Energy conservation in building arena is essential issue for achieving sustainable environment. However, buildings experienced significant amount of heat gain or loss through window and this will ...affect the thermal comfort of buildings׳ occupants. Building without window is able to save energy, but it is not recommended due to the benefits of natural light on visual comfort and the biological effect of natural light on humans. Hence, window design plays important role in building architect. One of the essential parts of window is the glazing. Selecting a window glazing is complicated when energy saving and daylighting aspects of a building are considered concurrently. Optimization techniques offer a balance solution for the contradictions in selecting a window glazing of energy-efficient building. This paper intended to reveal the impacts of window glazing on the energy and daylighting performances of building through the previous researches. Then, the optimization techniques used by various researchers in choosing a glazing are highlighted. The emerging glazing technologies were discussed as well.
Lighting is necessary for all kinds of buildings and consumes a large amount of electricity. Tubular daylighting devices (TDDs) can serve as an alternative, but they may also have thermal effects on ...the indoor environment, which has not been studied yet. In this paper, a lighting-heating coupled TDDs system was designed and built, to improve the use of TDDs for building energy savings and sustainability, where antimony tin oxide (ATO) nanofluids were introduced to absorb extra unexpected heat and then supply domestic hot water. Meanwhile, a new method was developed to calculate the annual amount of energy output of TDDs under different mass concentrations of ATO nanofluids. Results showed that the ATO nanofluids of 100 ppm can absorb ∼ 50% solar radiation coming along with more efficient visible lighting. Furthermore, in the case study in Beijing, TDDs with 100 ppm ATO nanofluids could generate over 10 tons of domestic hot water while saving 30.9 kWh of electricity for refrigeration, resulting in a ∼ 10% improvement on total energy-saving performance. This research work demonstrates the high potential of using the designed lighting-heating coupled TDDs system in buildings for both energy savings and daylighting benefits.
•This research introduces novel daylighting enhancement techniques tailored for the unique architectural characteristics of traditional military settlements in Xiangxi, China.•The study effectively ...combines the need for cultural preservation with contemporary living standards.•Advanced simulation tools, including Ladybug and Honeybee software, were employed to model various lighting improvement strategies, ensuring a thorough and scientific approach to renovation design.•The research prioritizes cost-effective measures and promotes energy efficiency, addressing financial constraints commonly faced in rural home renovations in China.
This study scrutinizes daylight optimization strategies within traditional military settlement residences in Lahao Village, Xiangxi, focusing on augmenting natural illumination while safeguarding historical architecture and ensuring cost efficiency. Employing Ladybug software for simulations, this research delineates the variations in indoor lighting effects attributable to alterations in the window-to-wall ratio, skylight-to-roof ratio, and wall reflectance. Analyzed strategies include the expansion of window areas to elevate the window-to-wall ratio, the incorporation of transparent tiles to augment the skylight-to-roof ratio, and the application of light-colored wallpaper to increase wall reflectance. The findings reveal that both enlarging window areas and integrating transparent tiles significantly enhance indoor lighting in a cost-effective manner, without detracting from the traditional architectural integrity. Conversely, the adoption of light-colored wallpaper emerged as an expensive and less effective method for improving indoor illumination. This investigation endeavors to furnish sustainable renovation strategies that harmonize contemporary living standards with the conservation of cultural heritage, offering a valuable framework for analogous initiatives.
An artificial neural network (ANN) model was developed for office buildings with daylighting for subtropical climates. A total of nine variables were used as the input parameters – four variables ...were related to the external weather conditions (daily average dry-bulb temperature, daily average wet-bulb temperature, daily global solar radiation and daily average clearness index), four for the building envelope designs (solar aperture, daylight aperture, overhang and side-fins projections), and the last variable was day type (i.e. weekdays, Saturdays and Sundays). There were four nodes at the output layer with the estimated daily electricity use for cooling, heating, electric lighting and total building as the output. Building energy simulation using EnergyPlus was conducted to generate daily building energy use database for the training and testing of ANNs. The Nash–Sutcliffe efficiency coefficient for the ANN modelled cooling, heating, electric lighting and total building electricity use was 0.994, 0.940, 0.993, and 0.996, respectively, indicating excellent predictive power. Error analysis showed that lighting electricity use had the smallest errors, from 0.2% under-estimation to 3.6% over-estimation, with the coefficient of variation of the root mean square error ranging from 3% to 5.6%.
•A solar lighting/heating system using spectrum-sensitive nanofluids was developed.•The light transmission efficiency was close to that of current solar lighting systems.•1 m2 collection area ...provided 466.4 MJ of thermal energy in summer season.•The effect of operation condition on the system efficiency was explored.
Solar lighting is considered as a promising technique, which has huge potential in conserving energy and relaxing the residents. However, current solar lighting systems used a filter to allow only visible light to enter buildings, releasing all the other energy contained in the long wave of the solar into the surrounding air. Such practice leaded to low efficiency of solar energy utilization and high costs. In this paper, a solar lighting/heating system was developed which used a hollow lens filled with ATO nanofluid to separate the long wave and short wave of solar energy. A series of tests were conducted to explore the performance of system. Results indicated that under the test condition of Case 1 (0.025%/0.0001% ATO/Graphite nanofluid, 100 L/h flow rate), the light transmission efficiency was 19.5% which was comparable to that of current solar lighting systems, and the heat absorption efficiency was 25.35%. The heat energy collected by the such a system from June to August (three months) in the city of Harbin was about 466.4 MJ in per square meter of collection area. The volume concentration of nanofluids had great influence on both the light transmission efficiency and the heat absorption efficiency. The flow rate had little influence on the light transmission efficiency, but had great influence on the heat absorption efficiency of the system.
In tropical urban areas, the vertical facades of buildings often play a crucial role in capturing solar radiation and heat, especially for office buildings facing west during the afternoon. In Dhaka, ...a tropical city, the construction of major arterial roads connecting the northern and southern regions of the city has led to the emergence of numerous commercial buildings along these roads, predominantly facing in east or west directions. This research investigated the efficiency of different existing fenestration types (glass curtain walls, glass windows with horizontal and vertical louvres, overhangs, vertical fins, and egg crate shading) of west-facing office buildings in Dhaka in terms of daylight, thermal comfort and energy efficiency, and explore strategies to enhance existing performance. From the field survey, a 'case office building' was selected, and simulations were carried out with the six different fenestrations, as mentioned above, while keeping other aspects constant as found during the survey, e.g., floor plan, equipment and number of occupants. In this research, the simulation process encompasses daylighting simulation, energy simulation, and multi-objective optimisation. The study utilised a case model created with Rhinoceros and ClimateStudio, while performance metric optimisation was achieved using Grasshopper and Octopus. Multi-objective optimisation techniques were employed to improve the shading configurations. The TT toolbox facilitated data exportation and Design Explorer assisted in data visualisation. The window with egg crate shading was found to be the most effective fenestration type among the studied shading configurations. Further parametric simulation was conducted to develop an optimised egg crate shading design configuration. It was found that egg crate shading with a 1.0 m depth provided optimum daylight and solar heat gain inside the office building among the studied configurations in the context of Dhaka. A comparison was also made between the optimised egg crate option and a customised egg crate with some detailing (popularly known as brise soleil). Brise soleil showed better performance with 12.2% higher sDA and 98 lux additional average illuminance compared to the previous optimum one. The findings underscore the significance of employing optimisation methodology to devise shading configurations while also revealing substantial opportunities to enhance performance further by tailoring details on the optimised design recommended from simulation analysis.
•Influences of the transient daylight fluctuations on building are quantified.•It requires 140–700 h/year lighting duration due to the daylight instability.•It requires 5–17 min lighting duration to ...prevent each potential on/off switching.•Daylight instability is not symmetric in east and west spaces of the building.
Fluctuations of daylight can cause uncertainties in evaluating its accessibility for building design and optimization tasks by the time-averaged solar and daylight data in hourly interval. This study thus investigates the transient daylight fluctuations and their consequences on the electric light that operates under the typical dead-band and time-delay controlling methods for a hot and humid subtropical region. We quantified the duration and its occurrence probability of the electric lighting operation due to the daylight instability with typical lighting control methods, and its correlations with the weather condition. For the controlling methods under study, results show the instability-associated lighting duration ranges from 140 to 700 h per year. This length account for 3.84% to 19.18% of the office hours, and is comparable to the period length with indoor illuminance below 450 lx during the day. This operation length is expected to be highest in cloudy condition, roughly taking 100 min per day, much higher than the overcast and clear conditions with around 30–40 min. The temporal lengths per day under dead-band and delay methods are less than around 50, and 130 min for more than 80% cases. The findings are essential to the accurate evaluation of daylight performance in buildings especially for buildings with unstable and cloudy weather conditions.
This paper presents a critical review of studies addressing the effects of window views, daylighting, and lighting on occupant behavior, perception, performance, and well-being. A systematic search ...in the Scopus database was performed in November 2021 and yielded 515 hits. Seventy-six studies were selected according to the following criteria: i) papers presenting research results with participants' responses and ii) accounting for daylighting, lighting, or window view assessments. The study and setting features, participants, predictors and outcomes, the statistical approach, the reported significance level, and study limitations were extracted from each paper. The analysis then identified differences in the effect of the predictor on the outcome. The number of records obtained through the structured analysis was 240. A wide range of predictors have been used in indoor daylighting, lighting, and window view research to assess people's responses. The most commonly used predictors were artificial lighting features and window features -qualitative predictors - followed by some properties of the light sources, such as correlated color temperature, spectral distribution and horizontal illuminance. Differences in the methods for data collection, the used predictors, the outcomes, and the ways to measure the outcomes generated inconclusive results or results that were limited to the specific study. We extracted data from selected studies to suggest a simple model for the prediction of occupant performance from illuminance and correlated color temperature. The data points were few and scattered and the model, therefore, suffers from considerable uncertainties. Yet, it quantifies performance effects in ranges that are comparable with similar models from other indoor environment domains.
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•Most used predictors were artificial lighting features and window features.•Frequently used quantitative predictors were CCT and illuminance.•Differences in the methods, predictors and outcomes generate inconclusive results.•An initial model to quantify occupant performance based in E and CCT was suggested.
The semi-transparent photovoltaics (STPV) window is recognized by many as an innovative and emerging technology. However, the applications of building-integrated STPV windows are restricted to a ...certain extent by potential conflicts between the daylighting quality and energy efficiency. In this study, a novel metric named the ratio of N-Daylit area was derived to quantify the daylighting quality. On this basis, parametric analysis with different PV cell coverage ratios, window-wall-ratios (WWR) and orientations of double-skin STPV windows were performed to obtain annual daylighting quality and net electricity use for a generic reference office located in cold region of China. An optimal design of DS-STPV facing south with PV cell coverage ratio of 30% and WWR of 30%–40% was recommended according to the simulation results. Furthermore, a comparison study of DS-STPV against with other five types of commonly used was also conducted. The results revealed that the utilization of STPV was beneficial for the improvement of daylighting quality and led to a reduction of annual energy consumption of the office. By using the DS-STPV, the ratio of N-Daylit area was increased to 56.8% with an increment of 31%, while the net electricity use of the space was as low as 36.1 kW h m−2∙yr−1.
•The daylighting simulation model in Daysim was experimentally validated.•A new metric named “N-Daylit area” was proposed to quantify the daylighting quality.•The daylight and energy performance of STPV facades was investigated simultaneously.•An optimal design of STPV facades was recommended according to simulation results.•Benefits with the application of STPV facades have been further demonstrated.
A simulation algorithm is proposed that predicts the lighting energy performance of manually and automatically controlled electric lighting and blind systems in private and two-person offices. ...Algorithm inputs are annual profiles of user occupancy and work plane illuminances. These two inputs are combined with probabilistic switching patterns, which have been derived from field data, in order to predict the status of the electric lighting and blinds throughout the year. The model features four different user types to mimic variation in control behavior between different occupants.
An example application in a private office with a southern facade yields that––depending on the user type––the electric lighting energy demand for a manually controlled electric lighting and blind system ranges from 10 to 39 kW
h/m
2
yr. The predicted mean energy savings of a switch-off occupancy sensor in the example office are 20%. Depending on how reliably occupants switch off a dimmed lighting system, mean electric lighting energy savings due to a daylight-linked photocell control range from 60% to zero.
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