•Performance of PCM office building in five cities of China was evaluated.•Energy saving potential of Shenyang was found to be the best.•The dynamic payback period was employed for energy economic ...analysis.•PCM investment appears to be attractive in Shenyang, Zhengzhou and Changsha.•PCM investment in Kunming and Hong Kong do not offer economic benefits.
In this research, the effect of phase change material (PCM) on energy consumption of a typical multistory office building located in five different cities (Shenyang, Zhengzhou, Changsha, Kunming and Hong Kong) representing different climate regions of China, was simulated for a whole year using EnergyPlus. Based on the simulation results, the energy savings resulting from PCM application were evaluated. For economic analysis, the static payback period (SPP) and dynamic payback period (DPP), considering different discount rates, were used to assess the application of PCM in a typical official building. Test results showed that the energy savings resulting from PCM application are more prominent for office building located in cold region such as Shenyang and Zhengzhou as well as in hot summer and cold winter (Changsha). From economic analysis, the application of PCM in Shenyang, Zhengzhou and Changsha showed high economic value and the investment appeared to be attractive. However, at current prices, the PCM investment in Kunming and Hong Kong cannot be recovered and do not offer economic benefits.
•Urban form factors that affect heating load in severe cold regions are discovered.•Heating load can be saved by 6.76% with every unit increased in surrounding FAR.•Heating load can be saved by ...12.76% with every unit increased in surrounding RHR.•How urban morphology influence heating load in severe cold regions is discussed.•Urban design strategies are provided for reducing heating load in severe cold regions.
Studies have suggested that the energy demand of buildings can be significantly influenced by urban morphological factors. However, little research has focused on urban-morphology-related heating energy consumption in severe cold regions, where buildings are facing greater pressure to save energy because of long heating periods. In this paper, the aim is to fill this knowledge gap through a combination of energy simulation and statistical analysis. First, taking 73 office buildings in Harbin as the study objects, the theoretical energy consumption (TEC) is stimulated and the external influence energy consumption (EIEC) of each building is obtained by subtracting the TEC from the measured actual energy consumption. Then, using regression analysis, the effects of 7 urban morphological factors on heating energy consumption are evaluated. The results indicate that greater building site cover (BSC), floor area ratio (FAR), building height (BH), road height-width ratio (RHR), total wall surface area (WSA), and lower green space ratio (GSR) are beneficial to the reduction of heating energy consumption. Among them, FAR is the most critical factors in saving heating energy by up to 10.820 kW·h/m2/y, with the addition of one more unit. This result confirms the significant role that energy saving-oriented urban morphology can play in making heating energy more efficient and sustainable in severe cold region cities.
The measurement of the COsub.2 concentration has a wide range of applications. Traditionally, it has been used to assess air quality, with other applications linked to the experimental assessment of ...occupancy patterns and air renewal rates. More recently, the worldwide dissemination of COVID-19 establishing a relationship between infection risk and the mean COsub.2 level has abruptly led to the measurement of the COsub.2 concentration in order to limit the spread of this respiratory disease in the indoor environment. Therefore, the extensive application of this measurement outside of traditional air quality assessment requires an in-depth analysis of the suitability of these sensors for such modern applications. This paper discusses the performance of an array of commercial wall-mounted COsub.2 sensors, focusing on their application to obtain occupancy patterns and air renovation rates. This study is supported by several long-term test campaigns conducted in an in-use office building located in south-eastern Spain. The results show a spread of 19-101 ppm, with a drift of 28 ppm over 5 years, an offset of 2-301 ppm and fluctuations up to 80 ppm in instantaneous measurements not related to concentration changes. It is proposed that values averaged over 30 min, using a suitable reference value, be used to avoid erroneous results when calibration is not feasible.
•The energy performance, annual daylight glare, and interior illuminance performance of PDLC window were evaluated by EnergyPlus in two climate zones.•Building energy modelling evaluation was ...conducted by employing PDLC window using solar radiation and outdoor temperature as a control shading strategy.•PDLC achieved the highest annual energy reduction by 12.8% and 4.9% in Riyadh and London, respectively.•Percentage of annual glare and interior illuminance of PDLC were evaluated for three daylight zones for two weather conditions.•The PDLC window achieved the highest interior illuminance in the low daylight zone and intermediate daylight zone in Riyadh and London, respectively.
Polymer dispersed liquid crystal (PDLC) is an electrically switchable smart window, that can provide privacy and control solar radiation, resulting in a potential energy saving. The optical properties of the PDLC window can be altered from translucent to transparent when an alternating current power supply is applied. However, little attention has been paid to the PDLC smart window in terms of overall building energy performance. Therefore, this study aims to investigate the impact of the PDLC window on heating, cooling, and lighting loads and daylight performance, for an office building utilising energy building modelling and daylight analysis tool. The study is limited to two contrasting climate zones; an arid climate (Riyadh, Saudi Arabia) and a temperate climate (London, United Kingdom). The results showed that the PDLC window was more effective in Riyadh (arid climate) with a cooling reduction of 12.8% than London (temperate climate) with a heating reduction of 4.9%. PDLC provided excellent interior illuminance in both cities.
Similar to their optic counterparts, acoustic components are anticipated to flexibly tailor the propagation of sound. However, the practical applications, e.g. for audible sound with large ...wavelengths, are frequently hampered by the issue of device thickness. Here we present an effective design of metasurface structures that can deflect the transmitted airborne sound in an anomalous way. This flat lens, made of spatially varied coiling-slit subunits, has a thickness of deep subwavelength. By elaborately optimizing its microstructures, the proposed lens exhibits high performance in steering sound wavefronts. Good agreement has been demonstrated experimentally by a sample around the frequency 2.55 kHz, incident with a Gaussian beam at normal or oblique incidence. This study may open new avenues for numerous daily life applications, such as controlling indoor sound effects by decorating rooms with light metasurface walls.
Personal control is one of the influential factors for user satisfaction and environmental comfort due to its physical and psychological impacts. This paper aims to identify the relationship between ...the degree of personal control over indoor environmental conditions and user satisfaction with thermal and visual comfort. Trying to answer the question, field studies on user control were conducted in 5 office buildings in the Netherlands. Occupants assessed their perceived satisfaction online by means of a questionnaire. Based on the dataset, Pearson's Chi-Square test was conducted to investigate the relationship. The results showed that a higher controllability leads to more satisfaction in terms of thermal and visual comfort. The research also revealed the psychological impact of personal control on user satisfaction by showing differences in perceived satisfaction according to “no control” and “do not have” between thermal and visual comfort. Personal control of ventilation was the most significant factor influencing the satisfaction with thermal comfort. These findings provide support to workplace management and to the design of personal environmental control systems.
•The relationship between personal control over indoor environment and user satisfaction in workplaces is investigated.•Empirical research was conducted to investigate satisfaction level of thermal and visual comfort in different seasons.•Pearson's Chi-Square test was conducted to reveal the relationship of the degree of personal control and user satisfaction.•Personal control is essential factor to increase user satisfaction in workplaces.
Indoor air quality (IAQ) has significant impacts on office occupants' productivity, well-being and health. Addressing IAQ not only means ensuring that contaminants are below harmful concentration but ...also that people exposed are satisfied. However, current standards often lack clear metrics and thresholds dedicated to Perceived Air Quality (PAQ). Therefore, it is important to examine whether there is a prevalent method in the literature that could lead towards standardization. This review study constitutes the first comprehensive critical exploration of the subject. Adopting the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines, the objective is to synthesize and compare diverse methods (subjective vs instrumental evaluations; object of judgment; component of perception; rating scales) for assessing PAQ in office buildings, based on insights from 93 field and laboratory studies. Results show that the assessment of PAQ predominantly relies on questionnaires (90 %), with a very smaller percentage using alternative methods such as olfactory indices, diaries, interviews, sensory testing, and text mining techniques. Workers’ satisfaction is the most commonly evaluated aspect in PAQ questionnaires, often measured on a 7-point Likert scale. Odours are typically characterized in terms of intensity by utilizing a continuous 6-point unidirectional scale. Olfactory stimuli are usually considered with a negative connotation, being the absence of odour the target of IAQ design. The present study proposes a future research agenda that introduces the importance of a perceptual approach to evaluate the indoor olfactory environments (or smellscapes), aiming to create working spaces that are not only odour-neutral but also olfactorily pleasant.
•This study synthetises perceived air quality (PAQ) assessment methods in offices.•93 field and laboratory studies were systematically reviewed.•37 existing PAQ evaluation scales are compared.•The limits of traditional odour control approach are highlighted.•An alternative indoor smellscape framework is proposed.
•Establish a building energy database for 30 Hong Kong office buildings.•Analyse key energy performance indexes of EUI, CO2e and energy breakdown.•Identify the gap between design and measured COP for ...HVAC system.•Compare the energy performance of district cooling and in-building chiller system.•Predict building energy consumption by two modelling techniques.
A study of energy performance of 30 existing commercial office buildings in Hong Kong has been carried out. Energy audits have been conducted and the data obtained from utility bills, design documents and on-site measurements have been thoroughly assessed. Energy Utilization Index (EUI) as well as carbon emission of each building have been calculated to compare with previous studies and other benchmarks. EUI study in terms of over-time evolution and by categories have been also undertaken. An energy breakdown of 30 buildings by end-user systems was derived, showing that 68% of energy on average was consumed by HVAC system, while lighting accounted for 14% and the other systems shared the else 18% of consumption. Compared with other countries, HVAC system in Hong Kong consumed the highest proportion of energy among all end-user systems. Moreover, the COP of HVAC systems have been analyzed, indicating that with an average deviation of 16% between the design and measured chiller COP for all studied buildings, the measured chiller COP can barely meet the standard issued by the government. A district cooling system for a group of office buildings has been investigated as well, demonstrating better chiller and system efficiencies but resulting in the over-capacity installation of cooling units. To further predict building energy consumption, a mathematical model based on the measured data has been built through the multiple regression analysis and verified by the back-propagation neural network algorithm. This research is expected to provide theoretical guidance and practical data reference for the relevant evaluations of building energy efficiency.
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