Categories of indoor environmental quality and building energy demand for heating and cooling

Maintaining suitable indoor climate conditions is a need for the occupants’ well being, while requiring very strictly thermal comfort conditions and very high levels of indoor air quality in buildings represents also a high expense of energy, with its consequence in terms of environmental impact and cost. In fact, it is well known that the indoor environmental quality (IEQ), considering both thermal and indoor air quality aspects, has a primary impact not only on the perceived human comfort, but also on the building energy consumption. This issue is clearly expressed by the European Energy Performance of Buildings Directive 2002/92/EC, together with the most recent 2010/31/EU, which underlines that the expression of a judgment about the energy consumption of a building should be always joint with the corresponding indoor environmental quality level required by occupants. To this aim, the concept of indoor environment categories has been introduced in the EN 15251 standard. These categories range from I to III, where category I refers to the highest level of indoor climate requirement. In the challenge of reducing the environmental impact for air conditioning in buildings, it is essential that IEQ requirements are relaxed in order to widen the variations of the temperature ranges and ventilation air flow rates. In this paper, by means of building energy simulation, the heating and cooling energy demand are calculated for a mechanically controlled office building where different indoor environmental quality levels are required, ranging from category I to category III of EN 15251. The building is located in different European cities (Moscow, Torino and Athens), characterized by significantly different wheatear conditions. The mutual relation between heating and cooling energy demand and the required levels of IEQ is highlighted. The simulations are performed on a typical office room which is adopted as a reference in validation tests of the European Standard EN 15265 to validate calculation procedures of energy use for space heating and cooling.     

对热舒适、空气感觉质量及能耗的模拟研究

室内空调设计温度和新风量对热舒适，室内空气质量及能耗量有重要影响，然而对它们之间相互关系进行研究的文献却较少。通过计算机模拟空调系统在7种室内设计温度和7种新风量条件下的运行情况，得到不同的设计条件组合对热舒适、人体感觉空气质量及建筑能耗量的影响。基于这项分析，提出了此办公建筑合理的室内设计温度和新风量取值。     

The impact of zoning regulations on thermal comfort in non-conditioned housing in hot,humid climates: findings from Dhaka,Bangladesh

In parts of the developing world where densities are high but the availability of air conditioning is limited, building massing and height regulations can influence interior comfort levels. Dhaka, Bangladesh, is characterized by high population densities, a lack of open spaces, and high poverty levels, combining to produce living conditions which are not only uncomfortable, but may lead to the spread of disease. A recent change in zoning regulations provides an opportunity to assess the success of building heights and setbacks in improving indoor thermal comfort conditions. We assess the impact on thermal comfort within Dhaka’s non-conditioned apartment buildings of four zoning schemes which differ in their specifications for setbacks, maximum buildable area, and building heights; but that maintains the current density. Computer simulation techniques model the buildings to test solar, daylight, and ventilation inside the central building to calculate resultant indoor temperature, mean radiant temperature, relative humidity and air velocity. Comparison between these values helps to determine which zoning schemes produce the most favorable thermal conditions. Findings suggest that zoning schemes that provide better solar protection and better natural ventilation are able to reduce indoor temperature and increase indoor air velocity over that provided by current zoning regulations. Recommendations for revising current zoning regulations are given along with general recommendations for how buildings in hot, humid climates can maximize passive cooling, encouraging energy savings and environmental sustainability.     

Study of thermal environment inside rural houses of Navapalos (Spain): The advantages of reuse buildings of high thermal inertia

The main purpose of a residential building is to provide a comfortable environment for human activities. Nowadays this objective is the responsible for the consumption of more than 40% of total energy demand in European Union. The construction sector in Spain has been in rapid growth in the last decades, yet there exists many abandoned buildings in rural areas. In this article we try to analyze the environmental advantages of reuse abandoned rural buildings. Due to their thick exterior walls of high thermal inertia, the indoor environment inside them can be comfortable with less energy consumption than new buildings. Here we show the monitoring results of three different houses, two traditional and one modern building, constructed of different building materials. The aim of this work is to analyze and compare the thermal behaviour of existing constructive solutions in a Spanish district, not to improve them. The field test results show better indoor conditions inside the traditional houses. In summer, thermal comfort is achieved with no energy supply inside traditional houses but not inside the modern one. In winter, the indoor environment is more stable inside the traditional houses, however none of them were able to provide thermal comfort naturally. In the case studied, the only inhabitant of a small village lives in a prefabricated wooden house, and it is demonstrated that the indoor conditions of traditional houses in the same location are of higher quality.     

An investigation of naturally ventilated teaching spaces with windcathers in secondary school where site is constrained by noise and air pollution

Built environment consumes the bulk of the UK’s fossil fuel. Schools account for 15% of the public sector’s carbon emissions. Energy efficient building design can play a vital role in achieving the national carbon emission reduction target of 80% by 2050. Natural and mixed mode ventilation is at the forefront of suggested energy efficient strategies for reducing carbon emissions from schools while maintaining good indoor air quality and thermal comfort. However, it is challenging to naturally ventilate many urban school buildings through side openings because of high noise and particulate air pollution. An alternative strategy, such as multi floor operation of windcatchers was assessed in this research as a sole source of fresh air in teaching spaces. Dynamic thermal simulation (DTS) and computational fluid dynamics (CFD) simulations assessed the performance of the adopted natural ventilation (NV) strategy in meeting the approved requirements for fresh air, indoor air quality (IAQ) and summertime overheating. Simulation results show that it is challenging to meet approved guidelines on air quality and thermal comfort, only when windcatchers are employed for ventilation purpose. However, fan assisted ventilation in conjunction with windcatchers provided satisfactory results. Detailed performance assessments using CFD seem desirable to validate DTS based findings.     

Literature survey on how different factors influence human comfort in indoor environments

The present paper shows the results of a literature survey aimed at exploring how the indoor environment in buildings affects human comfort. The survey was made to gather data that can be useful when new concepts of controlling the indoor environment are developed. The following indoor environmental conditions influencing comfort in the built environment were surveyed: thermal, visual and acoustic, as well as air quality. The literature was surveyed to determine which of these conditions were ranked by building users as being the most important determinants of comfort. The survey also examined the extent to which other factors unrelated to the indoor environment, such as individual characteristics of building occupants, building-related factors and outdoor climate including seasonal changes, influence whether the indoor environment is evaluated as comfortable or not. The results suggest that when developing systems for controlling the indoor environment, the type of building and outdoor climate, including season, should be taken into account. Providing occupants with the possibility to control the indoor environment improves thermal and visual comfort as well as satisfaction with the air quality. Thermal comfort is ranked by building occupants to be of greater importance compared with visual and acoustic comfort and good air quality. It also seems to influence to a higher degree the overall satisfaction with indoor environmental quality compared with the impact of other indoor environmental conditions.     

建筑节能性能对室内环境影响评估

室内环境质量是影响建筑舒适度的重要因素.建筑节能性能对室内环境的影响极少被关注.借助计算机建造模型及计算数据,对3种不同节能性能的建筑进行室内环境比较分析,包括对室内空气温度、空气交换速度及室内光线质量比较分析.研究表明：建筑节能性能不仅影响到建筑的能耗,而且对室内环境也会产生影响,但节能性能的优劣并不与室内环境成正比,节能性能好的建筑其室内环境质量并不绝对优于节能性能差的建筑;对同一建筑,可持续能源的使用在短期内只会对室内环境质量产生微小的影响.     

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.     

Utilizing modulating-temperature setpoints to save energy and maintain alliesthesia-based comfort

ABSTRACT

One area with the greatest potential for energy savings in buildings is heating and cooling. However, it is often argued that any energy-saving techniques should not have a negative impact on comfort for inhabitants. This is where the concept of alliesthesia comes into play. This paper examines the impact of utilizing modulating temperature setpoints to take advantage of the pleasure experienced through change. Simulations were conducted using EnergyPlus to explore the potential for energy savings. It was found that savings of up to 5–15% could be achieved by modulating indoor temperatures in cooling applications. However, modulating temperature setpoints resulted in larger energy usage than constant setpoints in heating applications. Results from human comfort experiments show that modulating temperatures could lead to greater thermal pleasure than a constant temperature environment for cooling situations due to a resetting of the thermal comfort achieved when the indoor temperature is decreased. However, the same comfort benefits are not shown for heating situations. Nonetheless, the simulations and the comfort experiments together show potential for both energy savings and increased human comfort levels in cooling applications.     

Life cycle inventory of buildings: A contribution analysis

A companion paper presented the life cycle inventory (LCI) calculation model for buildings as a whole, developed within a global methodology to optimise low energy buildings simultaneously for energy, environmental impact and costs without neglecting the boundary conditions for thermal comfort and indoor air quality. This paper presents the results of a contribution analysis of the life cycle inventory of four typical Belgian residential buildings. The analysis shows the relative small importance of the embodied energy of a building compared to the energy consumption during the usage phase. This conclusion is even more valid when comparing the embodied energy of energy saving measures with the energy savings they realise. In most studied cases, the extra embodied energy for energy saving measures is gained back by the savings in less than 2 years. Only extremely low energy buildings might have a total embodied energy higher than the energy use of the utilisation phase. However, the sum of both remains small and the energy savings realised with these dwellings are large, compared to the energy consumption of average dwellings.     

Impact of psycho-social factors on perception of the indoor air environment studies in 12 office buildings

The main function of a mechanically ventilated office building is to provide a healthy and comfortable working environment for occupants, while maintaining minimum energy consumption. Twelve mechanically ventilated buildings were selected. They varied greatly in surface area, number of floors, occupant density, and building use. The indoor air quality, thermal comfort, energy consumption, and perception of occupants were investigated in these buildings. A total of 877 subjects participated in the questionnaire survey during the hot summer months of June, July, and August, and during the cold winter months of January, February, and March. The questions included in the questionnaire dealt with health, environmental sensitivity, work area satisfaction, personal control of the workstations environment, and job satisfaction. Measured parameters concerning the quality of indoor air included ventilation rate, concentration of TVOC, CO₂, CO, RH, and formaldehyde. The thermal comfort parameters included room air, mean radiant, plane radiant asymmetry, and dew point temperatures, as well as air velocity and turbulence intensity. Monthly energy consumption data was also gathered for each building. Ventilation performance, in terms of air flow rate and indoor air quality, was compared with the ASHRAE Standard 62-89R (Ventilation for Acceptable Indoor Air Quality. Atlanta: American Society of Heating, Refrigerating, and Air Conditioning Engineers, Inc. U.S.A. [1]). The measured and calculated thermal environmental results were also compared with the ASHRAE Standard 55-92 (Thermal Environmental Conditions for Human Occupancy. Atlanta: American Society of Heating, Refrigerating, and Air Conditioning Engineers, Inc. U.S.A. [2]). CO₂ and CO levels satisfied the recommended limits. The outdoor airflow rate was half that recommended in only one building. The formaldehyde and TVOC levels were moderately higher than suggested comfort levels. However, more than 56% of the occupants rated dissatisfaction with the indoor air quality. Only 63% of the indoor climatic observations fell within the ASHRAE Standard 55-92 summer comfort zone; 27% in the winter. However, only 69% of those surveyed agreed with the comfort zones. More symptoms were reported by workers who perceived IAQ to be poor. Positive relationships were observed between the job satisfaction and satisfaction with office air quality, ventilation, work area temperature, and ratings of work area environment. However, job dissatisfaction did not correlate with symptom reports. The occupants were more dissatisfied with IAQ when they preferred more air movement. In other words, the higher the perceived air movement, the greater the satisfaction with IAQ.     

Energy performance and indoor environmental quality in Hellenic schools

School buildings constitute a major part of the non-residential building stock, though due to their operational characteristics, they represent a low percentage of the overall energy balance of the building sector. Although health and productivity of pupils and teachers is strongly affected by the indoor environmental quality of their school, poor indoor air quality has been reported in published literature, even so for recently constructed school buildings. The same applies for the energy consumption, with large amounts of energy being wasted because no energy saving measures are applied for the operation of schools. This paper presents the outcome of a study on the energy performance of Hellenic school buildings. The general features of the contemporary building stock are presented along with the results from an energy survey in 135 Hellenic schools. The derived energy consumption benchmarks are compared with published literature. Finally, the energy performance and indoor environmental quality of a representative sample of schools in metropolitan Athens are assessed in a holistic approach to the “energy efficiency – thermal comfort – indoor air quality” dilemma. The IEQ assessment was based on an objective evaluation by monitoring crucial indoor conditions and a subjective occupant evaluation using standardized questionnaires. The potential of several energy conservation measures is evaluated in terms of energy savings and reduction of greenhouse gas emissions along with the related payback periods.     

上海世博园部分建筑室内空调环境状况测试分析

为了了解上海世博园建筑室内空调环境状况和行为节能情况,采用实测方法对上海世博园13栋建筑的夏季室内空调环境进行了测试分析。结果表明:一些被测建筑的夏季室内空气温度偏低,最低室温为21.7℃;对于南方湿热地区的剧场建筑,采用开敞式建筑方案不利于室内热舒适环境的营造和节能,且仅利用自然通风和蒸发冷却降温手段难以营造出满足人体基本热舒适性要求的室内环境;展厅观众人数快速增加时室温变化较大,但相对湿度变化较小;一些展馆外门常开,冷风渗漏现象比较严重,加强行为节能是展馆建筑节能设计和运行管理需要考虑的一个重要问题。     

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。     

Passive environment control system of Kerala vernacular residential architecture for a comfortable indoor environment: A qualitative and quantitative analyses

The modern day practice does not give due respect to passive and natural environment control measures in buildings. With modern materials and technology, the buildings of present architectural style results in high energy consumption, in an attempt to provide thermal comfort indoors. The vernacular architecture at any place on the other hand has evolved through ages by consistent and continuous effort for more efficient and perfect solutions. The authors have conducted a qualitative analysis of the passive environment control system of vernacular residential architecture of Kerala that is known for ages for its use of natural and passive methods for a comfortable indoor environment. The orientation of building, internal arrangement of spaces, the presence of internal courtyard, use of locally available materials and special methods of construction, etc. have together created the indoor environment. A quantitative analysis was also carried out based on field experiments by recording thermal comfort parameters in a selected building. The study has provided positive results confirming that the passive environment control system employed in Kerala vernacular architecture is highly effective in providing thermal comfort indoors in all seasons.     

Life cycle inventory of buildings: A calculation method

Traditionally, life cycle assessment (LCA) is mostly concerned with product design and hardly considers large systems, such as buildings, as a whole. Though, by limiting LCA to building materials or building components, boundary conditions, such as thermal comfort and indoor air quality, cannot be taken into account. The life cycle inventory (LCI) model presented in this paper forms part of a global methodology that combines advanced optimisation techniques, LCI and cost-benefit assessment to optimise low energy buildings simultaneously for energy, environmental impact and costs without neglecting the boundary conditions for thermal comfort, indoor air quality and legal requirements for energy performance. This paper first outlines the goal and scope of the LCI. Then, the partial inventory models as well as the overall building inventory model are presented. Finally, the LCI results are shown and discussed for one reference dwelling for the context of Belgium.     

Indoor thermal environment and energy saving for urban residential buildings in China

The purpose of this survey is to investigate the actual conditions of the residential indoor thermal environment in urban areas in China for evaluating thermal comfort and predicting the energy conservation feasibility for space heating and cooling.The apartment homes under investigation were located in the urban areas of nine major cities. The questionnaire survey revealed building characteristics, the types of space heating and cooling system in use, aspects of life style, during winter and summer seasons, and so on. The measurement showed that winter indoor temperatures in Harbin, Urumqi, Beijing and Xi’an remain at a relatively stable level near 20 °C due to the central heating system installed. However in the other cities lacking central heating systems, indoor temperatures fluctuated as a function of the change of outdoor temperature. On the other hand, summer indoor evening temperatures in Shanghai, Changsha, Chongqing and Hong Kong were higher than the comfort zone of ASHRAE. Therefore it is expected that energy use for space heating and cooling in the southern China will increase in the near future because of occupants’ requirement for comfortable indoor environment. Based on the results yielded by this study, in Beijing the calculation of space heating and cooling loads indicated that the energy used to heat indoor spaces can be halved by installing thermal insulation and properly sealing the building.     

Parametric study on the performance of green residential buildings in China

The parametric study of the indoor environment of green buildings focuses on the quantitative and qualitative improvement of residential building construction in China and the achievement of indoor thermal comfort at a low level of energy use. This study examines the effect of the adaptive thermal comfort of indoor environment control in hot summer and cold winter (HSCW) zones. This work is based on a field study of the regional thermal assessment of two typical cases, the results of which are compared with simulated results of various scenarios of “energy efficiency” strategy and “healthy housing” environmental control. First, the simulated results show that the adaptive thermal comfort of indoor environment control is actually balanced in terms of occupancy, comfort, and energy efficiency. Second, adaptive thermal comfort control can save more energy for heating or cooling than other current healthy housing environmental controls in China's HSCW zone. Moreover, a large proportion of energy use is based on the subjective thermal comfort demand of occupants in any building type. Third, the building shape coefficient cannot dominate energy savings. The ratio of the superficial area of a building to the actual indoor floor area has a significant positive correlation with and affects the efficiency of building thermal performance.     

农村被动式住宅通风换气对室内热舒适性影响模拟分析

被动式建筑具有密闭性良好、减少能量损失的优势,在我国农村地区应用具有重要的节能意义。由于围护结构密闭性较高,被动式农村住宅通风换气技术对提高和保障室内空气品质和环境热舒适性尤为重要。针对沈阳某高校示范建筑,分析通风换气技术对其室内环境热舒适性影响,应用Airpak软件进行数值解算,给出室内温度场、速度场和PMV、PPD指标的分布状况。分析不同送风温度、送风风速工况条件下的室内空气温度分布情况,以及PMV、PPD指标对室内环境热舒适性的影响,确定满足环境热舒适性要求的送风工况,为农村被动式住宅的通风换气技术应用提供基础依据。     

Energy consumption and potential energy savings in old school buildings

Energy and indoor environmental audits of energy consumption and indoor air quality were taken in 24 school buildings in Slovenia. The audits show that these buildings are high energy consumers and have poor indoor air quality, as expressed by 60% of the surveyed pupils. This article deals with energy consumption in the analysed schools. The nominal heating power of boilers, and heat exchangers, which are used in district heating, show a 57% overcapacity. The heat losses of the school buildings are 89% higher than the recommended values. According to our analysis of the possible measures to improve the situation in the school buildings, it will not be possible to ensure rational energy use and good indoor air quality with low investment costs. Should we change from hot-water heating systems and natural ventilation to energy efficient blown air systems with which one device provides the comfort of both heating and air conditioning?