Design support for energy efficiency and summer comfort of dwellings in early design phases: A framework for a design tool adapted to the architects’ practice in Flanders

Abstract

With regard to present issues of climate change, sustainable construction is a very current topic. In the broad context of sustainable building, this research focuses on energy efficiency, considering the large energy reduction potential of the building sector. Due to increased awareness of energy use, the European EPBD was introduced in 2002, with a recast in 2010 requiring nearly zero‐energy performance from 2021. In this frame, the energy performance regulation (EPB) was implemented in Flanders in 2006. Because of the potential of architectural design parameters to influence the building’s energy performance, combined with the fact that important decisions with impact on energy are taken in the early design phase, energy efficiency should be integrated from the start of the design. In addition to energy use, summer comfort is also important. As to the extensive insulation, together with increased outdoor temperatures the importance of summer comfort increases. However, the simultaneous integration of energy and summer comfort constitutes a very complex matter. Hence, to be able to make informed decisions in this regard, project specific information is needed about the impact of architectural parameters on energy consumption and summer comfort, from the start of the design. The architectural practice in Flanders mainly comprises small architectural offices with a dominant focus on small scale projects. Therefore, this research focuses on dwellings. For these project types, budgets are often too restricted to involve specialists in the design. Hence, information should be made available to architects in a different way. In general, these aspects indicate the importance of early design support for architects, regarding energy and summer comfort performance. The integration of building simulation in the design process might be a possible solution in this regard, but most existing tools are not developed from the designer’s perspective. Also, a link with regulations proves to be important. The Flemish EPB software is specifically connected to the Flemish legislation, but requires too much input and is not easy to use. Overall, there is no tool available that is capable of supporting Flemish architects from early design. In this regard, research is needed into a design support tool that aids architects to gain understanding about the impact of their decisions in the field of energy and summer comfort from the start of the design. Aim of this research is the development of an underlying framework for such a tool. The specific focus lies on the early design phase and on providing relevant feedback concerning energy and summer comfort, taking into account the limited input that is available in the early phase. In first instance, the focus lies on the development of a scientific based calculation module. In addition, it is important that the framework for an energy design tool is optimally adapted to the working method of architects and to the design process. Hence the user‐friendliness of a tool also constitutes an important research focus. The actual development of the tool itself is outside the scope of this Ph.D. research. Three aspects are important in relation to the framework, being the user of a tool (i.e. architects), the context (Flanders, single family dwellings) and the design process. Furthermore, this thesis comprises 3 parts, “design process and support” (part 1), “energy and summer performance” (part 2) and “transition” (part 3).

Part 1: Design process and support Considering the practice oriented nature of the framework, a large part of the research constitutes of empirical research. In this regard, the development of a theoretical base is necessary. Therefore, as a first step in the research, an analysis of the design process and of design support is conducted through literature review (chapter 2). Aim is to gain insight into the general characteristics of the design process and the existing methods and criteria for the integration of simulation in the design process, among other. Chapter 3 examines the available design parameters, pertaining to energy and comfort, in the design phases through case studies. Based on a resulting scheme, the parameters for which default values are necessary can be identified, adapting the framework to the early design phase. In addition, the integration of energy aspects into design is examined. Chapter 4 specifically focuses on important criteria for the framework of an energy design tool. First, the roles of and needs for design support tools in general are examined through a survey. Then, the use of energy tools in particular and architects’ needs for energy tools are examined based on interviews and a survey. These findings result in a conceptual frame, defining the user‐friendliness of energy tools from an architect’s perspective. Finally, the strengths and weaknesses of existing energy simulation tools are identified. Part 2: Energy and summer performance The second part focuses on the scientific foundation to adapt the framework to the limited available information of early design, while still providing relevant feedback regarding the expected energy and summer comfort performance. To calculate energy consumption, the EPB calculation model is used. This model constitutes the core of the framework. The model for summer comfort, on the other hand, is more independent and can always be replaced. In addition to a description of the EPB model, chapter 5 describes a search after a simple approach for summer comfort. Chapter 6 then specifically addresses the adaptation of the underlying calculation model to the early design phase through the application of default values. The default values primarily focus on energy and are determined through a detailed parametric study on the EPB model. Subsequently, the applicability of the default values is tested in a number of cases. Part 3: Transition Starting from a rather theoretical focus of part 1 and 2, part 3 forms a transition to the practical implementation, despite the fact that an actual tool will not be developed. Important aspects for an energy design tool regarding input, interface, output and usability in the design process are investigated through focus groups with architects (chapter 7). Here, the underlying idea of integrating energy assessment in a 3D program is taken along as point of departure. An important part of this chapter focuses on the content and visualization of the output for the framework of an energy tool. Part 3 closes with the general conclusions of this thesis and perspectives for future research. After part 3, an extended epilogue is incorporated, providing a first indication of the implementation of the research results in practice.