Visual comfort assessment of daylit and sunlit areas: A longitudinal field survey in classrooms in Kashan, Iran

Visual comfort in schools enhances not only health and wellbeing, but also satisfaction and therefore learning and visual performance. This research aims at testing students’ evaluations on visual comfort through questionnaires in daylit and non-daylit areas in classrooms. Dynamic daylight metrics including Spatial Daylight Autonomy (sDA) and Annual Sunlight Exposure (ASE), codified in LEED v4, are calculated and compared to students’ evaluations. A typical high school in Kashan was selected in which subjective and field measurements were carried out simultaneously in two different oriented (south and north) classrooms during a school year (2014–2015). Simulation results show that 71% of the space in south facing classroom and 20% of the space in north facing classroom receives adequate amount of daylight while 29% of the space in south facing classroom and 0% of it in north facing classroom receives excessive amount of sunlight. According to simulations, each classroom has been divided into daylit and sunlit areas, in which students’ assessments about daylight and sunlight have been separately analyzed based on their position. Comparing simulation and survey results show that while students’ evaluation about daylight availability in daylit areas is mostly positive, daylight uniformity is not considered “enough” in these areas. Moreover, students’ impression about daylight availability in non-daylit areas is rather neutral and more optimistic than simulation results. More interestingly, most students in both sunlit and non-sunlit areas of classrooms do not feel much direct sunlight and glare. In fact, questionnaires’ results show a wider range of sunlight acceptance in south facing classroom and visual comfort in north facing classroom than simulation results. According to the results non-daylit areas or sun-lit areas defined by dynamic metrics would not necessarily cause visual discomfort, suggesting that some other factors (e.g., view, configurations of windows, expectations and region) can change the degree of comfort experienced in each space

Energy and economic performance of rooftop PV panels in the hot and dry climate of Iran

Photovoltaic (PV) Panels, one of the more promising renewable energy technologies, are growing rapidly nowadays, especially in developed countries. However, these systems have not achieved public acceptance in some countries due to low energy efficiency and poor economic performance, especially in countries which are subsidized in energy tariffs. In this paper, the energy and economic performance of fourteen rooftop PV systems with the power of 5 kW in the hot and dry climate of Iran are assessed by monitoring the total annual energy production and simulation. The monitored data is used to analyze systems’ economic performance via Pay-Back Period (PBP), Net Present Value (NPV), Return of Investment (ROI) and Levelized Cost of Energy (LCOE). Results show that single array configuration systems have the maximum energy production while dividing the system decreases the production. Economic analysis shows that the average PBP is 11.6 years under actual price of electricity (0.21$), however it is 46.9–50.5 years under subsidized average tariffs. ROI values range from 2.6 to 3.2 with the average of 2.9 for actual prices. Under subsidized prices, the cash generated by investment cannot even offset the costs that the investment requires during its lifetime with NCF and NPV being both negative. Overall, the systems are not economically beneficial under subsidized average tariffs in Iran, which discourages private and public sectors to investment on these systems. Environmentally, each PV system can averagely reduce 500 kg CO2 emission in the first year of installation and fourteen of them can approximately reduce 1,613,900 kg of CO2 emission during life time of PV panels

Assessment of cost optimal solutions for high performance multi-family buildings in Iran

According to the international benchmarks proposed for the energy demand reduction, the Iranian government, for limiting domestic energy demand growth, has set some energy efficiency policies. In this regard, the present study proposes various solutions to investigate the feasibility of improving the performance of an existing typical multi-family building in Iranian context, to achieve a high performance one with proper cost-optimal levels of energy performance by using the global cost approach defined by EU legislation. Precisely 50 different packages of energy efficiency measures were analyzed in terms of economic and energy performance with consideration on the effects of different envelope thermal insulation, shading system, window types and highly efficient systems in addition to the solar renewable energy source. Then the impact of the selected measures on energy efficiency improvement and global cost were studied and revealed that obtaining high performance building simultaneously with the cost optimal levels can be fulfilled, just when the financial support from the government subsidies exist, otherwise there is still a long way from being economically feasible

Evaluating assumptions of scales for subjective assessment of thermal environments – Do laypersons perceive them the way, we researchers believe?

International audienc

Evaluating assumptions of scales for subjective assessment of thermal environments – Do laypersons perceive them the way, we researchers believe?

People's subjective response to any thermal environment is commonly investigated by using rating scales describing the degree of thermal sensation, comfort, and acceptability. Subsequent analyses of results collected in this way rely on the assumption that specific distances between verbal anchors placed on the scale exist and that relationships between verbal anchors from different dimensions that are assessed (e.g. thermal sensation and comfort) do not change. Another inherent assumption is that such scales are independent of the context in which they are used (climate zone, season, etc.). Despite their use worldwide, there is indication that contextual differences influence the way the scales are perceived and therefore question the reliability of the scales’ interpretation. To address this issue, a large international collaborative questionnaire study was conducted in 26 countries, using 21 different languages, which led to a dataset of 8225 questionnaires. Results, analysed by means of robust statistical techniques, revealed that only a subset of the responses are in accordance with the mentioned assumptions. Significant differences appeared between groups of participants in their perception of the scales, both in relation to distances of the anchors and relationships between scales. It was also found that respondents’ interpretations of scales changed with contextual factors, such as climate, season, and language. These findings highlight the need to carefully consider context-dependent factors in interpreting and reporting results from thermal comfort studies or post-occupancy evaluations, as well as to revisit the use of rating scales and the analysis methods used in thermal comfort studies to improve their reliability

The Scales Project, a cross-national dataset on the interpretation of thermal perception scales

Thermal discomfort is one of the main triggers for occupants' interactions with components of the built environment such as adjustments of thermostats and/or opening windows and strongly related to the energy use in buildings. Understanding causes for thermal (dis-)comfort is crucial for design and operation of any type of building. The assessment of human thermal perception through rating scales, for example in post-occupancy studies, has been applied for several decades; however, long-existing assumptions related to these rating scales had been questioned by several researchers. The aim of this study was to gain deeper knowledge on contextual influences on the interpretation of thermal perception scales and their verbal anchors by survey participants. A questionnaire was designed and consequently applied in 21 language versions. These surveys were conducted in 57 cities in 30 countries resulting in a dataset containing responses from 8225 participants. The database offers potential for further analysis in the areas of building design and operation, psycho-physical relationships between human perception and the built environment, and linguistic analyses

The Scales Project, a cross-national dataset on the interpretation of thermal perception scales

Thermal discomfort is one of the main triggers for occupants’ interactions with components of the built environment such as adjustments of thermostats and/or opening windows and strongly related to the energy use in buildings. Understanding causes for thermal (dis-)comfort is crucial for design and operation of any type of building. The assessment of human thermal perception through rating scales, for example in post-occupancy studies, has been applied for several decades; however, long-existing assumptions related to these rating scales had been questioned by several researchers. The aim of this study was to gain deeper knowledge on contextual influences on the interpretation of thermal perception scales and their verbal anchors by survey participants. A questionnaire was designed and consequently applied in 21 language versions. These surveys were conducted in 57 cities in 30 countries resulting in a dataset containing responses from 8225 participants. The database offers potential for further analysis in the areas of building design and operation, psycho-physical relationships between human perception and the built environment, and linguistic analyses

A Review of District-scale Energy Performance Analysis: Outlooks towards Holistic Urban Frameworks

Over the past few decades, the world has experienced a major population shift towards urban areas resulting in environmental degradation and increased energy consumption. To combat these challenges, energy efficiency measures are being deployed to improve the performance of different entities within urban built environments. However, effective implementation of such measures often requires a holistic approach to account for existing interrelated and complex relationships between entities at the urban scale. This paper presents a distillation of salient facts and approaches for energy performance evaluation of districts. The studies are reviewed in three sections; (1) concepts defining district energy performance, (2) approaches and methodologies for district energy performance evaluation and (3) system interactions between district entities. The state of the art review reveals that several challenges exist in the initial stages of energy performance assessment of districts. The suggested framework in this paper addresses this issue through pre-processing of data related to entities such as transportation systems and buildings. The framework classifies the available information under three potential categories, namely, 'subject and Scope’, ‘Input Data Management’ and ‘Methods’. This categorisation results in easier integration of multidisciplinary aspects of entities involved in district energy performance assessment.Science Foundation Irelan