Growing and even excessive use of digital technology has unquestionably fuelled demand for digital devices and online services leading to a wide range of societal and environmental impacts. In sustainability terms, ICT as a whole is estimated to produce up to nearly 4% of global greenhouse gas emissions. As presumed responsible innovators, the HCI community should now consider design strategies that will reduce use and demand for digital technology for the good of both its users and the planet—strategies perhaps even seen as retrogressive in an era where digital technology is constantly implicated in innovation and economic growth. Prior work has noted the potential to design “more moderate” interactions for sustainability, simultaneously addressing negative societal impacts on users’ wellbeing, relationships, productivity at work, and privacy. In this paper, we explore how we may design intentionally moderate digital interactions that retain our participants’ “more meaningful” experiences. We report on the outcomes of two design workshops to uncover experiences of meaningful device and service use, to inform practical designs for ‘moderate and meaningful’ interaction. From this, we offer design recommendations that aim to address the multiple negative impacts that digital technology can create, and discuss the possible barriers to these designs.

From Fanger's seminal work on thermal comfort in the 1970s, standards governing temperatures in the workplace enshrine clothing level calculations based on full business suits, and building regulations developed using only male metabolic data, locking in a default male perspective. Even later work that highlights gender biases with regard to metabolism calculation, inclusive of both genders has focused on younger women, and the voices of older working women are missing from this discourse. We invited women over 45 to explore what they find important in workplace thermal comfort, and how devices and interfaces might meet their needs and also encourage thermal adaptivity. Our study highlights factors such as 'fresh air', and the importance of empathy to fellow inhabitants. We bring new voices to the thermal comfort discourse which supports reducing energy use in the workplace, improving thermal environments and ensuring the needs of a diverse, aging workforce are considered.

Internet use and online services underpin everyday life, and the resultant energy demand is almost entirely hidden, yet significant and growing: it is anticipated to reach 21% of global electricity demand by 2030 and to eclipse half the greenhouse gas emissions of transportation by 2040. Driving this growth, real-time video streaming ('watching') is estimated at around 50% of all peak data traffic. Using a mixed-methods analysis of the use of 66 devices (e.g. smart TVs, tablets) across 20 participants in 9 households, we reveal the online activity of domestic watching and provide a detailed exploration of video-on-demand activities. We identify new ways in which watching is transitioning in more rather than less data demanding directions; and explore the role HCI may play in reducing this growing data demand. We further highlight implications for key HCI and societal stakeholders (policy makers, service providers, network engineers) to tackle this important issue.

The evaluation of research artefacts is an important step to validate research contributions. Sub-disciplines of HCI often pursue primary goals other than usability, such as Sustainable HCI (SHCI), HCI for development, or health and wellbeing. For such disciplines, established evaluation methods are not always appropriate or sufficient, and new conventions for identifying, discussing, and justifying suitable evaluation methods need to be established. In this paper, we revisit the purpose and goals of evaluation in HCI and SHCI, and elicit five key elements that can provide guidance to identifying evaluation methods for SHCI research. Our essay is meant as a starting point for discussing current and improving future evaluation practice in SHCI; we also believe it holds value for other subdisciplines in HCI that encounter similar challenges while evaluating their research.

This note discusses opportunities for the HCI community to engage with environmental public policy. It draws on insights and observations made during the primary author's recent work for a policy unit at Global Affairs Canada, which is a federal ministry of the Government of Canada. During that work, the primary author identified several domains of environmental public policy that are of direct relevance to the HCI community. This note contributes a preliminary discussion of how, why, with whom, and in what capacity HCI researchers and practitioners might engage with three types of environmental public policy: climate change, waste electrical and electronic equipment, and green ICT procurement policies. This builds on existing public policy and environmental knowledge within the HCI community and responds directly to calls from some members to engage with environmental public policy.

Motivated by mobile devices' growing demand for connectivity, and concern in HCI with the energy intensity and sustainability of networked services, in this paper we reveal the impact of applications on smartphones and tablets in terms of network demand and time use. Using a detailed mixed methods study with eight participants, we first provide an account of how data demand has meaning and utility in our participants' social practices, and the timing and relative impacts of these. We then assess the scale of this demand by drawing comparison between our fine-grained observations and a more representative dataset of 398 devices from the Device Analyzer corpus. Our results highlight the significant categories of data demanding practice, and the identification of where changes in app time and duration of use might reduce or shift demand to reduce services' impacts.

This paper empirically explores the role that mobile devices have come to play in everyday practice, and how this links to demand for network connectivity and online services. After a preliminary device-logging period, thirteen participants were interviewed about how they use their iPhones or iPads. Our findings build a picture of how, through use of such devices, a variety of daily practices have come to depend upon a working data connection, which sometimes surges, but is at least always a trickle. This aims to inform the sustainable design of applications, services and infrastructures for smartphones and tablets. By focusing our analysis in this way, we highlight a little-explored challenge for sustainable HCI and discuss ideas for (re)designing around the principle of 'light-weight' data 'needs'.

In many parts of the world, the electricity supply industry makes the task of dealing with unpredictable spikes and dips in production and demand invisible to consumers, maintaining a seemingly unlimited supply. A future increase in reliance on time-variable renewable sources of electricity may lead to greater fluctuations in supply. We engaged remote islanders as equal partners in a research project that investigated through technology-mediated enquiry the topic of synchronising energy consumption with supply, and together built a prototype renewable energy forecast display. A number of participants described a change in their practices, saving high energy tasks for times when local renewable energy was expected to be available, despite having no financial incentive to do so. The main contributions of this paper are in: 1) the results of co-development sessions exploring systems supporting synchronising consumption with supply and 2) the findings arising from the deployment of the prototype.

Tightly regulating indoor building temperatures using mechanical heating and cooling contributes significantly to worldwide greenhouse gas emissions. One promising approach for reducing the energy demand associated with indoor climate control is the adaptive model for thermal comfort. In this paper, we explore the challenges and opportunities for supporting the transition toward adaptive thermal comfort in conventionally heated buildings. We replaced the heating control system for eight university undergraduates living on campus for fifty days from January-March 2013. We report on the participants' experiences of living with and adapting to the change in conditions. We reflect on the lessons arising from our intervention for researchers and practitioners seeking to design for sustainability and thermal comfort.

To date, research in sustainable HCI has dealt with eco-feedback, usage and recycling of appliances within the home, and longevity of portable electronics such as mobile phones. However, there seems to be less awareness of the energy and greenhouse emissions impacts of domestic consumer electronics and information technology. Such awareness is needed to inform HCI sustainability researchers on how best to prioritise efforts around digital media and IT. Grounded in inventories, interview and plug energy data from 33 undergraduate student participants, our findings provide the context for assessing approaches to reducing the energy and carbon emissions of media and IT in the home. In the paper, we use the findings to discuss and inform more fruitful directions that sustainable HCI research might take, and we quantify how various strategies might have modified the energy and emissions impacts for our participants.

In four university student kitchens over twenty-one days, we captured participants' food preparation activity, quantified the greenhouse gas emissions and direct energy connected to the food and cooking, and talked to participants about their food practices. Grounded in this uniquely detailed micro-account, our findings inform sustainable design for cooking and eating at home and quantify the potential impacts. We outline the relation of the impacts to our participants' approaches to everyday food preparation, the organisation of their time, and the role of social meals. Our technique allows evaluation of opportunities for sustainable intervention design: at the appliance, in the digitally-mediated organisation of meals and inventory management, and more broadly in reflecting upon and reshaping diet.

In many parts of the world, mechanical heating and cooling is used to regulate indoor climates, with the aim of maintaining a uniform temperature. Achieving this is energy-intensive, since large indoor spaces must be constantly heated or cooled, and the difference to the outdoor temperature is large. This paper starts from the premise that comfort is not delivered to us by the indoor environment, but is instead something that is pursued as a normal part of daily life, through a variety of means. Based on a detailed study of four university students over several months, we explore how Ubicomp technologies can help create a more sustainable reality where people are more active in pursuing and maintaining their thermal comfort, and environments are less tightly controlled and less energy-intensive, and we outline areas for future research in this domain.

This paper develops a holistic framework of questions which seem to motivate sustainability research in computing in order to enable new opportunities for critique. Analysis of systematically selected corpora of computing publications demonstrates that several of these question areas are well covered, while others are ripe for further exploration. It also provides insight into which of these questions tend to be addressed by different communities within sustainable computing. The framework itself reveals discursive similarities between other existing environmental discourses, enabling reflection and participation with the broader sustainability debate. It is argued that the current computing discourse on sustainability is reformist and premised in a Triple Bottom Line construction of sustainability. A radical, Quadruple Bottom Line alternative is explored as a new vista for computing research.

In this paper we present a room-to-room thermal model used to accurately predict temperatures in residential buildings. We evaluate the accuracy of this model with ground truth data from four occupied family homes (two in the UK and two in the US). The homes have differing construction and a range of heating infrastructure (wall-mounted radiators, underfloor heating, and furnace-driven forced-air). Data was gathered using a network of simple and sparse (one per room) temperature sensors, a gas meter sensor, and an outdoor temperature sensor. We show that our model can predict future indoor temperature trends with a 90th percentile aggregate error between 0.61--1.50°, when given boiler or furnace actuation times and outdoor temperature forecasts. Two existing models were also implemented and then evaluated on our dataset alongside Matchstick. As a proof of concept, we used data from a previous control study to show that when Matchstick is used to predict temperatures (rather than assuming a preset linear heating rate) the possible gas savings increase by up to 3%.

Home heating is a major factor in worldwide energy use. Our system, PreHeat, aims to more efficiently heat homes by using occupancy sensing and occupancy prediction to automatically control home heating. We deployed PreHeat in five homes, three in the US and two in the UK. In UK homes, we controlled heating on a per-room basis to enable further energy savings. We compared PreHeat's prediction algorithm with a static program over an average 61 days per house, alternating days between these conditions, and measuring actual gas consumption and occupancy. In UK homes PreHeat both saved gas and reduced MissTime (the time that the house was occupied but not warm). In US homes, PreHeat decreased MissTime by a factor of 6-12, while consuming a similar amount of gas. In summary, PreHeat enables more efficient heating while removing the need for users to program thermostat schedules.

We present an efficient CDMA detection core suited for multiuser indoor acoustic positioning. An ultrasonic multi-code despreader is proposed, allowing simultaneous broadband acoustic ranging signals to be processed in real time by embedded sensors. The ranging performance is characterised using a dataset gathered from a real deployment of ultrasonic devices and is shown to be favourable. The proposed core can be used as a basis for more sophisticated receivers, such as those capable of detecting heavily Doppler-shifted signals.

For locating a set of stationary devices, algorithms such as MDS-MAP have been favoured by the sensor network community. This is generally because of their low computational complexity. Whilst comparisons for complexity and performance have been done for other algorithms, non-linear regression (NLR) has been neglected. The authors find that it is not much more expensive than MDS-MAP, yet can yield significantly better accuracy for sensor network localisation.

A large number of MAC protocols support energy efficiency in sensor networks by forming rigid sleep/wakeup schedules. This demonstration illustrates an energy-efficient protocol which adapts to changing sensor update rates, as required by certain application scenarios such as real time location tracking.

Ultrasonic location systems are a popular solution for the provision of fine-grained indoor positioning data. Applications include enhanced routing for wireless networks, computer-aided navigation, and location-sensitive device behavior. However, current ultrasonic location systems suffer from limitations due to their use of narrowband transducers, This paper investigates the use of broadband ultrasound for indoor positioning systems. Broadband ultrasonic transmitter and receiver units have been developed and characterized. The utilization of these units to construct two positioning systems with different architectures serves to highlight and affirm the concrete, practical benefits of broadband ultrasound for locating people and devices indoors.

If a mobile computing device knows how it is positioned and oriented in relation to other devices nearby, then it can provide enhanced support for multi-device and multi-user interactions. Existing systems that provide position information to mobile computers are reliant on externally deployed infrastructure, such as beacons or sensors in the environment. We introduce the Relate system, which provides fine-grained relative position information to co-located devices on the basis of peer-to-peer sensing, thus overcoming dependence on any external infrastructure. The system is realised as a hardware/software plug-in, using ultrasound for peer-to-peer sensing, USB to interface with standard mobile devices, and data abstraction and inferencing to map sensor data to a spatial model that maintains both quantitative and qualitative relationships. We present a set of services and applications to demonstrate the utility of the system. We report experimental results on the accuracy of the relative position and orientation estimates, and other aspects of system performance.

Many mobile applications can be greatly enhanced when provided with the locations of people and devices. Ultrasonic location systems have been shown to supply location information with centimeter accuracy at high update rates. Such high-performance systems, however, have relied upon a centralized or coordinated architecture, preventing the user from being in control of how their location information is handled and thus giving rise to privacy concerns. In this paper we present a privacy-oriented location system allowing users with mobile ultrasonic receivers to ascertain their position autonomously. We formulate a method of operation for the system, detail its implementation in a small office, and characterize the performance of the system. The utilization of broadband ultrasound makes it possible for the privacy-oriented location system to have competitive accuracy and high update rates, while allowing the user to be in direct control of their location information.