Radiation Shading Research Articles

창의 기울기에 따른 건축물 에너지 소비량 예측

Most of domestic building generally don`t have fixed shading devices considering of appearance and aesthetic issues. In this study is suggested that tilt window simultaneously has a role of shading and blocking solar radiation. The tilt window thermal performance is investigated by relation ship between inclination and heating cooling road. As comparing vertical window with and of tilt window respectively, the heating load is increased by 3.6% and cooling load is reduced by 8.1% on tilt window and the heating load is increased by 5.3% and cooling load is reduced by 11.5% on tilt window. Especially, the total load of alternative tilt window is showed the reduction rate 2.6% and3.6% compared of vertical window. Therefore, the tilt window is possible to role of shading of solar radiation and reduction of heating and cooling load.

The Layout and Form Design Research on BIPV External Sun-Shading Skin in Hot-Humid Areas

Building external sun-shading is an important building energy efficiency measure in hot-humid areas. Integrated photovoltaic sun shading, which is of energy saving as well as power production, is one method with great potential for sustainable development of building. This paper extends the external sun-shading modules design and explores the BIPV design possibilities in the area by discussing the combined building skin strategy in hot-humid areas, photovoltaic external sun-shading modules layout and the micro-structure technical analysis. The model is optimized and the specific application in construction is determined through the software simulation of solar radiation shading, indoor illumination effects and photovoltaic shading .The reasonable combination of photovoltaic sun-shading modules and the battery arrangement with different light transmission rate enrich the possibility of the building skin space in architectural heat shielding and aesthetic design.

THERMAL ASSESSMENT OF MIST SPRINKLING OVER THE SPACE BETWEEN SOLAR RADIATION SHADES AND GLASS

The authors installed vertical blinds outside glass windows and sprinkled mist over the space between the glass and the blinds, presuming that mist sprinkling would reduce the temperature of the space and that dampened blinds and glass would produce evaporative cooling of their surface. We also assumed that the installation of exterior blinds would boost the effectiveness of solar radiation shading and evaporative cooling. The blinds can be operated manually not to spoil the view. Tests were conducted both at a mock-up with windows facing south about two square meters and at an experimental building about 165 square meters. The test results show that energy can be saved by about 52 percent.

How Realistically Does Outdoor UV-B Supplementation with Lamps Reflect Ozone Depletion: An Assessment of Enhancement Errors

Limitations in the realism of currently available lamps mean that enhancement errors in outdoor experiments simulating UV-B radiation effects of stratospheric ozone depletion can be large. Here, we assess the magnitude of such errors at two Finnish locations, during May and June, under three cloud conditions. First we simulated solar radiation spectra for normal, compared with 10% and 20% ozone depletion, and convoluted the daily integrated solar spectra with eight biological spectral weighting functions (BSWFs) of relevance to effects of UV on plants. We also convoluted a measured spectrum from cellulose-acetate filtered UV-B lamps with the same eight BSWFs. From these intermediate results we calculated the enhancement errors. Differences between locations and months were small, cloudiness had only a minor effect. This assessment was based on the assumption that no extra enhancement compensating for shading of UV radiation by lamp frames is performed. Under this assumption errors between spectra are due to differences in the UV-B effectiveness rather than differences in the UV-A effectiveness. Hence, conclusions about plant growth from past UV-supplementation experiments should be valid. However, interpretation of the response of individual physiological processes is less secure, so results from some field experiments with lamps might need reassessment.

A STUDY ON THERMAL LOAD REDUCTION METHOD FOR DOUBLE SKIN IN COLD REGIONS

In cold regions, it is necessary to correspond to solar heat gain and heating load in winter in addition to solar radiation shading and cooling load in summer. Therefore, it becomes important to do the plan and design that should correspond to both high insulation of building and overuse of glasses. Double skin (DS) has attracted attention as architectural methods corresponding to these. The aims of this study are to show the influencing factor of shape, specification and control technique that are directly linked to thermal load reduction method of DS and to reveal the optimum design condition and the energy saving effect after we verified heat characteristic for DS in cold regions.

A microscale three-dimensional urban energy balance model for studying surface temperatures

A microscale three-dimensional (3-D) urban energy balance model, Temperatures of Urban Facets in 3-D (TUF-3D), is developed to predict urban surface temperatures for a variety of surface geometries and properties, weather conditions, and solar angles. The surface is composed of plane-parallel facets: roofs, walls, and streets, which are further sub-divided into identical square patches, resulting in a 3-D raster-type model geometry. The model code is structured into radiation, conduction and convection sub-models. The radiation sub-model uses the radiosity approach and accounts for multiple reflections and shading of direct solar radiation. Conduction is solved by finite differencing of the heat conduction equation, and convection is modelled by empirically relating patch heat transfer coefficients to the momentum forcing and the building morphology. The radiation and conduction sub-models are tested individually against measurements, and the complete model is tested against full-scale urban surface temperature and energy balance observations. Modelled surface temperatures perform well at both the facet-average and the sub-facet scales given the precision of the observations and the uncertainties in the model inputs. The model has several potential applications, such as the calculation of radiative loads, and the investigation of effective thermal anisotropy (when combined with a sensor-view model).

Afforestation and stream temperature in a temperate maritime environment

There have been few long term investigations of the effects of afforestation on stream temperatures in the UK, and the present study uses the results of continuous monitoring of water temperatures in a forest and a moorland stream of the Loch Grannoch area in southwest Scotland over a 4 year period to investigate the effects of planting coniferous forest on stream thermal regime. The presence of a coniferous tree canopy resulted in a lowering of mean water temperatures by ∼0·5 °C but larger reductions in summer monthly mean maxima and diel ranges of up to 5 °C and 4 °C respectively. The diel cycle in the forested stream lagged behind that of the moorland site in all months of the year, but the delay in timing was greater for the peak than for the trough in the diel cycle. Mean water temperatures were higher in the forest stream during the mid-winter months, reflecting higher minimum values. Contrasts in stream thermal regime between forest and moorland showed relatively little interannual variability over the study period. Continuous monitoring of air temperatures during 2002 revealed contrasts between the study sites that were less pronounced for air than for water temperature, and suggested it is the shading of incoming solar radiation that has a strong effect in determining the water temperature behaviour of the forested stream. Although the biological impact of the observed contrasts in stream temperature between land uses is likely to be relatively modest, the presence of forest cover moderates the occurrence of high summer temperatures inimical to the survival of some salmonid species. Copyright © 2005 John Wiley & Sons, Ltd.

屋内用ロールシェイドの日射遮蔽係数に関する実験的研究

Windows are largely affected by solar radiation, controlling heat radiation from window surfaces is of particular importance. The present study was performed with the recognition that, in order to calculate air-conditioning energy, the radiative component and the convective component of radiant heat must be known separately as they exhibit different heat transfer characteristics. This paper describes a method for measuring the solar radiation shading coefficient (SC) separated into a radiative and a convective component by a heat quantity-based shading coefficient measuring apparatus. The values of shading coefficients of ten conventional roller sahdes were measured with the experimental apparatus. The measured values of total SC were approximated by the measured reflectance of window, the values of short wave component of SC were approximated by the transmittance of window and the values of long wave component as well as the values of convective component of SC were approximated by the absorptance of window.

Effects of different light levels on the initial growth and photosynthesis of Croton urucurana Baill. in southeastern Brazil

Four levels of shading (full sunlight (0%), 30, 50, 70% of solar radiation interception on growth, chlorophyll concentration and photosynthetic rate were studied in Croton urucurana Baill., a pioneer plant species. This species seedlings are of potential interest for reforestation projects and recovery of degraded areas. The seedlings were grown in pots containing soil and sand (2:1) and later transferred to plastic bags of 3 dm³ and submitted to different levels of shading (30, 50, 70%) of solar radiation and full sunlight, as control. The experimental design was completely randomized with five replicates and each experimental unit was composed of five plants. The results suggest that plants submitted to 70% shading showed higher dry weight accumulation in leaf and root, and higher plant height and leaf area. However, the seedlings root system showed higher dry biomass under full sunlight. It was observed a tendency to increase chlorophyll concentration and to decrease photosynthetic rate with the increase of the shading level.

Shading effects on spatial growth and biomass partitioning of Cynodon dactylon

Cynodon dactylon is a low‐growing C4 weed that is highly sensitive to shading. This species shows severe biomass reductions and highly plastic morphological changes in response to resource availability. The objective of this study was to analyse the effect of shading on the spatial and biomass growth of C. dactylon. Two experiments were carried out exploring different environmental conditions. Six treatments were applied on C. dactylon patches. Daylight and 18%, 41%, 48%, 69% and 85% shading of daylight photosynthetic active radiation (PAR) were imposed in Expt 1 and 0%, 22%, 44%, 50%, 74% and 87% shading of daylight PAR in Expt 2. Patches were slightly elliptical in shape and grew 3.2 and 1.5 cm d−1 with 0% shading, on average, during the whole studied periods in Expts 1 and 2 respectively. Biomass was significantly reduced from 41% shading onwards in Expt 1 and from 50% shading in Expt 2. However, patch extension rate was only significantly reduced from 85% and 74% shading in Expts 1 and 2 respectively. Biomass partitioning was modified by shading in both experiments. A functional analysis of C. dactylon patches showed that the patch extension rate diminished linearly when patch biomass growth rate was lower than 1.66 g d−1; above this value, the extension rate remained constant.

Low Irradiance During Rooting Improves Propagation of Oak and Maple Taxa

Abstract Rooting trials were conducted to determine if the duration of exposure to low levels of solar irradiance during root initiation influenced rooting and survival of semihardwood cuttings of six tree species. Cuttings of oak (Quercus imbricaria, Q. nigra, Q. palustris, Q. rubra) and maple (Acer rubrum ‘Bowhall’, and A. truncatum) were treated with IBA and placed in a fog-humidified polyethylene tent rooting chamber for 119 or 117 days (A. rubrum and Q. nigra) under either 82% (control) or 93% (low irradiance) shading of ambient outdoor solar radiation. Cuttings were exposed to either 0, 10, 20, 40, or 119 days of 7% irradiance followed by placement under control conditions (18% irradiance) for the remainder of the treatment. Percentage rooting, the number of roots per cutting, and the number of days to root were significantly influenced by exposure to 7% irradiance during rooting, but responses were dependent on taxa. For most taxa, the highest rooting percentages required at least 10 days of exposure to 7% irradiance. Overwinter survival of rooted cuttings averaged 58.8% and was not affected by treatment. Results of this study demonstrate that low irradiance in the rooting environment can increase the rooting of cuttings of oak and maple taxa.

Alpine lithofacies variation: Working toward a physically-based model

Local scale variation in the deposition of alpine lithofacies (moraines, rock glaciers, and talus) within single mountain ranges or alpine valleys is hypothesized to reflect the control of three topoclimatic parameters (altitude, radiation shading and show-fence/wind-drift effects) that interact to varying degrees with sourcewall fracturing. A conceptual model that incorporates local and regional scale controls over facies deposition is formalized and indirectly tested using simple comparison-of-means, correlation analysis, and numerical simulations based upon two data sets from mountain ranges in the southern Rocky Mountains. Results from these exploratory analyses suggest that there is great promise for a physically-based approach to the study of alpine lithofacies. For example, the patterns of early-and mid-Holocene moraines in the Colorado Front Range can be reproduced by manipulating, in a spatially consistent fashion, the radiation shading and wind-drift components of the model. Preliminary analyses of cirque floor deposits in the Sangre de Cristo mountains suggest that the range of altitude, radiation shading and sourcewall fracturing values for rock glaciers and talus overlap, but that the facies can be roughly distinguished on the basis of a dimensionless interaction value combining all three of the topoclimatic and lithologic parameters. A more detailed set of field data from a portion of the Colorado Front Range allows the identification of a threshold separating talus deposits from active rock glaciers on the basis of topoclimatic situation and sourcewall characteristics. Full simulation of facies deposition during the Holocene is complicated by the differing responses of the facies to changing (macro) climatic conditions. Simulation of talus slope and rock glacier response to changing weathering rates underscores the complexity of rock glacier response, and highlights the need for caution in interpreting the morphology of these features and the timing of climatic events.

Simulation of within-tree and between-tree shading of direct radiation in a forest canopy: effect of crown shape and sun elevation

The pattern of momentary within-tree and between-tree shading of foliage in direct radiation flux was simulated in fully-stocked model stands with a Poisson distribution of trees. The canopies were composed of umbrella-like (crown-height/crown-radius, or H/ R = 3), average ( H/ R = 8) or columnar ( H/ R = 20) tree crowns. The momentary radiation-extinction probability was calculated for a large number of points (10 6−10 7 points per ha) within the canopy. The radiation-attenuation rate depended on the projected leaf-area density within the crown. At solar elevations of 5° and 45°, columnar crowns had the most between-tree and the least within-tree shading, while at a high sun elevation (85°) the same was true for umbrella-like crowns. At low and medium sun elevations (5° and 45°) the crown shape had a rather small effect on the total shading of foliage. At a high sun elevation, flat, horizontally extended crowns were clearly best-illuminated, because both within-tree and between-tree shadings were low.

Thermal behavior of a small, saltless solar pond with the semitransparent multilayer surface insulation system

This article presents experimental and theoretical results for a small, saltless solar pond with three semitransparent air-filled surface insulation layers. The inner dimensions of the pond are 1 m × 1.77 m × 1.77 m. The experiments were done in Ohita, Japan (33°14′ N and 131°37′ E) during two periods: March 21–August 5, 1986 and August 12, 1986-February 14, 1987. The mean temperature of the pond was found to be 10 to 20°C higher than the daily mean ambient temperature. Theoretical analyses show that heat losses through the upper surface of the pond and the shading of the incident solar radiation due to the bank of the pond played a decisive role in determining the pond temperature.

Simplified Techniques to Study Components of Solar Radiation Under Haze and Clouds

Estimates of the global (G), diffuse (D) and direct-beam (I) irradiances at the surface of the earth can be obtained with a single instrument, the “dial” radiometer. The dial assembly intermittently shades a solid-state sensor on a continual automatic basis. This is a very simple instrument that does not require mechanical adjustments of the shade. When corrections for imperfect cosine response and excessive shading of sky radiation are performed, measurements averaged over 1 h should be accurate well within ±5%. Estimates of atmospheric turbidity or haziness can be expressed as an extinction coefficient, computed for I in reference to that obtained under cloudless clean skies for the same solar zenith angle. The uneven spectral response of silicon-cell and PAR (photosynthetically active radiation) sensors should be considered when comparing estimates of G, D or I to measurements of these components by a wide-band sensor. Linear relationships seem adequate for a variety of cloud conditions. This allows the use of a single dial silicon-cell radiometer, for example, to estimate quite accurately the values of G, D and I that would be seen by wide-band or PAR radiometers. An alternative, but less exact, means of obtaining estimates of hourly averages of D and I is to measure only G and use the ratio of G to that which would be obtained under clean, cloudless conditions as the sole determining factor.

Shading effects of collector rows tilted toward the equator

collectors tilted toward the equator. They also accounted for the beam radiation shadowing by consideration of the shaded area on a collector. They attempted to approximate the shading of diffuse radiation, but, as we will show later, an error was introduced in their model. Here we present a totally analytical model for calculating the daily total radiation on rows of fixed collectors tilted toward the equator, This method is an extension of the Liu-Jordan model[3]. Rather than considering the beam radiation shadow area, we use the shading plane concept introduced by Jones [4]. In order to utilize the shading plane method it is necessary to invoke the restriction that the length of the row be very long in comparison with the other system dimensions. This may be a reasonable approximation for practical situations as Appelbaum and Bany[2] concluded the row length has little overall effect since the effect is pronounced only close to sunrise or sunset when the radiation is low.

Thermal stress fracture of solar control window panes caused by shading of incident radiation

The phenomenon of thermal stress fracture in solar control window panes in high-rise buildings due to shading of incident radiation is investigated in this paper. An experimental method, in which a bank of infra-red lamps was used as the simulated solar source, was developed to measure thermal strains and hence thermal stresses built up at the cool edges of the glass pane which was glazed in a480 mm square aluminium frame. Horizontal and diagonal shadows both increased the thermal stresses by approximately10% when compared with the unshaded glass panes. It is shown that fracture mechanics can be used to analyse and predict fracture stresses once the mirror radius and the fracture toughness of the glass pane are known. These predictions agree very well with experimental measurements. Finally, a new glazing technique using a thermal conducting sealant in the rebate is suggested to minimise the incidence and risk of thermal stress fracture. This is achieved by raising the temperature of the cool edges and thus lowering the differential heating effect. Preliminary experiments show that the method is promising.

3069 プラスチック布日覆いの日射遮蔽計算(環境工学・設計計画,第1回 日本建築祭 研究発表会 学術講演要旨集)

3069 プラスチック布日覆いの日射遮蔽計算(環境工学・設計計画,第1回 日本建築祭 研究発表会 学術講演要旨集)