This work investigates the impact of state-of-charge estimation methods on the formulation of operational strategies for a packed-bed thermal energy storage (TES) system using phase change material (PCM), integrated with a heat pump for Nordic residential heating applications. Two heat transfer fluid (HTF)-based state of charge (SOC) estimation approaches, including a global energy balance method and a packed-bed layer-wise energy balance method, are compared using experimental data from a 42 kWh PCM-TES system using macro-encapsulated PCM RT57HC, showing close agreement between the two methods. The PCM-TES reaching 80% SOC within 8 hours demonstrates the feasibility of different charging strategies for demand-side flexibility. A PCM temperature-based method is currently being implemented at the Testbed KTH in Live-in-Lab to improve the SOC estimation accuracy and thereby refine operational strategies.

Digital twin technology is an emerging technology within the built environment. Yet, there are many unexplored opportunities to utilize digital twins for facilitating the transformation toward a climate-neutral building stock while also meeting the expectations from the building occupants. This article presents a case study of a digital twin, developed for an existing commercial building stock of campus areas in Sweden. The overarching purpose of the digital twin is to support both building occupants and building operators. This two-fold human-centric approach represents a novel approach for building digital twins. The digital twin is based on 3D scanning, and together with geospatial data, a real-like navigational indoor environment is created. Three innovative features are presented: the building analysis module, the digital twin mobile application, and the building operations module. The results show that the digital twin improves the building occupant’s experience by supporting navigation and providing access to the room booking system via this dedicated interface. Building management is also benefited by the digital twin through easier access to building data aggregated into one platform and a state-of-the-art analysis tool for optimizing the use of indoor space. The digital twin holds future potential to achieve operational excellence by incorporating feedback mechanisms and utilizing artificial intelligence to enable intelligent fault detection and prevention.

In the light of global climate change and the current energy crisis, it is crucial to target sustainable energy use in all sectors. Buildings still remain one of the most energy-demanding sectors. Campus buildings and higher educational buildings are important to target due to their high and increasing energy demand. This building segment also represents a research gap, as mostly office or domestic buildings have been studied previously. In the quest for thermal comfort, a key stakeholder in building energy demand is the building occupant. It is therefore crucial to promote energy-aware behaviors. The building systems are another key factor to consider. As conventional building systems are replaced with smart building systems, the entire scenario is redrawn for how building occupants interact with the building and its systems. This study argues that behavior is evolving with the smartness of building systems. By means of a semi-systematic literature review, this study presents key findings from peer-reviewed research that deal with building occupant behavior, building systems and energy use in campus buildings. The literature review was an iterative process based on six predefined research questions. Two key results are presented: a graph of reported energy-saving potentials and a conceptual framework to evaluate building occupants impact on building energy use. Furthermore, based on the identified research gaps in the selected literature, areas for future research are proposed.

The adoption of innovation in the building sector is currently too slow for the ambitious sustainability goals that our societies have agreed upon. Living labs are open innovation ecosystems in real-life environments using iterative feedback processes throughout a lifecycle approach of an innovation to create sustainable impact. In the context of the built environment, such co-creative innovation and demonstration platforms are needed to facilitate the adoption of innovative technologies and concepts for more energy-efficient and sustainable buildings. However, their feasibility is not extensively proven. This paper illustrates the implementation and demonstrates the feasibility of the Living Labs Triangle Framework for buildings living labs. This conceptual framework has been used to conceive the KTH Live-In Lab, a living lab for buildings. The goal of the Live-In Lab was to create a co-creative open platform for research and education bridging the gap between industry and academia, featuring smart building demonstrators. The Living Lab Triangle Framework has been deployed to meet the goals of the Live-in Lab, and the resulting concept is described. This paper then analyses the methodological and operational results introducing performance metrics to measure the economic sustainability, the promotion of multidisciplinary research and development projects, dissemination and impact. The results are completed with a SWOT analysis identifying its current strengths and weaknesses. The results collected in this work fill a missing gap in the scientific literature on the performance of living labs and provide empirical evidence on the sustainability and impact of living labs.

Energy-intense activities and the unpredictable and complex behavior of building occupants lead to an increase in building energy demand. It is, therefore, crucial to study underlying factors for building energy demand related to the users. Higher educational buildings are relevant to study for several reasons: they host the future workforce and citizens, they are predicted to increase in numbers, and they represent a building type less studied. Furthermore, green-rated buildings equipped with smart building systems also represent a research gap that is relevant to address since such a building design involves IoT-functionalities and digital features for the building occupants to interact with. There is also a conceivable risk that if the users know that the building is green-rated and technologically advanced, this may alter their perception of the building operation and thus their behavior. To study the relationship between building occupants and such green and smart educational structure, a survey was conducted in a Swedish higher educational building; as a result, 300 responses were collected and analyzed. The responses revealed that the building occupants act with energy awareness, and they are conscious about energy-saving behaviors. One building feature in particular was studied: the Digital Room Panels (DRPs). The DRP allows the building occupants to modify the indoor temperature and is, therefore, essential for thermal comfort. One key finding from the survey revealed that 70% of the building occupants did not know how the DRPs operate. This study argues that this result can be explained with a lack of communication and user friendliness. Inadequate interactions with building systems could also result in opportunities for energy saving might not be realized. The findings of this case study led to valuable recommendations and suggestions for future research endeavors.

This paper presents a path towards the implementation of a Digital Twin for campus environments. The main purpose of the Digital Twin is to accomplish an advanced analytical tool, which supports building owners, building operators and building users to reach an improved performance of the building. Digital Twins is new to the building and the real estate industry, hence research within this field is scarce. This paper contributes to the research by providing a methodology to implement a Digital Twin of an existing building stock of campus areas in Sweden. The main results obtained so far are presented. They indicate that the potential of a Digital Twin expands beyond the aspects of a navigational digital 3D model, including a state-of-the-art app that is developed from the Digital Twin platform.

In the scientific literature and in practice, quite a lot of attention is paid to the actors’ network analysis in living labs. Still, there is a lack of studies on value exchange between different actors in living laboratories. This study selected the distributed structure of the actors’ network in living lab since most European residential laboratories function according to this model. In the course of this exploratory study, we conducted two workshops: the first with participants from several European residential laboratories to discuss and co-design a framework for analyzing the exchange of value between different stakeholders, and the second workshop—case study, where the proposed framework was applied on the actors network of the existed living laboratory—KTH Live-in-Lab. As a result, we got a detailed picture of the network of actors and value exchange within the value co-creation model for KTH Live-in-Lab (Smart Home Services project).

This exploratory study analyses the daily activities of the end-user in terms of assessing the potential for conserving direct and indirect energy. In the course of the study, a socio-technological system approach was applied, which made it possible to combine the methods of analysis and interaction of the social group (students) and technical infrastructure (living laboratory). The method of creating personas was also applied to segregate a large group of the population within one segment. This approach allowed us to consider in more detail the different types of behavior in the same segment. As a result, we got more personalized strategies for changing a behavior tailored for each individual persona. In conclusion, a recommendation was given on which policies implications and to which organizations to address.

Compared to pure fluids, zeotropic mixtures have the potential to lower the irreversibilities in low temperature Rankine cycles by better temperature profile matching of the working fluid with the heat source/sink. However, having a gliding temperature does not guarantee performance boost over pure fluids, as many factors influence the exergy efficiency of the cycle. In this study, 25 pure fluids and 104 binary mixtures of natural working fluids are analyzed in subcritical ORCs with heat source temperature range of 125-300 degrees C and different condensing conditions and the results are investigated within two frameworks: (1) comparing the mixtures to their pure constituents, (2) comparing the mixtures to the best performing pure fluid. In one behavior type, the performance of the mixture falls between the performance of its pure constituents for all evaporator pressure range, and the mixture provides no benefit. However, some mixtures could provide performance boost in a specific evaporator range. Therefore, the maximum allowable evaporator pressure plays an important role in the performance comparison of zeotropic mixtures to their pure constituents. Mixtures which outperform their pure constituents in the first perspective, are further analyzed in the second perspective. Finally, a screening method is presented to map the binary mixtures with performance boost compared to their pure constituents and high absolute exergy efficiency. This method is based on the key thermophysical properties of the fluids including critical temperature and normal boiling point, as well as working conditions such as heat source and heat sink temperature and PPTD in the evaporator and the condenser.

The purpose of this study is to synthesize the widely used theories about co-creation from two main perspectives: co-creation as an innovation process and co-creation as a design process applied to the service concept design in the built environment context. The architecture, engineering, and construction (AEC) industry do not have much application of end-user-oriented service design in general, especially with intensive co-creation processes. To facilitate such a process, we are using a living lab environment as a laboratorial model of the real built environment, but with the opportunity to have access to the end-users and different types of stakeholders. Using the KTH Live-in-Lab explorative case study, we were able to discuss the concept of co-creation by distinguishing between co-creation as innovation and co-creation as a design process, facilitating the process of co-creation of service concepts for the proposed built environment including methods from both perspectives: innovation and design, and evaluating the process of service concepts co-creation for the built environment from the point of innovation, knowledge transfer, sustainability, and user experience.

Today’s commercially-off-the-shelf (COST) wearable devices can unobtrusively capture several important parameters that may be used to measure the indoor comfort of building occupants, including ambient air temperature, relative humidity, skin temperature, perspiration rate, and heart rate. These data could be used not only for improving personal wellbeing, but for adjusting a better indoor environment condition. In this study, we have focused specifically on the sleeping phase. The main purpose of this work was to use the data from wearable devices and smart meters to improve the sleep quality of residents living at KTH Live-in-Lab. The wearable device we used was the OURA ring which specializes in sleep monitoring. In general, the data quality showed good potential for the modelling phase. For the modelling phase, we had to make some choices, such as the programming language and the AI algorithm, that was the best fit for our project. First, it aims to make personal physiological data related studies more transparent. Secondly, the tenants will have a better sleep quality in their everyday life if they have an accurate prediction of the sleeping scores and ability to adjust the built environment. Additionally, using knowledge about end users can help the building owners to design better building systems and services related to the end-user’s wellbeing.

End use energy services have an important role in the ongoing energy transition process by improving the value proposition to the customer through better needs fulfillment and experience and providing system value to the energy system. This study presents a framework for end use energy services, developed as a result of co-creation with multiple stakeholders for a case study in a living lab context. The framework has been co-created using the principles of systems thinking to identify and map both existing and emerging elements and interactions within the energy system and customers. The framework is organized to include aspects from energy system and human system perspectives and divides the energy services development process into three distinct stages. The development stages comprise the strategic planning stage, service design stage, and solution stage. Key considerations are provided for each stage to develop a clearer understanding of the overall end use energy service process.

Low temperature Rankine cycle is a prominent solution for power generation in Waste Heat Recovery (WHR) application. The performance of this cycle is affected by various parameters including characteristics of the heat source, working fluid and constraints in the system. In cases where the heat source has a limited mass flux and therefore variable temperature, the amount of extracted heat affects the performance of the cycle including net power and efficiency which is also related to the working fluid. This is in the paper expressed in terms of a heat utilization factor, ψ, which shows the ratio of extracted heat to the maximum possible extraction rate in the specific case. This factor affects the performance of the cycle by moving the pinch point location in the evaporator. Results indicate that this factor has great impact on the performance of the cycle and the effect varies for different working fluids.

The concept of sustainable buildings includes not only technological aspects related to energy efficiency and resources usage optimization, but also aspects related to end-users' comfort, wellbeing, and everyday needs support. To understand the end-users' life activities in general and their preferences in particular, is necessary to enrich standard Building Management Systems (BMS) with human-generated and personal data. In this conceptual paper, we present an end-user context information management framework, which includes a reasoning layer, an acquisition layer, and a dissemination layer. The proposed framework is currently implemented in the KTH Live-in-Lab - a fully equipped testbed for research and innovation in the build environment.

Working fluid selection determines various characteristics of low temperature Rankine cycles. Among other factors, the selected working fluid affects thermal performance, apparatus size and economic feasibility of the cycle. Beyond only affecting characteristics of the system, unrealistic preconditions for the working fluid of the system may force the designers in using environmentally harmful mixtures and force the outcome beyond boundaries of environmental regulations. There has been numerous research and scrutiny on various working fluids, but due to the unstructured and unorganized orientation of previous studies, there is no comprehensive insight on relationship of different characteristics of the working fluid and overall performance of the system. This work intends to develop a numerical evaluation approach, using a modified stochastic optimization algorithm as a search engine. The paper further explores and questions the existing criteria for optimization of working fluids in Rankine cycle. Rather than just finding the optimum fluids for different cases, this study aims to investigate the behavior of different fluids around optimum points and see the bigger picture to find trends in different fluid behaviors. Analysis of results show two main behaviors among the fluids in subcritical cycles. In the first type behavior, the optimum points for output work, thermal efficiency and exergy efficiency lie very close to each other, while in second type, these optimum points are not close. There is a transition from first type behavior to second type for a ratio of critical temperature around 0.9 of heat source inlet temperature. These results also show the importance of key performance parameter determination.

Analysis of global energy efficiency of thermal systems is of practical importance for a number of reasons. Cycles and processes used in thermal systems exist in very different configurations, making comparison difficult if specific models are required to analyze specific thermal systems. Thermal systems with small temperature differences between a hot side and a cold side also suffer from difficulties due to heat transfer pinch point effects. Such pinch points are consequences of thermal systems design and must therefore be integrated in the global evaluation. In optimizing thermal systems, detailed entropy generation analysis is suitable to identify performance losses caused by cycle components. In plant analysis, a similar logic applies with the difference that the thermal system is then only a component, often industrially standardized. This article presents how a thermodynamic "black box" method for defining and comparing thermal efficiency of different size and types of heat engines can be extended to also compare heat pumps of different apparent magnitude and type. Impact of a non-linear boundary condition on reversible thermal efficiency is exemplified and a correlation of average real heat engine efficiencies is discussed in the light of linear and non-linear boundary conditions.

Small-scale woody biomass energy systems have an inherent ability to aid in emissions reduction while stimulating local economies and, as collective energy systems, are strongly connected to supply chain design based on local conditions and stakeholder integration. Despite an abundance of forest area alongside the promotion of biomass in energy policies, however, woody biomass utilization still remains low in Japan. The woody biomass supply chain, considered as a socio-technical system, involves a complex, cross-sectoral stakeholder network in which inter-organizational dynamics necessitates well-organized management based on an understanding of formal factors such as technology, as well as informal factors such as social relations and culture. In this paper, success factor perceptions from across the woody biomass supply chain are investigated based on semi-structured interviews with four stakeholders in the Kyushu region of Japan. Identified success factors here are: 1) respect of values & traditions, 2) transportation infrastructure, 3) business model integration, 4) relationship & trust, 5) local vitalization and 6) biomass quality control. A convergence as well as divergence of perceptions are observed, involving both formal and informal dimensions. Aiming to balance perceptions and to enable long-term success of woody biomass in Japan, a series of policy implications are drawn, including cross-ministerial integration, knowledge building on wood logistics, forest certification, local coordinators, biomass quality control standards and a feed-in-tariff for heat. This paper suggests a new arena of policy-making based on the importance of considering both informal and formal dimensions in energy policy.

Solar heat pump systems (SHPs) have been investigated for several decades and have been proven to increase the share of renewable energy and reduce electric energy demand in residential heating applications. Many review articles have been published on the subject, however literature discussing the techno-economics of different solar technologies (thermal, photovoltaic and hybrid thermal/photovoltaic) in combination with heat pumps is lacking, and thus to directly compare the merits of different SHPs is not an easy task. The objectives of this study are: a) review the different system boundaries and the main performance indicators used for assessing energetic and economic performances; b) review techno-economic studies in the literature and identify which studies give enough information and are compatible enough for making an economic inter-comparison; c) present an economic inter-comparison based on the identified systems. The results show that there is a lack of studies including an economic assessment of solar photovoltaic and heat pump systems. Additionally, there are no consistent boundaries or approaches to the study structures, making comparisons between systems difficult. In conclusion, a standardized or broadly accepted definition of technical and economic performance for SHPs is needed. Despite this, the study has shown that there are clear trends for decreasing payback times for SHPs, both solar thermal (ST) and photovoltaic (PV), with decreasing heating degree-days and with increasing solar resource.

The Swedish Strategic Innovation Agenda for Geoenergy develops a strategy for highlighting the need for geoenergy research, development and innovation in relation to the business community and authorities. Sweden has a strong global position in the field. Geothermal energy is the third­largest renewable energy source in Sweden, along with wind power. Currently, approximately 18 TWh of renewable heat per year is supplied to household, industrial and commercial buildings. In addition, there is 1­2 TWh of cooling. There is a great need for a long­term strategy and financial plan for geoenergy research and innovation in Sweden, in order to maintain and further develop research groups and the country's leading position in the field. Today, Swedish research in this field comprises about 14 full­time positions at universities, institutes and companies. This is little compared to the existing use of geothermal energy, about 19 TWh, which is worth about 15 billion SEK in consumer sales. It is also little in relation to possible future contributions to sustainable development in Sweden and abroad. The agenda is divided into short independent chapters that are tailored to different target groups/ applications. Each chapter consists of an introduction to the current situation, how geoenergy can strategically contribute to a sustainable society, and what actions/needs are a priority. (Less)

This study examines current governance structures related to multifamily buildings designed by single actors (developers) and operated in cooperative forms. The study analyses the long-term sustainability of the resource regime of study (multifamily buildings) and inked governance structures by applying Ostrom's eight design principles for long-term survival of self-organized resource regimes (Common-pool resources or CPR's). The study also searches for signs of movement towards social innovation and collective action in current governance structures. We argue that the structures governing planning, production and operation of housing cooperatives in Sweden do not fulfil the eight design principles for the long-term survival of the resource regime of study, nor do they encourage movement towards social innovation or collective action. In order to ensure the long-term survival of the resource regime of study and to increase innovation in governance structures, five adjustments are proposed; changes in the structures governing risk/profit distribution, communication, collaboration and information between actors in the Swedish cooperative housing sector.