Understanding occupancy pattern and improving building energy efficiency through Wi-Fi based indoor positioning

Detailed visualisation and data analysis of occupancy patterns including spatial distribution and temporal variations are of great importance to delivering energy efficient and productive buildings. An experimental study comprising 24-h monitoring over 30 full days was conducted in a university library building.Occupancy profiles have been monitored and analysis has been carried out. Central to this monitoring study is the Wi-Fi based indoor positioning system based on the measured Wi-Fi devices' number and locations and data mining methods. Distinct from traditional occupancy and energy studies,more detailed informationrelated to the indoor positions and number of occupants has offered a better understanding of building user behaviour. The implication of the occupancy patterns for energy( e. g. lighting and other building services) efficiency is assessed,assisted with data from lighting sensors where needed. It is found occupancy patterns change dramatically with time. Also,the energy waste patterns have been identified through the method of data association rule mining. If the identified energy waste is removed,the total energy consumption can be reduced by 26. 1%. The indoor positioning information also has implications for optimizing space use,opening hours as well as staff deployment. The work could be extended to more rooms with diverse functions,other seasons and other types of non-domestic buildings for a more comprehensive understanding of building user behaviour and energy efficiency.     

上海M50创意产业园的使用后评价研究

该文以上海发展较成熟的创意产业园M50为例,采用使用后评价（POE）的研究方法,通过问卷调查、自由访谈和量化分析的方法,对产业园内外环境进行了综合评价。从调查结果可以看出,M50创意产业园在使用上存在着交通的可达性较差,绿化景观和公共休息设施不足,标识系统不够完善及室内采光较弱等问题,且使用者在这些方面的满意度也较低。此外,该文进一步探讨和揭示产生这些问题的原因,并尝试提出符合使用者需求的设计建议,为今后创意产业园区的建设提供一定的参考依据。     

Indoor air quality control in case of scheduled or intermittent occupancy based building: Development of a scale model

When a building is used only for intermittent occupancy, continuous operation of ventilation system is not necessary for achieving good indoor air quality during the occupation periods. Such buildings have a great energy saving potential which is not harnessed enough yet. Indeed, energy loss can be avoided by promoting natural means and managing mechanical ones. Therefore, control strategies based on time and/or occupancy scheduled ventilation associated to pre-purge ventilation constitute a key for an energy efficient ventilation system.     

Sources and dynamics of semivolatile organic compounds in a single‐family residence in northern California

Semivolatile organic compounds (SVOCs) emitted from building materials, consumer products, and occupant activities alter the composition of air in residences where people spend most of their time. Exposures to specific SVOCs potentially pose risks to human health. However, little is known about the chemical complexity, total burden, and dynamic behavior of SVOCs in residential environments. Furthermore, little is known about the influence of human occupancy on the emissions and fates of SVOCs in residential air. Here, we present the first‐ever hourly measurements of airborne SVOCs in a residence during normal occupancy. We employ state‐of‐the‐art semivolatile thermal‐desorption aerosol gas chromatography (SV‐TAG). Indoor air is shown consistently to contain much higher levels of SVOCs than outdoors, in terms of both abundance and chemical complexity. Time‐series data are characterized by temperature‐dependent elevated background levels for a broad suite of chemicals, underlining the importance of continuous emissions from static indoor sources. Substantial increases in SVOC concentrations were associated with episodic occupant activities, especially cooking and cleaning. The number of occupants within the residence showed little influence on the total airborne SVOC concentration. Enhanced ventilation was effective in reducing SVOCs in indoor air, but only temporarily; SVOCs recovered to previous levels within hours.     

Towards a model of user behaviour regarding the manual control of windows in office buildings

This paper presents the results of a field study of manual control of windows which has been carried out in 21 individual offices within the Fraunhofer Institute's building in Freiburg, Germany, from July 2002 to July 2003. Window status, occupancy, indoor and outdoor climatic conditions were measured every minute. Previous research findings are validated and extended by the results of this field study. The analysis of user behaviour reveals a strong correlation between the percentage of open windows and the time of year, outdoor temperature and building occupancy patterns. Most window opening is connected with the arrival of a person. Based on the results, a preliminary user model is proposed to simulate and predict window status in office buildings with varying outdoor temperature and occupancy.     

Improving thermal comfort in mosques of hot-humid climates through passive and low-energy design strategies

Mosques have intermittent operational schedules with short-term occupancy during the five daily prayers. The occupancy level of the daily prayers is a fraction compared to the mandatory Friday prayers with full occupancy. Usually, the same thermal control mechanism is operated within the same large prayer hall to maintain the thermal comfort of the occupants. Yet, the comfort requirements are often not met due to the short span of operation during prayer times. Nevertheless, mosques have a very high energy usage as the same energy-intensive system is operated even during minimal occupancy profiles. The current research aims at using a passive approach towards design to achieve the comfort conditions during the low occupancy daily prayer times without employing mechanical intervention. Numerical simulations are carried out on a validated model of the case study building to investigate the impact of the west-facing Qiblah wall as the congregation stands in proximity to this wall. The design alternatives are tested in conjunction with ventilation strategies to holistically assess the thermal comfort of the occupants. Results show that as much as 4–6°C reduction in indoor wall surface temperature can be achieved with a suitable Qiblah wall design, which reduces the mean radiant temperature of the occupants by 2–4°C. Combined with ventilation strategies, thermal comfort can be significantly improved by at least 40% for the prayers during the hottest times of the day, and as much as 80% for night-time prayers. Results suggest that suitable comfort conditions can be achieved without the need for air-conditioning for at least two or three of the five daily prayers.     

Fluorescent biological aerosol particles: Concentrations,emissions, and exposures in a northern California residence

Residences represent an important site for bioaerosol exposure. We studied bioaerosol concentrations, emissions, and exposures in a single‐family residence in northern California with 2 occupants using real‐time instrumentation during 2 monitoring campaigns (8 weeks during August‐October 2016 and 5 weeks during January‐March 2017). Time‐ and size‐resolved fluorescent biological aerosol particles (FBAP) and total airborne particles were measured in real time in the kitchen using an ultraviolet aerodynamic particle sizer (UVAPS). Time‐resolved occupancy status, household activity data, air‐change rates, and spatial distribution of size‐resolved particles were also determined throughout the house. Occupant activities strongly influenced indoor FBAP levels. Indoor FBAP concentrations were an order of magnitude higher when the house was occupied than when the house was vacant. Applying an integral material‐balance approach, geometric mean of total FBAP emissions from human activities observed to perturb indoor levels were in the range of 10‐50 million particles per event. During the summer and winter campaigns, occupants spent an average of 10 and 8.5 hours per day, respectively, awake and at home. During these hours, the geometric mean daily‐averaged FBAP exposure concentration (1‐10 μm diameter) was similar for each subject at 40 particles/L for summer and 29 particles/L for winter.     

Natural ventilation potential for gymnasia-Case study of ventilation and comfort in a multisport facility in northeastern United States

The natural ventilation potential to maintain acceptable indoor air quality(IAQ) and thermal comfort in gymnasia was investigated using a university multisport facility in northeastern United States as a case study building. A parametric modeling study was conducted considering the effects of opening configurations and control strategies during the summer months. The thermal accuracy of the model was verified using field measurements during August 2015. Performance metrics for IAQ and thermal comfort were the percentages of occupied hours during which ventilation rate met or exceeded ASHRAE Standard 62.1-2013 and temperature met adaptive thermal comfort criteria of ASHRAE Standard55-2013, respectively. Wind direction was found having a major effect on cross ventilation rate. Wind and buoyancy driven forces could complement or oppose each other depending on the wind direction and opening position. Relative to the base case, larger net openings that were more evenly distributed performed better.Rooftop vents improved ventilation performance, particularly under unfavorable wind conditions. With improved opening configurations, the acceptable ventilation hours increased from 21.5% to99.5% of occupied time for the maximum occupancy. The strictest temperature-controlled strategy had the best thermal performance.Thermal comfort conditions could be maintained during 85.3% of the occupied hours. However, the temperature rule largely shortened the opening operation time, and consequently decreased the acceptable ventilation hours to only 47.1%. Continuously natural ventilation during occupied time gave the longest combined IAQ-thermal acceptable hours, 73.9% of the occupied time, although it moderately decreased the thermal comfort hours to74.2%.     

Occupancy implications of spatial,indoor-environmental,and organizational features of office spaces

The quality of office spaces has been said to have a significant effect on the health, comfort, satisfaction, and productivity of office workers. Numerous studies and projects aim at documenting the postulated impact of office space quality on occupancy factors. Nonetheless, there is a need for further systematic research efforts and reliable empirical data in this area. This paper presents a study of a number of architectural offices in Vienna, Austria. Data pertaining to certain spatial and indoor-climatic features of these offices was collected via observation and snap-shot measurements. Simultaneously, an occupancy evaluation was performed via interviews with professionals who work in these offices. The observations and evaluations addressed the relationship between the workplace and the outdoor environment, the layout and refurbishment of the workplace, the technical infrastructure of the workplace, the communication patterns in the workplace, and the thermal, visual, and acoustical indoor climate. The “subjective” evaluations were compared with the “objective” measures of workplace architecture and indoor climate.     

数字环境下高校用户信息检索行为初探

高校用户信息行为是用户信息行为研究的一个热点,高校的信息用户群体在信息需求、信息检索和信息利用方面有其自身的规律和特点。根据网络环境的特点对此进行深入的探讨和研究。     

On the effect of service life conditions on the maintenance costs of healthcare facilities

Global competitiveness and increasing performance requirements have placed facilities management (FM) under constraints of limited resources, particularly in non‐core aspects of facilities, such as maintenance and operations. The hypothesis applied in this research is that the actual service life of buildings, their occupancy and their ambient environmental conditions affect the required maintenance resources of these facilities. The objective was to develop a facility coefficient aiming to adjust the allocation of maintenance resources to prevailing service conditions in healthcare facilities. The research uses deterioration patterns and predicted service lives of building components and systems under moderate, standard and intensive occupancy and under two categories of environment: marine and inland. In total, five configurations combining occupancy and environmental conditions were investigated through simulations and compared to a reference configuration defined as standard occupancy and inland environment along with a building designed service life of 75 years. The findings of the simulations show that maintenance resources in healthcare facilities vary between ?9% and +18% of the standard configuration. The simulation results can be used for reliable allocation of resources for maintenance of healthcare facilities. Findings can be adapted for residential, office, public and educational facilities.     

The MERMAID study: indoor and outdoor average pollutant concentrations in 10 low‐energy school buildings in France

Indoor air quality was characterized in 10 recently built energy‐efficient French schools during two periods of 4.5 days. Carbon dioxide time‐resolved measurements during occupancy clearly highlight the key role of the ventilation rate (scheduled or occupancy indexed), especially in this type of building, which was tightly sealed and equipped with a dual‐flow ventilation system to provide air refreshment. Volatile organic compounds (VOCs) and inorganic gases (ozone and NO₂) were measured indoors and outdoors by passive techniques during the occupied and the unoccupied periods. Over 150 VOC species were identified. Among them, 27 species were selected for quantification, based on their occurrence. High concentrations were found for acetone, 2‐butanone, formaldehyde, toluene, and hexaldehyde. However, these concentrations are lower than those previously observed in conventional school buildings. The indoor/outdoor and unoccupied/occupied ratios are informative regarding emission sources. Except for benzene, ozone, and NO₂, all the pollutants in these buildings have an indoor source. Occupancy is associated with increased levels of acetone, 2‐butanone, pentanal, butyl acetate, and alkanes.     

Occupancy modelling in shared spaces of buildings: a queueing approach

This paper describes the development of a queueing model for the simulation of occupancy patterns in shared spaces of buildings. Specifically, occupancy is modelled via an infinite-server queue with time-varying arrival and departure rates. In order to better capture the abrupt changes in occupancy, we also present an algorithm that efficiently learns the locally homogeneous intervals from the data and estimates the model parameters separately on each learned interval. Evaluated on the real-world occupancy data, the model has proved its capability of realistically reproducing the variations of occupancy, as well as the key properties, such as peak occupancy time, first arrival and last departure times, and occupied duration. We also compare our model with several occupancy models in the previous work, and show that our model is preferable in terms of simple structure, agile construction, minimal effort of manual calibration and the ability to reflect the occupancy patterns truthfully.     

User problems with individual temperature control in offices

Individual thermal control is important for handling personal differences in thermal preference. Several studies have shown that comfort, health and productivity in offices can be improved by individual thermal control. Local controls for temperature are commonly available in modern office buildings. However, office occupants are often still dissatisfied with the thermal environment and their control options. In this study we used contextual techniques to gain an understanding of the user problems with individual temperature control. A total of 27 office occupants in 13 Finnish buildings were interviewed in their offices. They were asked to show and tell us how they use the controls. The results show that the temperature controls were often not used in thermal discomfort. A diversity of problems with individual temperature control was identified and are listed with proposed solutions. The main reason for the many of the problems is that systems are planned and constructed without a realistic view of their users, and end users are presumed to have knowledge they don’t have. The users should be studied and more effort should be put into user interface development.     

Statistical analysis and modeling of occupancy patterns in open-plan offices using measured lighting-switch data

Occupancy profile is one of the driving factors behind discrepancies between the measured and simulated energy consumption of buildings. The frequencies of occupants leaving their offices and the corresponding durations of absences have significant impact on energy use and the operational controls of buildings. This study used statistical methods to analyze the occupancy status, based on measured lighting-switch data in five-minute intervals, for a total of 200 open-plan (cubicle) offices. Five typical occupancy patterns were identified based on the average daily 24-hour profiles of the presence of occupants in their cubicles. These statistical patterns were represented by a one-square curve, a one-valley curve, a two-valley curve, a variable curve, and a flat curve. The key parameters that define the occupancy model are the average occupancy profile together with probability distributions of absence duration, and the number of times an occupant is absent from the cubicle. The statistical results also reveal that the number of absence occurrences decreases as total daily presence hours decrease, and the duration of absence from the cubicle decreases as the frequency of absence increases. The developed occupancy model captures the stochastic nature of occupants moving in and out of cubicles, and can be used to generate a more realistic occupancy schedule. This is crucial for improving the evaluation of the energy saving potential of occupancy based technologies and controls using building simulations. Finally, to demonstrate the use of the occupancy model, weekday occupant schedules were generated and discussed.     

依据面积温差数的计量供热分户计费方法

在分析计量供热各用户之间热传递的基础上,以整栋住宅楼为研究对象,每一用户为一个等温单元,建立热平衡方程组,计算确定各用户供暖期室内计算平均温度。依据各用户使用面积和供暖期室内外平均温差,提出确定热费的方法。     

Optimizing energy efficiency and occupant comfort with climate specific design of the building

Designing energy efficient and comfortable buildings requires harmonizing the complex interactions of architecture, construction and building service engineering. The building envelope has a particular importance, since it integrates many functions and has direct influence on indoor climate. Focusing on satisfaction of the user means that the indoor climate is a key for a holistic design approach. Only a satisfied user will not intervene with the designed energy concept or the indoor climate control; dissatisfaction results in multiple system interventions which may cause waste of energy and sometimes even damage to building envelope components. Satisfaction with the indoor environment also increases working productivity or enables effective recreation of residents.The paper deals with international research activities in the field of climate specific building design. Various comfort and energy monitoring surveys of office buildings as well as residential buildings provide substantial information about the occupants' behavior and their needs during specific situations under different outdoor climates. This information allows summarizing basic climate dependent design principles which architects should keep in mind during the early stages of the design process. It also helps to develop strategies aiming at reducing building energy demand and at the same time consider comfort aspects. The second part of this paper demonstrates application of the climate dependent design principles in a housing project in Dubai.     

Indoor airborne bacterial communities are influenced by ventilation,occupancy, and outdoor air source

Architects and engineers are beginning to consider a new dimension of indoor air: the structure and composition of airborne microbial communities. A first step in this emerging field is to understand the forces that shape the diversity of bioaerosols across space and time within the built environment. In an effort to elucidate the relative influences of three likely drivers of indoor bioaerosol diversity – variation in outdoor bioaerosols, ventilation strategy, and occupancy load – we conducted an intensive temporal study of indoor airborne bacterial communities in a high‐traffic university building with a hybrid HVAC (mechanically and naturally ventilated) system. Indoor air communities closely tracked outdoor air communities, but human‐associated bacterial genera were more than twice as abundant in indoor air compared with outdoor air. Ventilation had a demonstrated effect on indoor airborne bacterial community composition; changes in outdoor air communities were detected inside following a time lag associated with differing ventilation strategies relevant to modern building design. Our results indicate that both occupancy patterns and ventilation strategies are important for understanding airborne microbial community dynamics in the built environment.     

Developing English domestic occupancy profiles

ABSTRACT

Occupancy patterns are necessary to estimate energy demand and evaluate thermal comfort in households. Because of this, many European countries are developing representative domestic schedules to replace outdated criteria. This paper evaluates the state of knowledge of UK domestic occupancy patterns and develops new domestic occupancy profiles for England. The presented research (1) characterizes methods for collecting occupancy data and inferring patterns; (2) identifies and assesses the quality of categories of occupancy patterns used in building simulation; and (3) develops updated occupancy profiles. A systematic scoping review identified social and monitoring surveys as the most deployed data-collection methods. A systematic literature review also established that the occupancy categories most frequently used in UK building simulation are (a) a family with dependent children where the parents work full time; and (b) a retired elderly couple who spend most of their time indoors. The interview sample from the English Housing Survey 2014–15 was used to map household typologies. Results show that categories (a) and (b) combined amount to only 19% of England’s households, which suggest models are over-reliant on these groups. Considering this result, the paper develops occupancy patterns for England derived from 2015 UK Time Use Survey diaries for each household typology previously identified.     

Characterizing sources and emissions of volatile organic compounds in a northern California residence using space‐ and time‐resolved measurements

We investigate source characteristics and emission dynamics of volatile organic compounds (VOCs) in a single‐family house in California utilizing time‐ and space‐resolved measurements. About 200 VOC signals, corresponding to more than 200 species, were measured during 8 weeks in summer and five in winter. Spatially resolved measurements, along with tracer data, reveal that VOCs in the living space were mainly emitted directly into that space, with minor contributions from the crawlspace, attic, or outdoors. Time‐resolved measurements in the living space exhibited baseline levels far above outdoor levels for most VOCs; many compounds also displayed patterns of intermittent short‐term enhancements (spikes) well above the indoor baseline. Compounds were categorized as “high‐baseline” or “spike‐dominated” based on indoor‐to‐outdoor concentration ratio and indoor mean‐to‐median ratio. Short‐term spikes were associated with occupants and their activities, especially cooking. High‐baseline compounds indicate continuous indoor emissions from building materials and furnishings. Indoor emission rates for high‐baseline species, quantified with 2‐hour resolution, exhibited strong temperature dependence and were affected by air‐change rates. Decomposition of wooden building materials is suggested as a major source for acetic acid, formic acid, and methanol, which together accounted for ~75% of the total continuous indoor emissions of high‐baseline species.