Some countries are shifting to a smarter form of development, such as Japan, which has invested around 507 million USD since 2010 in order to rebuild earthquake-destroyed cities into SCs. With a 333 billion USD investment plan, China plans to transform 80% of its cities into smart cities by 2050 ^[1][4].

The efficiency of SCs is heavily dependent on smart buildings (SBs) ^[2][5]; SBs build SCs ^[3][6]. By 2026, the SBs global market will grow to 121.6 billion USD, at a compound annual growth rate of 10.9% ^[2][5]. So far, no certification or rating system exists to identify SBs ^[3][6].

Since 2012, real estate (RE) technology-based companies have raised almost 6.4 billion USD in funding in the United States alone. RE smart technologies are used by different participants in the RE industry, including lenders, owners, and investors, in order to collect and distribute industry-related data ^[4][7]. However, the CB-Insights and Warburton report revealed that the global RE industry lags five years behind the technology curve ^[5][8]. Almost a third of the global RE industry, worth 11 trillion USD, is not utilizing innovative and smart technologies ^[6][9]. Most RE establishments lack innovations in the marketplace and so they must catch up in order to support current demands and requirements ^[3][6].

SCs and Smart Real Estate (SRE) technologies improve quality of life and facilitate sustainable development ^[7][10]. However, no recommendations exist on how these new technologies should be applied to SRE in a SC ^[8][11]. Moreover, the EU Parliament revealed that defining city smartness and determining its success is complicated. In addition, it is difficult to point out particular issues and potential improvements within SCs ^[9][12]. As such, this study aims to identify the features and success indicators for SCs and SRE and to introduce a new evaluation framework for both levels. The framework is utilized to identify these indicators, evaluate selected benchmarks, define potential improvements, classify the status of SC and SRE, investigate their capabilities, and show their integration and relationship.

2. Defining Smart Development of Cities and Real Estate Projects

Over the years, the determination of smart development level and understanding its ingredients has been proposed and developed ^[10][13]. The initial concepts of smart development faced many criticisms, due to a restricted focus on the technological side alone. The smart development concept evolved to adopt an anthropocentric approach that invested in human and social development, in addition to the techno-oriented infrastructure; this led to the enhancement of economic status and quality of life ^[11][14]. Nowadays, smart development concepts extend beyond the initial perception of using technology and innovation to tackle urbanization issues and now include the incorporation of sustainable development policies and practices to actively mitigate the effects of urbanization ^[10][13]. The origin of the term SC can be traced back to the 1990s ^[12][15]. It began with the concept of a knowledge-based city, considering that city development elements change based on knowledge. In the following year, the term global city was invented; this was the first time a direct impact on the whole globe occurred. The term gave the city a direct and tangible impact on global affairs through socioeconomic means. In 1993, the phrase ‘ubiquitous city’ was first mentioned; this phrase is considered, to an extent, as a synonym to SC. It foresaw the link that digital networks in the built environment could provide for users to both connect with other users as well to all goods they might need at any time ^[13][16]. With the evolution of these concepts, the MESH (Mobile, Efficient, Subtle, Heuristics) city concept was born; this is the primary association of the term ICT in connection with the modern infrastructure of a city ^[14][17]. The definition of SC has been used with different meanings. However, no definition has been agreed upon by researchers. An SC can be identified as a city encompassing many interrelated sectors, including transport, education, healthcare, public security, infrastructure, logistics, resource use, RE, ICT, and others. These sectors have an impact on the daily lives of the urban population ^[14][17]. SRE is a combination of user-centered, sustainable, and innovative technologies for efficiently managing RE resources in an urban area and making key information available to consumers, managers, and agents. SRE process management includes data collection and its processing and dissemination by computers and connected technologies to enhance the user’s quality of life. It has specific measures for privacy and data security ^[5][8]. Cisco identified SRE as one of the four main pillars of SCs ^[14][17]. In theory, the smart development model is a derivative of other existing smart urban development concepts; despite the fact that cities differ from one another in terms of culture, climate, economy, ethnicity, and geography, most SC concepts align ^[11][14]. Adopting a ‘lessons learned’ approach, where cities implement policies from successful SCs, could help in improving the performance of traditional cities in a limited way. This process can be a starting point towards smart development ^[10][13]. In practice, to provide beneficial smart development solutions for cities and RE to turn into smart versions, adopting the “one-size-fits-all” model of SCs and SRE would not be applicable ^[11][14]; instead, they must develop their own best-point solutions ^[10][13]. The smart development model is channeled through scoring systems and benchmarks, while the smart components and frameworks are developed as a tool to assess and implement smart development ^[11][14]. SCs and SRE ranking and assessment should be reconsidered based on this unified framework in order to test their performance.

3. Smart City (SC) Components

Based on the review of various sources ^{[15][16][17][18][19][20][21][22][23]}[18,19,20,21,22,23,24,25,26], Figure 1 summarises SC components and their smart dimensions and elements. Seven smart city components were selected due to being interrelated with the SC and SRE. The components were categorized as smart governance, smart people, smart environment, smart infrastructure, smart energy, smart technology, and smart buildings. These components are linked together with SC technologies, and they are critical factors for developing the evaluation framework. Multiple dimensions of smartness would contribute to the development of each component. For example, smart governments include: participation, as a smart government allows public participation in decision-making and the ability to contribute and provide suggestions; transparency, to make data available for all users as the decisions and plans should be shared via different social platforms ^[16][19][24][19,22,27]. In addition, IoT devices, as these contribute toward improving the general quality of life for smart citizens; these devices focuses on promoting the creativity and engagement of the people. Health and safety dimensions are critical for this component; these factors should be provided through E-health, telecare, accessibility to public and open spaces, and video surveillance to provide safety for the people ^[11][25][14,28]. The smart energy system consists of the intelligent integration of decentralized sustainable energy sources, efficient distribution, and optimized power consumption. Efficient distribution in the smart energy system is made possible by the use of smart infrastructure, smart grid, and smart meters. The core of a smart energy system is the information infrastructure; this is responsible for collecting energy consumption information as well as sharing provider rate information ^[20][22][23,25]. Smart technology is key for the design, implementation, and operation of SCs. It is linked to all the smart components through a variety of state-of-the-art technologies that contribute to smart development ^[22][25]. The smart environment includes environmental data collection, monitoring and analysis for pollution reduction and control, water quality and supply monitoring, and smart waste management. Smart environment applications are typically based on ambient and chemical sensors. However, these applications are not only limited to sensors. They also contain smart policies and strategies, including waste management strategies and waste production control policies ^[20][25][26][23,28,29]. Smart buildings are empowered by ICT in the context of merging the Internet of Things (IoT); these buildings are equipped with sensors, actuators, and smart systems that allow for data collection, filtering, and production, thereby increasing user satisfaction ^[27][30]. Smart Infrastructure includes the ICT infrastructure that is fundamental to the construction of SCs and depends on factors related to its availability and performance, including communication infrastructure ^[22][25]. The Smart transportation system is part of this component, which shifts from traditional transportation systems to Mobility-as-a-Service, where a smart IoT infrastructure connects different users and entities (personal devices, transport systems, sensors, etc.) ^[20][23].

4. Smart Technologies

Smart technologies and solutions have a crucial role in SCs that goes beyond the traditional objectives of optimizing urban services and improving quality of life ^[28][3]. The core concept of a SC is the idea of using data to measure and improve the performance of urban systems through the integration of ICT, big data, and the various devices and technologies connected to the IoT network. This is achieved by employing data and communication through Artificial Intelligence (AI), Machine Learning, Geographic Information Model (GIS), and Digital Twin (DT) and creating systems that efficiently optimize city operations and services ^{[29][30][31][32][33]}[31,32,33,34,35]. Figure 2 illustrates the relationship between different technologies within the SC. When combined, these technology frameworks allow for the establishment of urban systems that can collect a vast array of data related to the functioning of a city in real-time, and that can analyze the data and adapt the system in response. The degree of urban intelligence can be measured by the available smart elements that the city has access to. However, integrating these elements is based on smart technologies ^[34][36]. SC systems are capable of learning by monitoring responses and can thereby optimize performance. SC technology does not only connect to citizens, but also it allows city officials to interact with the community and the infrastructure ^[12][15]. SC applications are developed in order to allow responses in real-time; therefore, the SC has a better responses to challenges ^[22][25]. Ullah’s 2018 ^[5][8] study reviews the adoption of disruptive technologies in RE, with a focus on nine technologies under the title ‘Big 9’. These include big data, virtual realities VR, 3D scanning, drones, IoT, software as a service (SaaS), clouds, robotics and AI, and wearable tech. These technologies were examined and reviewed based on 213 related published articles. In addition to the Big 9 study, other authors ^{[3][35][36][37]}[6,37,38,39] identified additional RE technologies and solutions. Table 1 categorizes and lists these technologies.

5. Strategies for Real Estate Integration into Smart Cities

The level of RE integration into the SC depends on the SC network’s capabilities and the resources provided by the RE developer. Several RE developments in SC strategies are possible, but the RE smartness and intelligence level differ from one strategy to another. Three integration strategies were identified. In the ‘leading’ strategy, RE development became the dominant factor in smartness, affecting its surroundings and setting a new level for other developers to follow. In the ‘following’ strategy, the development follows the dominant and leading developments as a benchmark; these developments might be in another location to the original development. Lastly, in the ‘waiting strategy’, the development uses the fragmented features of intelligence and smartness. All strategies should follow a coherent plan ^[27][30].

6. Added Values of Integration of Smart Technologies in Real Estate and City Development

The smart development concept is more than just creating an app; instead, it is the complex integration of components, application networks, and infrastructure for the city. There are numerous correlations between urban planning and city growth. Many elements are necessary when the population of a region or neighborhood grows. To understand and make smart decisions for city growth, an in-depth knowledge of these elements is required ^[28][3]. The successful SC and thus also the smart neighborhood should follow the triple bottom line of sustainability of social, economic, and environmental improvements. They must improve the quality of life for its inhabitants, maximize resource efficiency to decrease pressure on the environment, and provide a green economy focused on innovation as well as developing governance and local democracy ^[1][4]. Nowadays, cities consume about 75% of the world’s resources and energy while producing about 80% of the greenhouse effect ^[12][15]. SCs reduce resource and energy consumption, improve operational efficiency and enable efficient asset management and allocation. In terms of the environment, SCs improve the waste management system and reduces greenhouse emissions; this is in contrast to traditional cities. SCs enhance real estate development (RED), increase stakeholder participation, and increase the transparency of government affairs information through the big data platform, leading to smart decision-making by the government ^[7][30][38][10,32,40]. SCs provide a flexible adaptation to consolidated city development and offer an innovation platform for new entrepreneurial initiatives, followed by economic and social improvement. Additionally, SCs save public funds on services and infrastructures as a result of optimization and provide real-time information, making the residents aware of their needs ^[12][15]. Traditional buildings consume more than 40% of the world’s energy and account for 24% of greenhouse gas emissions. In addition, they are major water, materials, and land users. Reducing the environmental impact of buildings is a priority ^[39][41]. SRE has numerous advantages for the occupants and the owner. These developments are designed to preserve limited resources, contribute to perceived quality of life growth, and integrate individual building systems. Studies have shown that smart real estate can increase employee productivity by up to 23% through smart lighting systems and smart workplaces ^[40][1]. Additionally, smart real estate provide high security, ventilation, sanitation, physical comfort, and space availability measures. They improve sustainability and reduce energy consumption. The operational energy efficiency of smart buildings is defined through various automation factors, such as power management, HVAC control, metering, and lighting control. The use of smart devices provides accurate data on the usage of buildings that assists effective decision-making processes. Sensors provide precise data that assists in making effective decisions ^[38][40]. The development of SRE enhances the SC, urban development, and national economy, thereby leading to a better quality of life ^[27][30].