Optimizing Shading and Thermal Performances of Vertical Green Wall on Buildings in a Hot Arid Region

Due to global concerns about energy issues, global warming, and urban quality, vertical greening systems (VGS) are receiving more attention in construction and design research. Therefore, VGS has become part of building envelope design as a passive technique for saving energy in building sectors. The current study aimed to investigate shading and energy performances of VGS in buildings in hot climate regions and to optimize VGS design as a building design element. The study was conducted through simulation and field experiments in a student housing building at a university campus (Irbid, Jordan). Field measurements were taken to assess the thermal effect of the green wall and daylight performance as well as the efficiency of the typical green wall design configuration. Furthermore, a methodology for accurately representing green walls was established and used. Both simulation and experimentation demonstrated that the thickness of the air cavity and the percentage of foliage coverage can have a substantial impact on the performance of the green wall system. Results showed that green wall systems are effective natural sunscreens and shading systems. A green wall helped to reduce the exterior wall surface temperatures by a range of 6 to 11 °C compared to the base case of the wall without a VGS on different days. In addition, it decreased the interior surface temperature of the investigated southern façade by an average of 5 °C compared to the base case. Green wall design configurations for hot climate regions, such as Jordan, will help designers to use the VGS as a design element. Our findings indicate that GW could help to improve the thermal and daylight environment and thus the results could be taken as indicative for GW wall design in other areas or buildings

Optimizing Shading and Thermal Performances of Vertical Green Wall on Buildings in a Hot Arid Region

Due to global concerns about energy issues, global warming, and urban quality, vertical greening systems (VGS) are receiving more attention in construction and design research. Therefore, VGS has become part of building envelope design as a passive technique for saving energy in building sectors. The current study aimed to investigate shading and energy performances of VGS in buildings in hot climate regions and to optimize VGS design as a building design element. The study was conducted through simulation and field experiments in a student housing building at a university campus (Irbid, Jordan). Field measurements were taken to assess the thermal effect of the green wall and daylight performance as well as the efficiency of the typical green wall design configuration. Furthermore, a methodology for accurately representing green walls was established and used. Both simulation and experimentation demonstrated that the thickness of the air cavity and the percentage of foliage coverage can have a substantial impact on the performance of the green wall system. Results showed that green wall systems are effective natural sunscreens and shading systems. A green wall helped to reduce the exterior wall surface temperatures by a range of 6 to 11 °C compared to the base case of the wall without a VGS on different days. In addition, it decreased the interior surface temperature of the investigated southern façade by an average of 5 °C compared to the base case. Green wall design configurations for hot climate regions, such as Jordan, will help designers to use the VGS as a design element. Our findings indicate that GW could help to improve the thermal and daylight environment and thus the results could be taken as indicative for GW wall design in other areas or buildings

Singlet molecular oxygen regulates vascular tone and blood pressure in inflammation

Singlet molecular oxygen (O-1(2)) has well-established roles in photosynthetic plants, bacteria and fungi(1-3), but not in mammals. Chemically generated O-1(2) oxidizes the amino acid tryptophan to precursors of a key metabolite called N-formylkynurenine(4), whereas enzymatic oxidation of tryptophan to N-formylkynurenine is catalysed by a family of dioxygenases, including indoleamine 2,3-dioxygenase 1(5). Under inflammatory conditions, this haem-containing enzyme is expressed in arterial endothelial cells, where it contributes to the regulation of blood pressure(6). However, whether indoleamine 2,3-dioxygenase 1 forms O-1(2) and whether this contributes to blood pressure control have remained unknown. Here we show that arterial indoleamine 2,3-dioxygenase 1 regulates blood pressure via formation of O-1(2). We observed that in the presence of hydrogen peroxide, the enzyme generates O-1(2) and that this is associated with the stereoselective oxidation of L-tryptophan to a tricyclic hydroperoxide via a previously unrecognized oxidative activation of the dioxygenase activity. The tryptophan-derived hydroperoxide acts in vivo as a signalling molecule, inducing arterial relaxation and decreasing blood pressure; this activity is dependent on Cys42 of protein kinase G1 alpha. Our findings demonstrate a pathophysiological role for O-1(2) in mammals through formation of an amino acid-derived hydroperoxide that regulates vascular tone and blood pressure under inflammatory conditions

Design optimisation of solar shading systems for tropical office buildings: Challenges and future trends

© 2018 Elsevier Ltd Most high-rise office buildings in the tropics, particularly in Malaysia and Singapore, exceed the required level of the energy efficiency index. The implementation of conventional shading systems in the tropics has been proven to have limitations in terms of controlling the quantity and quality of received solar light throughout the year, especially at different solar angles with varying sky conditions. Therefore, the main objective of this work is to investigate the challenges and future trends of solar shading systems by examining their mechanisms, functions and materials for application in tropical regions. This study used evidence review to evaluate various types and models of shading systems based on a systematic method to identify patterns and trends through classification and comparison. Three main categories of shading systems were identified based on the energy involvement and the design approach: (i) passive systems with zero energy use, (ii) active systems that use mechanical devices and (iii) hybrid systems integrated with a biomimetic approach. Specific conclusions were drawn to emphasise the efficiency of developed shading systems in the tropics