The atmosphere protects humans, plants, ani- mals, and microorganisms from damaging doses of ultra- violet-B （UVB） solar radiation （280-320 nm） because it modifies the UVB reaching the Earth＇s surface. This modif...The atmosphere protects humans, plants, ani- mals, and microorganisms from damaging doses of ultra- violet-B （UVB） solar radiation （280-320 nm） because it modifies the UVB reaching the Earth＇s surface. This modification is a function of the solar radiation＇s path length through the atmosphere and the amount of each attenuator along the path length. The path length is deter- mined by solar zenith angle （SZA）. The present work ex- plains the dependence of hemispherical transmittance of UVB on SZA. The database used consists of five years of hourly UVB and global solar radiation measurements. From 2001 to 2005, the South Valley University （SVU） meteorological research station （26.20°N, 32.75°E） car- ried out these measurements on a horizontal surface. In addition, the corresponding extraterrestrial UVB （UVBe^d and broadband solar radiation （Gext） were estimated. Consequently, the hemispherical transmittance of UVB （KtuvB） and the hemispherical transmittance of global solar radiation （Kt） were estimated. Furthermore, the UVB redaction due to the atmosphere was evaluated. An analy- sis of the dependence between KtuvB and SZA at different ranges of Kt was performed. A functional dependence between KtuvB and SZA （KtuvB=-a（SZA）＋b） for very narrow Kt-ranges （width of ranges was 0.01） was devel- oped. The results are discussed, and the sensitivity of AKtuvB to △SZA for very narrow Kt-ranges was studied. It was found that the sensitivity of △KtUVB to ASZA slightly increases with increased Kt, which means KtuvB is sensi- tive to SZA as Kt increases. The maximum correlation （R） between KtuvB and SZA was equal to -0.83 for Kt= 0.76.展开更多
Embracing renewable energy technology makes a lot of sense for the public sectors and schools as it meets the government sustainability goals and provides a financially viable means of achieving carbon savings while o...Embracing renewable energy technology makes a lot of sense for the public sectors and schools as it meets the government sustainability goals and provides a financially viable means of achieving carbon savings while offering income potential. This study is aimed to quantify the achievable energy saving by spread use ofphotovoltaic systems on public building stock in the city of Rome. The installation of PV （photovoltaic） systems in the historic center depends on the feasibility conditions, generally more complex compared to the cases examined in the consolidated city, because they require compliance with the formal and aesthetic characteristics of the buildings, so the choice must be made between compatible components, which allow to minimize the transformation. The suburbs are characterized by large plane roofs in bad conditions and belonging to isolated buildings, so the useful surface, according to shading condition, offers a big potential for renewable technologies. The research provides an evaluation of maximum production of solar energy and the subsequent energy saving and reduction of greenhouse gasses, using parametric data, and an evaluation of the cost-effectiveness, with a rough calculation of return on investment.展开更多
基金supported by the Deanship of Scientific Research from King Saud University
文摘The atmosphere protects humans, plants, ani- mals, and microorganisms from damaging doses of ultra- violet-B （UVB） solar radiation （280-320 nm） because it modifies the UVB reaching the Earth＇s surface. This modification is a function of the solar radiation＇s path length through the atmosphere and the amount of each attenuator along the path length. The path length is deter- mined by solar zenith angle （SZA）. The present work ex- plains the dependence of hemispherical transmittance of UVB on SZA. The database used consists of five years of hourly UVB and global solar radiation measurements. From 2001 to 2005, the South Valley University （SVU） meteorological research station （26.20°N, 32.75°E） car- ried out these measurements on a horizontal surface. In addition, the corresponding extraterrestrial UVB （UVBe^d and broadband solar radiation （Gext） were estimated. Consequently, the hemispherical transmittance of UVB （KtuvB） and the hemispherical transmittance of global solar radiation （Kt） were estimated. Furthermore, the UVB redaction due to the atmosphere was evaluated. An analy- sis of the dependence between KtuvB and SZA at different ranges of Kt was performed. A functional dependence between KtuvB and SZA （KtuvB=-a（SZA）＋b） for very narrow Kt-ranges （width of ranges was 0.01） was devel- oped. The results are discussed, and the sensitivity of AKtuvB to △SZA for very narrow Kt-ranges was studied. It was found that the sensitivity of △KtUVB to ASZA slightly increases with increased Kt, which means KtuvB is sensi- tive to SZA as Kt increases. The maximum correlation （R） between KtuvB and SZA was equal to -0.83 for Kt= 0.76.
文摘Embracing renewable energy technology makes a lot of sense for the public sectors and schools as it meets the government sustainability goals and provides a financially viable means of achieving carbon savings while offering income potential. This study is aimed to quantify the achievable energy saving by spread use ofphotovoltaic systems on public building stock in the city of Rome. The installation of PV （photovoltaic） systems in the historic center depends on the feasibility conditions, generally more complex compared to the cases examined in the consolidated city, because they require compliance with the formal and aesthetic characteristics of the buildings, so the choice must be made between compatible components, which allow to minimize the transformation. The suburbs are characterized by large plane roofs in bad conditions and belonging to isolated buildings, so the useful surface, according to shading condition, offers a big potential for renewable technologies. The research provides an evaluation of maximum production of solar energy and the subsequent energy saving and reduction of greenhouse gasses, using parametric data, and an evaluation of the cost-effectiveness, with a rough calculation of return on investment.
