Sustainable development is the key solution to mitigate the impact of the 21st century’s major challenges such as the depletion of our natural resources, emissions that accelerate climate change together with the large waste generation. One of the largest contributor to the aforementioned issues is the existing building stock, in particular the office sector. Upgrading the sustainability performance of the existing building stock is not only in the interest of regulators or society. Real estate professionals are interested in the sustainability performance of their property, portfolio or occupied property. Due to the complexity, it is not feasible for market participants to verify the sustainability performance of a property. As a consequence, voluntary certification schemes have emerged to provide an objective evaluation. However, at the same time, appraisers are paradoxically expected to provide an objective estimation/opinion on the potential added value of sustainability while their duty according to governances is to derive the market value by analysing available data. The inability of current valuation practices for incorporating a thorough sustainability assessment resulted in decision-makers to focus solely on energy-related costs and justify their investment decisions based on energy-related benefits. For this reason, many investment decisions are believed to be profitable for users instead of owners. However, previous research has shown that property owners of sustainable offices might achieve positive effects in relation to an enhanced image, corporate social responsibility, less risky profile for investors and improved marketability. In the effort to shed light on these far-reaching tentacles of sustainability, this thesis sets forth the base for developing an indicator-based sustainability assessment framework for the appraisal of offices. The proposed framework integrates sustainability and the value it holds for various stakeholders by conceptualizing the relationship between sustainability indicators and different value systems as well as the economic parameters that are adjustable by an appraiser in the income capitalization method. In this way, an appraiser is able to provide an objective estimation of the possible added value of sustainability. Starting from an extensive literature review of different certification schemes, a pre-selection of sustainability indicators was made. Through conducting 8 semi-structured interviews with sustainability experts, the first selection of indicators could be determined together with their goals, measurement and criteria. It is remarkable that according to the participants, actively monitoring the consumption and other management-related indicators are defining the sustainability performance of an office as well, next to the physical characteristics. The online survey was distributed among sustainability experts with a questionnaire designed with the constant sum method and were requested to allocate points over the indicators as well as the categories to determine the relevance. Ultimately, the selection resulted in a set of 34 indicators. Combining the findings from the interviews, data from the survey and the literature review resulted in a framework which was discussed in an expert interview with an appraiser. The findings of the expert interview indicate that there is still a huge gap between practice and theory. The nature of the current valuation techniques hampers the integration of sustainability by focussing mainly on the rental agreement. In order to integrate sustainability aspects into the appraisal, a shift from only looking at the rental agreement to looking at the current use and the fitness for use would be needed. Future research could focus on validating and expanding the linkage between the sustainability indicators and the economic adjustable parameters and reducing the subjectivity of input for the indicators.

Nonintrusive Load Monitoring (NILM) can be used to disaggregate household energy usage collected from a central meter to the level of individual appliances, but has so far mostly been applied in controlled, small-scale settings. Further potential such as the application for energy efficiency classification and management have remained largely untapped. In this research a machine learning model was developed and deployed to determine energy consumption, usage pattern and energy efficiency characteristics of real-life dishwasher usage based on smart meter data. The developed NILM system was deployed on a full year of smart meter data for nearly 130.000 households in the Netherlands. The analysis was accompanied by a survey to gain additional information on the households usage behaviour. The average energy consumption for all households was found to be 1.18kWh per wash, with dishwashers used 240 times per year on average. Dependencies are shown for household size, washing temperature, machine efficiency label as well as time of day, week and year. It was estimated that 9 in 10 households could reduce their dishwasher energy consumption, with an average saving potential of more than 30% per year. The developed method showed to be suitable to gain insight into average electricity consumption and usage patterns on an appliance level, non-intrusively and at large-scale. Additional survey data was shown to provide comparative insight between different user groups. The developed framework can be easily expanded for other major appliances and could be used to drive tailored consumer feedback on energy efficiency improvements within households.

The Dutch government claims that upgrading office buildings to an energy label C building is enough to reduce the environmental footprint of companies for now. Research has shown that when a building receives an energy label, it does not mean that the operational energy use of the building is in line with the received energy label; this results into an energy performance gap. The gap consists of the building-related energy use or the user related energy use. This research focusses on how the behaviour of office users can be influenced to reduce the energy performance of an office building in use. This research is divided into four parts. First the energy performance gap is discussed, afterwards measures which influence the energy performance of an office building are researched, followed by which factors stimulate pro-environmental behaviour and finally which methods are effective to implement the measures and behavioural changes. First, the energy performance gap can be explained by the difference between the theoretical energy label and the operational energy use. There are two possible causes for this gap: the building related energy use or the user related energy use. This research focusses on how to reduce the user-related energy by activating the user behaviour. Secondly, during this study a measurement list is developed to show possible measures to reduce the energy performance and environmental impact of a building. Significant change can be achieved, not by implementing these measures on a small scale (one office), but on a large scale (all offices). It is also the case that these types of measures will not always have a significant effect the environmental impact of the building or the energy use of the building, this depends on the current building characteristics. When a building already implements that measure, the impact will be less significant than when they do not use the measure. Third, pro-environmental behaviour (PEB) is a behaviour type that focusses on minimizing the negative impact of the consequences of human behaviour on the environment (V. Blok et al., 2015). Trough literature, interviews and the delphi panels it can be concluded that comfort, economic and intention play an important role in shaping pro-environmental behaviour (Kollmuss & Agyeman, 2002). The factors which do have the highest impact on encouraging and stimulating Pro-environmental behaviour according to the users and experts are: Intention to act, Perceived behaviour control, Social norms and Eco-communication. Finally, methods to activate these factors are related to the measure and how this measure affects the behaviour factors. In this research three examples of implementing measures are given. The three main methods to reduce the environmental impact of an office building and thereby activating the pro-environmental behaviour of the user are: Pro-environmental behaviour guidelines, Eco- communication platform and Social incentivesCombining the methods will get the optimum result of the measures which are implemented. These four parts combined answers the research question: How can the behaviour of office users be influenced to reduce the energy performance of office buildings in use? 

Municipalities are aware that professionalizing their real estate management is necessary to become CO2 neutral before 2050 and that it even can create cost reduction and can add value in the long term. Many municipalities are now working on a specified portfolio identification while maintaining this portfolio. Some municipalities are ready to think about how to change their portfolio into one that is almost CO2 neutral. However, there are also municipalities that are struggling due to the lack of (energy) information of their portfolio and choosing the appropriate tools to help them achieve their goals. Some municipalities do work on the sustainability goal as seen at the benchmark of 2017, but here is also evident that around 25% of the public building stock is still categorized at label G, the worst label. Therefore the aim of the research is to provide insight into the facts, processes, possibilities, and challenges of sustainable strategies for municipalities to create an energy neutral real estate portfolio and given this national goal, provide a road map for municipalities. We can conclude from literature and case studies that there are special contracts, approaches, and guidelines municipalities can use to make their building portfolio energy neutral. However, there is not one uniform tool that can entirely transform the total building portfolio. So, the strategy tools need to be used for the right buildings at the right time with the right expertise and information. This approach needs to be in balance with the three added values of MREM, namely: political goals, financial policies, and user satisfaction. The considerations to set the pace of the energy transition is predominately based upon the financial possibilities, the amount of support of the council, the physical context, and the professionalization of the real estate department. The DAS-Framework and four C/P/MREM perspectives, used in the approach of the case studies, can help municipalities to structure and balance the values of the organization when making a sustainable strategy.

European policy makers have established a set of 20-20-20 targets for the year 2020 in the energy sector, goals based on security of supply, competitive markets and sustainability. The 3 key objectives include a 20% reduction of greenhouse gases (GHG) and CO2 compared to 1990 levels (and up to 80% by 2050), a 20% improvement in energy efficiency and a 20% share of basis energy consumption from renewable sources. On its own, the building sector is responsible for 1/3 of the world’s energy consumption, of which 60% is due to heating and cooling. In the European Union, this proportion achieves 40% of the total energy consumption, of which heating, cooling and domestic hot water account for around 70%. Fossil fuels represent 75% of the primary energy supply for heating and cooling needs whereas renewable energies account for only 18% followed by nuclear energy with 7%. A brief energy context being stated, this work focused on the assessment and the optimization of a heating, ventilation and air conditioning (HVAC) system, coupled with a building integrated photovoltaic and thermal (BIPV/T) system and a simple BIPV system. The objective was to reduce the overall energy consumption of a very well insulated dwelling aiming to make it a net zero energy building (NZEB). This HVAC system incorporated a dual-tank water-to-water heat pump (WWHP), used for space heating and cooling, using the BIPV/T system as a heat source thanks to preheated air. The dwelling is a so-called Deep Performance Dwelling (DPD) developed by the Solar Decathlon team from Canada: TeamMTL. This DPD was used as case study all along this Master thesis. On the one hand, this study aimed at the modelling of both integrated PV systems which were developed firstly with the MATLAB software and then with the TRNSYS software. One of the objectives was to highlight the impact of the thermal recovery from the BIPV/T system on its PV modules efficiency compared to the BIPV system. Furthermore, the same initial and boundary conditions were used to ensure a truthfulness on-site energy production from both BIPV/T and BIPV systems as well as for the validation of these systems, later integrated to the complete DPD modelling. On the other hand, sensitivity analyses were conducted to investigate the effects of various parameters on the NZEB objective and the on-site energy fraction (OEF) covered by the energy produced by the DPD. These parameters included the efficiency of the PV modules, their tilt angle, the materials used for both floors and walls as well as the size and the control strategy used of both electrical and thermal storage. First, even if the comparison of both MATLAB and TRNSYS modellings led to a similar net increase in the BIPV/T average electrical efficiency of + 0.0014 [-] compare to the BIPV one, the TRNSYS one achieved an 11.0% lower yearly electrical generation due to an intrinsic factor used in TRNSYS called Incidence Angle Modifier (IAM). The impact of this factor affected all the more the thermal yield, namely a reduction by 28.6% for the annual thermal production along with a 32.0% lower thermal efficiency of the BIPV/T system compared to the one modelled in MATLAB. However, given that TRNSYS was required to model the transient behaviours of the DPD, not conceivable with MATLAB due to the time constraint of this Master thesis, it was logically concluded to use the TRNSYS modelling of the integrated PV systems. Then, to have a good representativeness of the performances of the DPD, 4 cities with very different climates were chosen. For each location, the DPD was categorized as a nearly zero energy building (nZEB). Then, the simulation results emphasized that an optimal tilt angle adapted to every location, concrete-based floors as well as high efficiency PV modules allowed for reaching the NZEB objective in 3 cities, the 4th one facing low annual irradiation. Moreover, sensitivity analyses were carried out in order to improve the energy performance of the DPD. Based on the interpretation of the results concerning both on-site energy indices and energy outputs, a better configuration than the one of the as-built DPD was suggested for each city. Indeed, the sensitivity analyses indicated that the bigger the electrical storage, the better the electrical OEF index. Then, a 300-litre hot water tank as well as a 150-litre cold water tank led to a better overall OEF index and a lower energy consumption compared to the initial configuration. These results were obtained by applying the initial control strategy relying on price benefits of the grid based on bidirectional power flows between the batteries and the grid. However, a grid-tied configuration with no more batteries-grid connection and not taking anymore advantage of incentive prices of the grid stood out an even better overall electrical OEF index, making a higher use of the on-site power generation. Finally, the proportion between the on-site PV production and the amount of energy supplied by the grid to meet the demand of the DPD were calculated. Besides, the impact of the solar house in terms of CO2 emissions as well as its advantages for the grid were alluded.

The study of energy consumption across various building clusters offers a path to discerning intricate patterns and establishing energy efficiency metrics. However, these analyses have mostly been limited to small, controlled settings, leaving a vast potential for broader application in energy efficiency management and classification untapped. This research leverages machine learning models to determine gas consumption patterns and energy efficiency characteristics of buildings in real-life settings, based on a range of parameters including insulation properties and year of construction. The developed system was applied to a comprehensive dataset comprising eight distinct clusters of buildings, with a total of nearly 10,000 hourly gas consumption. To supplement the analysis, additional data was gathered concerning the building features. The findings indicate that the average gas consumption varies significantly across clusters, with dependencies shown for the age of the building, insulation characteristics, and building orientation The developed framework proved to be suitable for gaining insights into average gas consumption and usage patterns at a building level, non-intrusively and on a large scale. The additional data provided comparative insights between different building groups. The developed system can be easily expanded for other building characteristics and could be used to drive tailored feedback on energy efficiency improvements within buildings. This research paves the way for a more comprehensive approach to building energy efficiency, one that goes beyond the traditional parameters to include a broader set of variables such as building usage, occupant behavior,and heating system efficiency

Buildings are a central element in our everyday private and social life, meeting some of our most basic needs such as shelter, sanitation and easy access to energy. However, these comforts do not come without a cost: European buildings alone consume 40% of the total final energy and are responsible for 36% of all CO2 emission. In Italy, 60% of the residential building stock was built before the first national law on energy efficiency and in fact some 25% of it can be considered as being highly energy inefficient. In 30 years, many of these buildings will still be standing and this threatens to lock-in the Italian residential sector on its historical emission pathways....

The building sector's substantial environmental impact, responsible for 40% of total energy consumption and one-third of CO2 emissions globally, emphasises the urgency to enhance energy efficiency. While there are potentials for energy savings, there are still challenges that need to be faced. In particular, a significant ‘performance gap’ exists between the predicted and actual energy usage in buildings. This gap, observed during the operational phase, poses challenges for realising high-performance buildings. The focus of this thesis will be on renovated office buildings, acknowledging their significance in sustainability efforts. A critical aspect of the performance gap is attributed to the operation and maintenance of the energy systems compared to the intended usage. The research will therefore address the critical main research question: “How can operation and maintenance-related energy performance gap in renovated office buildings be effectively addressed to meet the Paris Proof commitment targets?” By conducting literature reviews and employing a mixed-method approach, including both qualitative and quantitative methods combined, the study will utilise interviews and a case study, using data from advanced systems. Focusing on the complexities of influencing factors, specifically in operation and maintenance, the research aims to address the energy performance gap. Findings indicate that the main challenges are knowledge gaps among stakeholders due to fragmented collaboration, inadequate commissioning and monitoring, and tuning practices, including the lack of a feedback loop. A strategic roadmap of a restructured redevelopment process is proposed, emphasising enhanced commissioning practices, continuous monitoring, and improved stakeholder collaboration. The strategic roadmap therefore suggests practical steps for addressing the performance gap, fostering more energy-efficient building operations, and aiming for redeveloped office buildings to achieve the Paris Proof standards.