Based on the previous assessment, the four main objectives of the research were defined as:
•
To empirically evaluate the mid- to long-term effectiveness of HEMS.HEMS are defined as intermediary products that can visualize, manage and/or monitor the energy use of products or entire households. Effectiveness is defined as the extent to which users can maintain significant energy savings in energy consumption over a prolonged period. Mid- to long-term refers to a period of longer than four months, with an emphasis on including all seasons.
•
To identify and explore factors that might influence the use effectiveness of HEMS. ‘Factors’ is a general term and to manage the scope of this exploratory research, this thesis focuses only on factors within the home. Therefore, the structure of the home should also be seen as the boundary to the elements that are discussed. In other words, the factors referred to in this thesis are related the house, its technical installations and appliances, people living within the home, the HEMS, and the relationships between these elements. Aspects such as legislation, policies and society are excluded because they require a different research approach.•
To infer design-related strategies for industrial designers and the building industry to improve the use and effectiveness of HEMS.•
To reflect on the implications for sustainable housing transformation, the HEMS industry and researchers, and their goal of reducing the energy consumption of households.Numerous parties are involved in HEMS and therefore HEMS industry is a comprehensive that includes -but is not limited to- designers, developers, energy companies, installers, and housing associations involved in the development and implementation of HEMS. Here, both practical and scientific implications for the fields of the building industry and industrial design engineering are intended. To achieve these goals, the following questions were explored:
•
What are the medium- to long-term results of HEMS on energy savings?•
What typical use patterns emerge when households have a HEMS in their homes over a prolonged period of time?•
What factors might influence the use and effectiveness of HEMS?•
What is the overall effectiveness of HEMS when taking their lifecycle and embedded energy into account?•
What can industry and researchers learn from implementing HEMS and conducting research with HEMS in existing households?The combined answers to these research questions led to the answer to the question: What design-related insights and guidelines can be inferred that influence the use and effectiveness of HEMS?
§ 1.4.1
Methodology
To achieve the objectives and address the four limitations of past research(§ 1.2), the author executed case studies with HEMS. The methodology for this largely exploratory research is discussed in this section.
The first two objectives concerning the mid- to long-term effectiveness of HEMS and factors that might influence the use effectiveness of HEMS, necessitated that HEMS be largely studied in their natural context of use. This allowed for the investigation of real-life household patterns, dynamics, longitudinal use and effectiveness, and changes over time. The HEMS were placed as an intervention in participants’ homes, which permitted the empirical evaluation of the mid- to long-term effectiveness of the intervention. However, as explained in § 1.2.4, there were large variances in the use of HEMS and the achieved energy savings; in other words, the outcome of past research on HEMS is not clear or straightforward. Therefore, the second objective lent itself to exploratory case studies. The natural environment supported the exploration of
influencing factors rather than focusing on a specified set of variables. In order to study the usability of the HEMS, experiments were also conducted in which participants (from the case studies) were invited to a lab for short sessions. In this way, the usability and first-time use could be studied in a controlled environment and with controlled ways in which the HEMS could be used. The third and fourth objectives concerning design-related strategies and the implications for the different parties could be gleaned from the findings of the case studies.
Furthermore, the design of the HEMS was expected to be an influencing factor on their use and effectiveness, due to the differences that were stated in the typology in § 1.1.2. This warranted the study of distinctly different HEMS in each of the case studies. Therefore, three case studies were set up in the Netherlands in cooperation with HEMS manufacturers, energy providers and TU Delft. Through the cooperation with commercial parties, the drawbacks resulting from the current gravitation of research towards studying monitors that give factual feedback on overall electricity consumption (as mentioned in § 1.2.1) could be addressed. As a result, the three HEMS cover a variety of characteristics: mono-functional and multifunctional, energy monitoring and energy managing, aggregated and disaggregated feedback, and feedback on gas and on electricity consumption.
To achieve the various goals, different methods were applied. The first case study focused on the longitudinal effectiveness of HEMS and therefore used qualitative research methods. The second and third case studies were more exploratory in nature and therefore both quantitative and qualitative research methods were initially applied in a mixed-method approach. The quantitative data was intended to be used to support the qualitative findings. However, due to a number of challenges in the execution of the case studies, the quantitative results from the second and third case studies were either unusable or unobtainable, as is explained in more detail in Chapters 5 and 8. Therefore, the approach used in the second and third case studies was made qualitative during their execution. The initial research objectives and questions were adjusted to correct for the shift in data; the objectives and research questions in § 1.4
reflect the final approach. The research was therefore more exploratory; certain findings can be substantiated with qualitative data but not with quantitative data.
§ 1.4.2
Framework to interpret the findings
The objectives highlight the exploratory nature of this research and reveal an aim to provide an expansive view of the HEMS landscape and the effectiveness of HEMS. To be able to do this in a structured manner within the domains of architecture and industrial design engineering, and with consideration for social sciences, a
framework was sought. The framework needed to fit within and give consideration to the multidisciplinary facets of the research. It also needed to be practicable yet comprehensive for the exploration and mapping of the relevant factors. I therefore felt that the human-computer interaction framework in Figure 1 (adapted from van Kuijk (2010) and Wever et al. (2008)) was applicable, as is explained in more detail in Chapter 3.
context of use
user HEMS
other
people otherproducts
time total energy consumption and possible reductions Figure 1
Factors influencing the use and effectiveness of HEMS. Adapted from Wever et al. (2008) and van Kuijk (2010)
The framework visualizes the elements and relational lines -or interactions- that influence the usability of a product. This thesis hypothesises that, specific for a HEMS, both the use and the effectiveness of a HEMS are dependent on the surrounding factors. A HEMS needs to be used and usable to enable households to receive feedback, and feedback is intended to reduce the energy consumption of households.
In this holistic approach, HEMS are discussed in relation to all the elements surrounding their use and household energy consumption, including housing, its technical installations and appliances, its inhabitants’ behaviours and social dynamics, and the practices that surround the use of products and energy (Figure 1). The element of time is added to include possible variances in use over time and the uncertainties with regard to the longitudinal effectiveness of HEMS in previous research as discussed
in § 1.2.2 and § 1.2.4. Additionally, a home is visualized as the perimeter of the framework. This both demarcates the boundary of the findings discussed in this thesis and also visualizes the context of the use of HEMS. This framework is used to categorize the findings in this thesis and to frame the chapters, as is explained in the following section.