Evaluation on energy and thermal performance for residential envelopes in hot summer and cold winter zone of China

As a result of rapid economic growth in the last several decades, energy issue is becoming more and more important in today’s world because of a possible energy shortage in the future; the usage of residential electricity has increased rapidly in China and building energy efficiency is included as one of the 10 key programs targeting energy efficiency improvement in the 11th Five-Year Plan. In response to the growing concerns about energy conservation in residential buildings and its implications for the environment, systematic evaluation on energy and thermal Performance for residential envelops (EETP) is put forward to assess the energy efficiency of envelop designs and to calculate the energy consumption of cooling and heating systems. Hot summer and cold winter zone of China was selected for EETP analysis because of its rigorous climatic and huge energy consumption. The correlations between EETPs and electricity consumptions in cooling season, heating season, and the whole year were built in Shanghai, Changsha, Shaoguan and Chengdu, which represent A, B, C and D subzone of hot summer and cold winter zone in China, respectively. Illustrations indicate that the algorithm is simple and effective, energy and thermal performance of residential envelopes can be evaluated easily. The maximum allowable values of EETPs were determined when just meeting the compulsory indices of Standard JGJ134-2001, the corresponding allowable EETPs were also gained when achieving different energy-saving degrees on basis of it. EETP method can suggest possible ways to improve the energy efficiency for envelope designs of new building and retrofits of existing buildings and provide governments some useful information for the establishment of new policy on energy efficiency buildings. It has important meanings to carry out sustainable residential building designs with high thermal comfort and low energy consumption.     

Technology diffusion and energy intensity in US commercial buildings

This paper analyzes the 1992 and 2003 US Commercial Buildings Energy Consumption Survey microdata files to show the extent to which certain heating, cooling, lighting, and window technologies are entering use, and the resulting impacts on the intensity of energy use. Excepting the case of fluorescent lights, no technology dominates the entire market but instead each conquers a specific niche. Most of the buildings in which these technologies are installed do not have lower-than-average energy intensity, measured as annual energy use per square meter of floor space. The exceptional technology that does measurably correlate with reduced energy intensity is daylighting. These results suggest that technologies are adopted to serve comfort or quality objectives rather than to save energy, or that buildings’ users confound the designers’ intentions. Decision makers thus should improve operating and maintenance practices, invest in building commissioning, and rely more heavily on passive design features to save energy.     

Novel heating and cooling concept employing rainwater cisterns and thermo-active building systems for a residential building

This paper introduces and evaluates a novel heating and cooling concept employing thermo-active building systems and environmental energy, harnessed from two 11-m³ rainwater cisterns for a 285-m² residential building in passive house standard in Germany. The building strives for a significantly reduced primary energy use with carefully coordinated measures, such as high quality building envelope, by means of vacuum insulated panels, supply and exhaust air system with heat recovery, reduced solar heat gains (solar shading), and the integration of thermal solar collectors and photovoltaic in the plant system. On this premise, a comprehensive long-term monitoring in high time-resolution was carried out for the building for two years with an accompanying commissioning of the building performance. Measurements comprise the energy use for heating, cooling, and ventilation, as well as the auxiliary equipment, the performance of the environmental heat source and sink (rainwater cistern), thermal comfort, and local climatic site conditions.     

District heating and energy efficiency in detached houses of differing size and construction

House envelope measures and conversion of heating systems can reduce primary energy use and CO₂ emission in the existing Swedish building stock. We analysed how the size and construction of electrically heated detached houses affect the potential for such measures and the potential for cogenerated district heating. Our starting point was two typical houses built in the 1970s. We altered the floor plans to obtain 6 houses, with heated floor space ranging between 100 and 306 m². One of the houses was also analysed for three energy standards with differing heat loss rates. CO₂ emission, primary energy use and heating cost were estimated after implementing house envelope measures, conversions to other heating systems and changes in the generation of district heat and electricity. The study accounted for primary energy, including energy chains from natural resources to useful heat in the houses. We showed that conversion to district heating based on biomass, together with house envelope measures, reduced the primary energy use by 88% and the CO₂ emission by 96%, while reducing the annual societal cost by 7%. The choice of end-use heating system was decisive for the primary energy use, with district heating being the most efficient. Neither house size nor energy standard did significantly change the ranking of the heating systems, either from a primary energy or an economic viewpoint, but did affect the extent of the annual cost reduction after implementing the measures.     

Energy efficient design of building: A review

Energy saving is a high-priority in developed countries. For this reason, energy-efficient measures are being increasingly implemented in all sectors. The residential sector is responsible for an important part of the energy consumption in the world. Most of this energy is used in heating, cooling, and artificial ventilation systems.With a view to developing energy-efficient structures, this article provides an overview of building design criteria that can reduce the energy demand for the heating and cooling of residential buildings. These criteria are based on the adoption of suitable parameters for building orientation, shape, envelope system, passive heating and cooling mechanisms, shading, and glazing. An analysis was made of previous studies that evaluated the influence of these parameters on the total energy demand and suggested the best design options. This study is useful for professionals who are responsible for decision-making during the design phase of energy-efficient residential buildings.     

Path Analysis of Energy-Saving Technology in Yangtze River Basin Based on Multi-Objective and Multi-Parameter Optimisation

The Yangtze River Basin in China is characterised by hot-and cold-humid climates in summer and winter, respectively. Thus, increased demand for heating and cooling energy according to the season, as well as poor indoor thermal comfort, are inevitable. To overcome this problem, this study focused on the influence of passive design and heating, ventilation, and air conditioning equipment performance on the energy performance of residential buildings, and explored potential energy-saving technology paths involving passive design and improved coefficient of performance through a multi-objective and multi-parameter optimisation technique. A large-scale questionnaire survey covering a typical city was first conducted to identify family lifestyle patterns regarding time spent at home, family type, air conditioner use habits, indoor thermal comfort, etc. Then, the actual heating and cooling energy consumption and information of model building were determined for this region. Subsequently, the design parameters of an individual building were simulated using Energyplus to investigate the cooling and heating energy consumption for a typical residential building with an air conditioner. The results indicated an improvement of approximately 30% in energy efficiency through optimisation of the external-wall insulation thickness and the external-window and shading performance, and through use of appropriate ventilation technology. Thus, a multi-objective and multi-parameter optimisation model was developed to achieve comprehensive optimisation of several design parameters. Experimental results showed that comprehensive optimisation could not only reduce cooling and heating energy consumption, but also improve the thermal comfort level achieved with a non-artificial cooling and heating source. Finally, three energy-saving technology paths were formulated to achieve a balance between indoor thermal comfort improvement and the target energy efficiency(20 kWh/(m2?a)). The findings of this study have implications for the future design of buildings in the Yangtze River Basin, and for modification of existing buildings for improved energy efficiency.     

建筑形式对太阳能热利用的影响研究

以上海地区的住宅建筑为研究对象,通过模拟分析的方法,采用DeST软件计算确定建筑逐时的采暖、空调能耗,研究分析窗墙比对建筑全年采暖能耗、全年空调能耗以及全年采暖、空调总能耗的影响规律,研究分析太阳辐射热增加所导致采暖能耗的降低幅度与外围护结构保温性能两者之间的定量关系。计算结果表示在夏季外窗遮阳和夜间通风的条件下,加大南向窗墙比可增强太阳能的热利用效率,降低建筑全年的采暖、空调总能耗;而外围护结构保温性能的增强则可降低室内向室外散热的程度,相应提高对冬季太阳辐射的热利用程度,从而达到降低采暖能耗的目的。     

Long-term energy savings and greenhouse gas emission reductions in the Swiss residential sector

The aim of this paper is to explore the possibilities to reach two long-term targets regarding energy consumption and greenhouse gas emissions of the Swiss residential building stock: a reduction of the final energy consumption by a factor of 3 and of _CO2${\mathrm{CO}}_2$ emissions by a factor of 5 until 2050. A model is constructed to describe the dynamics of the energy-relevant properties of the residential building stock. Appropriate scenarios are discussed in terms of decisions made during construction or renovation of residential buildings which affect heat demand and determine the energy carriers used for heating and hot water generation. We show that both targets could be reached, although ambitious efforts are necessary. The central element of a successful strategy is to reduce the specific heat demand of existing buildings during renovation and to substitute the heating and hot water systems by less carbon intensive ones. Our results suggest that there is more flexibility to reach the emission target than the energy reduction target.     

某节能住宅小区地下水源热泵系统应用的经济性及节能性分析

针对咸阳市某节能住宅小区供冷供热的需求,依据建筑节能规范指标要求,进行围护结构热工设计与计算。结合当地丰富的浅层地下水资源条件,确定了利用地下水源热泵系统对该住宅小区进行供冷供热方案。对系统经济性和节能性进行计算与分析,对比分析了建筑围护结构和空调系统对建筑节能的贡献率,指出了建筑节能集成效益的优势。     

Cost optimal analysis of heat pump technology adoption in residential reference buildings

In European Union (EU) buildings consume approximately the 40% of total primary energy. Heat pump (HP) systems have proven to be an efficient and economically viable alternative to conventional systems to provide heating and cooling services in buildings. An effective penetration of this technology in the built environment is critical to achieve the ambitious goals set by the recent EU Directives on energy efficiency and energy performance of buildings. Although this technology is very versatile, its optimal design and management are related to specific climate, operational and economic conditions. The research presented aims to evaluate the performance of technical solutions for heating and cooling in residential buildings, using a “reference building” methodology. The comparison involves performance indicators such as primary energy consumption, CO₂ emission and net present cost.The potential improvements with respect to conventional baseline solutions are assessed and the performance gap between air-source and water-source HP systems is shown referring to realistic operational and climate conditions within the Italian territory. The research suggests the possibility of reducing this performance gap by concentrating future research effort on design and control optimization.     

Incentive mechanism design for the residential building energy efficiency improvement of heating zones in North China

Starting with analyzing the investigation results by Ministry of Housing and Urban–Rural Development of China in 2005, more than half of the 10,236 participants are willing to improve the residential building energy efficiency and accept an additional cost of less than 10% of the total cost, the authors illustrate that incenting actions are necessary to improve building energy efficiency and build a central government–local government–market model. As a result of the model analysis, to pursue good execution effects brought by the incentive policies, the executors are required to distinguish the differences of incentive objects’ economic activities and strongly respect the incenting on the energy conservation performance. A case study on the incentive policies of existing residential building energy efficiency improvement in heating zones in North China is given as well. Finally, it is strongly recommended to give the first priority to performance-based incentives so that to reduce the lazy behaviors of the incented objects and ensure the targets to be achieved.     

Energy and economic analysis of an integrated solar absorption cooling and heating system in different building types and climates

The use of solar energy in buildings is an important contribution for the reduction of fossil fuel consumption and harmful emissions to the environment. Solar thermal cooling systems are still in their infancy regarding practical applications, although the technology is sufficiently developed for a number of years. In many cases, their application has been conditioned by the lack of integration between cooling and heating systems. This study aims to evaluate the potential of integrated solar absorption cooling and heating systems for building applications. The TRNSYS software tool was used as a basis for assessment. Different building types were considered: residential, office and hotel. The TRNSYS models are able to run for a whole year (365 days), according to control rules (self-deciding whether to operate in heating or cooling modes), and with the possibility of combining cooling, heating and DHW applications. Three different locations and climates were considered: Berlin (Germany), Lisbon (Portugal), and Rome (Italy). Both energy and economic results are presented for all cases. The different local costs for energy (gas, electricity and water) were taken into account. Savings in CO₂ emissions were also assessed. An optimization of solar collector size and other system parameters was also analysed.     

Energy efficiency measures and conversion of fossil fuel boiler systems in a detached house

There is a large potential to reduce primary energy use and CO₂ emissions from the Swedish building stock. Here detached houses heated by oil, natural gas or electric boilers were assessed. CO₂ emissions, primary energy use and heating costs were evaluated before and after implementing house envelope measures, conversions to more efficient heating systems and changes to biomass fuel use. The study included full energy chains, from natural resources to usable heat in the houses. The aim was to evaluate the societal economic cost effectiveness of reducing CO₂ emission and primary energy use by different combinations of changes. The results demonstrated that for a house using an electric boiler, a conversion to a heat pump combined with house envelope measures could be cost efficient from a societal economic perspective. If the electricity was based on biomass, the primary energy use was at the same time reduced by 70% and the CO₂ emission by 97%. Large emission reductions were also seen for conversions from oil and gas boilers to a biomass-based system. However, for these conversions the heating cost increased, leading to a mitigation cost of around €50/tonne C avoided. The price of oil and natural gas greatly influenced the competitiveness of the alternatives. House envelope measures were more cost-effective for houses with electric boilers as the cost of energy for this system is high. The results are specific to a Swedish context, but also give an indication of the potential in other regions, such as northern European and large parts of North America, which have both a cold climate and a widespread use of domestic boilers.     

Impacts of city-block-scale countermeasures against urban heat-island phenomena upon a building’s energy-consumption for air-conditioning

This study quantifies the possible impacts of urban heat-island countermeasures upon buildings’ energy use during summer in Tokyo metropolis. Considering the dependency of the buildings air temperature upon the local urban canopy structure, Tokyo urban canopies were classified in the city-block-scale using the sky-view factor (svf). Then, a multi-scale model system describing the interaction between buildings’ energy use and urban meteorological conditions was applied to each classified canopy.     

Prediction of greenhouse gas reduction potential in Japanese residential sector by residential energy end-use model

A model is developed that simulates nationwide energy consumption of the residential sector by considering the diversity of household and building types. Since this model can simulate the energy consumption for each household and building category by dynamic energy use based on the schedule of the occupants’ activities and a heating and cooling load calculation model, various kinds of energy-saving policies can be evaluated with considerable accuracy. In addition, the average energy efficiency of major electric appliances used in the residential sector and the percentages of housing insulation levels of existing houses is predicted by the “stock transition model.” In this paper, energy consumption and CO₂ emissions in the Japanese residential sector until 2025 are predicted. For example, as a business – as-usual (BAU) case, CO₂ emissions will be reduced by 7% from the 1990 level. Also evaluated are mitigation measures such as the energy efficiency standard for home electric appliances, thermal insulation code, reduction of standby power, high-efficiency water heaters, energy-efficient behavior of occupants, and dissemination of photovoltaic panels.     

严寒地区节能建筑采暖能耗实测结果分析

实测的节能建筑采暖能耗数据对建筑节能的研究是必不可少的。本文介绍了长春市某节能建筑住宅楼的建筑围护结构及其低温辐射电热膜供热系统,对该建筑采暖能耗进行了采暖期的逐日实测与计算分析,提出降低节能建筑采暖能耗的几点新思路与实际作法。     

Thermal energy storage in building integrated thermal systems: A review. Part 1. active storage systems

Energy consumed by heating, ventilation and air conditioning systems (HVAC) in buildings represents an important part of the global energy consumed in Europe. Thermal energy storage is considered as a promising technology to improve the energy efficiency of these systems, and if incorporated in the building envelope the energy demand can be reduced. Many studies are on applications of thermal energy storage in buildings, but few consider their integration in the building. The inclusion of thermal storage in a functional and constructive way could promote these systems in the commercial and residential building sector, as well as providing user-friendly tools to architects and engineers to help implementation at the design stage. The aim of this paper is to review and identify thermal storage building integrated systems and to classify them depending on the location of the thermal storage system.     

Energy analysis of a low‐temperature heat pump heating system in a single‐family house

Energy costs and environmental concerns have made energy optimisation a viable option for buildings. Energy‐efficient heating systems together with an effective use of buildings thermal mass and tightness have a significant impact on the energy requirement and on the possibility for sizeable running cost savings. In this study we use the simulation tool TRNSYS‐EES to model and analyse the performance of a residential house and the low‐temperature heating system that serves its thermal needs. The building is a single‐family house with controlled ventilation and the chosen heating system is a hydronic floor heating system connected to an exhaust air heat pump. The aim of the simulation is to study the performance of the building, the heating system and the controls in an integrated manner. Overall, the results indicate that the energy efficiency issue implicates system design and system thinking concerns as well as techno‐economic difficulties. The controls and the choice of the operation mode are of a great importance. Copyright © 2004 John Wiley & Sons, Ltd.     

Simulation of façade and envelope design options for a new institutional building

This paper presents a simulation case study of façade and envelope preliminary design options for the new Engineering building of Concordia University in Montreal. A major principle of the analysis was to create a high quality building envelope in order to optimally control solar gains, reduce heating and cooling energy demand and reduce electricity consumption for lighting, while at the same time maintain a comfortable and pleasant indoor environment. The stated approach of the design team was to aim for an energy-efficient building, employing innovative technologies and integrating concepts such as daylighting and natural ventilation. Detailed energy simulations were therefore performed from the early design stage, in order to present recommendations on the choice of façade, glazings, shading devices, lighting control options, and natural ventilation. Integrated thermal studies, a daylighting analysis and the impact of the above on HVAC system sizing were considered. Simulation results showed that, using an optimum combination of glazings, shading devices and controllable electric lighting systems, the energy savings in perimeter spaces can be substantial. Perimeter heating could be eliminated if a high performance envelope is used. The building is currently being commissioned.