**2. Methodology**

A systematic and rigorous review process was conducted in this paper. The primary focus of such reviews is to point out the related available studies established on pre-formulated research queries to synthesize the conclusion based on the evidence [33]. It is notable to mention that the systematic review features substantial leverages contrast to conventional narrative approaches of literature work. The conventional review does not apprehend formal methodological approaches, whilst the systematic review incites to minimize research biases through the adoption of search strategies, preordained inquiry string, and inclusion and elimination criterion [33]. Moreover, the comprehensive documentation nature of review enhances the clarity of review as well as facilitates subsequent replication [34].

In this paper, the relevant literature search methodology comprised of scientific literature sources, mainly the "Scopus" and "Web of Science" as both of the sources are well accepted in academia for their research quality and reliability [35]. We checked the online databases indexed in "Scopus" and "Web of Science" to identify the articles based on our keyword. In this research, the selected keywords to sort out the literature are "Energy Management", "Industry", "Energy Management Model", "Energy Management Practices", and "Energy E fficiency". Nonetheless, there was no specific starting timeframe for searching the literature in the database, though attempts were made to consider the recent researches. Table 1 presents the selection basis of the literature review.


**Table 1.** Selection basis of the literature review.

Each of the selected articles has been checked manually for content analysis in stage 2, the "screening" process. During the screening process, expulsion criteria that are followed in this research are presented in Table 2. Articles were discarded in this stage based on the criterion EXC 1, EXC 2. In stage 3, a backward review was conducted to reconsider relevant articles based on our selected keywords. The following stage consists of the exclusion of articles based on the criterion EXC 2, EXC 3, EXC 4, EXC 5, EXC 6, and EXC 7. Finally, the last step of methodology replicates the content analysis of selected articles. The entire methodological steps are illustrated in Figure 1.

In the phase of analyzing the content, it was essential to distinguish between energy managemen<sup>t</sup> and energy managemen<sup>t</sup> assessment framework/model. Therefore, the situation was very critical and decisive to the inclusion of such specification in this study. Nonetheless, discarding any concept related to energy managemen<sup>t</sup> and its framework additional resolutions and aspects were also introduced that were not considered in the initial phase.


**Table 2.** Exclusion criterion of the literature.

**Figure 1.** The methodological steps followed in the research.

## **3. Results and Analysis**

## *3.1. Energy Management Definition*

Defining energy managemen<sup>t</sup> is significant when it comes to the point at energy managemen<sup>t</sup> modelling or energy system practices implementation. Energy managemen<sup>t</sup> concept is specified by many studies that incorporate multiple arenas. The prime areas covered by multiple studies to define energy managemen<sup>t</sup> are energy consumption, strategic aspect, the involvement of managerial perspective, and people relevancy [25].

The German Federal Environment Agency defined energy managemen<sup>t</sup> as the inclusion of planned and execution of actions to ensure predefined performance by a minimum amount of energy input [37]. B.L. Capehart has characterized the term energy managemen<sup>t</sup> as the proficient and effective usage of energy towards maximization of profits and increasing reasonable positions [38]. O'Callaghan et al., defined the energy managemen<sup>t</sup> as the application of resources in regards of supply, conversion, and utilization which integrates monitoring, measurement, archiving, critical examination and analyzation, control, and rerouting of energy as well as material flows through the systems for ensuring minimal energy usage and achieve meaningful goals [39]. To define energy management, Bunse et al. focused on the inclusion of control, supervision, and improvement activities towards energy efficiency [6]. On the contrary, Ates et al. strengthened on the combination of techniques, activities, and managerial processes that leads to reduce energy cost and anthropogenic emissions [40]. One of the studies by Abdelaziz et al. promoted energy managemen<sup>t</sup> focusing on energy optimization strategy that incorporates compelling the energy demand [41]. A comprehensive definition of energy managemen<sup>t</sup> has been proposed by Schulze et al. that incorporates all necessary energy managemen<sup>t</sup> elements and energy managemen<sup>t</sup> practices in the industries [32].

In academic literature, energy managemen<sup>t</sup> is portrayed as a holistic combination of applying resources, conversion, and application of energy [16,20,25,32]. The system involves checking, auditing, recording, scrutinizing, and more importantly controlling the energy flows to ensure the minimum consumptions of energy but to achieve maximum energy productivity [16,42]. Academicians have pointed some of the minimal prerequisites for implementation and operation of energy managemen<sup>t</sup> in the industries [27,40,41,43,44]. Table 3 illustrates the requirements toward energy managemen<sup>t</sup> with specifications whether the requirements are considered full, partly, or not under consideration.


**Table 3.** Minimal prerequisites for energy managemen<sup>t</sup> in the industries. This table is adopted from Schulze et al. [32].

> Abbreviations: -- (Full Consideration); - (Partial Consideration); × (Not Considered).

It becomes discernible by analyzing the minimum requirements for energy managemen<sup>t</sup> from Table 3 that the sets of minimum requirements elucidated in the studies contrast in the number of elements as well as conformation of the individual features. In addition, it shows indistinctness on the conclusiveness of the list of minimum requirements whether it is suitable to describe a fully developed energy management. By analyzing earlier contributions on the topic, we can note the lack of a comprehensive conceptual framework about energy management. Therefore, in this study, we respond to this research gap by complying a review of academic journal publications in the area of industrial energy managemen<sup>t</sup> and use its results to propose future research avenues to explore further.

#### *3.2. Approaches to Energy Management Models*

There are research streams which are considered in academia as well as the industries to assess the energy managemen<sup>t</sup> models. The streams can be categorized as "Minimum requirements", "Maturity models", and "Energy managemen<sup>t</sup> matrixes" [25]. Furthermore, there is assessment tool namely "Energy Management Measures Characterization Framework", so to shape the energy managemen<sup>t</sup> aspects accordingly". This is practice based, therefore basing on energy managemen<sup>t</sup> practices with characteristics.
