Comparative analysis of energy performance between courtyard and atrium in buildings

In this paper, the energy performance of a central atrium is investigated and compared with the energy performance of a courtyard with the same geometric proportions. The atrium and the courtyard design used for the analysis are square in plan and surrounded by the building on all four sides. The glazing type and percentage for the courtyard walls and atrium skylight are varied in the analysis. Weather data from four cities representative of climatic conditions of cold, temperate, hot-humid and hot-dry were used. The results show that, in general, the open courtyard building exhibits a better energy performance for the shorter buildings. As the building height increases, however, at some point the enclosed atrium exhibits a better energy performance. This “break even” point for the number of stories depends on different factors like glazing and climate parameters discussed above.     

Evaluation of energy efficient design strategies for different climatic zones: Comparison of thermal performance of buildings in temperate-humid and hot-dry climate

Since the Kyoto protocol signed in December 1997 the majority of governments around the world have committed themselves to reducing the emission of the greenhouse gases. Thus, efficient use of energy and sustainability has become a key issue for the most energy policies. Sustainability and energy saving terms take place in building construction industry too since buildings are one of the most significant energy consumers. It is known that heating energy demand of a building has a great rate in building total energy consumption. In addition to that, the most of the heating energy has been lost from building envelope. TS 825, Heating Energy Conservation Standard for Buildings in Turkey, aims the reducing of heat loss in buildings through the envelope. But within buildings, one of the fastest growing sources of new energy demand is cooling and especially in hot-humid and hot-dry climatic parts of Turkey cooling season is much longer than the heating season. Moreover in hot-dry climate heat storage capacity of the envelope becomes more important issue than heat insulation for energy efficiency of the building. Since the Turkish standard is considering only heating energy conservation by using degree-day concept, Istanbul and Mardin are considered in the same zone, however those are in temperate-humid and hot-dry climatic zones, respectively. In this study energy efficient design strategies for these climatic zones have been explained and thermal performance of two buildings, which are constructed according to the TS 825 in Mardin and Istanbul cities were evaluated to show the importance of thermal mass in hot-dry climates.     

Potential of emerging glazing technologies for highly glazed buildings in hot arid climates

In order to improve the sustainability of buildings one of the challenges is to address the role of the building envelope as the key climate moderator between the internal and external environments. The envelope is exposed to the elements and needs to control air exchange as well as sunlight and sound passing through to the occupants. Therefore, it has a major impact not only on the energy utilisation within the space it controls but also on the quality of comfort. However, inside highly glazed modern buildings, achieving good comfort is often at the cost of high-energy consumption. Therefore, in the light of ever increasing energy costs, improved façade design can contribute to a reduction of operational costs. The aim of this paper is to explore technical, economic, environmental and indoor comfort implications of emerging glazing technologies for energy control of highly glazed buildings in arid Middle Eastern climates, which is one of the harshest climates for this building type. The work includes predictions through thermal simulation of the impact of electrochromic glazing, holographic optical elements (HOE), aerogel glazing and thin film photovoltaics on two example buildings. Potential reductions in cooling demand are assessed.     

Using passive cooling strategies to improve thermal performance and reduce energy consumption of residential buildings in U.A.E. buildings

Passive design responds to local climate and site conditions in order to maximise the comfort and health of building users while minimising energy use. The key to designing a passive building is to take best advantage of the local climate. Passive cooling refers to any technologies or design features adopted to reduce the temperature of buildings without the need for power consumption. Consequently, the aim of this study is to test the usefulness of applying selected passive cooling strategies to improve thermal performance and to reduce energy consumption of residential buildings in hot arid climate settings, namely Dubai, United Arab Emirates. One case building was selected and eight passive cooling strategies were applied. Energy simulation software – namely IES – was used to assess the performance of the building. Solar shading performance was also assessed using Sun Cast Analysis, as a part of the IES software. Energy reduction was achieved due to both the harnessing of natural ventilation and the minimising of heat gain in line with applying good shading devices alongside the use of double glazing. Additionally, green roofing proved its potential by acting as an effective roof insulation. The study revealed several significant findings including that the total annual energy consumption of a residential building in Dubai may be reduced by up to 23.6% when a building uses passive cooling strategies.     

Evaluating the potential impact of global warming on the UAE residential buildings – A contribution to reduce the CO2 emissions

There is significant evidence that the world is warming. The International Panel of Climate Change stated that there would be a steady increase in the ambient temperature during the end of the 21st century. This increase will impact the built environment, particularly the requirements of energy used for air-conditioning buildings. This paper discusses issues related to the potential impact of global warming on air-conditioning energy use in the hot climate of the United Arab Emirates. Al-Ain city was chosen for this study. Simulation studies and energy analysis were employed to investigate the energy consumption of buildings and the most effective measures to cope with this impact under different climate scenarios. The paper focuses on residential buildings and concludes that global warming is likely to increase the energy used for cooling buildings by 23.5% if Al-Ain city warms by 5.9 °C. The net CO₂ emissions could increase at around 5.4% over the next few decades. The simulation results show that the energy design measures such as thermal insulation and thermal mass are important to cope with global warming, while window area and glazing system are beneficial and sensitive to climate change, whereas the shading devices are moderate as a building CO₂ emissions saver and insensitive to global warming.     

Development of an adaptive thermal comfort equation for naturally ventilated buildings in hot-humid climates using ASHRAE RP-884 database

The objective of this study was to develop an adaptive thermal comfort equation for naturally ventilated buildings in hot-humid climates. The study employed statistical meta-analysis of the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) RP-884 database, which covered several climatic zones. The data were carefully sorted into three climate groups including hot-humid, hot-dry, and moderate and were analyzed separately. The results revealed that the adaptive equations for hot-humid and hot-dry climates were analogous with approximate regression coefficients of 0.6, which were nearly twice those of ASHRAE and European standards 55 and EN15251, respectively. The equation using the daily mean outdoor air temperature had the highest coefficient of determination for hot-humid climate, compared with other mean temperatures that considered acclimatization of previous days. Acceptable comfort ranges showed asymmetry and leaned toward operative temperatures below thermal neutrality for all climates. In the hot-humid climate, a lower comfort limit was not observed for naturally ventilated buildings, and the adaptive equation was influenced by indoor air speed rather than indoor relative humidity. The new equation developed in this study can be applied to tropical climates and hot-humid summer seasons of temperate climates.     

降低建筑空调能耗研究

在分析贵阳市气候特点及实例建筑空调负荷特性的基础上,采用建筑环境模拟软件DeST对实例建筑室内基础室温以及全年建筑冷热负荷进行模拟,在分析模拟结果的基础上,结合贵阳市气候特点,提出如下三条贵阳市降低建筑空调能耗建议：1)舒适性空调设计应首先满足冬季采暖,然后考虑夏季制冷;2)自然通风是夏季降温的优先考虑方式,过渡季节调节是降低建筑制冷能耗的重要手段;3)增加围护结构保温和控制窗墙比是降低建筑采暖能耗的首要手段。研究结果不但能对贵阳市的建筑节能提供参考,而且还对广大温和地区建筑节能有参考意义。     

寒冷地区半围合式庭院空间风环境研究

半围合式建筑庭院作为建筑室内与室外的缓冲空间,在寒冷地区可以创建较为温和的微气候,维持建筑热环境的相对稳定,同时为人们提供开放自然舒适的室外交流与活动空间。以地处寒冷地区的典型半围合式庭院建筑为例,通过实地测量和数值模拟分析,研究基于室外气候要素的半围合式庭院空间风环境适宜性空间尺度,采用风速、空气龄等风环境评价指标来模拟评价庭院不同空间尺度与比例条件下的舒适度与建筑性能。研究成果可为寒冷地区建筑半围合式庭院空间设计提供空间价值尺度参考,探讨通过可持续性设计的方法对半围合式庭院空间进行优化设计来提高室外空间的舒适性。     

Quantifying the impact of building envelope condition on energy use

ABSTRACT

The gap between the architectural information and the as-is building condition has been known as one of the pivotal factors influencing deviations between actual and predicted building energy consumption. Despite such significance, quantifying the impact of deviated building information on energy use has not been fully investigated. This paper explores building information modelling (BIM)-driven experimental simulation to quantify the impact of building envelope condition on energy use, which can infer the impact of reflecting the as-is building conditions in as-designed BIMs on the reliability of energy analysis. First, BIM-driven energy simulations are conducted with varied thermo-physical properties of building envelope elements in gbXML-based BIMs under different climate conditions. Building upon the impacting factor for energy analysis (IFEA), the simulation results are then used to infer the impact of the deviated building condition on energy consumption. Through case studies, it is observed that the annual energy consumption of a residential building can deviate by 18–20%, whereas thermal resistances of exterior walls can deviate by 1?m²K/W. This paper validates quantitatively the potential benefits of reflecting the as-is building condition in BIM-based energy performance analysis. This provides practitioners with insights into how to improve the reliability of energy analysis of existing buildings.     

ECOTECT能耗模拟下既有住宅建筑围护结构节能改造的热环境分析研究

目前,既有住宅建筑节能改造主要有围护结构改造和供热计量改造两方面。围护结构节能改造主要包括:外墙节能改造、外窗节能改造、屋面节能改造等技术措施的研究;建筑物围护结构节能改造除了能够降低建筑能耗之外,对建筑物室内热环境也有很大影响。采用ECOTECT能耗模拟软件,对西安市某住宅建筑围护结构不同节能改造方案的热环境进行模拟,深入分析不同节能改造方案的能源消耗、不舒适度、围护结构得热、温度分布和热舒适度情况,以热舒适为前提、节能为目的选择最优的节能改造方案。为既有住宅建筑节能改造方案优选提供依据。     

Glazing energy performance and design optimization with daylighting

This study systematically explores the influence of glazing systems on component loads and annual energy use in prototypical office buildings. The DOE-2.1B building energy simulation program, which contains an integrated daylighting model, is used to determine fenestration energy performance in diverse climates. The sensitivity of total energy use to orientation, window area, glazing properties (U-value, shading coefficient, visible transmittance), window management strategy, installed lighting power, and lighting control strategy are all described. We examine the conditions under which daylighting reduces net anual energy use as well as those conditions under which energy use may increase. Combinations of wall and fenestration properties that minimize net energy requirements as a function of climate and orientation are described.     

Code compliance of fully glazed tall office buildings in hot climate

In this research, the effect of glazing type and other energy conservation measures on the peak power demand of air-conditioning (AC) systems is investigated for tall and fully glazed government and private office buildings. The EnergyPlus building simulation program is used in the analysis assuming climate conditions similar to that experienced in hot countries of the Arabian Gulf, such as Kuwait. The main objective of the investigation is to meet the limits stipulated in the mandatory Kuwaiti code of practice for energy conservation, with respect to peak AC demand, for both air-cooled and water-cooled AC systems. It is found that for government office buildings with air-cooled AC system, the code limit of 70 W/m² for the AC peak power is met when tint low-e glazing is used with either heat recovery units or with AC systems with higher coefficient of performance (COP); whereas for private office buildings, the limit can be met when using a number of conservation measures. Overall, the water-cooled AC system showed better performance even though the code limit is 50 W/m² which is mainly due to the higher COP values achievable with such AC systems.     

Energy modelling studies of thermochromic glazing

Theoretically thermochromic glazing has the potential to reduce energy consumption in buildings by allowing visible light for day lighting, reducing unwanted solar gain during the cooling season, whilst allowing useful solar gain in the heating season. In this study building simulation is used to predict the savings made by novel thermochromic glazing coatings compared to standard products, for locations with different climates. The results suggest that thermochromic glazing can have a significant energy saving effect compared to current approaches.     

整合光环境分析的外窗节能设计研究——以寒冷地区点式高层办公楼为例

关于窗墙比与能耗关系的现有研究中,大量的是关注窗墙比对采暖、制冷能耗的影响,而窗墙比的变化对办公空间室内光环境的影响被忽视了。基于此背景,以寒冷地区点式高层办公楼为研究对象,在能耗模拟中耦合室内光环境的分析,研究窗墙比与采暖、制冷和照明能耗间的定量关系。研究结果表明,改变东西向窗墙比对能耗影响最大,东西向窗墙比宜控制在较小的范围内。北向窗墙比其次,宜控制在0.6以下。改变南向窗墙比变化对建筑总能耗影响不大。     

Investigation on energy performance of double skin façade in Hong Kong

Double skin façade can be defined as a building façade covering one or several stories with multiple skins. The skins may be air tight or ventilated. With sophisticated study and design, buildings constructed with double skin façade can have better thermal performance than the conventional single skin façade. This paper reports the findings on the energy performance of double skin façade applied to a typical office building under the climatic condition in Hong Kong. An experimental setup was established and the measured data were used to verify the theoretical model developed via the EnergyPlus simulation program. The validated model was then used to evaluate the energy performance of double skin façade with various configurations including glazing type (clear, absorptive or reflective glass), glazing position (inner or outer pane) and glazing layers (single or double glazing material). The results indicate that a double skin façade system with single clear glazing as the inner pane and double reflective glazing as the outer pane can provide an annual saving of around 26% in building cooling energy, as compared to a conventional single skin façade with single absorptive glazing. However, the long payback period of 81 years makes the double skin façade system economically infeasible. Support and motivation are needed from the local government in order to foster successful and widespread application of the double skin façade system in buildings.     

玻璃窗在建筑节能中的作用及其特性分析

本研究根据中国不同地区的气候特点,利用玻璃窗模拟软件Window5.1和建筑环境设计模拟分析软件DeST2,以一个典型住宅建筑模型为研究对象,通过模拟计算9种典型玻璃窗的热工特性以及冬季供暖和夏季供冷的能耗,分析并评估了不同类型玻璃窗的节能特性和对建筑能耗的影响。从而可得出如下结论:在严寒和寒冷地区建议采用中空高透射Low-e玻璃窗;在夏热冬冷地区选用中空 内遮阳窗户类型可比普通单窗节能近20%;而在夏热冬暖地区可以选择低透射Low-e玻璃窗、中空 内遮阳模式或者普通单玻 内遮阳模式均可达到理想的节能效果。为将来的建筑外窗节能设计以及玻璃窗的合理选型设计提供参考依据。     

Heating energy use management in residential buildings by temperature control

This paper presents the results of analytical investigations to determine the potential heating energy savings that can be achieved in residential buildings by controlling the house temperature through either night setback or night setback plus day zone setback. A typical U.S. single family house is analyzed for different levels of thermal integrity of the building envelope (i.e., levels of insulation, window glazing, and infiltration). Reduced infiltration, insulated interior walls, and various window orientations are also considered. Results are given for four major U.S. climate zones—cool, temperate, hot-humid, and hot-arid. The analysis shows that both types of setbacks are most effective in loose houses, with the greatest absolute savings for the cool climates, and the greatest percent savings for the hot climates. However, the benefits from thermostat setbacks are smaller for tighter houses, and may actually be counterproductive owing to corollary effects such as increased peak loads and degradation of system efficiency.     

Occupant performance and building energy consumption with different philosophies of determining acceptable thermal conditions

Based on building energy and indoor environment simulations, this study uses a recently developed method relying on Bayesian Network theory to estimate and compare the consequences for occupant performance and energy consumption of applying temperature criteria set according to the adaptive model of thermal comfort and the more conventional PMV model. Simulations were carried out for an example building with two configurations (with and without mechanical cooling) located in tropical, subtropical, and temperate climate regions. Even though indoor temperatures differed significantly between building configurations, especially in the tropical climate, the estimated performance differed only modestly between configurations. However, energy consumption was always lower in buildings without mechanical cooling, particularly so in the tropical climate.     

中国被动房外围护系统研究——以寒冷、严寒气候区被动房项目为例

德国的被动房是目前世界公认的具有超低能耗、超低碳排放量、超高室内舒适度等特点的建筑技术体系。德国的气候特征与中国华北地区的气候特征具有相似性,因此,研究并建造被动房对于我国建筑节能工作的发展具有重大的意义。外围护系统作为被动房设计的重点要素,对建筑的节能效率有重大的影响。以寒冷、严寒气候区的被动房项目为例,对被动房外围护系统进行分析与阐述,并以秦皇岛"在水一方"被动式住宅示范项目为例,进行能耗模拟与对比分析。提出适合我国寒冷、严寒气候区气候特点的被动式超低能耗建筑外围护系统的设计策略。     

Analysis of annual heating and cooling energy requirements for office buildings in different climates in Turkey

A great amount of world energy demand is connected to the built environment. Electricity use in the commercial buildings, accounts for about one-third of the total energy consumption in Turkey and fully air-conditioned office buildings are important commercial electricity end-users since the mid-1990s. In the presented paper, the interactions between different conditions, control strategies and heating/cooling loads in office buildings in the four major climatic zones in Turkey – hot summer and cold winter, mild, hot summer and warm winter, hot and humid summer and warm winter – through building energy simulation program has been evaluated. The simulation results are compared with the values obtained from site measurements done in an office building located in Istanbul. The site-recorded data and simulation results are compared and analyzed. This verified model was used as a means to examine some energy conservation opportunities on annual cooling, heating and total building load at four major cities which were selected as a representative of the four climatic regions in Turkey. The effect of the parameters like the climatic conditions (location), insulation and thermal mass, aspect ratio, color of external surfaces, shading, window systems including window area and glazing system, ventilation rates and different outdoor air control strategies on annual building energy requirements is examined and the results are presented for each city.