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Evaluation of the daylighting performance in UAE traditional buildings turned into museums
Limited attention has been paid to daylight performance concerning layout design and human perception of luminance environments in museums. Assessments are focused on the illuminance preservation requirements in order to minimize the damage that can be caused by light. However, assessment criteria of current daylight performance metrics provide an indicator for the space as a whole, with no account for the spatial distribution. A few recent metrics have addressed the qualitative aspects through contrast measures to assess how exciting or calming the luminous environment is. Pointing to the quantitative daylighting design aspects (illuminance, distribution, and exposure), as well as qualitative aspects implied in spatial contrast, this paper proposes a simplified daylighting design workflow for facades to maintain preservation standards and to provide a more interesting spatial ambience for the visitors. The idea starts with pixelating the facade to provide random small openings that contribute to a higher spatial contrast. This workflow accounts for the layout design to overcome the averaging of current daylight metrics that may underestimate the overexposure to daylight in critical areas where sensitive objects are located. For daylighting assessment in exhibitions, this study suggests that Continuous Daylight Autonomy (CDA) and Annual Sunlight Exposure (ASE) are the most suitable metrics to be adapted to meet standards according to the light sensitivity of objects in the space. Furthermore, it provides an approach to integrate the recently developed modified spatial contrast (mSC5) metric to estimate a sense of visual interest of the exhibition space through daylight luminance maps.
Over the last few years, the UAE government has been dedicated to transforming many of its treasured heritage buildings into museums. One issue with this, however, is that these buildings were not designed for this purpose. Therefore, ensuring they operate well in their new roles is a crucial question that has been thoroughly researched by the authors. This chapter aims to study the daylighting performance inside two selected heritage building cases. The daylighting system employed by these buildings is one that is engrained in the traditional architectural practice of Dubai (latitude 25°N longitude 55°E). It captures daylight by its traditional window (termed locally the Dreesheh) from a private courtyard (through a midway arcade) or from a public alley. Numerous site visits to four heritage museums were executed in order to categorize the main artifacts and assess the illuminance exposure based on each category type. Moreover, for the simulation process, measurements of the different lighting levels were taken on site, in order to calculate the reflectance values of the interior and exterior surfaces. Two exhibition spaces with different sizes were selected to conduct the required detailed analysis. Computer simulation was used to evaluate the luminous environment in the spaces with special consideration to artifacts’ exposure to the light and potential problems of deterioration. The results were analyzed, and design improvements with regard to spatial arrangement, openings, and implementation of shading were suggested.
Museum buildings perform ambitious demands for sound conditions of exhibits and comfort of visitors. There is a narrow allowance for room temperature and relative humidity, which has to be maintained for varying situations of weather and occupancy. Lighting has to assure an excellent visual performance but to avoid deterioration of exhibits. Energy consumption can be kept extremely low contrariwise. Several high quality and low energy museum buildings could be realised recently by utilisation of energy efficient measures and renewable energies. Outstanding pieces of architecture, e.g. Kolumba Art Museum, Cologne (architect P. Zumthor), Emil-Schumacher-Museum, Hagen (architect M. Lindemann), are presented and integrated advanced technologies like thermal active room surfaces, low air change ventilation, geothermal heating and cooling, and controlled daylighting are explained.
This work proposes a multi-method approach that combines advanced microscopy (SEM/EDX, AFM) and spectroscopy (UV-vis and FTIR) techniques. This approach not only characterises the behaviour of the additives of two commercial poly(vinyl acetate) (PVAc) and acrylic emulsion paints but also simultaneously characterises the changes in chemical composition and morphology observed in the paint films as a result of ageing due to the paints being exposed to an intense source of simulated daylight. In parallel, a series of mechanical tests were performed that correlate the chemical changes in composition and the changes observed in the films’ mechanical properties. This work was a comparative study between both types of acrylic and PVAc paints. The results obtained are of great interest for the modern paint conservation field as they provide valuable information on the mid- and long-term behaviours of these synthetic paints.
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Tensile test of phthalocianyne blue Liquitex® paint film
A spectral aging test was developed to estimate the photochemical damage of oil, acrylic and gouache paints exposed to permanent lighting. The paints were irradiated at seven different wavelengths in the optical range to control and evaluate their spectral behaviour. To reach this objective, boxes with isolated aging cells were made. In each of box, one LED of a different wavelength and one photodiode were installed. Inside the boxes, the temperature of an exhibit area was recreated through a thermocouple sensor that controlled the temperature using a fan. The heat produced by the LED was dissipated by a thermal radiator. Moreover, to evaluate the exposure time dependence of the irradiation level, the test was performed using two different irradiation levels in ten exposure series. After each series, the spectral reflectance was measured, and the data collected for each paint and wavelength were used to develop a model of damage produced by the interaction between the spectral radiant exposure and the paint.
In a series of experiments using three different sources of visible and ultraviolet radiation, post-irradiation darkening at room temperature of water-leaf papers made from various pulps is shown to be chiefly influenced by the content of lignin and by the pH of the test sheets.
Daylighting is an important issue in modern architecture that has been characterized by the use of curtain walls in commercial buildings. In Hong Kong, the overall thermal transfer value (OTTV) calculations are mandatory requirements in the submission of building plans to control the building energy use, but daylighting credits are not included in calculating the OTTV of building envelope designs. Natural daylight helps reduce the electricity use and the associated sensible cooling load due to artificial lighting. Hence, proper daylighting designs can contribute to smaller air-conditioning system and lower the peak power demand of buildings. We use the computer simulation tool, DOE-2, to demonstrate the energy performance of a generic commercial building with different OTTV designs in terms of peak cooling plant requirement and peak building power demand due to various daylighting systems. The peak loads are determined from the simulation results. Regression techniques are conducted to correlate the incremental peak electricity use and incremental peak cooling capacity with OTTV and daylighting aperture (DA) (window-to-wall ratio (WWR) times light transmittance (LT)). Contours of equal incremental peak electricity use and incremental peak cooling plant demand for different building envelope parameters are developed. Important features for daylighting schemes are highlighted and implications for OTTV designs discussed.
A large number of the indigenous buildings in the UAE are used nowadays as museums. The purpose of this research is to investigate the daylighting performance in terms of museum lighting requirements via one of the most common daylighting systems found in the indigenous architecture of Dubai (latitude 25°N longitude 55°E); i.e., the traditional double panel window, Dreesheh. The study at the outset included several site visits to a number of traditional UAE museums to select a proper space with the system under study for investigation; and to specify how typical displays of these museums are classified. This helped to associate the total acceptable illuminance exposure limits to the specified classifications, based on IESNA recommendations. The Desktop RADIANCE 2.0 program (DR) was used to evaluate the lighting performance of the daylighting system under clear sky conditions. On-site measurements were conducted to find characteristics of the interior surfaces and validate the simulation accuracy. The difference between the actual measurements and the simulated ones was estimated as ±4%. The lighting performance issues examined by detailed simulations were direct sunlight, horizontal illuminance levels and artifact exposure, diversity and uniformity of illuminance, and contrasting luminances in the field of view. These parameters were compared to the standard values or recommended ranges specified in lighting codes and handbooks such as CIBSE and IESNA. The study revealed several potential problems with this kind of exhibit spaces that can lead to permanent damage of artifacts and occupants’ discomfort. Finally, it concluded with recommendations to improve these issues.
This study investigated the potential of shade-trees to improve lighting conditions in the indoor space of a standard classroom in the United Arab Emirates (UAE) using computer simulation with the Radiance program. Shade trees are defined as selected suitable types of trees using certain criteria (i.e. evergreen, proper canopy density, proper height, growth in extreme hot climate conditions, safe roots) based on literature survey and consultation with landscape experts. It focuses on analysis of illuminance levels at desk locations (task) inside a standard classroom oriented to the North, East, South, and West for the selected critical times that are relevant to the locality. An initial group of simulation runs was done at the outset to choose proper tree spacing. The dependent variables are illuminance level and illuminance range resulted from manipulating two independent variables, shade tree type and orientation. The simulation runs includes a base case with no shade trees against other improvement cases with shade trees. The findings show the significance of the shade trees for improved lighting distribution and quality. This is evident in the reduction of illuminance ranges throughout the classroom as it is the case with the Neem shade trees at 2 m providing the lowest range from 125-570 Lux on front of the window and from 130-498 Lux on front of the wall. Yet, some reduction in the overall levels of illuminance is experienced (18-31% reduction for North orientation; 87-96% reduction for other orientations) and an increase in the estimated operating hours of electric lighting. Finally, some passive methods such as high strip windows and roof monitors were recommended to compensate for the illuminance reduction, rather than using electric lighting.
Light displays a vital role in the exhibition environment especially in Art gallery. Illumination, show of the exhibits' colour & details, and atmosphere creation can't work without light. But both natural light and artificial light do harm to the exhibits, which will reduce the strength of the paint and material, even cause the paint fading and paper curl. The damage can't be recovered , and the exhibits will not exist anymore if the light design is ignored. So the relationship between the exhibits protection and the art visual will become one of the core issues of Art gallery design research.
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