Search

Windows are responsible for the largest amount of energy loss related to building envelope. Past studies on the energy consumption of windows have mainly focused on residential and commercial buildings, while few studies have explored the energy consumption of windows in educational buildings. The sizes and locations of classroom windows affect not only the building energy consumption but also the indoor environment quality, which is an issue that needs to be balanced. This paper takes a classroom in Guangzhou as the object. Under the premise of meeting the lighting standards of the classroom, two parameters—window height and sill height —were simulated in different corridors of north–south and east–west classrooms to analyse the impact of their changes on the indoor environment as well as energy consumption based on the parametric platform Grasshopper and its plug-ins Ladybug and Honeybee. The energy consumption of a number of fenestration combinations on both sides of the classroom was optimized automatically by genetic algorithm, and the sizes and positions of windows that benefitted energy savings were obtained. In the best case ~16.6% of energy consumed in a whole year can be saved compared with the worst case. This conclusion can provide a quick decision-making process for the design of window shapes for the purpose of energy savings in the early design stage of educational buildings in the Pearl River Delta such that energy savings can be quickly and clearly guaranteed in the subsequent window configuration. [ABSTRACT FROM AUTHOR]

The skylight on the roof of an atrium can be popular for commercial malls to illuminate the core area of the building. However, the solar radiation and its heat can get into the building together with the daylight, causing excessive cooling load. This paper studies the daylighting and energy performances of skylight coverage area for the air-conditioned atriums in the hot and humid regions. The energy performance with different atrium heights, glass types and the coverage ratios of the skylight are studied. The daylight performance was simulated by the ray-tracing Radiance and was transferred into EnergyPlus for energy evaluations. The finding suggested that, for hot and humid climates, the skylight coverage ratio should be controlled carefully to prevent the excessive solar heat gain. When the on/off lighting control is applied, the total energy consumption of the single-floor cases (or of the top floor for the multi-floor cases) leveled off when the coverage ratio of the skylight reached 9%. Thus, the skylight is favorable to the energy saving of the low-rise or single-floor commercial buildings only under the current assumptions, as the ground of the atrium cannot be well illuminated while the excessive solar radiation gets into the building. The skylight should be shaded in cooling seasons to prevent the excessive solar heat gains. [ABSTRACT FROM AUTHOR]

• Energy resilience of residential sectors under climate change are evaluated. • Uncertainties in climates, building characteristics and use patterns are considered. • The energy demand of residential sector in hot-humid area can rise by 102.2%. • Building with a high shape coefficient value tends to be more affected by climate. • Family pattern is another important factor that influences the energy trend. Residential sector is one of the main consumers of the energy market. This study conducts a comprehensive analysis on the future energy resilience performance of urban residential sector in hot-humid area of China in the 21st century. Uncertainties, including future climate, building characteristic and occupancy behavior, are considered in future energy projections. Since the local climate is characterized by hot summer and warm winter, and local building energy is cooling-dominated, this study focuses on the changes in future cooling load. The results indicate that future energy demand of residential sector in hot-humid areas will increase over time except under the Shared Socioeconomic Pathway (SSP) 1-2.6, and the magnitude of the rise could be significant. Under the SSP5-8.5, the most severe scenario for climate change, the average annual energy demand of residential sector in the long-term future is about 90 kWh/m2, which is above twice the energy demand under current typical climate. The annual building energy fluctuates more in a hotter future. Energy demands of dwellings with different building forms and use patterns may vary disproportionately in the changing climate. The framework and findings could give implications on future energy system design in cities. [Display omitted] [ABSTRACT FROM AUTHOR]

• Occupant behavioural data of bedrooms were collected by smart meter • Representative occupants of bedrooms were identified by clustering • Three usage clusters were detected among the samples (night, noon, low-usage) • Identities of users were correlated with their AC usage behaviours • Typical AC on/off pattern was determined by its running rate and thermal comfort 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). [ABSTRACT FROM AUTHOR]

Moisture significantly affects indoor thermal comfort and energy demand. However, the coupled heat and moisture transfer (HAMT) effect inside the wall assemblies is often ignored in building performance calculations. To quantify its impact on building performance under hot and humid climates, the thermal environment and energy demand of an apartment in Guangzhou (China) were evaluated with and without HAMT finite element algorithm, respectively. The HAMT effects are quantified and analyzed in different periods. Different boundary conditions regarding climate uncertainty, wind-driven rain effect, and wall solar absorptance are considered. The results show that under naturally ventilated conditions, ignoring the effect of HAMT in walls can lead to an overestimation of indoor operative temperature by 1.2 °C in summer and an underestimation of 1.7 °C in winter. The deviation in indoor operative temperature calculated by the two models is noticeable from noon to midnight. On the other hand, cooling and dehumidification demand energy demand can be underestimated by 8.4% and 12.4%, respectively, without consideration of HAMT. The HAMT also increases the probability of high hourly energy demand for cooling and dehumidification under the HAMT effect. These findings emphasize the importance of considering the HAMT effect when evaluating building performance in hot and humid regions. [ABSTRACT FROM AUTHOR]

• A novel index is proposed to analyse quantitatively the local climate potential of free-running buildings. • The summer climate potential of free-running buildings in Harbin, Beijing, Wuhan, Kunming, and Guangzhou was found to be 90%-98%, 83%-96%, 75%-88%, almost 100%, and 62%-93%, respectively. • Cities in Northern China are better suited for passive cooling design due to higher summer climate potential. • There is a decrease pattern in the summer climate potential across China from 1971 to 2012. This study gathered hourly temperatures and solar radiation data from 42 years for walls in five cities within the five major climate zones across China. The long-term hourly operative temperatures in summer were determined in accordance with the ISO standard. A novel index is proposed to analyse quantitatively the local climate potential of free-running buildings. The index calculates the number of hours when the indoor operative temperature is above/below the acceptable upper limit of thermal comfort, counted in summer or throughout a year. In Harbin, Beijing, Wuhan, Kunming, and Guangzhou, the summer climate potential of free-running buildings was found to be 90 %-98 %, 83 %-96 %, 75 %-88 %, almost 100 %, and 62 %-93 %, respectively. Cities in Northern China are better suited for passive cooling design because they have a diminishing pattern of climate potential from colder climates in the north to warmer climates in the south. Additionally, positive slopes were found for the long-term shifting patterns of hour proportion from 1971 to 2012, pointing to a decrease in the summer climate potential across China. These findings have significant effects on the analyses of how buildings can adapt to and mitigate climate change and the likely changes in energy use. [ABSTRACT FROM AUTHOR]