Life cycle energy analysis of buildings: An overview

Buildings demand energy in their life cycle right from its construction to demolition. Studies on the total energy use during the life cycle are desirable to identify phases of largest energy use and to develop strategies for its reduction. In the present paper, a critical review of the life cycle energy analyses of buildings resulting from 73 cases across 13 countries is presented. The study includes both residential and office buildings. Results show that operating (80-90%) and embodied (10-20%) phases of energy use are significant contributors to building's life cycle energy demand. Life cycle energy (primary) requirement of conventional residential buildings falls in the range of 150-400 kWh/m² per year and that of office buildings in the range of 250-550 kWh/m² per year. Building's life cycle energy demand can be reduced by reducing its operating energy significantly through use of passive and active technologies even if it leads to a slight increase in embodied energy. However, an excessive use of passive and active features in a building may be counterproductive. It is observed that low energy buildings perform better than self-sufficient (zero operating energy) buildings in the life cycle context. Since, most of the case studies available in open literature pertain to developed and/or cold countries; hence, energy indicative figures for developing and/or non-cold countries need to be evaluated and compared with the results presented in this paper.     

Building energy-efficiency standards in a life cycle primary energy perspective

In this study we analyze the life cycle primary energy use of a wood-frame apartment building designed to meet the current Swedish building code, the Swedish building code of 1994 or the passive house standard, and heated with district heat or electric resistance heating. The analysis includes the primary energy use during the production, operation and end-of-life phases. We find that an electric heated building built to the current building code has greater life cycle primary energy use relative to a district heated building, although the standard for electric heating is more stringent. Also, the primary energy use for an electric heated building constructed to meet the passive house standard is substantially higher than for a district heated building built to the Swedish building code of 1994. The primary energy for material production constitutes 5% of the primary energy for production and space heating and ventilation of an electric heated building built to meet the 1994 code. The share of production energy increases as the energy-efficiency standard of the building improves and when efficient energy supply is used, and reaches 30% for a district heated passive house. This study shows the significance of a life cycle primary energy perspective and the choice of heating system in reducing energy use in the built environment.     

西北地区被动式太阳房可行性与设计方法

从太阳房的原理和相关概念出发,重点对被动式太阳房的可行性和设计进行分析与研究。分别从当前西北地区部分农村的经济情况、能源利用情况及建筑状况等进行阐述,指出在西北地区构筑被动式太阳房是可行的。分析了被动式太阳房的优点和经济效益,给出了被动式太阳房典型设计方法。     

浅论太阳能建筑

分析了在建筑中利用太阳能的必要性及可能性，指出太阳能建筑的应用应符合今后世界建筑发展的方向，太阳能建筑的发展经历了主动式太阳房、被动式太阳房以及零能房屋三个阶段，阐述了太阳能建筑在国外的发展概况以及在我国对于主动式太阳房和被动式太阳房的研究和已取得的成就，指出其具有良好的发展前景。     

Life cycle energy of single landed houses in Indonesia

Building enclosures contribute 10–50% of the total building cost and 14–17% of the total material mass. The direct as well as indirect influence of the enclosure materials plays an important role in the building life cycle energy. Single landed houses, the typical houses in Indonesia, have been chosen for this study. The life cycle energy of the house enclosures and energy consumed during their life spans shows intriguing results. The initial embodied energy of typical brick and clay roof enclosures is 45 GJ compared to the other typical walls and roof material (cement based) which is 46 GJ. However, over the 40 years life span of the houses, the clay based ones have a better energy performance than the cement based ones, 692 GJ versus 733 GJ, respectively. The material selection during the design phase is thus crucial since the buildings have at least 40–50 years’ life span.     

综合式太阳房辅助通风性能模拟

被动式太阳房是降低建筑能耗的有效方法之一。针对带有阳光间的综合式太阳房在夏季用于辅助通风时的通风性能进行了计算分析。通过对其阳光间建立传热模型,计算求解阳光间内空气的平均温度,从而求得太阳房辅助通风的通风量。结果表明,综合式太阳房的辅助通风性能可以满足一般住宅的新风要求,但对于有更高通风要求的建筑物则能力有限。文中的模拟计算,为今后对综合式太阳房进行深入的理论和实验研究提供了必要的理论基础。     

Life cycle primary energy analysis of residential buildings

The space heating demand of residential buildings can be decreased by improved insulation, reduced air leakage and by heat recovery from ventilation air. However, these measures result in an increased use of materials. As the energy for building operation decreases, the relative importance of the energy used in the production phase increases and influences optimization aimed at minimizing the life cycle energy use. The life cycle primary energy use of buildings also depends on the energy supply systems. In this work we analyse primary energy use and CO₂ emission for the production and operation of conventional and low-energy residential buildings. Different types of energy supply systems are included in the analysis. We show that for a conventional and a low-energy building the primary energy use for production can be up to 45% and 60%, respectively, of the total, depending on the energy supply system, and with larger variations for conventional buildings. The primary energy used and the CO₂ emission resulting from production are lower for wood-framed constructions than for concrete-framed constructions. The primary energy use and the CO₂ emission depend strongly on the energy supply, for both conventional and low-energy buildings. For example, a single-family house from the 1970s heated with biomass-based district heating with cogeneration has 70% lower operational primary energy use than if heated with fuel-based electricity. The specific primary energy use with district heating was 40% lower than that of an electrically heated passive row house.     

Investigation of energy performance of newly built low-energy buildings in Sweden

Energy use in the built environment represents a large part of total energy use in Sweden and is one important sector where energy conservation needs to be significantly improved in order to meet the national implementation of the European goals. One key question that needs to be investigated in relation to these goals is the performance and implementation of passive or low-energy houses. This paper presents results and an evaluation of a newly built house in an area with passive houses in Linköping, Sweden. Nine passive houses were built with the aim to be energy efficient, with an annual space heating demand of 21 kWh/m², and at the same time to have the same visual appearance as any other building in the surrounding area.This study evaluates the energy performance of a residential area with low-energy buildings based on Building Energy Simulation (BES) (IDA ICE 4), and measurements from the real object. Both annual and hourly validation is performed using room by room modeling and internal heat gains. A novel approach to internal heat gain modeling is presented using time-use data (TUD). The results show possible improvements in the design, the building envelope and in the heating control.     

冷风渗透对太阳房热性能的影响研究

通过对青海某地太阳房的测试分析研究,确定了冷风渗透量对太阳房集热量和室温影响的计算方法。并知该太阳房的供暖效果和节能效果较好,但其集热墙的玻璃幕墙和房间门窗的密闭性较差,导致该玻璃幕墙和房间冷风渗透量较大,影响了集热墙的集热量及集热效率和太阳房的供暖与节能效果。因此在太阳房建设的设计与施工的各个环节中必须充分重视玻璃幕墙和房间门窗的密封性问题,以减少冷风渗透的能耗,提高太阳房的供暖效果和节能效率。     

Life cycle energy analysis of a zero-energy house

Most zero-energy concepts focus on a reduction of the non-renewable operational energy use in buildings rather than taking the reduction of their life cycle energy use as a starting point. Nevertheless, the life cycle embodied and end-of-life energy will become more important, especially in buildings with low operational energy. Therefore, the life cycle energy use of a Belgian zero-energy reference house is examined by means of life cycle energy assessment. The influence of design decisions and regulations on the building construction type, the building services, and the performance of the building envelope are investigated. In terms of thermal performance of the building, the results show that the life cycle embodied energy in zero-energy houses with passive or standard thermal performance was not substantially different. From a life cycle energy perspective, passive house requirements are not essential criteria for zero-energy houses in Belgium. On the other hand, large life cycle energy savings were obtained through a proficient selection of all building construction materials and services. For the life cycle embodied energy in building constructions, the best timber frame and masonry houses were equally efficient. Wood pellets and photovoltaic panels were decisive factors in the life cycle embodied energy of building services.

Les concepts <<zéro-énergie>> sont axés pour la plupart sur une réduction de l'utilisation de l'énergie d'exploitation non renouvelable dans les bâtiments plutôt que de prendre la réduction de leur consommation d'énergie sur le cycle de vie comme point de départ. Néanmoins, l'énergie grise sur le cycle de vie et l'énergie de fin de vie vont gagner en importance, en particulier dans les bâtiments nécessitant une faible énergie d'exploitation. La consommation d'énergie sur le cycle de vie d'une maison belge «zéro énergie» de référence est donc étudiée au moyen d'un bilan énergétique du cycle de vie. Sont étudiés l'influence des décisions de conception et de la réglementation sur le type de construction du bâtiment, les services au bâtiment, et les performances de l'enveloppe du bâtiment. En termes de performance thermique du bâtiment, les résultats montrent que l'énergie grise sur le cycle de vie n'était pas fondamentalement différente dans les maisons «zéro énergie» offrant des performances thermiques passives ou standard. Du point de vue de l'énergie du cycle de vie, les exigences d'une maison passive ne sont pas des critères essentiels pour des maisons «zéro énergie» en Belgique. En revanche, d'importantes économies d'énergie sur le cycle de vie ont été obtenues par un choix opéré avec compétence de tous les matériaux de construction et services au bâtiment. S'agissant de l'énergie grise sur le cycle de vie dans la construction de bâtiments, les meilleures maisons, qu'elles aient été à ossature bois ou en maçonnerie, ont été tout aussi performantes. Les granulés de bois et les panneaux photovoltaïques ont été des facteurs décisifs concernant l'énergie grise sur le cycle de vie des services aux bâtiments.

Mots clés: services aux bâtiments, énergie grise, analyse énergétique du cycle de vie, [construction] passive, bâtiments résidentiels, <<zéro-énergie>>     

Indonesian residential high rise buildings: A life cycle energy assessment

This study evaluates the effect of building envelopes on the life cycle energy consumption of high rise residential buildings in Jakarta, Indonesia. For high rise residential buildings, the enclosures contribute 10-50% of the total building cost, 14-17% of the total material mass and 20-30% of the total heat gain. The direct as well as indirect influence of the envelope materials plays an important role in the life cycle energy consumption of buildings. The initial embodied energy of typical double wall and single wall envelopes for high residential buildings is 79.5 GJ and 76.3 GJ, respectively. Over an assumed life span of 40 years, double walls have better energy performance than single walls, 283 GJ versus 480 GJ, respectively. Material selection, which depends not only on embodied energy but also thermal properties, should, therefore, play a crucial role during the design of buildings.     

漫谈太阳能在建筑中的利用

介绍建筑围护结构（太阳墙系统、被动式太阳房等）的生态建筑特征,以及其太阳能利用原理,并通过实例分析生态建筑大师托马斯·赫尔佐格在利用太阳能进行建筑设计的先进理念,探讨对我国太阳能建筑设计的启示作用．     

被动除湿太阳房实验研究

从节能、环保、战略与效率的角度阐述了被动太阳房除湿与传统除湿方法相比，有其独特的优势。而且，高湿环境不仅影响到室内人员的热舒适感，而且对室内卫生条件，人体健康，室内设备，室内家具的使用寿命等也有不利影响。为了降低室内湿度，我们设计了一种新的除湿构件，利用太阳能使其再生循环使用，试验证明，这种除湿构件具有很好的除湿效果，可以在一定范围内推广使用。     

Exergy efficiency analysis in buildings climatized with LiCl–H2O solar cooling systems that use swimming pools as heat sinks

Solar cooling is emerging as one of the most interesting applications in the harnessing of solar energy for alternative uses. Current devices can effectively control the climates of small buildings while addressing the issues associated with the excessive thermal energy captured during the summer months. This article presents an exergy analysis of buildings with solar thermal systems used for Domestic Hot Water (DHW) production and heating and cooling support. The cooling system analyzed is a LiCl–H₂O thermally driven heat pump with integral energy storage that uses outdoor swimming pools as heat sink. All subsystems were integrated into the model and considered as a single energy system, and data from installations in three different locations were used. The influences of the heating and cooling demand ratios and the dead state and house temperatures were analyzed. Further, the use of dissipated energy was analyzed, demonstrating that the proposed method facilitates the realistic study of these systems and provides useful analytical tools for improving the overall exergy performance. The energy delivered for heating, cooling and DHW production strongly influences global performance, suggesting that the appropriate sizing of each system is a priority.     

Directionally selective shading control in maritime sub-tropical and temperate climates:Life cycle energy implica-tions for office buildings

Scheduling directionally selective shading devices to increase or decrease their level of occlusion relative to the total incoming solar radiation has the benefit of controlling solar heat gain during a variety of sky conditions and allowing more constant illuminance levels to be achieved within a building.In this study,hourly sky condition and annual solar angles were used to describe the tilt of the slats of an external directionally selective shading control for an external venetian blind on an office building in Mel-bourne and Brisbane,Australia.The life cycle energy demand associated with this shading control was compared to a static base case with an external overhang and internal venetians.The analysis was extended to the HVAC system which was sized to account for the effect of the shading on solar gain and the artificial lighting requirement.It was found that the embodied energy of the HVAC and shading components accounted for between 21.7%and 25.5%of the total life cycle energy of these systems over 25 years.There was a reduction in embodied and operational energy requirements over a 25 year life cycle for the external venetian blind control of24.9%for Melbourne and 24.0%for Brisbane relative to the static base case.Based on the simulation results,office buildings with equator facing facades located in similar climates and latitudes may have the potential for equivalent life cycle energy reductions when external directionally selective shading controls are employed to moderate overheating and daylighting.     

Evaluation of the impact of internal partitions on energy conservation for residential buildings in Serbia

In Serbia, around 50% of energy is used in built environment and most of it for 6-month heating in residential buildings. Because of actual international efforts to protect environment, energy conservation in heating in residential buildings is an issue of permanent research interest. In this paper, we tried to determine how type of partitions inside a residential building influences energy consumption and demand for houses in cold climate and consequently energy conservation. For a typical house in Serbia, by using software HTB2, it was evaluated how its heating depends on six applied types of partitions. It was found that (1) the house with glass-wool partitions would have the minimum yearly heat consumption, (2) the house with masonry partitions would require heaters of minimum size, (3) the house with siporex partitions would require the lowest investment in partitions and heaters, and (4) the house with glass-wool partitions would yield the highest net savings during the life cycle of the house.     

村镇住宅建设与太阳能利用

通过对我国太阳能资源分布情况的分析以及太阳能应用可行性研究,提出了一种既节约能源又节省投资的太阳能绿色建筑设计方案.将建筑设计技术与太阳能利用技术相结合,建造一种利用南外墙进行集热和蓄热的被动式太阳房或利用太阳能热水循环技术的主动式太阳房,解决严寒季节供暖问题以及生活热水供应问题,对发展村镇建设,提高人居环境质量,创建"和谐社会"有着重大的现实意义.     

定西地区被动太阳房室内热环境实测研究

分析了附加阳光间被动太阳房在冬、夏季室内、外气温和相对湿度的变化情况,并对建造技术进行了阐述,提出了改造措施,以便为当地既有民居的改造和新民居的建造提供参考依据。     

银川地区被动式太阳房的室温预测

被动式太阳房是一种经济有效地利用太阳能采暖的建筑,银川地区太阳能热水器已经得到了广泛的应用,但被动式太阳房的应用较少。本文对银川地区直接受益窗与集热蓄热墙的组合式太阳房的室内温度进行预测,分析其热舒适性,以便今后更近一步的研究。     

兵团小城镇被动式太阳房优化设计

介绍了兵团小城镇居住建筑围护结构的构造形式、热工特性和能源利用等情况,在此基础上提出了适合兵团小城镇居住建筑的发展思路:以被动式太阳房为主体,进一步改善建筑围护结构热工特性和室内热环境.并应用Ecotect Analysis 2010软件对优化设计方案进行了模拟分析,结果表明设计工况下平均室温16.3℃以上,温度波动在...