Sky Factor Research Articles

A Method for Evaluating the Daylighting of Premises Using BIM

The paper presents a method for assessing the daylighting of premises, which can be used directly at the stage of architectural and construction design of buildings in building information model (BIM) software complexes. The calculation method is based on the calculation of the sky factor by constructing a solid angle formed by the calculated point and the light opening of the outer wall. These operations are proposed to be performed automatically using visual programming programs that work together with the BIM complexes. Since the considered calculation method is based on the idea of the physical meaning of the daylight factor, it can be used to evaluate the daylighting according to almost any regulatory method. At the same time, all the data necessary for the calculation can be obtained directly from the building information model. The method is universal and can be used both for the calculation of side and top daylighting, considering the surrounding development. The proposed method can also be used as a tool for finding the best design solution for translucent structures of the designed building based on the requirements of thermal protection, daylighting, and safety.

Urban Form and Urban Materials as Controller of Urban Climate in Valparaiso, Chile

The urban heat island (UHI) effect on the city and urban climate are related whit urban form and urban materials: it’s an evidence of human influence in climate change. Into the cities, the air temperature increases in downtown and go to outskirts decreases. Valparaíso, Chile, is located in a Mediterranean climate in the southern hemisphere (-33°03’). The urban area of the city is 400 km2 and its population reaches 300,000 inhabitants. The behaviour of air temperature in the city in winter and summer and on sunny days and cloudy days has been recorded. In all days heat island phenomenon is registered. A greater increase of UHI in summer and in sunny day has been recorded. The variation of the temperatures of the materials that make up the urban canyons has also been recorded, presenting different dispersions and variation according to whether it is a sunny day or a cloudy day. In sunny day all day a large dispersion is registered, at afternoon spatially. An important factor in the behaviour of the street climate is its morphology. This condition has been recorded with the visible sky factor (SVF) and with the geographic orientation of the studied canyons. Both the global urban form, the visibility of the sky, the street morphology and the materials of the city affect the urban air temperature variations. City normative planning and designers should consider these variables and its influences.

Thermal environment mitigation effects in suburban area

The purpose of this paper is to clarify the relationship between the physiological and psychological responses of the human body and the outdoor environment evaluation index ETFe (enhanced conductioncorrected modified effective temperature). The experiments were carried out in summer. For the measurements, observation points were selected with consideration for the condition of the ground surface such as bare ground where the surface is gravel or soil; paved ground such as concrete, asphalt or blocks; green areas covered in plants and water surfaces and with consideration for the condition of the sky factor due to buildings or trees. 19 observation points were chosen. Subjects were 38 healthy young. ETFe that was considered to report neither hot nor cold, thermally neutral sensation, was 30.6°C. ETFe that was considered to report neither comfortable nor uncomfortable comfort was 35.5°C. It was considered that the threshold for the human body with regards to thermal environment stimuli in an outdoor space is higher than the thermal environment stimuli in a summer indoor space.

Effects of Outdoor Thermal Environment upon the Human Responses

In a summer outdoor space, the influence of short-wave length solar radiation on the human body is strongly apparent, heat is retained in the body, and the risk of heat disorders such as heat stroke increases. To avoid this, it is essential to seek shade to avoid the influence of short-wave length solar radiation. In addition, natural ground surfaces such as green spaces and water surfaces are useful in reducing the air temperature. It is indispensable to consider climate mitigation effect of outdoor space. The purpose of this study is to clarify the influence of the thermal environment of an outdoor space on the human body in rural and suburban regions where paddy fields remain. Subject experiments were conducted to examine the relationship between the thermal environment evaluation index enhanced conduction-corrected modified effective temperature (ETFe) in an outdoor space and the physiological and psychological responses of the human body. Experiment sites were selected with consideration for the natural ground surface such as bare ground where the surface is gravel or soil; paved ground such as concrete, asphalt or blocks; green areas covered in plants; and water surfaces, as well as the sky factor due to buildings or trees etc. and the proportion of the solid angle of components of greenery and water etc. comprising the solid angle of the total celestial sphere. A ground surface feature with a high heat capacity may promote sensation of hot and deteriorate the thermal sensation. A landscape of thick vegetation with a high green factor may have a strong feeling of confinement, which can make it somewhat hot and somewhat uncomfortable thermal environment due to the sense of stagnation. Compared with the urban environment, it is conceivable that the difference in the perceptual environment, whereby it is subconsciously assumed to be a comfortable thermal environment, had an effect in the rural and suburban regional environment, resulting in an ETFe lower than the upper limit of comfort in a summer urban environment.

An Exploration of the Role that the Night Sky Plays in the Lives of the Dark Sky Island Community of Sark

This paper is an exploration of the role the night sky plays in the lives of the Dark Sky Island community of Sark in the Channel Islands, using the qualitative method of intuitive inquiry. The fields of ecopsychology and environmental psychology consider how encounters with nature may be beneficial and transformative, but focus on “green”/grounded nature rather than encounters with the sky, while Dark Sky supporters claim dark skies enhance wellbeing but do not cite any supporting research. This paper explores the following themes: the human desire to see the night sky, the commercialisation of this desire through astronomical tourism, the nature of nature, fear of the dark, and nature and wellbeing. Data was gathered in March 2014 through a series of eight semi-structured interviews and a focus group on Sark, and email comments from three further participants. In addition, relevant entries from the researcher’s reflexive journal kept during the research process are included. Research findings show a high level of enjoyment and value placed on observing the night sky with others and that this facilitates family/community connections and the transmission of sky stories to others; at the same time, findings reveal the widespread belief that observing the night sky spontaneously or intentionally results in positive (and sometimes transformative) feelings, a common experience of the night sky evoking childhood sky memories, a universal fearlessness of the dark, and a sense that as there is often no visible horizon – that there is no differentiation between sky and land and that sky and land appear as one. The paper therefore begins to address the missing sky factor within the fields of ecopsychology, health psychology and environmental psychology. The findings can potentially be used to strengthen the Dark Skies movement’s claims that dark night skies can impact positively on wellbeing.

The Influence of the Solar Radiation Absorptivity up on the Outdoor Thermal Environment Evaluation Index and the Thermal Sensory Perceptions

When the thermal environment is under heated conditions, short-wavelength solar radiation shows a strong influence on the human body and the heat is accumulated in the human body. In order to demonstrate the effect of the short-wavelength solar radiation absorptivity of clothing on physiological temperature in an outdoor space, the relationship between the thermal environment evaluation index, ETFe, and the thermal sensory perceptions of the human body was investigated. A significant temperature difference of 2.7°C was shown for an ETFe that was thermally neutral (neither hot nor cold). The effect of short-wavelength solar radiation absorptivity was strongly apparent in ETFe when direct solar radiation was strong and in warmer outdoor spaces. In an outdoor space where the effect of the sky factor and albedo was strong, the setting of the short-wavelength solar radiation absorptivity was demonstrated to greatly impact the estimation of perceived and physiological temperature. When interviewing subjects on clothing in an outdoor space, it is essential to obtain the hue of clothing.

Recognition and adaptation of climatic areas in Chaharmahaland Bakhtiari province of Iran in terms of tourism climate comfort

Climatic phenomena play a significant role in development of the tourism industry. An appropriate climate may bring positive responses of tourists. The tourists plan their journeys considering the climatic and weather conditions of their destination. Chaharmahaland Bakhtiari Province is a mountainous region in west of Iran which enjoys various distribution of climatic elements especially rainfall and temperature due to topographic diversity. Statistical methods of factor analysis and cluster analysis were applied to obtain a precise recognition about the climatic zones of the province. 26 climatic variables were selected from six existing weather stations in the province. The results obtained from factor analysis showed that province climate is affected by four climatic factors which are listed here in order of significance: rainfall factor, serene sky factor, thermal factor and humidity factor. Then, four climatic regions were distinguished in the province by means of cluster analysis that was administrated on matrix of factor grades. At last, using PET index, evaluation and comparison were carried out for climate comfort at stations representing each climatic region during a year. The results revealed that May was the best month in terms of climate comfort conditions. Thermal stresss began from June and reached their peaks in July and August. Boroujen and Kouhrang stations entered the climate comfort range in September while same conditions happened for Shahr-e-kord and Lordegan in October.

Effects of Height Restriction and Relaxation by Sky Factor Focusing on Digestion Floor Area Ratio and Building Height

Effects of Height Restriction and Relaxation by Sky Factor Focusing on Digestion Floor Area Ratio and Building Height

Urban morphology indicators for solar energy analysis

Within the variation of energy performance at urban scale, the relation between solar irradiation and urban form takes a central role. The solar availability on façades which is influenced by the morphology of the urban context, is strictly related to building energy performance indeed. In this paper, we aim at identifying a set of urban morphology indicators (UMIs) that show the most accurate relations with the solar availability on façades (SIy) in the Mediterranean context. The analysis that relates to 14 urban textures of Rome and Barcelona comprises seven UMIs: gross space index, floor space index, façade-to-site ratio, average building height, volume-area ratio, building aspect ratio and sky factor of building façades. The SIy in each texture has been calculated with Heliodon2 software, using normalised models; the relation between SIy and UMIs were investigated using least-square regression analysis. Results suggest that gross space index, façade-to-site ratio and sky factor show very good correlation with SIy (R2 = 0,91) and could be used to develop a comparative assessment tool of solar performance at fabric scale. This could ease the work of urban planners and architects in the early stage of design, reducing both data and time normally needed to perform solar analyses at urban scale.

Universal Visible Sky Factor: A method for calculating the three-dimensional visible sky ratio

This paper developed a new methodology for evaluating the visible sky ratio of a vertical building surface. A visible sky ratio is based on a surface viewpoint and measured by projecting obstacles onto a virtual three-dimensional (3D) hemisphere. Typically, virtual sky projection methods use two-dimensional (2D) mapping to calculate the amount of view of the outside. A major concern with 2D mapping is loss of accuracy due to the distortions in geometry that occur during the projection process. To address this limitation, a new projection method has been developed, supported by a computational numeric model that calculates the actual projection area of obstacles onto a 3D hemisphere. The new method improves the accuracy of the visible sky ratio without distorting obstructions. This new method can handle more complex conditions such as the forms of surrounding buildings, as well as various layouts, orientations, and heights. This study examines the new method via existing calculation processes in order to determine its robustness and limitations. The proposed method compared positively to these other existing methods, especially in terms of vertical changes in the observation point.

Seasonal Differences of Psychological and Physiological Responses in Tropical Urban Climate

This research aims to use the outdoor thermal environment evaluation index ETFe to quantify effects on the thermal sense of the human body of a tropical region climate with small annual temperature differences, and to examine seasonal differences in the thermal sense. Given that the average temperature of the earth is forecasted to rise, studying the effects on the human body from outdoor thermal environments in tropical regions is important for considering how to spend time outdoors in the future. This study clarifies seasonal differences in effects on the human body by comparing the effects on the thermal sensations of the human body from outdoor thermal environments in the winter and the dry season of Bangkok, Thailand in the tropics. The mobile measurements were carried out on the campus of Chulalongkorn University, Bangkok, Thailand. The subjects reported the thermal sensation and the thermal comfort that they experienced while exposed at the observation point. Air temperature, humidity, air velocity, short-wave solar radiation, long-wave thermal radiation, ground surface temperature, sky factor and the ratio of green and water surface solid angles were measured. We found no large seasonal difference between the winter and the dry season in skin temperature due to body temperature regulation. It is clear that in the winter season, people prefer a lower temperature than in the dry season, and in the dry season they tolerate higher temperatures than in winter. The effect of the seasonal difference appears in the amount of change to thermal sensation. We found that it is difficult for seasonal differences to greatly affect the amount of change to thermal comfort. We found that the effect of seasonal difference is that people show stronger responses to thermal comfort for thermal sensation in winter than in the dry season.

Comparisons of Height Restriction and Relaxation by Sky Factor Focusing on Digestion Floor Area Ratio and Building Height

Comparisons of Height Restriction and Relaxation by Sky Factor Focusing on Digestion Floor Area Ratio and Building Height

GISデータを利用した寒冷地住宅の暖房負荷解析

Direct solar heat gain (hereafter DSHG) is expected to decrease heating energy consumption of housings with airtightness and thick insulation in northern region. It is important to calculate precise solar heat gain through window, since the values influence on the strategy whether we should use DSHG or not. In this report, we suggest the method to calculate solar radiation in a site where build a building. Then the relationship between thermal environment and heating energy is analyzed by using the climate data combined with GIS data. The results identify that southern sky factor is able to explain an effect of DSHG.

Experimental Change of the Orientation of Two Populations of Talitrus saltator (Crustacea Amphipoda Talitridae) from Cap Bon (North‐Eastern Tunisia)

AbstractThe orientation of sandhopper populations is adapted to the direction of the shoreline of the sandy beaches where they live; this behaviour was shown to be inherited in some Mediterranean populations. The question was open whether this behaviour could be adaptively modified in case of changing shoreline or passive transfer to a new differently oriented shoreline. The Cap Bon beaches in north‐eastern Tunisia are particularly interesting because they belong to two different Mediterranean Basins, the central and the eastern one, and their supra‐tidal populations do not come together. This work verified the effect of experimental change of the shoreline direction in two populations of Talitrus saltator from Cap Bon (north‐eastern Tunisia) through a displacement experiment. We transferred samples of T. saltator from two different localities (Korba and Ratiba) from their original beach to the familiar one and tested their solar and landscape orientation on the new beach that had an almost opposite direction with respect to the previous one. The comparisons of the results on the home beach and the new one confirmed the use of the solar compass in both populations, as well as the importance of landscape view and optical local sky factor in adjusting the escape direction. In both populations, an increase of scatter was observed on the new beach, especially when individuals could see the landscape. Also, a clear behavioural difference between the two populations was recorded, being Ratiba population not significantly oriented to the shoreline when tested on the unfamiliar beach, while Korba population maintained its home direction also on the new beach.

Occurrences of Standard Skies and Luminuos Turbidity Factor in Bratislava

Levels of daylighting in nature continually changing and their daily courses are different day to day. Effectiveness of daylight utilisation in buildings depends on exterior luminous conditions resulting from sunny and sunless situations. Generally, prevailing interiors are illuminated by diffuse skylight during year but sunny orientated rooms can be often exposed by direct sunlight. To describe these conditions the occurrence of sky luminance patterns and light attenuation properties of atmosphere expressed e.g. by luminous turbidity factor are needed. This paper presents the comparison and evaluation of occurrences of ISO/CIE General Standard Sky and luminous turbidity factor in two distant years on the base of measured instantaneous global and diffuse horizontal illuminance, global and diffuse horizontal irradiance and zenith luminance taken during 1995 a 2002 at ICA SAS in Bratislava. The different occurrences of luminous situations described by general standard sky types were found. Results of the luminous turbidity factor calculation show that various atmospheric pollutions during sunny situations can be expected.

The influence of outdoor thermal environment on young Japanese females

The influence of short wave solar radiation appears to be strong outdoors in summer, and the influence of airflow appears to be strong outdoors in winter. The purpose of this paper was to clarify the influence of the outdoor environment on young Japanese females. This research shows the relationship between the physiological and psychological responses of humans and the enhanced conduction-corrected modified effective temperature (ETFe). Subjective experiments were conducted in an outdoor environment. Subjects were exposed to the thermal environment in a standing posture. Air temperature, humidity, air velocity, short wave solar radiation, long wave radiation, ground surface temperature, sky factor, and the green solid angle were measured. The temperatures of skin exposed to the atmosphere and in contact with the ground were measured. Thermal sensation and thermal comfort were measured by means of rating the whole-body thermal sensation (cold-hot) and the whole body thermal comfort (comfortable-uncomfortable) on a linear scale. Linear rating scales are given for the hot (100) and cold (0), and comfortable (100) and uncomfortable (0) directions only. Arbitrary values of 0 and 100 were assigned to each endpoint, the reported values read in, and the entire length converted into a numerical value with an arbitrary scale of 100 to give a linear rating scale. The ETFe considered to report a neither hot nor cold, thermally neutral sensation of 50 was 35.9°C, with 32.3°C and 42.9°C, respectively, corresponding to the low and high temperature ends of the ETFe considered to report a neither comfortable nor uncomfortable comfort value of 50. The mean skin temperature considered to report a neither hot nor cold, thermally neutral sensation of 50 was 33.3°C, with 31.0°C and 34.3°C, respectively, corresponding to the low and high temperature ends of the mean skin temperature considered to report a neither comfortable nor uncomfortable comfort value of 50. The acceptability raised the mean skin temperature even for thermal environment conditions in which ETFe was high.

Relationships of light environment to stand attributes in a stand of bamboo, Phyllostachys pubescens

We investigated the relationships between the light environment beneath a forest canopy and stand attributes, i.e., culm density and total basal area, in a stand of bamboo, Phyllostachys pubescens. Mazel ex Houz. based on a thinning experiment. A 15 m × 15 m plot was established in the stand and 10 successive thinning regimes were performed, so that thinning ratio by the number of culm for each thinning was approximately 5%. The digital hemispherical photographs were taken before and after each thinning, and the sky factor was computed as a measure of light environment from the photographs. The light environment became brighter and homogeneous as the thinning regimes progressed. The culm density was a good predictor of the light environment, and the relationship between sky factor and culm density could be well expressed by an exponential equation. Because of the larger culm sizes and total leaf area, the change in light environment with thinning was more sensitive in the P. pubescens stand than Phyllostachys bambusoides Sieb. et Zucc. stands examined in previous studies. This suggested that species characteristics should be carefully considered when elaborating culm density control for improving light environment in bamboo stands.

Effect of settings of digital fisheye photography to estimate relative illuminance within forest under low light conditions

In order to evaluate the effects of settings of digital fisheye photography on estimates of relative illuminance (RI) within a forest under low light conditions, we assessed the effectiveness of some estimators, i.e., canopy openness (CO), sky factor (SF), and diffuse transmittance (DIF). The estimates were calculated from digital hemispherical photographs taken with two different exposure settings, i.e., the reference exposure setting and the auto-exposure setting. We also presented a new estimator (%Exposure), which does not require image analysis, and compared it with other estimators calculated from a digital hemispherical photograph using image analysis. The CO, SF, and DIF calculated from digital hemispherical photographs taken with auto-exposure setting were not significantly correlated with RI. However, those calculated from digital hemispherical photographs taken with reference exposure settings were significantly correlated with RI. On the other hand, %Exposure showed a slightly higher correlation with RI compared with the other estimators.

AN ANALYSIS OF URBAN LANDSCAPES WITH RESPECT TO SOLID ANGLES BASED ON COMPUTATIONAL GEOMETRY ALGORITHMS

The solid angle, which is closely related to the sky amount and sky factor, has been commonly used to assess urban landscapes. In this paper, we propose a new algorithm to calculate the solid angles of urban landscapes based on computational geometry. This algorithm enables us to incorporate the complicated landscapes which consist of multiple nonconvex polygons. Furthermore, using the algorithms, we assess the public space near Shibuya Station in terms of solid angles. In the analysis, we describe how advertising billboards disturb our visibility. We also develop the algorithm to calculate the sky amount and the sky factor, and evaluate both indexes.

３Ｄ‐ＣＡＤモデルを用いた荷重・法規制・日照条件に基づく緑化可能空間の抽出

Urban greenery has been attracting an increased attention as the mitigation against urban thermal environment. In order to establish a feasible greening plan, however, it is strongly needed to understand the potential spaces for greening in the substantial urbanized areas. This study developed a method for the extraction of potential spaces for greening considering live load, legal conditions and physical conditions for vegetation growth using 3D-CAD model. Firstly, we constructed the 3D-CAD model of a site in Aoyama, Tokyo, by collecting the information on spatial form using aerial photo, GIS data and the result of field investigation. Then, the potential spaces for greening were extracted examining the each buildings live load and legal conditions. As to the vegetation growth conditions, we calculated the distribution of sky factor ratio using numerical simulation, then excluded the areas of low daylight condition from the potential spaces. The result indicated that 26.8% of all rooftop areas and 7.2% of all wall areas and 0.6% of all ground areas were considered to be potential spaces for greening. Also, total potential area scored approximately the same amount of the present greenery areas. In addition, the characteristics of volume and locations of potential space for greening varied depending on the building use.