Building characteristics and energy use of energy-efficient renovated offices

Chapter 2 presented the physical and psychological satisfaction parameters for user-focused evaluation. In most renovation projects, the façade is a major consideration next to the HVAC system to optimise the performance of the building. Many studies reveal that façade renovation has a large impact on the energy efficiency. The aim of this chapter is to identify the characteristics of renovated offices, such as façade types, HVAC system, and sun shading, and compare the energy performance based on user typologies in renovated and non-renovated office buildings. Section 3.2 describes an overview of façade renovation strategies based on literature. The renovation strategies are classified into four strategies: passive add-in, replacement, climate skin, and active add-in. Section 3.3 presents the criteria to select case studies. Section 3.4 describes the characteristics of four renovated case studies and one non-renovated case located in the Netherlands. The building information was collected through interviews with architects, a review of project documents, and a field survey. Cross-analysis was used to compare the renovation plan, physical conditions. Energy consumption of each office building was compared by different energy metrics in section 3.5. Section 3.6 discusses the limitation of the renovation projects and suggestions for the future study. The finding from cross-evaluation of case studies are described in section 3.7

Impact of design factors on user satisfaction

Personal control was one of the influential parameters for user satisfaction presented in chapter 5. Personal control is not related to architectural office design, and in this thesis it is not associated with privacy and communication with colleagues. Thermal and visual comfort is analysed exhaustively in this chapter. Psychological comfort is an extra parameter for user satisfaction studies since the design factors such as office layout could be correlated to privacy, communication and so on. As a next step, chapter 6 investigates influential office design factors on user satisfaction related to thermal, visual, and psychological comfort and predicting which design factors may bring better satisfaction to users. Section 6.2 presents design factors affecting user satisfaction based on literature review. Five office cases in the Netherlands with 579 office occupants were studied using questionnaires, and interviews with facility managers and architects (section 6.3). Different statistical analysis tests were conducted to summarise satisfaction factors (section 6.4). The relative importance of design factors is described in section 6.5, and a regression analysis was used to predict profound outcomes in section 6.6

Energy-Efficient Office Renovation:

This research aims to develop user-focused design principles for energy-efficient office renovations. The goal of this is to improve the quality and comfort of workspaces without compromising on energy-saving goals. Due to increasing sustainability requirements, new ways of working and changing office user preferences, there is a growing need for office renovations that not only deal with the energy performance and the replacement of building facilities, but also the occupants’ health and well-being. The renovation of office buildings can substantially reduce energy demand and improve building performance. For this reason, most studies regarding office renovations have focused on achieving better energy performance and indoor environmental quality. Also, several studies have investigated employee satisfaction in the work environment. However, the users are only considered after the buildings have been built and taken into use (e.g., postoccupancy evaluation), but not in the early stage of the design phase. Although there are building regulations and norms regarding indoor comfort, no clear design principles or guidelines considering users have been developed for office renovations. Therefore, it is necessary to explore how office users can be included in the early design stage of office renovations to improve their comfort and satisfaction. This led to the following main research question to be answered in this thesis: How can design principles for energy efficient office renovation be developed, based on the evaluation of user satisfaction? To answer to this question, field studies were conducted in 5 office buildings in the Netherlands. The cases consist of four renovated offices and one non-renovated office, originally built in 1960s to 70s. Before conducting empirical studies, a literature was conducted that is implemented in the theoretical framework. Ten parameters for satisfaction, such as thermal comfort, air quality, light, noise, personal control, privacy, concentration, communication, social contact, and territoriality, were defined and were classified based on the findings from 124 items of studies focussing on physical and psychological satisfaction in the work environment. Each chapter and several sub-research questions address these parameters. Based on the findings, a classification of user satisfaction parameters is proposed, including a discussion about an hierarchy of ten parameters. This hierarchy is structured based on theoretical definitions of parameters and its physical, functional, and psychological influences.  For the empirical studies, a multidisciplinary methodology was applied to prioritise the important aspects of office renovations. The various methods for data collection and analyses included examining energy use and the quality of indoor climate after renovation, and investigating the impact of design factors on user satisfaction with thermal, visual, and psychological comfort. The design factors in this research are influential design factors on user satisfaction. These are office layout, orientation, window-to-wall ratio, and desk location. The empirical studies are structured in four parts. Energy consumption As a preliminary study, architects and facility managers were interviewed to identify the building characteristics of renovated offices and energy consumption. Henceforth, the five case studies were conducted. A cross-case-analysis was used to compare the building characteristics of the five case studies. The energy consumption of renovated and non-renovated offices were compared by different energy matrix. In addition, the limitations that hinder the achievement of better energy performance, were described. Indoor climate and users’ thermal comfort Indoor temperature and humidity were measured by using data loggers to identify the condition of the indoor climate for users’ thermal comfort after renovation. A questionnaire, including thermal sensation, preference, and satisfaction, was distributed among the building users. The monitored climate data of the thermal conditions were evaluated based on the Dutch building norms and users’ responses. Personal control This part aims to identify the relationship between the degree of personal control over indoor environmental conditions (e.g., temperature, ventilation, light) and user satisfaction with thermal and visual comfort. This study investigated the impact of personal control on user satisfaction through user surveys and statistical analyses. The results present that higher controllability leads to more satisfaction in terms of thermal and visual comfort. It also reveals the psychological impact of personal control on user satisfaction by showing differences in perceived satisfaction according to ‘no control’ and ‘do not have’. These findings provide support to workplace management and the design of personal environmental control systems. User satisfaction with thermal, visual, and psychological comfort Together with the indoor climate conditions of workspaces, 579 office users from the five cases were studied. The responses of the users were collected and analysed through statistical analyses. This study phase demonstrates the results of the impact of influential office design factors on user satisfaction with thermal, visual, and psychological comfort. It also contributes to predicting which design variables may bring better user satisfaction. After the empirical studies, the conceptual study was conducted through energy simulation to evaluate the impact of the combination of design factors on the energy demand. Twenty-four office model variants were created based on the combination of design factors, which are consisted of 3 or 4 variables. The energy demand is predicted according to the office model variants. As a next step, the design principles were developed by incorporating the previous findings and various perspectives of energy-efficient office renovation. An overview of the predicted user satisfaction and energy demand is graphically provided in this research. Based hereupon, a flow chart is created for applying the principles to the renovation process. First, the most influential design factors on thermal, visual, and psychological satisfaction are suggested in the design principles. Next, the values of predicted user satisfaction and energy demand can be evaluated by following the flow chart, to find the optimal renovation plan. In this step renovation alternatives are suggested in terms of office variants to create a balance between user satisfaction and energy efficiency. Last, if design limitations occur, the degree of personal control should be included to increase user satisfaction. The comprehensive design principles can help architects, designers, and facility managers to make design decisions in an early stage of office renovations. To summarise, this research demonstrates the relationship between design factors, indoor climate and user satisfaction, without neglecting the fundamental goal of office renovation: reducing the energy demand, upgrading facilities, and improving building performance. It also contributes to developing design principles for office renovations with integrated user perspectives, that improve users’ satisfaction and comfort, as well as energy efficiency. Although users’ individual control over the indoor environment has a significant impact on satisfaction, it needs to be explored further. In addition, it is important to mention that other variables such as building elements and various façade configurations need to be included in further research. In conclusion, design principles considering both energy efficiency and user satisfaction will not only contribute to an increase in the value of a building, but also serve as a stepping stone for user-focused office designs or user-related aspects of the built environment

User-focused design principles

Chapter 7 tested the energy demand of possible office typologies. However, the main aim of the thesis is to develop user-focused design principles for energy efficient office renovation. Therefore, it is important to compare the degree of user satisfaction of highly energy-efficient office typologies. Based on the results from chapter 7, chapter 8 introduces design principles that architects, and facility and real estate managers can use to select the combination of parameters with better user satisfaction during a conceptual design stage of office renovation. It contains a database of the different degrees of user satisfaction with thermal, visual, and psychological comfort, according to the combination of design parameters. Section 8.2 explains the design principles considering user satisfaction and energy efficiency. Section 8.3 provides the overview of predicted satisfaction of 144 office combinations. Recommended office combinations based on energy efficiency are explained in section 8.4. Section 8.5 describes the process of application of the design principles: how can designers interpret and use the principles and predicted models for energy-efficient office renovation

Impact of personal control on user satisfaction

Chapter 4 provided the impact of indoor climate on user satisfaction. Many studies reported that personal control over indoor environmental conditions is one of the influential factors for user satisfaction and environmental comfort due to its physical and psychological impacts. However, it is not clear to what extent users should be allowed to have control over the indoor environment. This chapter aims to identify the relationship between the extent to which users can personally control the conditions of their indoor environment and how satisfied they are with their thermal and visual comfort. Section 5.2 presents the data collection and assessment methods of occupants’ perceived satisfaction. The relationship between personal control and satisfaction is explained in section 5.3. Section 5.4 presents the dependency of user satisfaction with thermal comfort based on the degree of personal control over indoor environmental conditions, and section 5.5 explains the impact of the degree of person control on the user satisfaction with visual comfort. Section 5.6 discusses limitations of research of personal control, psychological impact of personal control, and how to design the personal control to optimise user satisfaction

Introduction

Energy-efficient office renovation is obviously required for the reasons mentioned in the previous section, and there is a great growth of energy renovation projects in practice. However, does a high energy performance office provide a comfortable working environment to its users? One of the reasons of office existence is to provide comfortable and healthy indoor environments (Ornetzeder et al., 2016). According to Klepeis et al. (2001), people spend over 80% of their time in enclosed spaces. Moreover, good indoor environments can lead to an increase of occupants’ productivity (Al-Horr et al., 2016). For these reasons, planning healthy and comfortable work environment can be as important as reducing energy use. The question is, how can we design healthy and comfortable work environments, with which the users are satisfied? The starting point to answer this question is to include building users’ requirements and satisfaction in workspaces in energy renovation schemes. A concern is that conventional renovation principles are mainly physical- and technical-oriented, whereas it does not focus on enhancing user satisfaction in the work environment. Moreover, as long as the renovated building does not offer sufficient quality or satisfaction, there will be less demand for renovated office buildings. When energy efficiency is considered as the only advantage of office renovation, it is difficult to convince developers, building owners, and investors that renovation is useful. From a managerial perspective, achieving better employee’s satisfaction should be a focal point to strengthen the market values of renovated offices, thereby achieving a higher demand from the market, preventing environmental degradation or vacancy of existing buildings. Therefore, office renovation also has to provide a high-level of comfortable work environment for the users’ well-being and satisfaction beside maximising energy reduction goals. Therefore, there is a significant need to investigate how to define the users’ satisfaction to contribute to better office renovations. The relationship between indoor climate and users’ physical health has been explored in extensive research (Al Horr et al., 2016; Bluyssen et al., 2016; Leder et al., 2016; Mandin et al., 2017). Followed by these studies, the framework of international green building rating systems such as Leadership in Energy and Environmental Design (LEED) and Building Research Establishment Environmental Assessment Method (BREEAM) include a category of social sustainability as a means of providing a healthy and comfortable environment to users for both new and renovated buildings (Sarkis et al., 2012; Zuo & Zhao, 2014). Although international green building rating systems address the significance of including user perspectives, there is a lack of guidelines and information that focus on user satisfaction in building renovation. Especially, the relationship between design factors and user satisfaction has rarely been investigated due to several reasons; user satisfaction is a subjective topic; design factors are closely related to energy efficiency and aesthetic aspects rather than user satisfaction. Therefore, the main problem is that in spite of the development of various renovation techniques, there is still a lack of renovation design principles considering user preferences and user satisfaction due to the indirect relationship with energy use. In any renovation project, the initiative is the most significant phase to ensure proper decisions and to optimise overall renovation values and results, that should be considered in the early renovation design stage. Jensen and Maslesa (2015) stated that the main barriers include lack of standard principles and a lacking overview of potential values in the initiative phase. To summarise all these aspects, it is required to develop an overview of potential values and standard design principles that not only focus on energy efficiency but also on the building users for office renovations

Conclusions

This research has explored the relationship between user satisfaction and design factors for office renovations considering energy efficiency. The findings of this research strongly support user-focused renovations of office buildings. My motivation for this research started from the consideration of comfort and satisfaction of building users and the focus on providing better and comfortable work environments for office users. The focus on user comfort and satisfaction is important, because literature shows that the increase of user satisfaction leads to the improvement of productivity and less absenteeism in workspaces. This research has been conducted by applying diverse research methods and analyses, such as monitoring the indoor climate of office buildings, interviewing architects and facility managers, conducting user surveys, and conducting statistical analyses. This chapter presents the conclusions by answering the main research question and corresponding sub-questions of each chapter. This chapter also includes the general conclusions highlighting the scientific contributions to the body of knowledge of the built environment and limitations of the research

Theoretical framework for user-focused evaluation in office design

As was stated in the introduction, a user-focused renovation approach can enhance user satisfaction in offices and the functional quality of the offices while meeting energy performance goals. The first step for this renovation approach is to identify users’ needs and the physical and psychological factors affecting user satisfaction, as input to office renovation projects. The main aim is to identify the factors that are affecting the physical and psychological satisfaction of users, based on what previous research has found in that field. Therefore, this chapter highlights the main parameters currently applied to the evaluation of user satisfaction, including the definitions based on the literature review. The research approach for the literature review is discussed in section 2.2. Searching was limited to the main key terms of office, work environment, and user satisfaction and comfort. Section 2.3 explores the relationship between office renovation and user satisfaction. The terms user satisfaction and the user’s expectations in workplaces are defined in section 2.4. In section 2.5, the important factors were searched through empirical-based international literature mainly. Based hereupon, section 2.6 discusses the challenge of evaluating user satisfaction. In section 2.7, the findings present ten main parameters to increase user satisfaction in office renovation. The parameters were categorised into three levels based on needs theories to organise the hierarchy of priorities