Influence of occupant's behaviour on indoor environmental quality and energy consumptions

Buildings are dynamic, and the interactions of operators, occupants, and designers all influence the way in which buildings will perform. At the core of this research is the belief that technical solutions alone are not sufficient to face great challenges of saving energy while still maintaining or even improving current comfort levels. Buildings are engineered using tested components and generally reliable systems whereas people can be unreliable, variable, and perhaps even irrational. The studies in literature also reveal the gap between how designers expect occupants to use a building, and how they will actually operate it. Actually, there is often a significant discrepancy between the designed and the real total energy use in buildings. The reasons of this gap are generally poorly understood and largely have more to do with the role of human behaviour than the building design. Knowledge of user’s interactions within building is crucial to better understanding and a more valid predictions of building performance (energy use, indoor climate) and effective operation of building systems. The present work undertakes a theoretical and empirical study of the uncertainty of energy consumption assessment related to occupants’ behaviour in residential buildings. The main purpose of this research is to propose a methodology to model the user behaviour in the context of real energy use and applied it to a case study. The methodology, based on a medium/long-term monitoring, is aimed at shifting towards a probabilistic modelling the occupant behaviour related to the control of indoor environment with respect to the energy-related issues. The goal is to determine users’ behavioural patterns describing user’s interaction with the building controls. The procedure is applied first at modelling occupants’ interactions with windows (opening and closing behaviour) and then at modelling the heating set-point preferences. This research is based on the assumption that only switching from a deterministic approach in building energy simulation to a probabilistic one it will be feasible to obtain energy consumption prediction closer to reality. This probability is related to variability and unpredictability during the whole building operation. In this way, it become crucial to take into account the occupants’ presence and interactions with the building and systems. Actually, building energy simulation tools often reproduce building dynamics using numerical approximations of equations modelling only deterministic (fully predictable and repeatable) behaviours. In such a way, “occupant behaviour simulation” could refer to a computer simulation generating “fixed occupant schedules”, representing a fictional behaviour of a building occupant over the course of a single day. This is an important limitation of energy simulation tools for modelling occupant’s interactions with buildings, and highlights that the results are essentially unrealistic. The whole dissertation consists of four parts. In the first part the development of a theoretical model of the occupant behaviour is described based on a comprehensive literature review. With respect to the complexity of this issue, a specific literature survey is addressed to derive the most dominating driving forces useful for a more accurate description of occupant behaviour related to the habits of opening and closing the windows. Existing studies on the topic of window opening behaviour are highlighted and a theoretical framework to deal with occupants’ interactions with building controls, aimed at improving or maintaining the preferred indoor environmental conditions, is elaborated. The analysis of the literature highlights how a shared approach on identifying the driving forces for occupants’ window opening and closing behaviour has not yet been reached. In the second part of this dissertation, a method for defining occupant behaviour in simulation programs based on measurements is proposed. The proposed approach is based on measurements of both indoor and outdoor environmental parameters and the behavioural actions of the building occupants (window opening, TRV’s set point adjustments, occupancy sensors, etc..). From the collected data, different suitable user behavioural patterns (models) were defined by means of statistical analysis (logistic regression, Markov chain, etc..) and implemented in a building energy simulation tool. Moreover, a probabilistic distribution instead that a single value is preferred as a representation of energy consumptions. The proposed procedure was applied for modelling the human behaviour related to the window opening and closing and the change in thermostatic radiator valves (TRVs), and its implementation in the simulation tool IDA ICE so that the results obtained are probabilistic in nature. The third part of the dissertation deals with the validation of the obtained models to ensure the effectiveness of the models. In this section, the validation procedure is carried out using other data coming from an analogue dataset of dwellings where the same indoor and outdoor parameters are measured. These data will be used to validate the models of window opening behaviour. The validation is performed by comparing the probabilities of window opening and closing with the actual measured state of the windows in the dwellings. In literature, a variety of logistic models expressing the probability with which actions will be performed on windows, as a function of indoor temperature, outdoor temperature or both. Previously published models are then also compared using this validation procedure. The fourth part of the thesis represents a sightseeing of the future application of this field of research, focusing on the understanding of how technology and building design can improve energy efficiency exploiting the goal of making users more aware and hence careful on energy consumption. Overall, this dissertation highlights the importance of researching the individual’s behaviour in order to understand the differences in real building energy usage. Besides being limited to the cases of window opening and closing for most of the analyses, the methodology presented can also be applied to other types of behaviours

Evolution of magnetic fields and energetics of flares in active region 8210

To better understand eruptive events in the solar corona, we combine sequences of multi-wavelength observations and modelling of the coronal magnetic field of NOAA AR 8210, a highly flare-productive active region. From the photosphere to the corona, the observations give us information about the motion of magnetic elements (photospheric magnetograms), the location of flares (e.g., H$\alpha$, EUV or soft X-ray brightenings), and the type of events (H$\alpha$ blueshift events). Assuming that the evolution of the coronal magnetic field above an active region can be described by successive equilibria, we follow in time the magnetic changes of the 3D nonlinear force-free (nlff) fields reconstructed from a time series of photospheric vector magnetograms. We apply this method to AR 8210 observed on May 1, 1998 between 17:00 UT and 21:40 UT. We identify two types of horizontal photospheric motions that can drive an eruption: a clockwise rotation of the sunspot, and a fast motion of an emerging polarity. The reconstructed nlff coronal fields give us a scenario of the confined flares observed in AR 8210: the slow sunspot rotation enables the occurence of flare by a reconnection process close to a separatrix surface whereas the fast motion is associated with small-scale reconnections but no detectable flaring activity. We also study the injection rates of magnetic energy, Poynting flux and relative magnetic helicity through the photosphere and into the corona. The injection of magnetic energy by transverse photospheric motions is found to be correlated with the storage of energy in the corona and then the release by flaring activity. The magnetic helicity derived from the magnetic field and the vector potential of the nlff configuration is computed in the coronal volume. The magnetic helicity evolution shows that AR 8210 is dominated by the mutual helicity between the closed and potential fields and not by the self helicity of the closed field which characterizes the twist of confined flux bundles. We conclude that for AR 8210 the complex topology is a more important factor than the twist in the eruption process

Towards high energy performing historical buildings. A methodology focused on operation and users’ engagement strategies

"Historical evidence indicates that when man first considered settlements and the order pertaining the rein, he showed concern for the conservation of this order and of monuments" [1]. Today, the conservation of historical buildings involves also the necessity to adapt them to the current lifestyles and legislation in order to maintain them, wherever possible, as living evidences of the past. One of the most important challenges of adapting historical buildings to future usages is represented by the enhancement of energy performances of these building, that is crucial both for environmental and economic reasons. The aim of this paper is to outline a methodology to investigate the potential energy savings and the enhancement of historical buildings’ livability by acting only on their operation, so that the building fabric could be maintained as much as possible as the original evidence. Furthermore, an example about methodology’s application on a real case study will be described in order to translate the theoretic phases into an operative pla

Insights on Smart Home Concept and Occupants’ Interaction with Building Controls

The increasing attention for energy efficiency in buildings stimulates the expansion of “Smart buildings”. In offices and homes, building automation systems are suited to individuals, foresighting their needs. Occupants’ compliance is a fundamental requirement for a successful adoption of building automation systems. An important warning regards that such “smart behaviour” of the building should match with the occupants’ satisfaction and their feeling of controlling the living environments. A balance between energy efficiency and occupants’ needs is required. This paper aims at providing insight on the concept of “Smart Home” considering the adaptive actions performed by occupants to restore their wellbeing

insights on pro environmental behavior towards post carbon society

Abstract The increasing phenomena related to urbanization and human impact on landscape leads to re-think the future of the cities. As well as in buildings, a careful design, the use of renewable sources and the use of advanced technical solutions, to achieve a significant energy savings, are strategies not sufficient to define a "Post-Carbon city" or a "Post-Carbon building". It is necessary that the citizen/occupant become a "Post-Carbon society", i.e. they pursue conscious lifestyle marked on energy saving principles. This suggest that the occupant's behaviour plays a fundamental role. In fact, many studies have shown that the human behaviour influences, mainly, the energy performance, explaining, in this way, the discrepancy gap between predicted and real consumptions. Since human behaviour is, in large part, influenced by several factors, a behavioural change towards sustainable lifestyle is desirable and this is possible, for examples, by providing to users feedback and information on comfort condition and energy use. The main goal of this research is to identify the pro-environmental behaviour by a questionnaire survey. Specifically, the structure of the survey will be described in this paper and the main results presented

Occupants’ perception of historical buildings’ indoor environment. Two case studies.

In Europe, some historical cities have more than 50% of buildings dated from before 1920. Nowadays, these buildings faces challenges when adapted to the current necessities of livability, environmental and economical sustainability. Literature demonstrates that occupants’ comfort perception and consequent behavior affect buildings’ energy efficiency and are influenced also by the building configuration. Despite a large number of studies in literature investigating occupants’ behavior and comfort in different situations, there is a lack of such studies for historical buildings. Therefore, the objective of this paper was to characterize occupants’ thermal and comfort perception in two historical buildings during summer season. In these terms, results of objective measures were compared to occupants’ evaluations of the indoor environment. Results showed that, for both case studies, despite the good thermal performances of the building fabrics and the fact that almost all of the occupants like to work in a historical building (they would also choose it instead of a modern one), most of them didn’t rate the building as comfortable from a thermal point of view

Validation of Occupants’ Behaviour Models for Indoor Quality Parameter and Energy Consumption Prediction

Occupants' behaviour related to building control system plays a significant role to achieve thermal comfort and air quality in naturally-ventilated buildings. Generally, the published models of occupant's behavior are not validated, meaning that the predictive power has not yet been tested. For this reason, the validation of occupant's behavioral models is an issue that is gaining importance. In this paper validation was carried out through dynamic Building Energy Performance simulation (BEPS); behavioral models of windows opening and thermostats set-point published in literature were implemented in a dynamic BEPS software and the obtained results in terms of temperature, relative humidity and CO2 concentration were compared to real measurements. Through this comparison it will be possible to verify the accuracy of the implemented behavioral models. The models were able to reproduce the general tendencies in the measured temperatures but the simulation results diverged from the measured CO2 concentrations and relative humidit

insights into the effects of occupant behaviour lifestyles and building automation on building energy use

Abstract In order to optimize building energy consumption, Member States will have to establish minimum efficiency requirements for systems, and promote the introduction of active control system in new constructions or major renovations. Energy saving, plant efficiency and environmental sustainability are also factors delineating smart buildings. Interestingly, occupant behaviour is known to be one of the key sources of uncertainty in the prediction of building energy use. The success of automation strategies is recognized to be dependent on how the occupants interact with the building. The present research describes the effect of different building occupants' lifestyles and building automation on a high performing building

Application of users’ light-switch stochastic models to dynamic energy simulation

The design of an innovative building should include building overall energy flows estimation. They are principally related to main six influencing factors (IEA-ECB Annex 53): climate, building envelope and equipment, operation and maintenance, occupant behaviour and indoor environment conditions. Consequently, energy-related occupant behaviour should be taken into account by energy simulation software. Previous researches (Bourgeois et al. 2006, Buso 2012, Fabi 2012) already revealed the differences in terms of energy loads between considering occupants' behaviour as stochastic processes rather than deterministic inputs, due to the uncertain nature of human behaviour. In this paper, new stochastic models of users’ interaction with artificial lighting systems are developed and implemented in the energy simulation software IDA ICE. They were developed from field measurements in an office building in Prague. The aim is to evaluate the impact of a user's switching action over whole building energy consumption. Indeed, it is interesting not only to see the variance related to electric energy consumption, but the overall effect on a building's energy load