# The Smart Buildings Revolution: A Comprehensive Review of the Smart Readiness Indicator Literature
## 1 Introduction
Furthermore, the SRI should articulate and amplify the practical benefits of building smartness for building key functionality and smart service providers [24]. The EPBD recast proposal includes mandatory SRI applications for large non-residential buildings with high energy demands [25]. This initiative is part of broader efforts to integrate smart technologies into the building sector, promoting energy savings and creating more responsive and efficient buildings [26]. Today, the SRI is also being tested nationally by the EU Member States through official test phases and various LIFE Clean Energy Transition projects [27], which are providing valuable insights and supporting the broader implementation of the framework across Europe. In conjunction with the energy performance certificate, the implementation of the SRI has been estimated to potentially reduce the total energy consumption by up to 198 terawatt hours (TWh) by 2050, consequently averting approximately 32 million tons of greenhouse gas emissions annually [28; 29]. The SRI is designed to enhance energy-saving policies and promote sustainable practices in buildings [22]. Thus, the SRI is recognized as a fundamental measure for evaluating buildings' capability to utilize electronic systems and information and communication technologies. This capacity enables buildings to adjust their operations dynamically to meet the needs of occupants and the grid, consequently improving the overall building performance [30]. The methodological framework of the SRI employs a multi-criteria assessment scheme, with methods that demand minimal input and present results in a way that is easily understandable for a nontechnical audience [10]. The proposed approach quantifies a building's or building unit's smart readiness score as a percentage, reflecting the relationship between its current smart readiness and its maximum potential readiness. The SRI framework encompasses a range of technical domains and impact criteria. Each domain includes different levels of smartness for various functionalities, typically ranging from two to five levels. During the audit, conducted by a third-party assessor, all the available services within the building are examined, and predefined weighting factors are applied to combine these services into a comprehensive parameter. These weighting factors are tailored to the specific case, considering factors such as the building type and climate zone. Two audit methodologies are proposed: a simplified approach and a detailed approach [31; 32]. To pave the way for the future development of the SRI, it is crucial to gain a thorough understanding of its progress and evolution. This topic is particularly important as Member States are currently piloting the framework and preparing to make key decisions about its implementation and methodology. These decisions will be instrumental in shaping the SRI's effectiveness and its potential to promote smart, energy-efficient buildings. To guide this exploration, the following research questions (RQs) are posed:  
* RQ1: What are the key topics and identified research gaps in the SRI literature? * RQ2: How does the current research literature consider the paths for the evolution of smart buildings? To answer the research questions, a comprehensive research study was conducted. The rest of this paper is organized into four sections. Section 2 introduces the methodology employed, while Section 3 describes the data employed for the quantitative analysis of the SRI-related literature through bibliometric and content analyses. In this section, the key contributors and keywords in the SRI field are also presented to further analyze the past and current research trends in the literature. Section 4 presents the results, introducing the six dominant themes that arose from the analysis as well as emerging topics and future research directions in the reviewed literature. Section 5 provides a conclusion and summarizes the research gaps in the SRI literature.