Shading

The efficiency of use of solar panels is influenced by many factors. This paper investigates, by experiment, the influence of artificial light and shading on solar panel cells . Firstly, the panel cells are exposed to artificial light of three different power levels. Secondly, the panel cells were shaded by one-quarter, half and three-quarters. Current-voltage and power-voltage characteristics were determined for both cases. Efficiency calculations were done at the maximu m power point. It was observed that when the panel cells were exposed to artificial light sources, the power output and efficiency slightly increased and when exposed to shading, there was a significant reduction in power and efficiency.

Can automatically controlled sun shades significantly reduce summer heat gain and optimize winter passive solar heating in residential applications? This paper reports the results of a two year study using a pair of full height test cells, one of which had a microprocessor controlled movable external or internal sun shade, while the other was an unshaded reference case. For comparison purposes the experimental cell was also operated with a whole house fan. The performance of selected representative tests are reported here for both summer and winter conditions. This paper also describes how hourly data recorded in these test cells was used to validate HEED, a well known whole-building energy simulation program. Once HEED was shown to accurately predict the measured performance of the shades in the test cells, then it was used to model the performance of these same automatic operable shades in each of California's sixteen climate zones.

There are several physical parameters that are taken into consideration when determining the level of agreeability of an enclosed space. For instance, when choosing the louvers for a room there are a multitude of criteria that might be considered such as colour, material or the degree of opacity. However, these apparently small fixtures may have a significant impact also on other apparently unimportant factors like the sound pressure level and the reverberation time. This paper aims to present different types of devices used to control the way daylight enters a room, from both the illuminance level and the acoustical point of view. During the experimental campaign, five of the most common types of louvers were examined regarding their main role of blocking the light and moreover their influence on the reverberation time and sound pressure level in the analysed chamber.

The recent increasing attention in energy production from renewable energy sources has led to photovoltaic (PV) elements, being located on greenhouse roofs. However, their assessment is almost underdeveloped in Italy. The present paper investigated the lack of a spatial database of PV greenhouses in Italy. The first aim is to detect the evolution of PV panels on the roof of greenhouses during several Energy counts (E.C.). The succeeding goal instead aims to examine the shading of PV panels of a prototype greenhouse that enables an environmentally adapting to the intrinsic characteristics. The shading on crops is one of the major limits for the PV installation on the roofs of greenhouses because it causes problems regarding the usual sequence of agricultural activity. Until now many studies applied PV panels as covering material of greenhouses concentrated on flat structures. The present study investigates tunnel greenhouses which, due to their curved shape, do not lend themselves to accommodate easily PV panels on their coverage. The shading variation was analysed inside our prototype greenhouse, by installing PV panels in a checker-board arrangement. The transparent flexible PV panels, with dimensions of 1.116 m × 0.165 m, are manufactured using mono-crystalline silicon cells, with an efficiency of 18%, incorporated into polymers with high resistance. The difference and distribution of the shading percentage were examined regarding the surface area affected by the PV roof, the total area and the section of the greenhouse. Particularly, variations in the percentage of shading and the size of the shaded area have been observed on the twenty-first day of each month of the year. Results exposed some consistency in the shading percentage, primarily because of the curvilinear shape of the section of the greenhouse. From mid-March to mid-September, the shading was practically and constantly inside the greenhouse during the daytime; while it was partly inside and partly outside the tunnel greenhouse during the remaining months. The percentage of shading with the PV arrangement adopted never exceeds 40% during the year.

This paper evaluates the influence of relief shading in finding labels on tourist maps. Two types of maps were compared, one in which terrain was depicted with contour lines and spot heights, and the other enhanced with relief shading. The task was to find specific hills and villages. Two aspects were investigated-whether shading helped users find hills, and whether shading made it more difficult to find villages. The eye-tracking method was used for this study. The results indicate that respondents prefer shaded maps from an aesthetic point of view. Pair-wise comparison of individual stimuli pairs and groups of stimuli was performed with the use of five eye-tracking metrics. Most of the eye-tracking metrics were significantly different for most of the stimuli. The results of the experiment show that shaded maps are less suitable for finding hills and villages. The least effective result was observed in finding villages on a shaded map.

To assess the spatial distribution of photosynthetic capacity within an isolated 20-year-old walnut tree (Juglans regia L.) crown, the distribution of relevant leaf characteristics was measured. Variations in leaf dry weight per area (Wa), and nitrogen concentration on a weight (Nw) and area basis (Na), were studied in relation to solar irradiance along one vertical and two horizontal transects, on July 30 and September 3. In addition, the concentrations of total nonstructural carbon on a weight (TNCw) and area basis (TNCa) were measured on July 30. Concurrently, the spatial distribution of daily integrated leaf irradiance within the crown was simulated by a three-dimensional radiation transfer model over a one-week period before sampling at each date. Within the crown, high spatial heterogeneity was observed for Wa (from 50 to 140 g m−2), TNCa (from 4 to 17 g m−2) and Na (from 1.2 to 3.6 g m−2). Although TNCw and Nw were not correlated and only weakly correlated to daily leaf irradiance, respectively, Wa, TNCa and Na were strongly correlated to daily leaf irradiance. The relationship between observed Na and simulated daily leaf irradiance was used to assess the spatial distribution of Na within the crown at each date. Total leaf nitrogen in the foliage was estimated to be 339 g in late July and 317 g in early September. For the whole crown (i.e., 1729 current-year shoots), Na increased strongly with basal shoot diameter (an index of shoot ‘‘vigor’’), highlighting the fact that large shoots were mainly located in sunlit locations and exhibited high photosynthetic capacity.

... and cultural changes in the arid zones of Islamic countries resulted in a breach between vernacular concepts and the modern urban forms. Traditional Islamic architecture usually displayed buildings with heavy facades and limited well shaded openings on external elevations. ...

Seagrasses of the Great Barrier Reef predominantly occur in coastal regions where terrestrial inputs modify water quality and photosynthetic light is highly variable. Responses to shading were tested for Cymodocea serrulata, Halodule uninervis, Thalassia hemprichii and Zostera muelleri. In aquaria, four light treatments – high (66% surface light), moderate (31%), low (14%) and very low light (1%) treatments – were

Retro-reflective coatings applied to blinds of reduced geometric complexity promise to provide view to the outside while effectively controlling solar gains and glare. To characterize the reflection characteristics of such coatings over the entire solar spectrum, a novel extension to a scanning gonio-photometer is developed. The extended instrument is tested and applied to measure a coating's Bidirectional Reflection Distribution Function including the region of the retro-reflected peak. The measured data-sets are compiled into a data-driven reflection model for the daylight simulation software Radiance. This model is applied to illustrate the coating's effect in a comparison to purely diffuse and specular surface finishes on geometrically identical, flat blinds. Daylight supply, the probability of glare, and solar gains are assessed for an exemplary, South-oriented office under sunny sky conditions. The results indicate the potential of the coating to effectively shade direct sun-light even if applied on blinds with minimalistic geometries. The modeling technique is shown to be a general means to replicate the irregular optical properties of the coating, which cannot be represented by the standard models in daylight simulation software.

The biochemically based leaf photosynthesis model proposed by Farquhar et al. (1980) and the stomatal conductance model proposed by Jarvis (1976) were parameterized for walnut. Responses of photosynthesis to CO2 and irradiance were used to determine the key parameters of the photosynthesis model. Concurrently, stomatal conductance responses to leaf irradiance (Q), leaf temperature (Tl), water vapor pressure deficit at the leaf surface (D), and air CO2 concentration at the leaf surface (Cs) were used to parameterize the stomatal conductance model. To test the generality of the model parameters, measurements were made on leaves from a 20-year-old tree growing in the field, and from sunlit and shaded greenhouse-grown seedlings. The three key parameters of the photosynthesis model (maximum carboxylation rate Vcmax , electron transport capacity Jmax , and dark respiration rate Rd) and the key parameter of the conductance model (reference stomatal conductance, gsref) were linearly correlated with the amount of leaf nitrogen per unit leaf area. Unique relationships could be used to describe nitrogen effects on these parameters for leaves from both the tree and the seedlings. Our data allowed separation of the effects of increasing total photosynthetic apparatus per unit leaf area from the effects of partitioning nitrogen among different pools of this apparatus for foliage acclimation to leaf irradiance. Strong correlations were found between stomatal conductance gs and Q, D and Cs , whereas the relationship between gs and Tl was weak. Based on these parameterizations, the model adequately predicted leaf photosynthesis and stomatal conductance when tested with an independent set of data obtained for the tree and seedlings. Total light-driven electron flows derived from chlorophyll fluorescence data obtained at different leaf temperatures were consistent with values computed by the model. The model was also tested with branch bag data acquired from a three-year-old potted walnut tree. Despite a relatively large variance between observed and simulated values, the model predicted stomatal conductance and photosynthesis reasonably well at the branch scale. The results indicate that the photosynthesis-conductance model developed here is robust and can be applied to walnut trees and seedlings under various environmental conditions where water is non-limiting.

Solar protection of buildings by fixed shading devices has the potential to increase user comfort and energy efficiency simultaneously. This is especially true for existing buildings not equipped with cooling facilities. Due to the inflexibility of these shading elements, their correct design is essential. This paper discusses different methodologies for the ideal dimensioning of such elements and proposes the new method “OPTIShade”. The method uses mathematical optimization strategies in building simulation. Basis for these simulations is EnergyPlus and Radiance, in addition to the generic optimization tool GenOpt. Using ray tracing software will allow for angle selective materials and objects in the simulation. The research for a suitable optimization algorithm has been conducted successfully. First tests of the general method have shown its potential for the improvement of fixed shading in building design.

During the last years, European government remuneration polices promoted the realisation of photovoltaic systems integrated with the structures instead of on ground photovoltaic (PV) plants. In this context, in rural areas, greenhouses covered with PV modules have been developed. In order to interdict the building of greenhouses with an amount of opaque panels on covering not coherent with the plant production, local laws assigned a threshold value, usually between 25% and 50%, of the projection on the soil of the roof. These ranges seem not to be based on scientific evaluation about the agricultural performances required to the building but only on empirical assessments. Purpose of this paper is to contribute to better understand the effect of different configurations of PV panels on the covering of a monospan duo-pitched roof greenhouse in terms of shading effect and energy efficiency during different periods of the year. At this aim, daylighting and insolation analysis were perfo...

Some amount of shade may be optimal to produce high-quality tomatoes in a greenhouse during summer months in the northeast United States. Simultaneous comparisons were made among greenhouse sections that were either not shaded or covered with reflective aluminized shadecloth that attenuated 15%, 30%, or 50% of direct sunlight. The shadecloth was applied at the start of warm weather in June. The houses were shaded for the rest of the summer, and fruit was picked until late August. Total yield decreased linearly with increasing shade, but there was no significant difference among shade treatments in marketable yield. The fraction of fruit that was marketable was greatest for plants grown under 50% shade. This fraction was 9% greater than in a greenhouse with no shade in 2003 and 7% greater in 2004 and 2005. Cracked skin was the defect most affected by shade. Among sensitive cultivars, up to 35% of the fruit produced in greenhouses with no shade had cracked skin, whereas in greenhouses...

Sketching a portrait of a particular object and making it a piece of art requires an excellent skill of shading. It is such a technique of drawing without which one can’t think of completing it.  Shading has paramount importance in the sketching a portrait. When we think of any sketch, it is shading what first comes to our mind. A complete visualization of drawing is done with it.

This study analyses shading performance on front house facades in Malaysia designed with early, modern, postmodern and neo-minimalist architectural
style. For the case study, four front facades of the terraced houses are selected. The reason for the selection of terraced houses as the case studies is that terraced houses are the most popular house type built in urban areas in this country. The Early Modern Terraced House Style was built in 1950s to 1970s, and Modern Terraced House Style was popularly built later in 1980s to 1990s. Postmodern Terraced House
Style was commonly integrated in the building design in 2000s while the Neo-Minimalist Terraced House Style has been integrated in the house design since
2010. The selected case studies are located in Petaling Jaya, Putrajaya and Shah Alam, the new towns ofKuala Lumpur, the capital city ofMalaysia. The SunTool software is used in the survey to calculate shading percentages on the front house facades. The survey will be conducted at a position when the sun path is perpendicular to the house facade. The study finds that the shading performance is improving over time. Recessed wall, balcony, attached roof and roof overhang are commonly used in the house facade design with car porch on the ground facade level.

Variations in leaf nitrogen concentration per unit mass (Nm) and per unit area (Na), mass-to-area ratio (Ma), total nonstructural carbohydrates (Ta), and photosynthetic capacity (maximum carboxylation rate, electron transport capacity, rate of phosphate release in triose phosphate utilization and dark respiration rate) were studied within the digitized crowns of two 3-year-old mango trees (Mangifera indica L.) on La Réunion Island. Additional measurements of Nm , Na , Ma , Ta and photosynthetic capacities were performed on young, fully expanded leaves of 11-year-old mango trees. Leaves of similar gap fractions were taken far from and close to developing fruits. Unlike N m , both N a and T a were linearly correlated to gap fraction. Similar relationships were found for all leaves whatever their age and origin, except for Ta , for which we found a significant tree effect. Photosynthetic capacity was non-linearly correlated to Na , and a unique relationship was obtained for all types of leaves. Photosynthetic acclimation to light was mainly driven by changes in M a , but allocation of total leaf N between the different photosynthetic functions also played a substantial role in acclimation to the lowest irradiances. Leaves close to developing fruits exhibited a higher photosynthetic capacity than other leaves, but similar Ta. Our data suggest that Ta does not control photosynthetic capacity in mango leaves. We used the data to parameterize a biochemically based model of photosynthesis and an empirical stomatal conductance model, allowing accurate predictions of net photosynthesis of leaves in field-grown mango trees.