment

The present study uses Greenhouse Gases, Regulated Emissions, and Energy Use in Technologies Model (GREET), to compare hydrogen generated via multiple pathways (Natural gas, methanol reforming; coal, petcoke, biomass gasification etc) with the conventional fuels like diesel and compressed natural gas and grid electricity under Indian context through a comprehensive well to tank assessment based on net CO₂ equivalent emission and energy consumption. Limited availability of customized studies comparing hydrogen production and supply with other energy options in India distinguishes the present work as it provides a fresh insight into potential pathways for hydrogen production while assessing feedstock availability and raw water consumption. The study reveals that biomass gasification and solar electrolysis are among the least GHG emitting pathways to fill one unit of energy equivalent in the tank. Hydrogen produced through natural gas reforming is 70% less emission intensive and 38% more energy efficient than Indian grid electricity.