Towards a circular home: Exploring opportunities for design to support households in sustainable resource use

Our use of natural resources has grown dramatically in recent years, with negative consequences for both the environment and human health. At home, resource use in the form of energy, water, food, and material objects may be related to a wide range of everyday practices as well as changes to, and adaptations of, our home environments. Thus, we as households play an important role in contributing to a less intensive use of resources. Even so, support is needed in the form of solutions that enable both reduced environmental impact and satisfaction with our homes. The research presented in this thesis aims to identify opportunities for more sustainable resource use at home. This has been addressed through the investigation of home-related resource use relating to households’ practices, lifestyles, and decisions concerning the home. The research has also explored design implications to support households in minimising their resource use and analysed households’ experiences of sustainability-orientated solutions for the home.Two field studies have been conducted. Study A investigated daily use and renewal of domestic kitchens and explored design implications to improve kitchens from a circular economy perspective. Qualitative data was collected in the form of interviews and a focus group, complemented by a diary or a short survey. Study B investigated perceptions and acceptance of demand-side management in residential space heating, to support an increased share of renewable energy. This study collected mainly quantitative data through a diary tool, complemented by surveys.The findings reveal that home-related resource use depends on a multitude of practices, preferences, choices, and contextual factors. In both studies, it seemed that dissatisfaction with the home environment may lead to additional resource use. For instance, kitchen renovations or practices to improve thermal comfort which either use energy or lead to energy being wasted. In the kitchen,design was found to play an important role, both in supporting sustainability in everyday kitchen practices and in allowing needs and preferences to be met over time, with little impact on the environment. Identified opportunities for increasing the circularity of kitchens were: improved technical and functional quality, timeless design, acknowledging emotional values, allowing aesthetical upgrades, allowing functional upgrades and repair, systemic changes and new business models, and increasing awareness of environmental impacts connected to kitchen renewal. Regarding demand-side management in space heating, perception and acceptance were found to depend on factors such as set indoor climate conditions, timing and magnitude of the load shifts, communication, and control. To conclude, this thesis contributes insights into home-related resource use from a household perspective and highlights opportunities for design to enable greater levels of circularity and renewable energy use at home

Fast-prototyping Approach to Design and Validate Architectures for Smart Home

The Internet of Things has contributed to make smarter houses and buildings in the last decades. Different existing works already integrate IoT technologies in homes, but end-user needs continuously change and researchers must face this challenge in identifying platforms to fast prototype solutions satisfying these new needs. This paper presents a solution that demonstrates how well-known fast-prototyping technologies like Node-RED, IBM Watson, Telegram, Raspberry Pi 4, and secured MQTT can contribute to develop complex systems facing the challenge. The selected tools are used within a smart home context to support features inspired by people needs and allow users to: a) consult real time conditions (i.e., temperature, humidity, gas), b) remotely manage lights, c) save energy through a light management system based on user movements, d) remotely monitor the house through dedicated webcams, e) generate warning notifications in case of danger. Users can interact with the systems through a web Node-RED dashboard and a Telegram bot. Differently from existing works, the feasibility of the implemented system and the efficacy of the exploited platforms are demonstrated through a running scenario extracted from a consolidated study on user needs in smart homes. The performed experiment can facilitate the fast prototyping of new solutions

Smart Energy Management for Households:

The aim of the research presented in this thesis was to infer design-related insights and guidelines to improve the use and effectiveness of home energy management systems (HEMS). This was done through an empirical evaluation of the longitudinal effectiveness of these devices and an exploration of factors that influence their use and effectiveness. Three case studies executed with three different HEMS in households, a life cycle assessment (LCA) on those three HEMS, as well as a reflection on the challenges of both researching and implementing HEMS in existing housing gave a comprehensive picture of the opportunities and barriers for HEMS. The research revealed five typical use patterns that emerged amongst households. It also revealed average energy savings of 7.8%, which however decreased in the follow-up that was conducted, and factors that may influence the use and effectiveness of HEMS. Nonetheless, the LCA calculations divulged that the HEMS can achieve net energy savings when taking their embedded energy into account. Problem statement The goal of reducing the energy consumption of existing housing formed the basis for this research. There are many facets to this energy consumption, including the characteristics of the house, its appliances, and the behaviours of its inhabitants. Because of this complexity, addressing only one of these facets is not effective in substantially reducing the overall energy consumption of households. This called for an interdisciplinary approach, merging the domains of design for sustainability, sustainable housing transformation and environmental psychology. In this thesis, HEMS were chosen as the intervention to address the various elements that contribute to household energy consumption, thereby functioning as a pivot. By giving feedback and/or helping manage consumption they can assist households in changing their behaviour and help save energy. However, in analysing literature on HEMS, four critique points were encountered. Past research tends to be limited in the types of HEMS and energy sources studied. Furthermore, limited knowledge was available on the longitudinal effectiveness of HEMS, the large variances in achieved energy savings and use of HEMS, and factors influencing their use and effectiveness. Conceptual framework To address these critique points and explore the influence of the factors: user, HEMS, other people, other products, context, and time; a framework was proposed. It postulated the pivotal role of HEMS and visualized the interdependence of the different elements. This framework structured the findings of the research. Case studies Three case studies were conducted. The first case study with an electricity monitor revealed that the effectiveness of HEMS tends to decrease over time. The initial savings in electricity consumption of, on average, 7.8% after four months were not sustained over a period of 15 months. The participants were divided into three groups, who all had the same rate of fall-back. However, the group that had a daily habit after 15 months of checking the monitor, achieved the largest savings in comparison to the groups that did not have a daily habit after 15 months or that returned the monitor after four months. The second and third case study with a multifunctional HEMS and a energy management device revealed five distinctive use patterns: there was often one main user who varied strongly in their knowledge of, interest in, and affinity with energy and technique in general, resulting in different needs and desires concerning the HEMS. Additionally, the studies revealed that contextual factors, such as the structure of the home and its energy meters, can impede the use and implementation of HEMS. Lifecycle assessment The positive result of the LCA was that all three types of HEMS can theoretically achieve net energy savings (where einvested < esaved) over the course of five years in the six scenarios that were created. However, it can take up to 24 months to achieve net energy savings, depending on the scenario and type of HEMS. No HEMS achieve a positive return on investment within five years in all six scenarios. Conclusions This research found that the role of HEMS in reducing the energy consumption of households is constrained when not taking the factors into consideration that were distilled in the case studies. For one, human factors, such as the characteristics of the user and other household members and family dynamics, may influence the use and effectiveness. Furthermore, physical elements, such as the design of the HEMS (e.g., the type of feedback, the quality of the technique, its usability and applicability) the design and functioning of appliances and the dwelling played a role. Particularly, the interplay between people and these physical elements such as the match/mismatch or compatibility/incompatibility between HEMS, users, appliances and the dwelling were influential, in part due to the complexity of reducing energy consumption and users’ preferred type of reduction approach. Based on these factors, design guidelines where formulated for HEMS with the aim to achieve lasting energy savings and increase the usability of HEMS. Examples of these guidelines are: HEMS should not be developed as standalone interventions but should be incorporated as part of a broader, overarching change strategy; one size does not fit all; and careful trade-offs needs to be made with regard to the design of the HEMS, e.g., while a small display size is positive for the LCA, it could limit the potential to influence behaviour. Relevance The resulting knowledge of these studies can be employed to inspire the different domains merged within this thesis. For the HEMS industry: in striving to designing HEMS that are capable of influencing users, effective in reducing energy consumption, and easily usable and implementable in everyday life. For the building industry this research illustrated the benefit of considering the behaviour of inhabitants in achieving sustainable housing transformation. Furthermore, lessons were presented in how the building industry can contribute to increasing the ease of implementation of HEMS. HEMS researchers may assimilate knowledge for future research to deepen the knowledge on ways of increasing the effectiveness of HEMS

Usable privacy and security in smart homes

Ubiquitous computing devices increasingly dominate our everyday lives, including our most private places: our homes. Homes that are equipped with interconnected, context-aware computing devices, are considered “smart” homes. To provide their functionality and features, these devices are typically equipped with sensors and, thus, are capable of collecting, storing, and processing sensitive user data, such as presence in the home. At the same time, these devices are prone to novel threats, making our homes vulnerable by opening them for attackers from outside, but also from within the home. For instance, remote attackers who digitally gain access to presence data can plan for physical burglary. Attackers who are physically present with access to devices could access associated (sensitive) user data and exploit it for further cyberattacks. As such, users’ privacy and security are at risk in their homes. Even worse, many users are unaware of this and/or have limited means to take action. This raises the need to think about usable mechanisms that can support users in protecting their smart home setups. The design of such mechanisms, however, is challenging due to the variety and heterogeneity of devices available on the consumer market and the complex interplay of user roles within this context. This thesis contributes to usable privacy and security research in the context of smart homes by a) understanding users’ privacy perceptions and requirements for usable mechanisms and b) investigating concepts and prototypes for privacy and security mechanisms. Hereby, the focus is on two specific target groups, that are inhabitants and guests of smart homes. In particular, this thesis targets their awareness of potential privacy and security risks, enables them to take control over their personal privacy and security, and illustrates considerations for usable authentication mechanisms. This thesis provides valuable insights to help researchers and practitioners in designing and evaluating privacy and security mechanisms for future smart devices and homes, particularly targeting awareness, control, and authentication, as well as various roles.Computer und andere „intelligente“, vernetzte Geräte sind allgegenwärtig und machen auch vor unserem privatesten Zufluchtsort keinen Halt: unserem Zuhause. Ein „intelligentes Heim“ verspricht viele Vorteile und nützliche Funktionen. Um diese zu erfüllen, sind die Geräte mit diversen Sensoren ausgestattet – sie können also in unserem Zuhause sensitive Daten sammeln, speichern und verarbeiten (bspw. Anwesenheit). Gleichzeitig sind die Geräte anfällig für (neuartige) Cyberangriffe, gefährden somit unser Zuhause und öffnen es für potenzielle – interne sowie externe – Angreifer. Beispielsweise könnten Angreifer, die digital Zugriff auf sensitive Daten wie Präsenz erhalten, einen physischen Überfall in Abwesenheit der Hausbewohner planen. Angreifer, die physischen Zugriff auf ein Gerät erhalten, könnten auf assoziierte Daten und Accounts zugreifen und diese für weitere Cyberangriffe ausnutzen. Damit werden die Privatsphäre und Sicherheit der Nutzenden in deren eigenem Zuhause gefährdet. Erschwerend kommt hinzu, dass viele Nutzenden sich dessen nicht bewusst sind und/oder nur limitierte Möglichkeiten haben, effiziente Gegenmaßnahmen zu ergreifen. Dies macht es unabdingbar, über benutzbare Mechanismen nachzudenken, die Nutzende beim Schutz ihres intelligenten Zuhauses unterstützen. Die Umsetzung solcher Mechanismen ist allerdings eine große Herausforderung. Das liegt unter anderem an der großen Vielfalt erhältlicher Geräte von verschiedensten Herstellern, was das Finden einer einheitlichen Lösung erschwert. Darüber hinaus interagieren im Heimkontext meist mehrere Nutzende in verschieden Rollen (bspw. Bewohner und Gäste), was die Gestaltung von Mechanismen zusätzlich erschwert. Diese Doktorarbeit trägt dazu bei, benutzbare Privatsphäre- und Sicherheitsmechanismen im Kontext des „intelligenten Zuhauses“ zu entwickeln. Insbesondere werden a) die Wahrnehmung von Privatsphäre sowie Anforderungen an potenzielle Mechanismen untersucht, sowie b) Konzepte und Prototypen für Privatsphäre- und Sicherheitsmechanismen vorgestellt. Der Fokus liegt hierbei auf zwei Zielgruppen, den Bewohnern sowie den Gästen eines intelligenten Zuhauses. Insbesondere werden in dieser Arbeit deren Bewusstsein für potenzielle Privatsphäre- und Sicherheits-Risiken adressiert, ihnen Kontrolle über ihre persönliche Privatsphäre und Sicherheit ermöglicht, sowie Möglichkeiten für benutzbare Authentifizierungsmechanismen für beide Zielgruppen aufgezeigt. Die Ergebnisse dieser Doktorarbeit legen den Grundstein für zukünftige Entwicklung und Evaluierung von benutzbaren Privatsphäre und Sicherheitsmechanismen im intelligenten Zuhause

Examining the customer journey of solar home system users in Rwanda and forecasting their future electricity demand

Globally, 771 million people lack access to electricity, out of which 75% live in Sub-Saharan Africa (IEA, 2020b). Electricity grid expansion can be costly in rural areas, which often have low population densities. Solar home systems (SHS) have provided people worldwide an alternative option to gain electricity access. A SHS consists of a solar panel, battery and accompanying appliances. This research aims to advance the understanding of the SHS customer journey using a case study of SHS customers in Rwanda. This study developed a framework outlining households’ pre- to post-purchase experiences, which included awareness and purchase, both current and future SHS usage and finally customers’ upgrade, switching and retention preferences. A mixed methods approach was utilised to examine these steps, including structured interviews with the SHS providers’ customers (n=100) and staff (n=19), two focus groups with customers (n=24), as well as a time series analysis and descriptive statistics of database customers (n=63,299). A convolutional neural network (CNN) was created to forecast individual SHS users’ future electricity consumption in the next week, month and three months based on their previous hourly usage. Despite the volatility of SHS usage data, the CNN was able to forecast individual users’ future electricity more accurately than the naïve baseline, which assumes a continuation of previous usage. The time series analysis revealed an evening usage peak for non-television users, whilst customers with a television experienced an additional peak around midday. SHS recommendations prior and post-purchase were common, highlighting the circular nature of the customer journey. The main purchase reason and usage activity were having a clean energy source and phone charging respectively. A better understanding of the SHS customer journey may increase the number of households with electricity access, as companies can better address the purchase barriers and tap into the power of customer recommendations