Simulation and visualization of energy-related occupant behavior in office buildings

In current building performance simulation programs, occupant presence and interactions with building systems are over-simplified and less indicative of real world scenarios, contributing to the discrepancies between simulated and actual energy use in buildings. Simulation results are normally presented using various types of charts. However, using those charts, it is difficult to visualize and communicate the importance of occupants’ behavior to building energy performance. This study introduced a new approach to simulating and visualizing energy-related occupant behavior in office buildings. First, the Occupancy Simulator was used to simulate the occupant presence and movement and generate occupant schedules for each space as well as for each occupant. Then an occupant behavior functional mockup unit (obFMU) was used to model occupant behavior and analyze their impact on building energy use through co-simulation with EnergyPlus. Finally, an agent-based model built upon AnyLogic was applied to visualize the simulation results of the occupant movement and interactions with building systems, as well as the related energy performance. A case study using a small office building in Miami, FL was presented to demonstrate the process and application of the Occupancy Simulator, the obFMU and EnergyPlus, and the AnyLogic module in simulation and visualization of energy-related occupant behaviors in office buildings. The presented approach provides a new detailed and visual way for policy makers, architects, engineers and building operators to better understand occupant energy behavior and their impact on energy use in buildings, which can improve the design and operation of low energy buildings.     

Perception of vibration and occupant comfort in wind-excited tall buildings

Wind-induced building vibration can interfere with building occupants’ daily activities and general well-being. However, human perception of vibration and tolerance of wind-induced tall building vibration are essentially a subjective assessment. Hence, there is currently no single internationally accepted occupant comfort serviceability criteria which set a design standard for satisfactory levels of wind-induced vibration in tall buildings. This paper reviews past studies on human perception of vibration and tolerance thresholds of wind-induced tall building vibrations. Building vibration acceptability and occupant comfort criteria that have been commonly adopted for the assessment of occupant comfort in wind-excited tall buildings are outlined.     

On the influence of building design,occupants and heat waves on comfort and greenhouse gas emissions in naturally ventilated offices. A study based on the EN 15251 adaptive thermal comfort model in Athens,Greece

According to the Intergovernmental Panel on Climate Change the buildings sector has the largest mitigation potential for CO₂ emissions. Especially in office buildings, where internal heat loads and a relatively high occupant density occur at the same time with solar heat gains, overheating has become a common problem. In Europe the adaptive thermal comfort model according to EN 15251 provides a method to evaluate thermal comfort in naturally ventilated buildings. However, especially in the context of the climate change and the occurrence of heat waves within the last decade, the question arises, how thermal comfort can be maintained without additional cooling, especially in warm climates. In this paper a parametric study for a typical cellular naturally ventilated office room has been conducted, using the building simulation software EnergyPlus. It is based on the Mediterranean climate of Athens, Greece. Adaptive thermal comfort is evaluated according to EN 15251. Variations refer to different building design priorities, and they consider the variability of occupant behaviour and internal heat loads by using an ideal and worst case scenario. The influence of heat waves is considered by comparing measured temperatures for an average and an exceptionally hot year within the last decade. Since the use of building controls for shading affects thermal as well as visual comfort, daylighting and view are evaluated as well. Conclusions are drawn regarding the influence and interaction of building design, occupants and heat waves on comfort and greenhouse gas emissions in naturally ventilated offices, and related optimisation potential.     

Building signatures: A holistic approach to the evaluation of heating and cooling concepts

A sustainable and environmentally responsible building concept aims at a high workplace comfort, a significantly reduced heating and cooling demand, a high-efficient plant system, and the use of renewable energy sources to condition the built environment. This paper presents a comprehensive analysis of the heating and cooling concepts of 11 low-energy buildings in terms of energy use, efficiency and occupant thermal comfort. All buildings investigated employ environmental energy sources and sinks – such as the ground, ground water, rainwater and the ambient air – in combination with thermo-active building systems. A limited primary energy use of about 100 kWh_prim/(m²_neta) as a target for the complete building service technology (HVAC and lighting) was postulated for all buildings presented. With respect to this premise, a comprehensive long-term monitoring in high time resolution was carried out for two to five years, with an accompanying commissioning of the building performance. Measurements include the useful heating and cooling energy use, auxiliary energy use for the hydraulic system, as well as end and primary energy use, occupant thermal comfort and local meteorological conditions. A new methodology is proposed for a holistic approach to the evaluation of heating and cooling concepts, which not only considers the occupants thermal comfort, but also the useful energy consumption and the efficiency of the generation, distribution and delivery of heating and cooling energy.     

Smart building management vs. intuitive human control—Lessons learnt from an office building in Hungary

Smart building management and control are adopted nowadays to achieve zero-net energy use in buildings. However, without considering the human dimension, technologies alone do not necessarily guarantee high performance in buildings. An office building was designed and built according to state-of-the-art design and energy management principles in 2008. Despite the expectations of high performance, the owner was facing high utility bills and low user comfort in the building located in Budapest, Hungary. The objective of the project was to evaluate the energy performance and comfort indices of the building, to identify the causes of malfunction and to elaborate a comprehensive energy concept. Firstly, current building conditions and operation parameters were evaluated. Our investigation found that the state-of-the-art building management system was in good conditions but it was operated by building operators and occupants who are not aware of the building management practice. The energy consumption patterns of the building were simulated with energy modelling software. The baseline model was calibrated to annual measured energy consumption, using actual occupant behaviour and presence, based on results of self-reported surveys, occupancy sensors and fan-coil usage data. Realistic occupant behaviour models can capture diversity of occupant behaviour and better represent the real energy use of the building. This way our findings and the effect of our proposed improvements could be more reliable. As part of our final comprehensive energy concept, we proposed intervention measures that would increase indoor thermal comfort and decrease energy consumption of the building. A parametric study was carried out to evaluate and quantify energy, comfort and return on investment of each measure. It was found that in the best case the building could save 23% of annual energy use. Future work includes the follow-up of: occupant reactions to intervention measures, the realized energy savings, the measurement of occupant satisfaction and behavioural changes.     

Impact of psycho-social factors on perception of the indoor air environment studies in 12 office buildings

The main function of a mechanically ventilated office building is to provide a healthy and comfortable working environment for occupants, while maintaining minimum energy consumption. Twelve mechanically ventilated buildings were selected. They varied greatly in surface area, number of floors, occupant density, and building use. The indoor air quality, thermal comfort, energy consumption, and perception of occupants were investigated in these buildings. A total of 877 subjects participated in the questionnaire survey during the hot summer months of June, July, and August, and during the cold winter months of January, February, and March. The questions included in the questionnaire dealt with health, environmental sensitivity, work area satisfaction, personal control of the workstations environment, and job satisfaction. Measured parameters concerning the quality of indoor air included ventilation rate, concentration of TVOC, CO₂, CO, RH, and formaldehyde. The thermal comfort parameters included room air, mean radiant, plane radiant asymmetry, and dew point temperatures, as well as air velocity and turbulence intensity. Monthly energy consumption data was also gathered for each building. Ventilation performance, in terms of air flow rate and indoor air quality, was compared with the ASHRAE Standard 62-89R (Ventilation for Acceptable Indoor Air Quality. Atlanta: American Society of Heating, Refrigerating, and Air Conditioning Engineers, Inc. U.S.A. [1]). The measured and calculated thermal environmental results were also compared with the ASHRAE Standard 55-92 (Thermal Environmental Conditions for Human Occupancy. Atlanta: American Society of Heating, Refrigerating, and Air Conditioning Engineers, Inc. U.S.A. [2]). CO₂ and CO levels satisfied the recommended limits. The outdoor airflow rate was half that recommended in only one building. The formaldehyde and TVOC levels were moderately higher than suggested comfort levels. However, more than 56% of the occupants rated dissatisfaction with the indoor air quality. Only 63% of the indoor climatic observations fell within the ASHRAE Standard 55-92 summer comfort zone; 27% in the winter. However, only 69% of those surveyed agreed with the comfort zones. More symptoms were reported by workers who perceived IAQ to be poor. Positive relationships were observed between the job satisfaction and satisfaction with office air quality, ventilation, work area temperature, and ratings of work area environment. However, job dissatisfaction did not correlate with symptom reports. The occupants were more dissatisfied with IAQ when they preferred more air movement. In other words, the higher the perceived air movement, the greater the satisfaction with IAQ.     

Occupant preferences and satisfaction with the luminous environment and control systems in daylit offices: a literature review

This paper presents an overview of peer-reviewed investigations of subjective issues linked to the use of daylighting in office buildings, particularly studies of preferred physical and luminous conditions in daylit office environments, and studies of occupant satisfaction and acceptance of electric lighting and window shading controls. The literature shows a consistent strong preference for daylight and a wide distribution between individuals in relation to the preferred illuminance levels in daylit offices. Existing knowledge about how people respond to daylight-linked lighting and shading controls in the workplace is very limited; therefore, this paper presents a summary of knowledge gaps in the field of daylighting and its interaction with the occupants. The resulting key directions for future research highlight issues for which a better understanding is required for the development of lighting and window shading control systems that are both energy efficient and suitable for the office occupants.     

Using results from field surveys to predict the effect of open windows on thermal comfort and energy use in buildings

Windows are one of the major means by which building occupants control the indoor environment. This research uses results from field surveys to formulate a method for simulation of office buildings to include the effects of window opening behaviour on comfort and energy use. The paper focuses on: (1) what is general window opening behaviour? (2) how can we frame an “adaptive algorithm” to predict whether windows are open? (3) how can the algorithm be used within a simulation to allow the effects of window opening on comfort and energy use to be quantified? We have found that: (1) the proportion of windows open depends on indoor and outdoor conditions, (2) logistic regression analysis can be used to formulate an adaptive algorithm to predict the likelihood that windows are open, (3) the algorithm when embedded in simulation software provides insights not available using more usual simulation methods and allows the quantification of the effect of building design on window opening behaviour, occupant comfort and building energy use.     

Towards occupant-centric simulation-aided building design: a case study

ABSTRACT

This paper aims at illustrating the importance of occupant modelling for decision-making during the building design process. It identifies the energy implications of conventional ways of modelling occupants for the design of office buildings. Furthermore, it presents a step towards bridging the gap between the research efforts and conventional practices within the field of building performance simulation (BPS) aided design. The paper first describes occupant-related assumptions that were made during the design process of a case study office building, obtained via stakeholder interviews. Then, the impact of these assumptions on the design decisions is examined through a simulation-based investigation. The stakeholder interviews revealed that professionals from each design discipline made significantly different assumptions about occupants. The simulation results showed that assumptions about occupants and their behaviour impacted predicted energy savings of some design decisions by a factor of five or more.     

The effect of indoor environmental quality on occupants’ perception of performance: A case study of refurbished historic buildings in Malaysia

This paper presents an assessment of occupants’ opinion of the internal environment of buildings, based upon their responses to questions relating to a range of discrete factors. The survey considers many aspects of the internal environment and seeks to gain occupants responses to each of these in terms of “User Satisfaction” and “Degree of Importance”. The questionnaire utilised a seven-point bi-polar scale to score these responses against each of the factors. In addition, the questionnaire elicits a ‘fingerprint’ that combines up to 22 factors relating to satisfaction with the building. The study documents and considers aspects of the building environment for which the users noted that they were least satisfied as well as those that are considered by the occupants as being of most importance. It is critical that sustainable development results not just in resource conservation, but also in increasing productivity and occupant well-being within buildings. This study hopes to provide insight for the design community on the perceptions of occupants in relation to building performance based on indoor environmental quality (IEQ) criteria. It also seeks to add to the growing body of research on sustainable design and occupants’ perception of IEQ.     

Occupants' migration in residential buildings towards comfort and energy efficiency (case of traditional residential architecture in Iran)

Recently, the role of occupants' behaviors on building energy efficiency has been much more taken into account. Occupants' migration on a building scale is a phrase on which this article focuses as one of the best occupants' responses to the climate condition for comfort and energy efficiency in traditional architecture. This paper attempts to step towards recovering the role of traditional adaptive occupants in contemporary buildings for comfort and energy efficiency. To this end, this study aimed to achieve the following objectives: (1) to summarize the socio-environmental and psychological elements of traditional housing that help occupants migrate in a building for their needs, comfort, and energy efficiency. (2) to reveal the interrelated factors affecting occupants' migration in building scale for comfort and energy efficiency. (3) to present types of occupant migration in buildings for comfort and energy efficiency. In order to achieve the objectives of this study, first, a literature review was conducted on the socio-environmental and psychological elements of traditional housing that help occupants migrate in a building for their needs, comfort, and energy efficiency. Also, the interrelated factors affecting occupants' migration in buildings and the types of occupant migration in building for comfort and energy efficiency were considered via both content analysis of available literature, and field survey methodologies. Besides, a comparison is made between the traditional style of housing and migration and the new style. Finally, the results showed that psychological, environmental, and social factors not only motivated people to move around to survive; achieve more thermal, visual, and mental comfort; but also contributed to more environmentally friendly spaces, which ultimately provide people with health, well-being, and energy efficiency. These movements and their associated contributing architectural elements were interrelated and affected one another in mutual respect. People underwent these movements in vertical and horizontal directions for their needs and energy efficiency because the space potentials provided incentives for them to do so.

     

A window of one’s own: a public office post-occupancy evaluation

ABSTRACT

The prevalence of mechanical climatization in office buildings, alongside the dictate to conserve energy, has misguidedly promoted the construction of buildings with non-operable windows. Research shows that such buildings are detrimental to their occupants’ wellbeing and productivity, sometimes causing them to feel overcooled or overheated. This post-occupancy evaluation illustrates such problems through the case study of a courthouse building in a hot arid environment. A strong association is shown between occupant satisfaction, building ventilation and sense of wellbeing at work. A positive correlation was found between satisfaction with personal control, and overall satisfaction survey results show that workers express a willingness to compromise future salary rises in order to receive operable windows. Key lessons for architects are discussed.     

A comparison of the occupant comfort in a conventional high-rise office block and a contemporary environmentally-concerned building

A comparative study of the occupant comfort (neutral) in a conventional high-rise office block and a contemporary environmentally-concerned building for Sheffield UK climate conditions was carried out. A questionnaire was designed for occupants to rate their workplace environment in terms of the thermal, visual, acoustic and overall perception and satisfaction level. The basic physical parameters were measured at the same time, e.g. air temperature, humidity, illuminance and sound level. It is inferred that (1) There is a noticeable difference between the conventional building and environmentally-concerned building in terms of their thermal and visual environment. (2) A clear distinction of the occupant sensation and satisfaction level towards their thermal and visual environment is presented between these two buildings. (3) The effect of basic physical variables on the occupants’ perception and satisfaction level becomes less significant when minimal standards are attained. (4) The acoustic satisfaction level however, was not perceived differently by the occupants of the two building types.     

Occupant behaviour simulation for cellular offices in early design stages—Architectural and modelling considerations

Building simulation is most useful and most difficult in early design stages. Most useful since the optimisation potential is large and most difficult because input data are often not available at the level of resolution required for simulation software. The aim of this paper is to addresses this difficulty, by analysing the predominantly qualitative information in early stages of an architectural design process in search for indicators towards quantitative simulation input. The discussion in this paper is focused on cellular offices. Parameters related to occupancy, the use of office equipment, night ventilation, the use of lights and blinds are reviewed based on simulation input requirements, architectural considerations in early design stages and occupant behaviour considerations in operational stages. A worst and ideal case scenario is suggested as a generic approach to model occupant behaviour in early design stages when more detailed information is not available. Without actually predicting specific occupant behaviour, this approach highlights the magnitude of impact that occupants can have on comfort and building energy performance and it matches the level of resolution of available architectural information in early design stages. This can be sufficient for building designers to compare the magnitude of impact of occupants with other parameters in order to inform design decisions. Potential indicators in early design stages towards the ideal or worst case scenario are discussed.     

Evaluating diverse patterns of occupant behavior regarding control-based activities in energy performance simulation

Simulation is recognized as an effective tool for building energy performance assessment during design orretrofit processes. Nevertheless, simulation models yield deviating outcomes from the actual building performance and a significant portion of this deviation originates from the dynamic nature of occupant behavior. Literature on occupant behavior indicates that occupant behavior is not integrated into building energy performance assessment procedures with appropriate resolution, instead they are acceptedas as sumedand fixed data sets that usually represent the presence of occupants. This study attempts to evaluate the effect of diverse patterns of occupant behavior on energy performance simulation for office buildings. Diverse levels of sensitivity of occupant behavior on control-based activities such as using lighting apparatus, adjusting thermostat settings, and presence in space are employed through three diverse occupant behavior patterns. These occupancy patterns are correlated with three identical office spaces simulated within a conceptual office building. EDSL Tas is used to run building energy performance simulations. Effects of occupant behavior patterns on simulation outcomes are compared for five sample winter and summer workdays, with respect to heating and cooling loads. Results present findings on how diversity of occupancy profiles influences the consumption outcomes.     

Indoor environmental quality,occupant satisfaction,and acute building‐related health symptoms in Green Mark‐certified compared with non‐certified office buildings

Indoor environmental quality (IEQ) has become an important component of green building certification schemes. While green buildings are expected to provide enhanced IEQ, higher occupant satisfaction, and less risks of occupant health when compared with non‐green buildings, the literature suggests inconsistent evidence due to diverse research design, small sample size, and weak statistical analysis. This study compared several outcomes pertinent to IEQ performance in green and non‐green office buildings in Singapore. Adopting a cross‐sectional study design, objective measurements were taken in eight green and six non‐green buildings, and satisfaction and acute health symptom risks of 367 occupants were obtained. Green buildings exhibited lower concentration of PM2.5, bacteria, and fungi and maintained temperature and humidity more consistently compared to non‐green counterparts. The mean ratings for satisfaction with temperature, humidity, lighting level, air quality, and indoor environment were higher in green buildings (with statistical significance P < 0.05). There was statistically significant reduction in risk of occupants having headache, unusual fatigue, and irritated skin in green buildings. Although matching of buildings and occupant characteristics, survey participation bias, and sampling duration (a 1‐week snapshot) of IEQ monitoring remain as limitations, this study offered positive association of green buildings with qualitatively and quantitatively measured performance of IEQ.     

Comparison of thermal comfort algorithms in naturally ventilated office buildings

With the actual environmental issues of energy savings in buildings, there are more efforts to prevent any increase in energy use associated with installing air-conditioning systems. The actual standard of thermal comfort in buildings ISO 7730 is based on static model that is acceptable in air-conditioned buildings, but unreliable for the case of naturally ventilated buildings. The different field studies have shown that occupants of naturally ventilated buildings accept and prefer a significantly wider range of temperatures compared to occupants of air-conditioned buildings. The results of these field studies have contributed to develop the adaptive approach. Adaptive comfort algorithms have been integrated in EN15251 and ASHRAE standards to take into account the adaptive approach in naturally ventilated buildings. These adaptive algorithms seem to be more efficient for naturally ventilated buildings, but need to be assessed in field studies. This paper evaluates different algorithms from both static and adaptive approach in naturally ventilated buildings across a field survey that has been conducted in France in five naturally ventilated office buildings. The paper presents the methodology guidelines, and the thermal comfort algorithms considered. The results of application of different algorithms are provided with a comparative analysis to assess the applied algorithms.     

夏热冬暖地区绿色建筑性能后评估研究

为了解夏热冬暖地区绿色建筑运行后实际能耗和室内环境品质，文章详细介绍了该气候区内绿色建筑主要技术的应用情况及应用效果。选取位于该气候区内共11个获得绿色建筑认证的办公建筑，通过调研实际能耗，结合用户主观问卷调研，与常规办公建筑的能耗和室内环境品质主观满意度进行了对比研究。结果表明，对于A类办公建筑，绿色建筑与常规建筑无明显差异，均略低于引导值；对于B类而言，绿色办公建筑的总能耗显著低于常规办公建筑，但与能耗指标相比二者能耗均较高，是建筑节能工作的重点。在室内环境品质满意度方面，用户对绿色建筑的满意度明显高于常规建筑，在空气品质和室内环境控制上尤为明显，光环境的差异则更多是归因于天然采光的设计，而非人工照明的优化。最后通过一个案例从节地、节能和室内环境等3个方面全面地介绍了适宜于夏热冬暖地区的绿色建筑设计。     

Ventilation,indoor environment quality and climate—comparison of European and Singapore office buildings

Indoor environment quality audits were performed in six European countries and in Singapore using the same methodology. Five to eight office buildings were audited in each country. The audits included airflow rate measurements, energy audit, indoor air quality (VOC₁ CO₂, dust concentrations), and questionnaires to occupants. Questions to occupants addressed their health, their comfort and well-being, as well as their perception of their environment. This paper compares the results obtained from these audits, with particular attention to the effects of ventilation or air conditioning systems and climate.

The number of building related symptoms is, on the average, significantly smaller in the buildings audited in Singapore than in Europe. One of the reasons may be the non-smoking policy common in Singapore. It is also once more observed that buildings are often over-warmed in cold climates and overcooled in warm climates. Surprising, but not new, is that there are no correlations between specific air flow rates and perceived air quality or health, as long as airflow rates are within accepted standards.     

The power of qualitative data in post-occupancy evaluations of residential high-rise buildings

Using a mixed-method, case study research design, the present study explores four Toronto high-rise residential buildings in order to produce feedback about how occupants experience and behave in these buildings. The primary dataset is 700 comments received on 165 questionnaires. Content analysis was performed on the data, identifying envelope, heating, cooling and ventilation (HVAC), hot water, indoor environmental quality, and layout and design as the primary themes. The comments revealed important feedback for the designers and managers of these buildings; including important insights into the HVAC system, envelope, balcony, hot water delivery system, and noise control strategies. Though subjective in nature, the comments received from occupants are revelatory and have implications for the amount of energy consumed by the buildings, as well as the level of occupant satisfaction. Though not a substitute for quantitative problem solving, they are a complimentary strategy in the pursuit to improve the satisfaction and sustainability of the built environment.