Self-report is widely used to collect subjective and experiential data in built environment studies, including comfort demand, environmental cognition, and behavior triggers. However, there exists longtime worries about the accuracy and applicability of self-report data. Ignoring the potential perception gap of respondents would cause cascaded uncertainties in further explorations. This study aims to quantify biases in self-report thermal parameters and figure out the perception process and influencing factors. A total of 71 participants from the hot and cool zones were recruited for the 7-day experiment, who were well-educated engineering students, as ideal respondents in built environment studies. A knowledge quiz was designed to estimate the thermal knowledge level of the participants. The perception gaps regarding ambient temperature and humidity were examined twice during the experiments, before and after a take-home learning intervention with thermo-hygrometers. High-accuracy environmental sensors and thermal imagers were adopted to quantify the measured-perceived data gap. Finally, path analyses checked the hypothesized perception process and identified key influencing factors. The results showed that we tended to overrate the knowledge level of our respondents, since the supposed ideal respondents achieved a mean score of 53 out of 100. Most participants underestimated ambient temperature and relative humidity, with mean errors of -1.1℃ and -17%RH. The biases decreased after the take-home learning intervention, to be -0.6℃ and -4%RH. The findings are to enhance understanding of thermal perception gaps and inform the design of reliable data collection methods with the reasonable use of self-report data.

Frequent heat extremes make indoor thermal comfort an urgent challenge, yet comfort perception is substantially shaped by cultural knowledge systems. In China’s temperate zone, traditional health preservation culture advocates attuning daily life to seasonal rhythms and prioritizing non-mechanical cooling, but how this cultural framework organizes adaptive behaviors remains underexplored. This study investigates adaptation modes and cultural roots of Chinese residents in temperate zone facing hot summer. A sequential mixed-methods design was employed, combining a survey of 667 residents with field monitoring and walk-along interviews of 10 households (22 adults) in China’s temperate zone. Three adaptation modes were identified, namely body-centric, nature-based, and AC-oriented. K-means clustering then revealed three user typologies, with the ”Moderate Baseline” group as the largest cluster (n=11), characterized by moderate use of body-centric and nature-based strategies and low reliance on air conditioning. Health preservation culture was positively associated with nature-based mode (ρ=0.46, p=0.033). It also served as a focal factor linking age and adaptive behaviors. That is, health preservation culture fully mediated the effect of age on nature-based mode (indirect effect=0.45, 95% CI [0.054, 0.978]); and age could lead to more fan ownership only for individuals with medium to high frequency of health preservation practice. The findings suggest that culturally embedded health beliefs steer adaptation toward low-energy, nature-attuned practices, offering insights for sustainable adaptation strategies in temperate regions.

Reducing operational carbon emissions from residential buildings is crucial for achieving carbon neutrality in high-density metropolises such as Hong Kong. However, existing studies on decarbonising the building sector have mainly focused on the impact of socio-economic factors, rather than technical factors, resulting in an unclear action plan. Aiming to fill the knowledge gap on the pathway to net-zero emissions from the operation of Hong Kong's residential buildings, this paper develops an emission prediction model integrating the Kaya identity and the Stochastic Impacts by Regression on Population, Affluence, and Technology (STIRPAT) model. Technical factors related to building operation, including energy use intensity, carbon emission factor and electrification rate, were incorporated into the model. The Logarithmic Mean Divisia Index (LMDI) decomposition method was then used to identify the key factors influencing the carbon emissions based on official statistics from 2000 to 2023. Finally, a total of 81 dynamic scenarios were developed within the context of Hong Kong to predict future emissions and analyse the contributions of different decarbonisation strategies. Electricity use intensity and carbon emission factor were identified as the most significant explicit influencing factors, while building electrification rate was identified as an implicit factor. Accordingly, the strategies of building energy efficiency, renewable energy use, and building electrification can respectively contribute to 48.0%, 44.5% and 7.4% of the reduction in operational carbon emissions from Hong Kong's residential building stock in 2050. The findings provide important implications for Hong Kong in formulating effective decarbonisation roadmaps for the operation of the residential building stock.

Water cycle resilience represents a vital part of sustainable water resources management for a region with severe water vulnerability issues. However, despite their importance, a current lack of systematic monitoring mechanisms has contributed to an insufficient grasp of their distribution in relation to water resources management practices, as well as their vulnerability to climate change and human impacts. This study develops a nature-society water cycle resilience index that integrates recover and supplement to water vulnerability, which is applied in the case study of China. The results indicate that the comprehensive level of water cycle resilience in China has been constantly improving in the past two decades, whilst varies significantly among provinces in water resources management performance and serious vulnerability issues. This study provides useful references for countries or large-scale regions around the world to promote resilience and sustainability in water resources planning and policy.

Passive design measures were regarded as a method to address the energy performance gap (EPG) in buildings.However, there is a lack of quantification of the impact of passive design measures on the EPG.This study aims to quantify the impact of passive design measures on the EPG using a case study of high-rise residential buildings in Hong Kong.First, key passive design variables were identified through a literature review, including window-to-wall ratio and window type.Second, an as-designed energy model and an asoccupied energy model were built using DesignBuilder and EnergyPlus.Third, sensitivity analysis was conducted using passive design variables as inputs in both the asdesigned and as-occupied energy models.Results show that the EPG of the case building was about 16%.The window type has a greater impact on the EPG than window-to-wall ratio.This study demonstrates the potential of passive design measures for closing the EPG.

Low-energy buildings (LEBs) play an important role in improving energy efficiency, reducing energy use, and mitigating carbon emissions to achieve the 2050 global decarbonisation target. However, increasing evidence indicates that energy performance gap (EPG), defined as the difference between predicted and actual energy performance, significantly inhibits the successful delivery of LEBs. This study aims to systematically examine EPG in the context of LEBs using the combination of the methods of literature review and meta-analysis with 76 carefully selected cases of LEBs from previous studies. Drawing on the dialectical system theory, the study develops a novel dialectical system framework to ensure the systematicity and comprehensiveness of the examination of EPG in LEBs. A new life cycle-human-technology-organisation framework is also established to clarify the complex causes of the EPG. The findings reveal that EPG in LEBs ranges from -86 % to +483 % with an average of +58 %. More than 80 % of the LEBs have a positive gap that their actual energy consumption is greater than their predicted energy consumption. It is found that technology-related and human-related causes of EPG have been popularly investigated, but organisation-related causes have been far inadequately explored. A roadmap for pursuing zero-energy gap is proposed to promote the successful delivery of LEBs. Knowledge gaps are identified, which point future research directions for achieving a systematic understanding of EPG in LEBs, bridging the EPG, and realising LEBs effectively.

Office buildings are a major contributor to energy consumption in high-density urban contexts where building high-rises is a norm. It is important to understand the parameters affecting high-rise office buildings’ energy consumption. However, previous research generally used isolated buildings as target buildings, regardless of the impact brought by the surrounding buildings. Also, there lacked a comprehensive calibration method to validate the energy baseline model in the literature. This paper aims to quantitatively analyse the energy use in high-rise office buildings by tackling these two issues and examining the impacts of various energy-saving measures (ESMs). A real-life 26-story office building in Hong Kong was selected as a base case. Multiple methods were used to calibrate the building energy model, including onsite microclimate measurement, metered data, architectural drawings and official documents, and onsite surveys. Parametric sensitivity analyses were then conducted to quantify the importance of ten selected parameters from five types of ESMs. Results indicate that building service efficiency and cooling setpoint had the most significant energy-saving potential. The base case of the ESMs in use was considered as the base scenario. Two new scenarios were proposed to examine the range of total energy consumption by adopting the most and least energy-efficient ESMs, which were referred to as the “optimistic scenario” and the “pessimistic scenario”. The maximum reduction/increase in energy use is expected to be approximately 13.2%/39.3% for the optimistic/pessimistic scenario compared to the base scenario. The findings on the sensitivities and scenarios contribute to a more comprehensive understanding of the critical parameters that influence energy use in high-rise office buildings in subtropical climate. The findings also provide scenario-based design solutions for delivering low-energy office buildings.

Increasing attention is paid to the influence of microclimate factors on building energy use.However, there is limited research focusing on high-rise office buildings.This study aims to analyse the accuracy of building energy performance for high-rise office buildings by considering microclimate factors.A real-life high-rise office building located in Hong Kong was selected as the case building.One-year onsite measurement for five microclimate factors was conducted.Three scenarios were considered to evaluate the microclimate effect on building energy use.By using different weather datasets, the deviation of the total building energy use is around 3%, while the deviation of the cooling energy use can be up to 7.9%.The results emphasise the importance of considering the urban microclimate effects on energy consumption.

Infrastructure sustainability assessment (ISA) has become increasingly important for achieving sustainable development goals. ISA systems are widely adopted by different stakeholders such as governments, architects, engineers, and academics to assess the manner in which sustainability is incorporated in infrastructure projects. However, a systematic understanding of ISA systems is lacking, and the multifaceted and complicated features of such systems were overlooked in the literature. Thus, this study aims to develop a four-level hierarchical framework (covering the levels of contexts, methods, measures, and results) based on the dialectical system theory, and to use this framework for a comprehensive review of international ISA systems. Fourteen existing ISA systems were reviewed, and six were carefully selected and examined in detail. An enhanced five-pillar concept (i.e. technology, economy, environment, society, and institution) of infrastructure sustainability is proposed to evaluate the measures included in the ISA systems. The results show that dialectics exist within, and encounter challenges at, all four levels of the systems. This study suggests four recommendations to improve the ISA systems: enhancing the balanced concept of sustainability, advancing the promotion of ISA systems, pursuing user-friendliness, and considering the synergies between the assessment components of ISA systems. The developed framework with its dialectical considerations provides a new approach to understanding the complexity and dynamics of ISA and will help raise practitioners' awareness of the dialectical connections in ISA systems and support practitioners’ management practices. In addition, the five-pillar concept of sustainability is beneficial for stakeholders in appraising infrastructure more comprehensively.

The energy performance gap (EPG) refers to the discrepancy between predicted energy performance and actual energy performance in buildings. Quantifying the EPG is important for achieving an accurate understanding of building energy performance. Although previous studies have examined the EPG, there lacks a comprehensive method for its quantification. This paper aims to develop a multi-indicator framework to quantify the EPG for achieving a better understanding of the energy performance of buildings. The developed framework provides indicators from three perspectives. First, the EPG of a whole building is quantified by comparing annual and monthly simulated and measured energy consumption. Second, the dynamic of the EPG, referring to how the EPG changes over time, is quantified by analysing its variations using hourly energy data. Third, the hidden gap, referring to the hidden EPG that is neutralised by positive gap and negative gap at building energy service level, is quantified by unfolding the EPG at building energy service level. The developed framework was demonstrated using a case study with a real-life high-rise office building in Hong Kong. The results show that the annual EPG of the case building was + 4

Inter-building effect (IBE), which refers to the shading effect from surrounding buildings, plays an important role in building energy use in high-density cities. However, it is customary to neglect the IBE during energy simulation. Four issues are observed on previous research: 1) it has been controversial whether the IBE significantly affects energy consumption, 2) most studies used low-rise or medium-rise residential buildings as references, 3) most studies were conducted with hypothesised buildings, 4) most studies did not consider window blinds effect on IBE. These issues inhibit the theoretical understanding of high-rise building energy performance in cities and jeopardise the achievement of accurate simulation. This paper thus aims to investigate the IBE on the energy use of high-rise office buildings in Hong Kong as a typical high-density city. The IBE of ten selected real-life office buildings in their real-life communities was analysed. Four scenarios were compared, namely, simulation of building with both IBE and window blinds (base case), simulation of building with IBE but no window blinds, simulation of isolated building with window blinds, and simulation of isolated building without window blinds. The results show that the IBE influences the total energy use by up to 13.1%. Compared with the base case, heating, ventilation, air-conditioning (HVAC) and the lighting consumption deviation with different scenarios fluctuated largely, ranging from −11.8% to 18.8% in HVAC consumption, and from 0.1% to −27.6% in lighting consumption. An offset effect was found between the decreased lighting consumption and the increased HVAC consumption. From the floor-level analysis, with real communities, lighting energy use decreased with height among all the buildings generally. A multi-variant regression model was established to evaluate the relationship between IBE variables and building energy deviation caused by IBE. In addition, the results conclude that shading blinds cannot be overlooked when examining IBE on building energy use. These findings reveal the importance of considering IBE on building energy consumption in high-density contexts on a case-by-case basis.

Urban areas afford 56% of the world population and the top 600 cities emit 70% of the world greenhouse gases, highlighting enormous challenges and potentials of carbon emission reduction and sustainability in high-density cities. Though vast research has reviewed the green building assessment (GBA) systems in different perspectives, little has explicitly examined the dialectics of GBA, particularly its complexity and dynamics. The assessment of green buildings, however, can be regarded as a complex dynamic system with multifaceted dialectics, particularly in high-density cities. Thus, this paper aims to examine the dialectics of GBA within the context of high-density cities by identifying 42 GBA systems and then comparing 12 widely adopted systems in depth. Dialectics denote the complex and dynamic interdependency among the elements of a system. A dialectical system framework is developed to guide the systematic comparison of the GBA systems in three dimensions: 'concept', 'methodology' and 'value'. The results reveal that dialectics exist and encounter challenges in all three dimensions, including a multi-perspective but inconsistent concept of GBA, well-organised but oversimplified methodology for GBA, and value-laden but insufficient stakeholder engagement in GBA. The developed framework provides a new approach to understanding the complex and dynamic interdependency among the various elements of GBA systems. The findings should raise the awareness of green building developers, planners and designers about the dialectics in GBA and thus inform the associated decision making and design optimisation, making it possible to more effectively achieve green buildings.

Space cooling is an important building energy end-use that was found in recent years to be significantly impacted by occupant behaviours.However,the majority of previous studies ignored the interplay between the operation of windows and air conditioners(ACs)on cooling load,particularly in building energy modelling.In addition,studies on the analysis of cooling load characteristics regarding high-rise buildings are insufficient.The vertical effect of high-rise buildings on cooling load remains vague.This study thus aims to examine how window and AC operation behaviours impact the cooling load of high-rise buildings in an urban context demonstrated by a real-life typical 40-floor residential building in Hong Kong.This study investigates window and AC operation behaviours jointly and examines the vertical effect on cooling load by using agent-based building energy modelling(BEM)techniques and initiating stochastic and diverse behaviour modes.A carefully designed questionnaire survey was conducted to help build behaviour modes and validate energy models.Ninety building energy models were established integrating meteorological parameters generated by the computational fluid dynamics(CFD)programme for ten typical floors and nine combinations of window and AC behaviour modes.The results show that comfort-based AC modes and schedule-based window modes yielded the lowest cooling load.Considering the combined effect of AC and window uses,the maximum difference in cooling loads could be 26.8％.Behaviour modes and building height induce up to 32.4％differences in cooling loads.Besides,a deviation between the behaviour modes and height on the cooling load was found.The findings will help develop a thorough energy model inferring occupants'window and AC behaviour modes along with the building height in high-rise residential buildings.The findings indicate that the interaction impact of window and AC behaviour modes and height should be jointly considered in future high-rise building energy modelling,building energy standards,and policymaking.

Buildings’ carbon emissions consist of embodied carbon (EC) associated with the production and transportation of materials and operational carbon (OC) generated from consumed energy during daily use. However, previous studies concentrated on either EC or OC but ignored an integrated analysis of their relationships. Therefore, this paper aims to explore appropriate building envelope design solutions by examining the trade-off between EC and OC of high-rise residential buildings. To achieve this aim, the life cycle assessment method was used to evaluate the EC and OC of the residential buildings using SimaPro and DesignBuilder software. A building information modelling (BIM) model was developed to extract the geometric data and material consumption. A typical 30-story public residential building in Hong Kong was examined. The EC and OC of the case building were calculated as 561 kg CO 2e /m 2 and 50.18 kg CO 2e /m 2 /yr, respectively. Different low carbon design scenarios were identified from the literature review and the semi-structured interviews with designers and contractors. Results indicate that low carbon concrete is an effective approach for not only reducing the EC by 5%-15%, but saving a mild percentage of OC, and is therefore encouraged. However, changing the thickness of external walls leads to a very limited life cycle carbon reduction (0.99%). Lower U-value of envelopes is recommended as 2.84% and 2.89% life cycle carbon is reduced when adopting insulations for external walls and triple-glazing windows. The findings are valuable for examining the relationships between EC and OC and can support low carbon building decision-making.

Urban form is a significant factor affecting building energy consumption and district energy efficiency design and its effects are difficult to quantify.This study aims to explore the effects of various urban forms on energy consumption at the community scale.In this work, different urban forms for nonresidential and residential districts were analyzed based on the generic form of buildings in Shanghai in terms of their overall energy consumption.Detailed simulations were carried out to quantitatively evaluate the impact of urban form on heating and cooling energy demand.The effect of morphological parameters including both building typology and urban morphology were examined using a dynamic building energy simulation tool, EnergyPlus.

Buildings account for more than 90% of total electricity consumption in Hong Kong, one third of which comes from the residential sector. High-rise buildings dominate Hong Kong, but energy use in high-rise buildings has been insufficiently examined in previous studies, especially at the household or occupant level. This paper aims to explore the multiple factors that influence energy consumption in high-rise residential buildings, including the impact of occupant behaviours. The research was conducted through a questionnaire and face-to-face interviews with 135 households of a typical forty-floor residential building in Hong Kong. The survey examined technical and physical factors, human-influenced factors and social factors of energy consumption, including building information, social demographics, energy-related occupant behaviour modes and the residents’ energy-saving attitudes. The results show that the monthly electricity bills of households at the twentieth floor or lower were 26% higher than those of households at higher floors during spring, summer and autumn, but similar during winter. This difference was attributed to various occupant behaviours, such as operating air-conditioners and opening windows. These findings expand the knowledge of occupant behaviour in high-rise residential buildings and inform building energy conservation policy-making in Hong Kong.

Reducing building energy demand plays a vital role in addressing the depletion of energy resources and energy-related environmental issues. Previous research identified the statistical correlations between embodied energy and costs of buildings. However, little research has explored the relationship between operational energy and life cycle cost performance of buildings. This paper aims to investigate the energy efficiency and cost effectiveness of energy saving measures (ESMs) and thereby identify the relationship between operational energy and life cycle cost performance of high-rise office buildings. Five types of ESMs with 32 scenarios were examined using a real-life 35-storey office building in Hong Kong as a typical high-rise high-density city. The five types of ESMs are (1) increase temperature setpoint, (2) adopt daylighting sensors and light-emitting diode lamps (3) replace with low-e glass, (4) upgrade heating, ventilation and air conditioning system, and (5) implement on-site renewable energy. The results discover a U-curve relationship between operational energy saving and initial investment cost of the five ESMs. Moreover, the results show a significant linear correlation between operational energy saving and net present value of the ESMs. Such relationship reveals trade-off and synergy effects largely existing between opertional energy and cost performance in improving energy efficiency of high-rise offic buildings. This research suggests that increasing indoor temperature setpoint should be prioritised in lowering operational energy. The results are also discussed drawing on the findings of previous studies in other city contexts. This research contributes a novel life cycle perspective to future systematic research into building energy and economics. The findings are important to building designers in their decision-making of reducing buildings’ operational energy consumption in a cost-effective way.

This article aims to comprehensively analyse the impact of meteorological factors on the energy consumption of high-rise office buildings in Hong Kong. Fifty-seven runs of EnergyPlus simulations based on 30 years of actual hourly meteorological data between 1989 and 2018 measured from one urban and one rural site as well as the Typical Meteorological Year (TMY) were conducted to examine the joint energy impact of climate change and urban heat island (UHI) effect. Spatiotemporal inaccuracies of TMY-based simulations were discussed in error analysis by comparing with those using actual meteorological data. In longitudinal and cross-sectional analyses, significant energy impact of both climate change and UHI was found and quantitatively reported in terms of total and heating, ventilation and air conditioning (HVAC) energy consumption; long-term dynamics and the winter-dominant intra-annual distribution of the UHI-driven energy discrepancies were revealed; and the inconsistency between UHI-driven energy discrepancies and temperature discrepancies was found and explained. Regression analysis shows that for high-rise office buildings in Hong Kong, energy consumption is more sensitive to temperature and moisture change in hot and humid conditions than in cold and dry conditions; and air pressure may also serve as an indicator for a rough estimation of building energy consumption. (C) 2020 Elsevier B.V. All rights reserved.

Occupant behavior has a significant impact on building energy consumption and sustainable development of the community. In-situ monitoring of occupant behavior is one of the most effective and widely used research methods. It collects data of occupant behavior using smart sensors in the natural environment and, if appropriately designed and applied, can effectively avoid bias in the results. However, previous studies have rarely discussed how to design and apply in-situ monitoring activities in residential buildings. This paper, through a comprehensive and critical literature review, aims to close the knowledge gap on in-situ monitoring of occupant behavior in residential buildings. Multiple review techniques were used. First, a conceptual framework of monitoring activities was proposed based on a narrative appraisal of related publications. Second, the body of literature was established through an exhaustive search of papers by Web of Science and Scopus, two popular search engines. In total, 68 monitoring activities from 74 journal papers were selected according to the inclusion criteria. Third, meta-analysis and meta-synthesis were applied to this body of literature under the conceptual framework to reflect the achievements of previous studies and to explore the challenges facing future research. Results show that previous studies had limited consideration of sampling methods, setting of time interval and monitoring duration, installation of sensors, and the impact of microclimate. Ignoring these issues would reduce the productivity of data collected from in-situ monitoring activities and thus bring bias into the results. To address such limitations, recommendations are given for the design procedure of in-situ monitoring activities. In addition, an empirical rule is proposed with regard to setting the time interval and monitoring duration. Possible areas of future research are also discussed, e.g. occupant behavior in high-rise residential buildings in hot humid zone. The findings of this paper should facilitate the application of in-situ monitoring in building energy research and familiarize future studies with regard to occupant behavior in residential buildings. (C) 2020 Elsevier B.V. All rights reserved.

Occupant behavior plays a critical role in building energy consumption, particularly in residential buildings. However, occupant behavior is complicated and varies significantly from case to case. Also, energy modeling of high-rise buildings is far less explored than that of low- or medium-rise buildings. This paper aims to improve accuracy in building energy simulation by utilizing Post Occupancy Evaluation (POE) data to calibrate energy model. Drawing on a review of the literature of occupant behavior and building energy modeling, the paper provides a calibration method of integrating POE data into an energy model, which is demonstrated using a real-life typical 40-storey residential building in Hong Kong. The developed method addresses seven updated input parameters, namely, schedule, devices, air-conditioners, windows, lights, domestic hot water, and cooking. By comparing the two energy modeling processes, i.e. with and without POE input, and their resultant estimated energy consumption, the paper quantifies the impact of occupant behavior on building energy consumption. Annual metered data together with energy bills obtained from the POE were utilized to validate the models. The results show that the use of the developed POE-integrated method helped to improve accuracy in energy consumption prediction by 14% for the total building floor area and by 16% for the total residential area. From examining the impacts of the seven input parameters, the paper reveals the key energy use sensitive occupant behaviors within high-rise residential buildings in Hong Kong. These include: the number of residents in each unit; adoption of window type and split type of air-conditioners; window and air condition operation modes; cooking time on weekdays and weekends; and time spent on hot water showering. The developed method can assist building designers and services engineers to estimate building energy use more accurately and provides a scenario analysis tool for clients and facility managers to develop effective energy conservation strategies. (C) 2019 Elsevier B.V. All rights reserved.