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Solar radiation is important in studies of the energy and environment of buildings. Calculations of the direct beam and sky diffuse radiation, however, usually rely on numerical approaches, which can lead to notable calculation burdens. This research evaluates the update interval of the daily solar position series and the skydome discretization densities as they affect the estimation accuracies of the direct beam and sky diffuse radiation, respectively. Additionally, an approach is proposed for studying the direct beam radiation using a number of representative sun directions, the density of which is optimized for efficient radiation studies under external obstructions. Field measurements and simulations show that 61 sky elements can be sufficient for diffuse radiation estimations in low-latitude regions. For the direct beam, on the other hand, more than 1100 representative sun directions are necessary. The accuracy is comparable to that of the approach in which the sun position is updated in the calculation interval every 2–10 days. The representative sun direction approach and the results of the optimized day interval and sky discretization density are essential to efficient building simulations conducted at high frequencies.
Siwei Lou; Yu Huang; Danny H.W. Li; Dawei Xia; Xiaoqing Zhou; Yang Zhao. Optimizing the beam and sky diffuse radiation calculations under random obstructions of urban environments. Building and Environment 2021, 196, 107806 .
AMA StyleSiwei Lou, Yu Huang, Danny H.W. Li, Dawei Xia, Xiaoqing Zhou, Yang Zhao. Optimizing the beam and sky diffuse radiation calculations under random obstructions of urban environments. Building and Environment. 2021; 196 ():107806.
Chicago/Turabian StyleSiwei Lou; Yu Huang; Danny H.W. Li; Dawei Xia; Xiaoqing Zhou; Yang Zhao. 2021. "Optimizing the beam and sky diffuse radiation calculations under random obstructions of urban environments." Building and Environment 196, no. : 107806.
Solar irradiance data on building façades are important for BIPV system evaluations and energy-efficient building designs. In urban cities where the building façades are always obscured by surrounding buildings, the determination of sky-diffuse solar irradiance can be complex. Previously, a mathematical model was proposed to estimate the obstructed vertical sky component (OVSC) under various skies by assuming that the obstructions are infinitely long. However, more often, in actual cases, the opposite obstructions are surfaces with different heights in azimuth which can form various irregular skyline patterns. Therefore, this study proposes new methods to determine vertical sky-diffuse solar irradiance on building façades under complex irregular obstructions. Various configurations of irregular obstructions were identified by a proposed quantification method, and the OVSCs were simulated using RADIANCE package. The simulated results were used to correlate with those of infinitely-long urban canyons. Both Artificial Neural Networks (ANN) based model and simple regression model were proposed to find the correlations between various angles defining the irregular obstruction and the equivalent obstruction angles of corresponding infinitely-long cases. The R2 values of the ANN model and regression model against simulated results using the testing datasets were above 0.97 and 0.98, respectively. Field measurements were carried out for model validations and the R2 value between the proposed methods and the measured readings was 0.8. The findings are significant to PV system designs, daylighting scheme evaluations and low/zero-energy building designs under complex obstructed environments.
Wenqiang Chen; Danny H.W. Li; Shuyang Li; Siwei Lou. Predicting diffuse solar irradiance on obstructed building façades under irregular skyline patterns for various ISO/CIE standard skies. Journal of Building Engineering 2021, 40, 102370 .
AMA StyleWenqiang Chen, Danny H.W. Li, Shuyang Li, Siwei Lou. Predicting diffuse solar irradiance on obstructed building façades under irregular skyline patterns for various ISO/CIE standard skies. Journal of Building Engineering. 2021; 40 ():102370.
Chicago/Turabian StyleWenqiang Chen; Danny H.W. Li; Shuyang Li; Siwei Lou. 2021. "Predicting diffuse solar irradiance on obstructed building façades under irregular skyline patterns for various ISO/CIE standard skies." Journal of Building Engineering 40, no. : 102370.
The diffuse radiation on building envelopes can be essential to the thermal environment and the energy study of buildings. Because a part of the skydome can be obstructed irregularly in city environments, the diffuse radiance distribution over the skydome should be determined to evaluate the radiation accurately. In this study, this distribution is described by several representative sky directions to specifying the radiance variation features over the skydome, especially the attenuation around the sun. The irradiance of each sky element (normalized by the horizontal diffuse) is correlated to the routine global radiation and the solar altitude as an all-sky model for simple engineering uses. According to two sets of one-month field measurements (in different sites) of the vertical irradiance under irregular obstructions in the hot and humid Hong Kong, the coefficient of determination (R2) is 0.041 and 0.142 higher than the classical single-direction anisotropic diffuse model that is adopted by many simulation tools, and the R2 difference can be up to 0.38 for partly cloudy days. When compared to the distribution models, the R2 outperformance of the proposed model can still be 0.057. The proposed approach is thus effective to the solar radiation studies in the city environments.
Siwei Lou; Danny H.W. Li; Isaac Y.F. Lun; Yu Huang; Wenqiang Chen; Dawei Xia; Yanping Yang. Radiance of the circumsolar and background parts of skydome for buildings under random obstructions. Energy and Buildings 2021, 236, 110796 .
AMA StyleSiwei Lou, Danny H.W. Li, Isaac Y.F. Lun, Yu Huang, Wenqiang Chen, Dawei Xia, Yanping Yang. Radiance of the circumsolar and background parts of skydome for buildings under random obstructions. Energy and Buildings. 2021; 236 ():110796.
Chicago/Turabian StyleSiwei Lou; Danny H.W. Li; Isaac Y.F. Lun; Yu Huang; Wenqiang Chen; Dawei Xia; Yanping Yang. 2021. "Radiance of the circumsolar and background parts of skydome for buildings under random obstructions." Energy and Buildings 236, no. : 110796.
Sky conditions, and the corresponding luminance and radiance distribution patterns are essential to daylighting, energy and thermal environmental studies. The CIE Standard Skies define the overcast, partly cloudy, and clear sky conditions intuitively by rigorous luminance distributions, which are, however, usually determined by sophisticated and uncommon measurements (e.g. radiation in multiple vertical directions). This study proposes a simple approach to identifying the hourly sky conditions from the global horizontal irradiance (EHG) that is most widely accessible in weather stations with basic radiation measurement facilities. The sophisticated measurements are, therefore, avoided for simple applications. The partly cloudy sky, especially, is identified by the notable disparity of its EHG measurement from the theoretical cloudless condition. The proposed approach interprets the ISO/CIE Standard Sky conditions and their diffuse luminance and radiance distributions successfully. From the datasets at two sites with different climates, the approach correctly identifies 7% more sky conditions than a previous work when the direct beam and diffuse radiation measurements were not accessible. The model can thus be essential to solar energy studies for places with ground-based solar radiation measurements only.
Siwei Lou; Yu Huang; Danny H.W. Li; Dawei Xia; Xiaoqing Zhou; Yang Zhao. A novel method for fast sky conditions identification from global solar radiation measurements. Renewable Energy 2020, 161, 77 -90.
AMA StyleSiwei Lou, Yu Huang, Danny H.W. Li, Dawei Xia, Xiaoqing Zhou, Yang Zhao. A novel method for fast sky conditions identification from global solar radiation measurements. Renewable Energy. 2020; 161 ():77-90.
Chicago/Turabian StyleSiwei Lou; Yu Huang; Danny H.W. Li; Dawei Xia; Xiaoqing Zhou; Yang Zhao. 2020. "A novel method for fast sky conditions identification from global solar radiation measurements." Renewable Energy 161, no. : 77-90.
The weather data is essential to simulation-based building energy studies. The weather data should render the features of the changing climate. The typical meteorological year (TMY) developments using the long-term climate data, however, may weaken the impact of the recent climate change and the corresponding building energy responses. This paper studies the changes of the climate data (by ground measurements) and their impacts on the simulation results of the subtropical Hong Kong over 37 years. The climate changes for solar radiation, temperature and wind speed were summarised, and their daily total, average, extreme, and/or deviation values were presented. The typical weather data developed by the ground measurements of different times and period lengths (within the 37 years) determined the cooling load of a representative building in the Hong Kong, and the outcomes were compared to that of the yearly data. The period (length) of the raw measurements and the update frequency of TMY were optimized for the building energy simulations in the changing climate.
Siwei Lou; Danny H.W. Li; Yu Huang; Xiaoqing Zhou; Dawei Xia; Yang Zhao. Change of climate data over 37 years in Hong Kong and the implications on the simulation-based building energy evaluations. Energy and Buildings 2020, 222, 110062 .
AMA StyleSiwei Lou, Danny H.W. Li, Yu Huang, Xiaoqing Zhou, Dawei Xia, Yang Zhao. Change of climate data over 37 years in Hong Kong and the implications on the simulation-based building energy evaluations. Energy and Buildings. 2020; 222 ():110062.
Chicago/Turabian StyleSiwei Lou; Danny H.W. Li; Yu Huang; Xiaoqing Zhou; Dawei Xia; Yang Zhao. 2020. "Change of climate data over 37 years in Hong Kong and the implications on the simulation-based building energy evaluations." Energy and Buildings 222, no. : 110062.
The CIE (International Commission on Illuminance) Standard Skies depicts the typical diffuse luminance and radiance distributions over the skydome. However, it can be challenging to interpret the luminance and radiance distribution into the irradiance and illuminance contributions on tilt planes by numerical integrations. This paper proposes a surrogate model that determines the ratio of the diffuse irradiance on an arbitrary tilt plane to that on the unobstructed horizontal plane without the complicated and time-consuming numerical integrations. The model is determined using solar altitude, sky conditions, and the angular distance of the plane (surface normal) and the sun. The proposed model is validated by measurement of the vertical illuminance and irradiance that are taken in 2004 and 2005, and the irradiance on planes of different tilt angles and azimuth directions from February to May in 2015. All measurements were in the 10-minute interval. For vertical planes, the proposed approach gives the ratio of the root mean square errors to the measurement average 1.38% to 2.04% lower than a classical model for irradiance and 3.6% to 4.6% for illuminance, when the Skies can be accurately identified. The model thus accurately interprets the luminance and radiance distributions of the CIE Standard Skies, which can be essential to a fast study for the solar energy potential as well as the thermal and daylight environments under different sky conditions.
Siwei Lou; Danny H.W. Li; Dawei Xia; Isaac Y.F. Lun; Wenqiang Chen; Yanping Yang. Solar energy and daylight on tilt planes under CIE standard skies. Energy Reports 2020, 6, 895 -905.
AMA StyleSiwei Lou, Danny H.W. Li, Dawei Xia, Isaac Y.F. Lun, Wenqiang Chen, Yanping Yang. Solar energy and daylight on tilt planes under CIE standard skies. Energy Reports. 2020; 6 ():895-905.
Chicago/Turabian StyleSiwei Lou; Danny H.W. Li; Dawei Xia; Isaac Y.F. Lun; Wenqiang Chen; Yanping Yang. 2020. "Solar energy and daylight on tilt planes under CIE standard skies." Energy Reports 6, no. : 895-905.
Danny H.W. Li; Wenqiang Chen; Shuyang Li; Siwei Lou. Estimation of hourly global solar radiation using Multivariate Adaptive Regression Spline (MARS) – A case study of Hong Kong. Energy 2019, 186, 1 .
AMA StyleDanny H.W. Li, Wenqiang Chen, Shuyang Li, Siwei Lou. Estimation of hourly global solar radiation using Multivariate Adaptive Regression Spline (MARS) – A case study of Hong Kong. Energy. 2019; 186 ():1.
Chicago/Turabian StyleDanny H.W. Li; Wenqiang Chen; Shuyang Li; Siwei Lou. 2019. "Estimation of hourly global solar radiation using Multivariate Adaptive Regression Spline (MARS) – A case study of Hong Kong." Energy 186, no. : 1.
The direction and environment of photovoltaics (PVs) may influence their energy output. The practical PV performance under various conditions should be estimated, particularly during initial design stages when PV model types are unknown. Previous studies have focused on a limited number of PV projects, which required the details of many PV models; furthermore, the models can be case sensitive. According to the 18 projects conducted in 7 locations (latitude 29.5–51.25N) around the world, we developed polynomials for the crystalline silicon PV energy output for different accessible input variables. A regression tree effectively evaluated the correlations of the outcomes with the input variables; those of high importance were identified. The coefficient of determination, indicating the percentage of datasets being predictable by the input, was higher than 0.65 for 14 of the 18 projects when the polynomial was developed using the accessible variables such as global horizontal solar radiation. However, individual equations should be derived for horizontal cases, indicating that a universal polynomial for crystalline silicon PVs with a tilt angle in the range 0°–66° can be difficult to develop. The proposed model will contribute to evaluating the performance of PVs with low and medium tilt angles for places of similar climates.
Siwei Lou; Wenqiang Chen; Danny H.W. Li; Mo Wang; Hainan Chen; Isaac Y.F. Lun; Dawei Xia. Tilted Photovoltaic Energy Outputs in Outdoor Environments. Sustainability 2019, 11, 6052 .
AMA StyleSiwei Lou, Wenqiang Chen, Danny H.W. Li, Mo Wang, Hainan Chen, Isaac Y.F. Lun, Dawei Xia. Tilted Photovoltaic Energy Outputs in Outdoor Environments. Sustainability. 2019; 11 (21):6052.
Chicago/Turabian StyleSiwei Lou; Wenqiang Chen; Danny H.W. Li; Mo Wang; Hainan Chen; Isaac Y.F. Lun; Dawei Xia. 2019. "Tilted Photovoltaic Energy Outputs in Outdoor Environments." Sustainability 11, no. 21: 6052.
Residential buildings are typically associated with high energy consumption, especially because of air-conditioning (AC) usage. Occupant behaviour can noticeably affect how an AC operates and thereby contribute to the increasing energy consumption. This problem is more pronounced with the split-type air-conditioner that is popular in South China. This study identified three representative patterns related to occupancy and AC on/off settings according to AC operation recordings from 102 bedrooms in several residential buildings of metropolitan Guangzhou, South China. Bedroom AC operation details were recorded using individual smart socket units. The resulting data showed clustering for daily on/off times, the duration of each operation, and AC ‘run-over-night’ probability. These clusters revealed three user-configuration patterns (i.e. night-time AC usage only (49%), both night-time and noon AC usage (6%), and low AC usage (45%)). Occupant age, total floors, and room area indices were most closely related to occupant behavioural patterns. Results indicated that AC units should be ‘turned on’ in timed steps when operation rates are higher than 30% or 20% to achieve acceptable thermal comfort performance. These findings should be useful for those intending to reduce overall energy consumption because the analysed schedules were based on realistic usage rather than conventional assumption (i.e. the full-time/full-space usage).
Dawei Xia; Siwei Lou; Yu Huang; Yang Zhao; Danny H.W. Li; Xiaoqing Zhou. A study on occupant behaviour related to air-conditioning usage in residential buildings. Energy and Buildings 2019, 203, 109446 .
AMA StyleDawei Xia, Siwei Lou, Yu Huang, Yang Zhao, Danny H.W. Li, Xiaoqing Zhou. A study on occupant behaviour related to air-conditioning usage in residential buildings. Energy and Buildings. 2019; 203 ():109446.
Chicago/Turabian StyleDawei Xia; Siwei Lou; Yu Huang; Yang Zhao; Danny H.W. Li; Xiaoqing Zhou. 2019. "A study on occupant behaviour related to air-conditioning usage in residential buildings." Energy and Buildings 203, no. : 109446.
An investigation into the effectiveness of bioretention cells (BCs) under potential climatic changes was conducted using representative concentration pathways. A case study of Guangzhou showed changes in peak runoff in climate change scenarios, with obvious growth in RCP8.5 and slight growth in RCP2.6. The performance of BCs on multiple parameters, including reduction of runoff volume, peak runoff, and first flush, were examined in different design storms using a hydrology model (SWMM). The effectiveness of BCs varied non-linearly with scale. Their performance fell by varying amounts in the various scenarios. BCs could provide sufficient effects in response to short-return-period and short-duration storms, but the performance of BCs decreased with heavy storms, especially considering climate change. Hence, BCs cannot replace grey infrastructure but should be integrated with them. The method developed in this study could be useful in the planning and design of low impact development in view of future climate changes.
Mo Wang; Dongqing Zhang; Siwei Lou; Qinghe Hou; Yijie Liu; Yuning Cheng; Jinda Qi; Soon Keat Tan. Assessing Hydrological Effects of Bioretention Cells for Urban Stormwater Runoff in Response to Climatic Changes. Water 2019, 11, 997 .
AMA StyleMo Wang, Dongqing Zhang, Siwei Lou, Qinghe Hou, Yijie Liu, Yuning Cheng, Jinda Qi, Soon Keat Tan. Assessing Hydrological Effects of Bioretention Cells for Urban Stormwater Runoff in Response to Climatic Changes. Water. 2019; 11 (5):997.
Chicago/Turabian StyleMo Wang; Dongqing Zhang; Siwei Lou; Qinghe Hou; Yijie Liu; Yuning Cheng; Jinda Qi; Soon Keat Tan. 2019. "Assessing Hydrological Effects of Bioretention Cells for Urban Stormwater Runoff in Response to Climatic Changes." Water 11, no. 5: 997.
The overcast, partly cloudy and clear sky conditions can determine the diffuse sky radiance and luminance distributions over the sky dome, and thus are crucial for evaluating the solar energy and daylight on and through building envelopes. It is preferable to properly identify the sky condition and determining its diffuse radiance and luminance distribution patterns by the readily available data. In this work, we propose a new approach to identifying the sky conditions, especially the cloudy and clear skies mainly by the horizontal illuminance fluctuation frequency. Illuminance on ground level may fluctuate at high frequency under cloudy skies due to the broken cloud, while vary smoothly under clear skies with few cloud blockages. For input data, the proposed approach needs the horizontal global illuminance that can be readily accessible for many places instead of the “uncommon” measurements on vertical planes or in sky zenith. The fluctuation frequency factor we propose can reduce the misclassification rate for daily and half-day representative sky conditions by 5.7% and 11.5%, respectively, compared to the classifications using the clearness index only.
Siwei Lou; Danny.H.W. Li; Wenqiang Chen. Identifying overcast, partly cloudy and clear skies by illuminance fluctuations. Renewable Energy 2019, 138, 198 -211.
AMA StyleSiwei Lou, Danny.H.W. Li, Wenqiang Chen. Identifying overcast, partly cloudy and clear skies by illuminance fluctuations. Renewable Energy. 2019; 138 ():198-211.
Chicago/Turabian StyleSiwei Lou; Danny.H.W. Li; Wenqiang Chen. 2019. "Identifying overcast, partly cloudy and clear skies by illuminance fluctuations." Renewable Energy 138, no. : 198-211.
In many parts of the world, the solar radiation and daylight illuminance data taken from surfaces of interest are not always readily available. Without direct measurement, the data can be predicted from empirical models based on geographical variations and meteorological parameters. Recently, the International Commission on Illumination (CIE) has adopted a list of 15 standard skies. Each standard sky represents a unique, well-defined sky radiance and luminance pattern expressed by mathematical equations that can use to compute solar irradiance and daylight illuminance on inclined surfaces and variously oriented vertical planes. An issue is whether the sky conditions can be correctly categorized. This paper reviews the solar radiation and daylight illuminance model developments and sky classification methods. The findings indicated that Machine Learning techniques have been effectively used for predicting solar radiation and daylight illuminance and classifying the standard skies. Such approaches could be globally adopted and useful to compute the required climatic data for renewable and sustainable developments and energy-efficient building designs.
Danny H.W. Li; Siwei Lou. Review of solar irradiance and daylight illuminance modeling and sky classification. Renewable Energy 2018, 126, 445 -453.
AMA StyleDanny H.W. Li, Siwei Lou. Review of solar irradiance and daylight illuminance modeling and sky classification. Renewable Energy. 2018; 126 ():445-453.
Chicago/Turabian StyleDanny H.W. Li; Siwei Lou. 2018. "Review of solar irradiance and daylight illuminance modeling and sky classification." Renewable Energy 126, no. : 445-453.
Siwei Lou; Danny H.W. Li; Joseph Choi Lam. CIE Standard Sky classification by accessible climatic indices. Renewable Energy 2017, 113, 347 -356.
AMA StyleSiwei Lou, Danny H.W. Li, Joseph Choi Lam. CIE Standard Sky classification by accessible climatic indices. Renewable Energy. 2017; 113 ():347-356.
Chicago/Turabian StyleSiwei Lou; Danny H.W. Li; Joseph Choi Lam. 2017. "CIE Standard Sky classification by accessible climatic indices." Renewable Energy 113, no. : 347-356.
This paper studied the payback period of grid-connected photovoltaic (PV) panels by the net present value method. The PV performance data were acquired by on-site measurements of two rooftop projects in subtropical Hong Kong. The sensitivity of various variables to the payback period was evaluated by the Extended Fourier Amplitude Sensitivity Test. The monetary payback periods were evaluated at different values of the most relevant variables and compared with the embodied energy and greenhouse gas payback periods. The PV panels of the two projects produced 122–143 kWh/m2 electricity per year in Hong Kong, which saved 139–163 HKD electricity tariff per square meter per year. The sensitivity analysis showed that the monetary payback period was sensitive to the initial cost and tariff increase rate uncertainties. The PV monetary payback period varied from 13.4 to 16.8 years at different tariff increase rates and investment costs, based on the current carbon trading benefit. The monetary payback period was much greater than the embodied energy and greenhouse gas payback periods, which were 10.8–12.7 years and 5.3–6.2 years, respectively. Implications of the payback period differences were discussed.
Siwei Lou; Danny H. W. Li; Wilco W. Chan; Joseph Choi Lam. Life-cycle analysis of photovoltaic systems in Hong Kong. Journal of Renewable and Sustainable Energy 2017, 9, 045901 .
AMA StyleSiwei Lou, Danny H. W. Li, Wilco W. Chan, Joseph Choi Lam. Life-cycle analysis of photovoltaic systems in Hong Kong. Journal of Renewable and Sustainable Energy. 2017; 9 (4):045901.
Chicago/Turabian StyleSiwei Lou; Danny H. W. Li; Wilco W. Chan; Joseph Choi Lam. 2017. "Life-cycle analysis of photovoltaic systems in Hong Kong." Journal of Renewable and Sustainable Energy 9, no. 4: 045901.
Siwei Lou; Ernest K.W. Tsang; Danny H.W. Li; Eric W.M. Lee; Joseph Choi Lam. Towards Zero Energy School Building Designs in Hong Kong. Energy Procedia 2017, 105, 182 -187.
AMA StyleSiwei Lou, Ernest K.W. Tsang, Danny H.W. Li, Eric W.M. Lee, Joseph Choi Lam. Towards Zero Energy School Building Designs in Hong Kong. Energy Procedia. 2017; 105 ():182-187.
Chicago/Turabian StyleSiwei Lou; Ernest K.W. Tsang; Danny H.W. Li; Eric W.M. Lee; Joseph Choi Lam. 2017. "Towards Zero Energy School Building Designs in Hong Kong." Energy Procedia 105, no. : 182-187.
The paper studies the horizontal global, direct-beam and sky-diffuse solar irradiance data measured in Hong Kong from 2008 to 2013. A machine learning algorithm was employed to predict the horizontal sky-diffuse irradiance and conduct sensitivity analysis for the meteorological variables. Apart from the clearness index (horizontal global/extra atmospheric solar irradiance), we found that predictors including solar altitude, air temperature, cloud cover and visibility are also important in predicting the diffuse component. The mean absolute error (MAE) of the logistic regression using the aforementioned predictors was less than 21.5 W/m2 and 30 W/m2 for Hong Kong and Denver, USA, respectively. With the systematic recording of the five variables for more than 35 years, the proposed model would be appropriate to estimate of long-term diffuse solar radiation, study climate change and develope typical meteorological year in Hong Kong and places with similar climates.School of Hotel and Tourism Managemen
Siwei Lou; Danny H.W. Li; Joseph Choi Lam; Wilco Chan. Prediction of diffuse solar irradiance using machine learning and multivariable regression. Applied Energy 2016, 181, 367 -374.
AMA StyleSiwei Lou, Danny H.W. Li, Joseph Choi Lam, Wilco Chan. Prediction of diffuse solar irradiance using machine learning and multivariable regression. Applied Energy. 2016; 181 ():367-374.
Chicago/Turabian StyleSiwei Lou; Danny H.W. Li; Joseph Choi Lam; Wilco Chan. 2016. "Prediction of diffuse solar irradiance using machine learning and multivariable regression." Applied Energy 181, no. : 367-374.
The estimation of solar heat gain via vertical fenestration is important in energy-efficient building design and operation especially for subtropical Hong Kong. Being one of the most populated cities in the world, buildings in Hong Kong tend to be densely constructed. In this regard, the shading effect of surrounding buildings could significantly limit solar radiation from the sun and sky to the window while certain amount of solar radiation would be reflected from the opposite façades. This paper presents a calculation approach to compute solar radiation on obstructed fenestration for both overcast and non-overcast skies. Performance of the proposed method is evaluated by comparing with simulated results of a sophisticated lighting program and field measurements. The findings are essential for the assessment of both active and passive building energy saving techniques including shading and building integrated photovoltaic systems in metropolitan environment.
Siwei Lou; Danny H.W. Li; Joseph Choi Lam; Eric W.M. Lee. Estimation of obstructed vertical solar irradiation under the 15 CIE Standard Skies. Building and Environment 2016, 103, 123 -133.
AMA StyleSiwei Lou, Danny H.W. Li, Joseph Choi Lam, Eric W.M. Lee. Estimation of obstructed vertical solar irradiation under the 15 CIE Standard Skies. Building and Environment. 2016; 103 ():123-133.
Chicago/Turabian StyleSiwei Lou; Danny H.W. Li; Joseph Choi Lam; Eric W.M. Lee. 2016. "Estimation of obstructed vertical solar irradiation under the 15 CIE Standard Skies." Building and Environment 103, no. : 123-133.
Solar irradiance data particularly on inclined planes are crucial to solar energy applications and energy-efficient building designs. However, the basic solar data for the planes of interest are not always readily available. Recently, the CIE (International Commission on Illumination) adopted a range of 15 standard skies which provide a good overall framework for representing the actual sky conditions. Each sky represents a unique sky-diffuse distribution. Upon the classification of the standard skies, the solar irradiance data at the plane of interest can be computed. This paper presents a method to estimate the solar irradiance on inclined plane based on the CIE Standard Skies. Data recorded in Hong Kong from the end of February to early June in 2015 were used to validate the calculation procedures. The results show that the approach can accurately estimate solar irradiance on inclined planes.
Danny H.W. Li; Siwei Lou; Joseph Choi Lam; Ronald H.T. Wu. Determining solar irradiance on inclined planes from classified CIE (International Commission on Illumination) standard skies. Energy 2016, 101, 462 -470.
AMA StyleDanny H.W. Li, Siwei Lou, Joseph Choi Lam, Ronald H.T. Wu. Determining solar irradiance on inclined planes from classified CIE (International Commission on Illumination) standard skies. Energy. 2016; 101 ():462-470.
Chicago/Turabian StyleDanny H.W. Li; Siwei Lou; Joseph Choi Lam; Ronald H.T. Wu. 2016. "Determining solar irradiance on inclined planes from classified CIE (International Commission on Illumination) standard skies." Energy 101, no. : 462-470.