Overheating and passive habitability: indoor health and heat indices

As extreme heat and weather events are predicted to increase due to global warming, the risk of human heat stress within buildings will increase. To be resilient, buildings will need the capacity to provide habitable indoor conditions without power for limited amounts of time. Additional indoor thermal standards are required for public health to address ‘passive habitability’ during power outages. Current research on building-related heat stress and numerous heat indices is examined in relation to the development of a new heat-safety metric for use in passively conditioned buildings. Most indoor overheating research relies on outdoor temperature data and has no common indoor heat index for evaluating indoor heat stress. A recommendation is made for using the wet-bulb globe temperature (WBGT) and predicted heat strain (PHS) indices for modelling and monitoring of indoor heat stress in healthy adult populations because both indices utilize the primary thermoregulation variables, have associated heat-stress thresholds, and can be assessed or tracked with existing environmental monitoring methods and predictive energy modelling techniques. Further research is recommended on health effects and exposure limits of vulnerable populations, and the variation in thermal factors within buildings and the building stock.     

基于建筑抗震韧性评价标准的某教学楼抗震韧性评价分析

对传统抗震设防目标和"可恢复功能"的抗震设计理念进行了介绍,采用新编国家标准《建筑抗震韧性评价标准》中的评价方法,对一栋新建小学教学楼进行了抗震韧性评价分析,对其修复费用、修复时间和人员损失进行了评估,以确定其抗震韧性等级。结果表明,抗震韧性评价可以对建筑物抗震性能进行量化分析,提供更易理解且更有价值的性能指标;同时,抗震韧性评价可以更加直观地验证"三水准"抗震设防目标,并发现非结构构件往往是造成人员伤亡和抗震修复代价的主要因素。     

Impact of adaptive comfort criteria and heat waves on optimal building thermal mass control

This article investigates building thermal mass control of commercial buildings to reduce utility costs with a particular emphasis on the individual impacts of both adaptive comfort criteria and of heat waves. Recent changes in international standards on thermal comfort for indoor environments allow for adaptation to the weather development as manifested in comfort criteria prEN 15251.2005 and NPR-CR 1752.2005 relative to the non-adaptive comfort criterion ISO 7730.2003. Furthermore, since extreme weather patterns tend to occur more frequently, even in moderate climate zones, it is of interest how a building's passive thermal storage inventory responds to prolonged heat waves. The individual and compounded effects of adaptive comfort criteria and heat waves on the conventional and optimal operation of a prototypical office building are investigated for the particularly hot month of August 2003 in Freiburg, Germany. It is found that operating commercial buildings using adaptive comfort criteria strongly reduces total cooling loads and associated building systems energy consumption under conventional and building thermal mass control. In the case of conventional control, total operating cost reductions follow the cooling loads reductions closely. Conversely, the use of adaptive comfort criteria under optimal building thermal mass control leads to both lower and slightly higher absolute operating costs compared to the optimal costs for the non-adaptive ISO 7730. While heat waves strongly affect the peak cooling loads under both conventional and optimal building thermal mass control, total cooling loads, building energy consumption and costs are only weakly affected for both control modes. Passive cooling under cost-optimal control, while achieving significant total cost reductions of up to 13%, is associated with total energy penalties on the order of 1–3% relative to conventional nighttime setup control. Thus, building thermal mass control defends its cost saving potential under optimal control in the presence of adaptive comfort criteria and heat waves.     

Longitudinal prediction of the operational energy use of buildings

Thus far most studies of operational energy use of buildings fail to take a longitudinal view, or in other words, do not take into account how operational energy use changes during the lifetime of a building. However, such a view is important when predicting the impact of climate change, or for long term energy accounting purposes. This article presents an approach to deliver a longitudinal prediction of operational energy use. The work is based on the review of deterioration in thermal performance, building maintenance effects, and future climate change. The key issues are to estimate the service life expectancy and thermal performance degradation of building components while building maintenance and changing weather conditions are considered at the same time. Two examples are presented to demonstrate the application of the deterministic and stochastic approaches, respectively. The work concludes that longitudinal prediction of operational energy use is feasible, but the prediction will depend largely on the availability of extensive and reliable monitoring data. This premise is not met in most current buildings.     

Performance assessment of low-energy buildings in central Argentina

This paper summarizes the results obtained from the energy and thermal performance assessment of residential and non-residential low-energy buildings that were designed to minimize fossil energy use. They are located in the province of La Pampa, central Argentina, in a temperate continental climate that shows extreme hot and cold records during the summer and winter seasons, respectively. The common applied technologies for saving energy were passive solar heating, natural ventilation for cooling and daylighting. The glazing area in the principal functional spaces facing to the North oscillates between 11 and 17% of the building useful areas. All the studied buildings are massive, with the exception of an auditorium that was designed with a lightweight insulated technology. The mean thermal transmittance of the envelope is 0.45 W/(m² K). Double glazing and hermetic carpentry were used to reduce thermal losses (U-value = 2.8 W/(m² K)). The volumetric heat loss coefficient (G-value) oscillates between 0.90 and 1.00 W/(m³ K). During the design and thermal simulation convective-radiative heat transfer coefficients were estimated through a dimensional equation (h = 5.7 + 3.8 ws, wind speed). On internal surfaces, convective-radiative heat transfer coefficients of 8 and 6 W/(m² °C) (for surfaces with and without solar gain, respectively) were applied. The monitoring process provided information on the energy and thermal behaviour under use and non-use conditions. The measured value of energy consumption was similar to the expected value that was used during the pre-design stage. Building technologies work well during the winter season, allowing 50–80% of energy savings. However, overheating is still an unresolved problem during the summer. Interviews with occupants revealed that they need both, information about functional details, and good-practice guidance to manage thermal issues of the building. In most cases, the annual consumption of energy was lower than those established by the Low Energy Housing German Standards and the Minirgie Switzerland Certificate. Despite their relative cost increase during the last years, the use of insulation technology and the application of passive solar devices involved an extra cost of only 3% in our works. Provided the expected depletion of natural gas production in the coming decade, the importance of applying energy-efficiency guidelines will increase very soon in Argentina in order to match the requirements of a new national energy matrix.     

GB/T 38591—2020《建筑抗震韧性评价标准》与国际相关标准对比研究

建筑抗震韧性是指建筑结构在设定水准地震作用后维持和迅速恢复使用功能的能力。建立系统化的抗震韧性评价方法是建设抗震韧性建筑乃至韧性城市的重要组成部分。国际上从2012年起提出和发展了建筑抗震韧性评价方法,形成了多本韧性评价标准或指南。中国GB/T 38591—2020《建筑抗震韧性评价标准》于2020年3月31日发布,将于2021年2月1日起实行。为了对比GB/T 38591—2020与国际相关标准所评定的建筑抗震韧性水平,介绍了建筑抗震韧性评价方法的发展和基本流程,说明并比较了各标准计算韧性指标的不同策略,包括建筑修复费用、建筑修复时间和人员伤亡。采用算例说明了修复策略、次序和工人数量对建筑修复时间的显著影响,并对比了不同标准划定韧性建筑等级的判别标准。分析发现,GB/T 38591—2020在计算建筑修复时间、人员伤亡和判定抗震韧性等级方面与国际相关标准差别显著,且其所包含的不确信性范围小于国际相关标准。GB/T 38591—2020所评定的一星建筑的韧性水平约等同于或略高于REDi的银级建筑或USRC的4星建筑。     

Hybrid ventilation for low energy building design in south China

Buildings and their related activities are responsible for a large portion of the energy consumed in China. It is therefore worthwhile to investigate methods for improving the energy efficiency of buildings. This paper describes a low energy building design in Hangzhou, south China. A hybrid ventilation system which employs both natural and mechanical ventilation was used for the building due to the severity of the climate. The passive ventilation system was tested using computational fluid dynamics (CFD) and the results showed that, in the mid-seasons, natural ventilation for the building is viable. The likely thermal performance of the building design throughout the year was evaluated using dynamic thermal simulation (DTS) with local hourly standard weather data. It is evident from the modelling results that the hybrid ventilation system is a feasible, low energy approach for building design, even in sub-tropical climates such as south China.     

Assessing the effects of flood resilience technologies on building scale

The impacts of floods on housing are increasing due to more frequent and severe weather events as well as the ongoing development of settlements in flood-prone areas together with the rising vulnerability of assets at risk. Therefore, the improvement of the resilience properties of buildings to better cope with flooding has become a key issue towards more flood resilient cities in European research in recent years. The implementation of flood resilience technologies (FReT) on the individual property scale provides a previously untapped potential to reduce flood damage to buildings due to insufficient transparency of their effects. To overcome this obstacle, the paper presents a four-step extension of a synthetic approach for flood vulnerability analysis to provide evidence on the potential effects of FReT uptake concerning flood damage mitigation. The proposed approach has been integrated in the GIS-based flood damage simulation model HOWAD to support the assessment of FReT alternatives. The simulation of flood damage to buildings in the case study Heywood, Greater Manchester (United Kingdom) revealed the potential of the extended approach to determine the consequences of FReT implementation on building scale.     

Quantitative evaluation and improvement of seismic resilience of a tall frame shear wall structure

Tall buildings are an important part of a city, and their earthquake-induced damage or collapse will lead to heavy losses, extended repair time, and casualties. Therefore, it is essential to quantify and improve the resilience of tall buildings. To this end, this paper develops a component damage-based metric to characterize tall buildings' functionality loss and then proposes a general quantitative evaluation process to evaluate tall buildings' resilience. Next, the evaluation process is applied to a 42-story reinforced concrete frame shear wall building to demonstrate its applicability. Finally, retrofit strategies on nonstructural components are discussed to enhance the building's resilience. It can be concluded that the proposed metric can be effectively used to evaluate tall buildings' functionality loss. The building being studied has great seismic resilience, with resilience values of 99.95%, 98.68%, and 88.69% at service level earthquake (SLE), design level earthquake (DBE), and maximum considered earthquake (MCE), respectively. The influence of nonstructural components on seismic resilience is greater than that of structural components at SLE and DBE levels. It is an effective alternative to enhance the seismic resilience of tall buildings under SLE and DBE by improving the performance of partition walls, ceilings, and equipment.     

住宅建筑节能保温的重要性及措施

随着我国对住宅节能工作的重视与不断发展,作为基础工作的建筑外墙保温正越发受到重视,尤其是外墙外保温系统然而,近几年来保温材料引发建筑火灾严重事故时有发生,使得国内业内人士对保温系统的安全性和必要性产生质疑文章首先分析了我国建筑能耗和建筑节能的现状,然后从建筑节能政策和建筑技术两方面针对性地提出了多种建筑节能的措施与对策这些将对我国在建筑行业进一步推进、发展和完善建筑节能具有重要的参考价值。并指出了我国发展外墙外保温虽然道路曲折,但其必要性毋庸置疑,并对在我国大力发展外保温提出了建议。     

Building typologies as a tool for assessing the energy performance of residential buildings - A case study for the Hellenic building stock

Successful strategies towards minimizing the energy consumption and greenhouse gas emissions attributed to the building sector require knowledge on the energy-related characteristics of the existing building stock. Despite the numerous studies on energy conservation applications in buildings, current knowledge on the energy-related characteristics of the building stock still remains limited. Building typologies can be a useful instrument to facilitate the energy performance assessment of a building stock. This work is based on a harmonised structure for European building typologies (TABULA) developed for residential buildings, but the methodology may be extended to the tertiary sector as well. National typologies are sets of model buildings with characteristic energy-related properties representative of a country's building stock. The model buildings are used as a showcase for demonstrating the energy performance and the potential energy savings from typical and advanced energy conservation measures (ECMs) on the thermal envelope and the heat supply system. The proposed Hellenic residential building typology is presented for the first time along with an assessment of various ECMs that are used for an estimate of the energy performance of building stock in Greece in an effort to meet the 9% indicative national energy savings target by 2016.     

Thermal zoning and interzonal airflow in the design and simulation of solar houses: a sensitivity analysis

Many assumptions must be made about thermal zoning and interzonal airflow for modelling the performance of buildings. This is particularly important for solar homes, which are subjected to high levels of periodic solar heat gains in certain zones. The way in which these passive solar heat gains are distributed to other zones of a building has a significant effect on predicted energy performance, thermal comfort and optimal design selection. This article presents a comprehensive sensitivity analysis that quantifies the effect of thermal zoning and interzonal airflow on building performance, optimal south-facing glazing area, and thermal comfort. The effect of controlled shades to control unwanted solar gains is also explored. Results show that passive solar buildings, in particular, can benefit from increased air circulation with a forced air system because it allows solar gains to be redistributed and thus reduces direct gain zone overheating and total energy consumption.     

Comparison of low-energy office buildings in summer using different thermal comfort criteria

Sustainable low-energy office buildings attempt to harness the buildings architecture and physics to provide a high quality working environment with the least possible primary energy consumption. A promising approach to condition those buildings in summer employs the utilization of the building's thermal storage activated by natural heat sinks (e.g., ambient air, ground water or soil) through night ventilation or thermally activated building systems (TABS). However, a certain room temperature cannot be guaranteed as occupants may influence the room energy balance by window opening, internal heat gains or sun shading control. Between 2001 and 2005, monitoring campaigns were carried out over 2 or 3 years in 12 low-energy office buildings which are located in three different summer climate zones in Germany. These climate zones are defined as summer-cool, moderate and summer-hot. The weather at the building site and the room temperatures in several office rooms were monitored by different scientific teams. The raw data are processed for data evaluation using a sophisticated method to remove errors and outliers from the database and to identify the time of occupancy. The comfort in all office rooms in each building is evaluated separately. For data presentation, these separate comfort votes per office room are averaged using the median instead of the arithmetic mean in order not to overestimate extremely cold or hot room temperatures. A comfort evaluation in these 12 low-energy office buildings indicates clearly, that buildings which use only natural heat sinks for cooling provide good thermal comfort during typical and warm summer periods in Germany. However, long heat waves such as during the extreme European summer of 2003 overstrain passively cooled buildings with air-driven cooling concepts in terms of thermal comfort.     

From the design of green buildings to resilience management of building stocks

ABSTRACT

The green and the subsequent sustainable building movements have been framed by changing societal contexts. Their main focus has been on the design of new buildings. However, these movements have neglected the life span of existing buildings and the long-term management of building stocks. The reasons why are considered: the changing interpretations of sustainability, the evolution of different forms of tacit knowledge, lack of a metabolic framework covering the built environment and lack of a consistent multi-scale building information modelling (BIM). The transition toward a ‘risk society’, with an increasing diversity and frequency of threats, challenges the current optimistic definition of sustainability. Resilience addresses fast- and slow-moving threats that can lead to unknown consequences and new risks. Alternative planning approaches (e.g. scenario planning, adaptive change and resilience heuristics) are discussed. The differences between anticipation- and resilience-based strategies are considered. Possible heuristics can be found in social–ecological systems, in resilience engineering and in the historic evolution of the built environment. Resilient solutions generally lead to a higher level of complexity and carry additional environmental costs. In the creation of resilience capacity, new knowledge will be co-produced through transdisciplinary research, scenario planning and design experiments under conditions of uncertainty.     

A holistic approach to energy efficient building forms

Minimizing energy consumption in buildings has become an important goal in architecture and urban planning in recent years. Guidelines were developed for each climatic zone aiming at increasing solar exposure for buildings in cold climates and at reducing solar exposure for buildings in hot climates. This approach usually plans for the season with the harshest weather; often forgetting that temperatures in cities at latitude 25° can drop below thermal comfort limits in winter and that temperatures in cities at latitude 48° often rise above thermal comfort limits in summer. This paper argues that a holistic approach to energy efficient building forms is needed. It demonstrates a generic energy efficient building form derived by cutting solar profiles in a conventional block. Results show that the proposed building form, the Residential Solar Block (RSB), can maximize solar energy falling on facades and minimize solar energy falling on roofs and on the ground surrounding buildings in an urban area in winter; thus maximizing the potential of passive utilization of solar energy. The RSB also supports strategies for mitigating the urban heat island through increased airflow between buildings, the promotion of marketable green roofs and the reduction of transportation energy.     

Thermal modelling of an industrial building with solar reflective coatings on external surfaces: case studies in China and Australia

Most industrial buildings rely almost entirely on air-conditioning systems to provide thermal comfort to staff and customers who use the premises. As an alternative to this active approach, passive strategy is recommended to either fulfil this task or to help reduce energy consumption of air-conditioning systems already installed. Applying solar reflective coatings on external surfaces of the building, a key passive strategy, appears to offer an effective solution to reduce solar heat, especially during the summer, penetrating through the building fabric. This article discusses a study that uses computer thermal modelling to investigate the effectiveness of this strategy and to explore its contribution to operational energy savings. Detailed mathematical modelling in accordance with thermodynamic and heat transfer theories through the building fabric is illustrated and solutions to the mathematical problems are presented. The study consists of a comparison between two scenarios (normal coating and reflective coating) in three locations in China and one in Australia. The application of solar reflective coatings on external surfaces of the building produces energy savings for all the four locations and is found to be more beneficial in hot climates where there is a considerable need to reduce summer solar gains.     

近零能耗建筑中相变建筑材料的研究进展

近零能耗建筑是采用被动式建筑设计和主动式节能技术、以最低的能源设备功耗获得舒适室内环境的建筑.相变建筑材料的使用可以提高建筑围护结构的热惰性,减少室内温度的波动,降低供暖、空调设备的容量,同时能与太阳能、空气能等可再生能源相结合,降低建筑设备能耗.从不同围护结构的角度介绍了相变建筑材料的分类与特点,综述了国内外相变围护...     

建筑热缓冲空间的设计理念和类型研究——以国际太阳能十项全能竞赛作品为例

对建筑热缓冲空间的设计理念和策略进行分析,将其功能归结为热缓冲空间的蓄热能力和对换热速率的调节两个因素;以历届太阳能十项全能竞赛的参赛作品为例,依据热缓冲空间的形式和在建筑中的位置,将其分为中庭式、包围式、外廊式和辅助空间式四个类型,并分别举例阐述其特点。分析结果表明,热缓冲空间是一种综合性的节能设计策略,它通过被动式节能措施的合理整合,建筑主次空间的合理组织,能有效的改善建筑的内部环境,其设计理念为绿色建筑设计提供了新思路。     

Appraisal of thermal performance of a glazed office with a solar control coating: Cases in Mexico and Canada

The use of solar passive strategies such as new solar control coatings on windows for buildings with large glazed areas, have recently become important and helpful tools, mainly because these developments help to reduce heat gains and/or losses through transparent materials, diminishing energy loads, and improving the environment inside buildings. This paper shows an assessment of the thermal performance for an office on top of a building with four different configurations of window glass, and their influence on the indoor conditions. The window glass configurations are: clear glass, glass-film (SnS–Cu_xS solar control coating), double-glass-film, and double clear glass. The simulations were carried out using weather data from Mexico City and Ottawa, which are a good representation of two extreme weather conditions, in order to assess the thermal behaviour inside offices, such as energy loads, costs for air conditioning, and the influence of interior heat transfer coefficient correlations. The results indicate that the glass-film proves to be the less appropriate configuration due to the high temperatures reached on the film surface, which has an impact on the air temperatures inside the office and contributes to increase the energy consumption. In general, the double glass-film configuration results to be adequate for both climates, nevertheless it shows a better performance for Ottawa than Mexico City, where a simple double clear glass would work the same way.     

Design strategy for low-energy ventilation and cooling within an urban heat island

Natural ventilation is a proven strategy for maintaining thermal comfort in non-domestic buildings in the UK. The energy consumption and thus the carbon dioxide emissions that contribute to global warming are lower than in conventional air-conditioned buildings. However, the ambient temperatures in the UK have risen over the last decade and new climatic data for use in the design of naturally ventilated buildings has been published. Using these data and dynamic thermal modelling, it is shown that passive stack ventilation alone was unlikely to maintain summertime comfort in a proposed University College London building within an urban heat island. The stack ventilation strategy was evolved by the introduction of passive downdraught cooling. This low-energy technique enables cooled air to be distributed throughout the building without mechanical assistance. The underlying principles of the technique were explored using physical models and the anticipated performance predicted using thermal modelling. The architectural integration is illustrated and the control strategy described. The resulting building is believed to be the first large-scale application of the passive downdraught cooling technique; construction began in late 2003.