1. Introduction
Energy problems and carbon emissions have become global issues, so there has been growing consciousness regarding energy consumption and carbon emission reductions. Based on past statistics, a global increase in energy demand of about 28% may occur by 2024 [
1]. More specifically, in terms of the building sector, energy consumption has remarkably increased in the last several decades [
2]. In China, the energy consumption of existing buildings is far larger than that of the total energy consumption [
3]. Specifically, the poor energy efficiency of existing residential buildings wastes a large amount of energy [
4]. To improve energy performance, the Chinese government focuses on the energy efficiency renovations of existing residential buildings in Northern China [
5]. For example, doors, windows, roofs, and external walls are renovated. However, various quality failures have happened and resulted in construction repair and even rework [
6,
7]. Additionally, some quality failures were repeated in building energy renovation projects [
8,
9], which caused losses for stakeholders [
10,
11].
These quality failures hinder energy efficiency during the construction and even usage processes of building energy renovation projects [
12]. Moreover, due to quality failures, a tremendous amount of energy is wasted annually in construction and usage processes, and hereby the high-quality performance of the constructions can reduce energy wastage [
7]. According to Forcada et al.’s studies, due to quality failures, a majority of the existing buildings that have been energy renovated do not save as much energy as the designs have predicted [
13]. Johnston et al. found that the heat-transfer coefficient is 1.6 times greater than predicted, caused by quality failures [
14]. Similarly, based on Bell et al.’s research, quality failures result in overall heat loss being 54% higher than predicted in residential buildings [
15]. Furthermore, occurrences of quality failures can lower the health and safety levels of residents [
16]. Thus, overcoming these quality failures is necessary to promote and boost the successful accomplishment of building energy renovation projects.
Building energy renovation projects lie at the heart of the implementation of energy-saving and low-carbon policies [
17]. Quality control and management in building energy renovation projects are challenging because of the presence of different technologies and government roles, which makes building energy renovation projects significantly different in scope from other construction projects [
18]. More precisely, building energy renovation projects have their own unique causes of quality failures [
19]. The mere identification of the causes alone is insufficient for understanding reasons for the quality failures during renovation construction. Therefore, it is important not only to identify but also to study the root causes to avoid quality failures happening in energy-saving renovations of residential buildings in the future.
In spite of building energy renovation projects’ significance, there are limited detailed studies that investigate the causes of quality failures [
20]. Therefore, this study took empirical cases and made field visits in Hohhot, the provincial capital of Inner Mongolia, in Northern China. The city was selected as the case site for research based on three selection criteria. First, Hohhot is located in the ‘heating areas’ in Northern China, and is well known as a building energy renovation city. Second, this city is supported by central and local governments to be an exemplar for building energy renovations. Third, as part of the energy renovation program in Hohhot, there is a requirement to record the occurrence of quality failures, and construction quality is strictly controlled and managed. These selection criteria ensure the renovation projects in Hohhot cover a broad diversity of the characteristics of the causes of quality failures, allowing an understanding of the quality failures that have occurred and their causes.
Fortunately, it was possible to locate cooperative respondents for the building energy renovation projects in Hohhot. The authors visited there twice, in 2018 and 2019, to organize expert interviews and a focus group. The respondents were representative of the stakeholders involved in the building energy renovation projects, including government officials, project managers, supervisors, and designers. The questionnaire survey was conducted in Northern China, and 113 valid questionnaires were received with a representative sample of the stakeholders playing different roles in energy building renovation projects.
Our research departs from previous studies. Some of these studies have identified and analyzed according to the impact or severity of the causes of quality failures (e.g., [
21,
22,
23,
24]). Others have paid attention to ranking the causes of the quality failures from the frequency angle (e.g., [
24,
25,
26,
27]). However, these previous studies have predominantly evaluated only one particular area, particularly the impact of the factors affecting the construction quality. Hence, they only offer limited information about the causes of the quality failures in practice, combining both their importance and levels of effort required to tackle a cause [
28]. Tackling a cause means to address the consequences of the causes after it occurs.
In the Chinese energy renovation context, the specific causes have not yet been treated in the academic literature in a systematic way. The importance and the level of effort required to tackle a cause are proposed as key indicators. As a result, there is a need for systematic identification and analysis of the causes: the importance of a cause (related to impact and frequency), and the level of effort required to tackle a cause (related to origin and scale). In this paper, the evaluation indicators adopted are the combination of the importance, origin, and scale for building energy renovation projects. The “importance of a cause” in this context refers to the impact and frequency of the causes before the causes occur. “The origin and scale” refer to the level of the consequences of the causes after they occur. The combination of four evaluation indicators provides a comprehensive comparison of different causes throughout the whole process of the causes occurring. Furthermore, this combination would be novel and meaningful for the main stakeholders, whose main priorities might tend to avoid and address the causes of quality failures in building energy renovation projects. This paper is the first to make sense of the evaluation of the causes of these four perspectives jointly.
The objectives of this paper are: (1) to identify the causes associated with quality failures in building energy renovation; (2) to determine their importance (related to impact and frequency); (3) to classify the causes based on their levels of effort required to tackle a cause (related to origin and scale).
The paper is organized as follows. A review of related studies on quality failures and the framework of their causes from global experiences are contained in
Section 2.
Section 3 presents the research methods to collect data.
Section 4 presents the interrelationships of the quality failures and their causes, the cause analysis of the importance (impacts and frequency), and efforts required to address a cause (origins and scales).
Section 5 discusses the critical causes and gives implications for policy makers and project coordinators. Finally, the main findings and recommendations for future research are concluded in
Section 6.
In more detail, first, the causes were identified based on a literature review, validated through experts’ interviews. The experts were interviewed to confirm if the causes were valid in empirical cases, and the relationships between quality failures and causes were obtained. Second, a questionnaire survey was carried out to collect data for analyzing the importance of the causes (impact and frequency) using a five-point Likert scale. Finally, the levels of effort required to tackle causes (origin and scale) were evaluated based on a focus group (see
Figure 1).
5. Discussion of Critical Causes
Although the awareness of the construction quality has increased during recent years, there are various causes to contribute the quality failures during construction stages. According to
Table 7, 10 causes extracted from a total of 18 selected causes were based on the responses from experts’ views and the literature review. All the 10 causes (E1, E2, E3, E5, I1, I2, I3, I4, I5, I6) obtained mean scores of impacts or/and frequency above the average total value.
The applications of renovation technologies play a fundamental role in the achievement of successful program goals. Various causes are closely related to the technical aspects. According to the technical guidelines in Inner Mongolia Autonomous Region, the distributions of the quality failures and their causes in technical procedures are “installation of new doors and windows”, “installation of thermal insulation materials”, “waterproofing the roof”, and ”painting the protection layer”. In short, the inadequate equipment, use of poor materials, and similar technical causes occur in these procedures. The advice for technical procedures is to strengthen the standardizations and technical design standards, both of which fall behind the actual work practices. Furthermore, from technical perspectives, thermal insulation materials have significant influences on the energy consumption of existing buildings, so more attention needs to be paid when selecting new thermal insulation materials coming to the market. In addition, various technical solutions are significant to reduce the causes of quality failures, like developing and applying online tools to share information efficiently in the building energy renovation projects. Meijer and Visscher [
64] also advised applying online systems further through the construction process. In contrast, Jingmond and Ågren [
41] considered that organizational solutions rather than technical advice need further attention to solving the causes of quality failures. Their solution is proposed to focus on training the workers with appropriate technical knowledge and hands-on skills.
To clearly understand the causes, it is essential to precisely separate all the causes. Based on the origin in the empirical investigation, this paper classifies the causes into those external and internal to the renovation projects, in line with Mosannenzadeh [
28] and Balasubramanian [
65].
The origin of the critical cause of quality failures is external if the cause originated outside the project, including policy implementation gap (E1, E2), adverse natural environment (E3), and fraud of construction companies (E5).
Although particular organizations are established for quality supervision to achieve the performance of high quality in the renovation projects of this nature [
53], there are still various causes that are internal to projects. These causes possibly lead to quality failures during the construction processes, which even affect the overall quality and energy performance. In this study, the results reveal that 13 causes have an internal origin to the project, and they all are at a micro-scale. In terms of impacts and frequency (see
Table 7), there are six top internal causes (I1, I2, I3, I4, I5, I6) to contribute to the quality failures during construction stages, all of which are greater than the average total value. It means that these causes can be avoided or reduced through better project organization, and so these causes need action from project stakeholders and policy makers. In line with previous findings [
23,
42], overcoming these internal causes can remarkably reduce quality failures and improve countries’ performance through improvements in construction behavior and management procedures.
In light of the analysis above, these findings help policy-makers and project coordinators to understand the allocations of their responsibilities better and to develop their proper actions in the future building energy renovation context in Northern China.
5.1. External Causes
5.1.1. Policy Implementation Gap (E1, E2)
The Chinese national government has published various policies and targets on energy-saving renovation [
66]. Ran [
67] illustrated that there is a gap between the national government’s energy-saving renovation policy and the outcomes of its implementation at empirical levels. Actually, high-time and high-cost pressure factors are related to the energy policy implementation gap [
68]. Moreover, these two causes are regarded as the dominant causes regarding the aspects of impacts and frequency (see
Table 7).
The government-led model is established in building energy renovation projects in the Chinese context. Indeed, the top-down mandatory targets for renovating magnitude are set according to national energy policies from the national government. National policy targets can then be translated to lower levels of governments through the allocation of the renovation targets. Accordingly, the municipal government releases its implementation plan, which establishes the objective of renovating building areas. However, local governments are under intense pressure to complete the targets from upper levels of governments. The priorities of local governments in achieving energy conservation and climate change targets are different, and in practice they focus on construction time more. Thus, the local governments reduced attention to the goal of energy conservation and climate change [
68]. From the viewpoint of the local government, their task is significantly more difficult to achieve than those of the national government. Hence, construction time pressure (E2) in building energy renovations is higher than that in other construction projects.
On the other hand, building energy renovation belongs to government investment projects. In order to complete targets, governments have to provide a renovation fee, so they minimize renovation costs as much as possible. However, the renovation cost is limited and fixed. The high-cost pressure (E1) exists in building renovation projects resulting in other levels of causes of quality failures.
5.1.2. Adverse Natural Environment (E3)
In Northern China, in the Severe Cold Zone and Cold Zone, the natural environment is an interference element of energy-saving renovation projects, such as inadequate solar energy, low temperature, high humidity wind, rain interference, etc. It is apparent that these natural environment elements would affect energy-saving renovation construction adversely and cause quality failures in Northern China.
5.1.3. Fraud of Construction Companies (E5)
Construction companies always aim to maximize income and minimize their cost to achieve their company profits because of the nature of the private companies. Thus, construction companies may tend to procure construction material at a lower price in order to reduce material costs. Thus, quality failures may appear, including non-specified fire resistance of EPS boards, non-specified volume, weight, and thickness of EPS boards, non-specified nylon net, missing rivets, non-specified rivets, non-specified anti-crack mortar, and other similar types of quality failures (see
Table 6). Wu et al. [
69] also stated that the fraud of construction companies is the primary cause of quality failures in construction projects. In the results of this study, the fraud of construction companies (E5) was ranked as the second cause for the impact on construction quality (
Table 7) and regarded as a macro cause, which is likely the most difficult to be dealt with and requires action mainly from policy-makers. In the Chinese context, the provision of monetary incentives is insufficient for triggering substantial behavioral changes of construction companies leading toward more sincerity in building energy renovation projects [
60]. Several solutions for policy makers are proposed to issue the incentives to drive the construction companies’ awareness of construction quality and the connection between construction quality and project value.
5.2. Internal Causes
5.2.1. Incomplete Construction Site Survey (I1)
The errors in the on-site survey are ranked first in consideration of the level of the impact. Indeed, an incomplete or even incorrect construction site survey will lead to errors such as “incorrect size of the new window frame and door frame”. In building energy renovation projects, a construction site survey could impact on the implementation steps of the projects directly, but it is always paid too little attention by the main stakeholders. Clearly, it would seem that a practical task would be to supervise the on-site survey allocated by the local government in the Chinese situation.
5.2.2. Poor Checking Procedures of Supervisors (I2)
Supervisors in energy-saving renovation projects co-supervise with local government. Inadequate supervision of materials and equipment are the main reasons for quality failures, for example, “non-specified fire resistance of expanded polystyrene (EPS) boards”, “non-specified anti-crack mortar”, and “non-specified nylon net”. The obligations of on-site supervisors are material and equipment supervision. However, some on-site supervisors do not strictly check the quality of raw materials, semi-finished products, or mix components. They fail to apply enforced inspection [
43]. Moreover, administrative supervisors responsible for checking construction documents ignore checking the construction plans. On the other hand, there has been a tendency for the causes to be induced at the construction design stage [
70]. Supervisors only focus on the construction stage, whereas the inspection and management of construction preparation are ignored [
69]. Therefore, the supervision during the construction preparation period needs to pay more attention to material and equipment preparation stage.
5.2.3. Poor Operational Skilled Workers (I3)
Due to the novelty of the energy-saving renovation projects, the specific technologies and operations are challenges to meet construction quality requirements for workers lacking operation skills. In most projects, construction work is the preferred occupation of migrant workers with low labor costs [
71]. Therefore, workers who have little knowledge and experience are more likely to make errors in operational processes. As a result, many quality failures arise, such as “incorrect installation of the steel nails” and “cracks of concrete”.
In an actual situation, “poor operational skilled workers” have a closer relationship with “inaccurate design work”. Because of incomplete design documents, workers probably make errors during their operational processes. In building energy renovation projects, it is difficult to remedy workers’ mistakes. Therefore, workers and other project participants need to be trained to identify incorrect design documents. According to the renovation policies in the context of China, it is not a mandatory requirement to train construction workers and other participants with design information and technical knowledge. Meanwhile, construction companies fail to train and manage on-site workers. Thus, to establish an internal training system is currently a necessary and urgent issue. Furthermore, mandatory requirements regarding training and educating workers and other construction participants could be needed in the renovation policy framework.
5.2.4. Inadequate Equipment Performance (I4)
Incorrect selection and usage of equipment are hindrances to the high-quality performance of energy-saving projects [
72]. According to Ashokkumar’s study [
73], some construction activities might use the wrong equipment, which is more likely to cause quality failures. In this empirical investigation during the processes of installing mechanical fixings, “incorrect drilling” occurs when the power of the electric drill is too low, or the drill bit is selected incorrectly. The selection and usage of equipment need to be checked and recorded strictly by construction management authorities. If the equipment performance does not meet the technical requirements, it is impossible to achieve the high-quality performance of renovation projects.
5.2.5. Lack of Experienced Project Managers (I5)
It is well known that various activities in construction work are heavily dependent on the organization of the project managers. In the current situation, the project managers’ lack of experience in energy-saving renovation results in quality failures. For the empirical investigation, some project managers ignore emphasizing to workers the knowledge of waterproofing techniques and other technical requirements. Often, project managers cannot clarify the scope of personnel responsibility due to a lack of experience in renovation construction. The “Lack of experienced project managers (I5)” in renovation projects is considered one of the most frequent causes in the Chinese context (shown in
Table 7).
Additionally, the chances for professional experience and training are very limited. It is meaningful that the local governments establish the education and training system for project managers in energy-saving renovation, and introduce a scheme mandating the employment certification of renovation projects for project managers.
5.2.6. Incomplete Building Information in Projects (I6)
Incomplete building information appears most frequently (see
Table 7). This is because all renovated buildings were built before 2007, and thus it is hard to find details of old building documents. Furthermore, the delay in information updates is a reason for “Incomplete building information in projects (I6)”. For example, the size of enclosure components (including windows and doors) reinstalled by the homeowners and other information different from the original design drawings are missing in renovation projects. Therefore, the building information suitable for site operations needs to be updated and then shared among the participants during the stages of survey, design, and construction.
6. Concluding Remarks
The energy renovation of existing residential buildings is increasingly influential in reducing energy consumption in the building sector. Undoubtedly, building energy renovations are failing the challenge to meet their goals of high-quality performance due to quality failures. Despite various statutory requirements to ensure high-quality performance in energy-saving renovation projects, quality failures frequently occur during the construction processes in energy-saving renovation projects. The impact of these quality failures has resulted in unsatisfactory energy performance throughout the usage phase of the existing buildings. Until this research study, the reasons why quality failures in building energy renovation projects occur in the Chinese context were unknown.
The causes of quality failures in energy renovation projects have, however, been identified and analyzed incompletely. This results in a limited understanding of why quality failures occur and how these quality failures could be avoided. The novelty of this paper lies in the fact that it has explored and analyzed the causes systematically from two main aspects: the importance of a cause and the level of effort required to address a cause in the context of China.
The analysis and understanding of the causes are a vital prerequisite in order to prevent and eliminate quality failures. Therefore, this research study first identified the 18 causes of quality failures based on a literature review and expert opinions. Then, the detailed analysis of these causes in Northern China concluded that the “Incomplete construction site survey” (I1) was ranked as the highest level of the impacts on quality, and the most common cause was “Incomplete building information in projects” (I6). The level of action required for tackling a cause of quality failures combined their origin and scale. The “Working under high-cost pressure” (E1), “Working under high-time pressure” (E2), “Adverse natural conditions” (E3), and “Fraud of construction companies” (E5) are external to projects at macro scale, with a high level of required action for tackling the challenge. Based on the evidence in this paper, they are more likely to be influenced at the policy level from the focus group. The Chinese framework of the causes of quality failures could provide a reference for improving the construction quality of energy-saving renovations globally.
Strategies of reducing the causes of quality failures were provided at the policy level and project level, which are different from previous studies in building energy renovations. At the policy level, there is a need for a common political interest in the implementation of renovation projects among different levels of governments. In terms of the project level, the government should establish an inspection system to track and inspect the project’s implementation. An effective inspection mechanism is necessary to avoid quality failures occurring.
This paper specified how the quality failures happened, and the causes of quality failures were identified and analyzed. Meanwhile, this study also confirmed that the appraisal method was applied as a means of assessing the causes in the building energy renovation projects. On the one hand, in this paper, the applicability of the recommendations for policy makers at a policy level refers to improvement of the top-down mandatory implementations of the energy renovation policies. On the other hand, the suggestions at a project level are applied to the quality management processes of the energy renovation construction.
The outcomes of this research may help both project participants and policy makers to better understand the causes of quality failures. Thus, the findings would be valuable for policy makers and project coordinators both for predicting and avoiding the quality failures, and for developing proper action and policy interventions to ensure successful building energy renovations with high-quality performance in the future.
A few limitations should be acknowledged for future studies. The case city was only chosen in the Chinese context, and thus its situation may be different from those in other countries. Moreover, this research did not address relationships of the causes for energy-saving renovations. Future research should be wider and include the interactions of these causes, as well as the international experience, indicating that placing more stringent requirements on details in the project documentation, including work sentencing, may reduce some sources of quality failures in the construction and allow shorter construction time.