Exploring Uncharted Territories in a Vertical Greening System: A Systematic Literature Review of Design, Performance, and Technological Innovations for Urban Sustainability

Abstract

Urban areas face escalating environmental and social challenges, including rising temperatures, air pollution, limited green spaces, and noise pollution, driven by rapid urbanization and energy-intensive systems. Vertical greening systems (VGS) have emerged as a promising passive design strategy to mitigate these issues by enhancing thermal regulation, air quality, biodiversity, and psychological well-being. However, existing research on VGS remains fragmented, often addressing isolated aspects rather than adopting a holistic approach that integrates design, fabrication, implementation, and long-term performance monitoring. This study employs a systematic literature review (SLR) to comprehensively analyze technological advancements in simulation, fabrication, and maintenance within VGS research. Key research gaps identified include the lack of an integrated design–simulation–optimization workflow, limiting the ability to improve VGS performance efficiently. By synthesizing current knowledge and proposing future research directions, this review aims to advance VGS as a scalable and adaptable solution for urban challenges, optimizing its functionality, sustainability, and overall effectiveness in improving urban livability.

1. Introduction

1.1. Background

Urban areas face increasing environmental and social challenges, including rising temperatures, worsening air pollution, limited green spaces, and noise pollution [1,2]. These issues are primarily driven by factors such as the use of hard surfaces [3,4,5], rapid urbanization [6,7,8], and technological advancements that contribute to excessive heat retention [9], poor air circulation, and increased reliance on energy-intensive cooling systems. These issues not only reduce residents’ comfort and air quality but also contribute to environmental problems such as poor air quality and higher energy consumption for cooling, which worsen challenges such as the urban heat island (UHI) effect [10].

To address these challenges, VGS has gained recognition as a passive design strategy that integrates vegetation into building facades. VGS offers multiple benefits, including mitigating temperature fluctuations, improving air quality, increasing biodiversity, reducing noise pollution, and contributing to the psychological well-being of city dwellers. Additionally, VGS reduces the demand for mechanical cooling, thereby improving energy efficiency [11,12,13].

Numerous studies have been conducted to develop VGS and evolved through several stages, starting with simulations aimed at improving its performance, such as temperature regulation and energy efficiency [1,2,14], followed by the creation of prototypes using various forms, devices, and materials [15,16,17]. More recently, studies have introduced monitoring systems to evaluate VGS effectiveness under real-world conditions [18,19,20]. While these studies offer valuable insights, existing research remains fragmented, with studies often focusing on specific aspects rather than providing a comprehensive framework for integrating VGS design, fabrication, and performance assessment.

A major research gap is the lack of an integrated review that connects all stages of VGS development—from initial conceptualization and material selection to fabrication, performance assessment, and long-term maintenance. Additionally, with technological advancements such as smart irrigation, advanced materials, automation, and real-time monitoring, there is a growing need to assess how these innovations enhance VGS scalability and effectiveness.

Therefore, this review aims to provide a comprehensive analysis of VGS development, focusing on its technological advancement aspects, including performance evaluation, fabrication methods, and IoT applications. Additionally, this study highlights the role of design in optimizing VGS workflows, ensuring effective material selection, construction techniques, and system efficiency.

1.2. Research Objectives

VGS includes a range of terms and classifications, each defining unique ways of incorporating greenery into architecture. Common types of VGS include green walls, which feature plants rooted directly into a wall structure, and green facades, where climbing plants grow up supports like cables or mesh [21]. Moreover, living walls specifically refer to green walls that utilize modular plant panels installed on a vertical structure [22]. Technological advancements have further expanded VGS applications. For instance, integrated sensor systems are now used to monitor factors such as humidity and temperature, ensuring optimal plant health and system performance [23]. Innovations such as modular panels with pre-grown plants and automated irrigation further simplify installation and maintenance [24].

VGS is widely evaluated based on performance metrics such as thermal insulation, energy efficiency, and carbon sequestration to ensure alignment with sustainability goals. By integrating emerging technologies, VGS continues to evolve as an integral component of urban sustainability strategies. This paper aims to address several key objectives:

• To identify technological advancements and how they are used in creating VGS as a facade.
• To evaluate how current VGS research optimizes its performance and functional efficiency.
• To establish a comprehensive framework and method of VGS design until fabrication and maintenance.

However, despite advancements in the technological and technical aspects of VGS, this analysis reveals that design plays a crucial role in optimizing the entire workflow. Design decisions influence not only material selection and construction techniques but also long-term system efficiency and adaptability. Therefore, integrating design considerations across all stages of VGS development is essential for ensuring a more effective and sustainable implementation. This study provides the following scientific contributions:

• Providing a novel perspective on VGS design methods by addressing the full framework from design to maintenance.
• Establishing future research directions by identifying research gaps at each stage of VGS development.
• Offering references for technical aspects at each stage, such as computational tools for performance simulation and materials suitable for tropical building facades.

This review paper explores VGS technological advancement using a systematic literature review, which is divided into five stages, namely, context (Section 4.1), form generation (Section 4.2), simulation (Section 4.3), fabrication (Section 4.4), and maintenance and monitoring (Section 4.5). Each topic discusses current research and technological advancement, including tools (simulation tools, measurement tools, fabrication tools, and monitoring tools), variables, and performance. The simulation section provides additional analysis of computational tools used for optimization or design evaluation, while the fabrication section also considers material selection, as it directly affects vegetation growth. Furthermore, the maintenance and monitoring section discusses the Internet of Things (IoT) and its role in monitoring algorithms.

2. Methods

A systematic literature review was conducted, focusing on three topics, including simulation, fabrication, and IoT applications in VGS. Simulation was analyzed for its role in variable evaluation and VGS performance optimization. Fabrication methods were evaluated for their feasibility in VGS construction and material selection. IoT advancements were examined for their impact on vegetation performance monitoring.

Relevant literature was sourced from Scopus, Institute of Electrical and Electronics Engineers (IEEE), and CumInCAD, chosen for their relevance to architecture and the built environment. The search strategy employed Boolean operators such as AND, OR, and AND NOT to refine the results, as outlined in

Table 1. Systematic searching approach.

Search Within Title, Abstract, Keyword	Database	Number of Studies
Main study: “green wall system” OR “vertical greening system” OR “living wall” OR “green facade” OR “green wall” Complementary study: “digital” OR “fabrication” OR “parametric” OR “additive manufacturing”	Scopus	53
	IEEE	132
	Cumincad	830
Main study: “green wall system” OR “vertical greening system” OR “living wall” OR “green facade” OR “green wall” Complementary study: “internet of things” OR “building automation system” OR “smart facade” OR “responsive” “irrigation” OR “nutrient” OR “carbon” OR “daylight” OR “sensor”	Scopus	228
	IEEE	15
Main study: “green wall system” OR “vertical greening system” OR “living wall” OR “green facade” OR “green wall” Complementary study: “computational” OR “simulation” OR “optimization” OR “form-finding” OR “parameter” AND “computational” OR “simulation” OR “optimization” OR “form-finding” OR “parameter”	Scopus	1015
	IEEE	42
	Cumincad	9

. The initial search yielded multiple articles, with some duplicates across different databases and topics. These duplicates were identified and removed before proceeding to screening stage. The selection was limited to fully published articles in English, available in final published form, and released no earlier than 2012. To ensure consistency in content, articles still in the press were not considered.

The summary of data-gathering methodology, outlined in Figure 1, includes the identification of relevant publications, the screening process, and the final selection of journals. Initially, research papers were screened based on titles, keywords, and abstracts (Step: identification). At this stage, journals that did not match the search keywords were automatically excluded. Additionally, duplicate journals were removed.

During the screening process, duplicate journals within each topic were excluded, and inaccessible documents were removed. The remaining studies were then examined in detail, with relevant data extracted to support the research objectives. Studies deemed irrelevant to VGS or outdated were excluded, along with research that fell outside the scope of technological advancements in the three discussed topics.

The literature review methodology, outlined in Figure 2, includes research objectioves, search criteria, and the process for selecting publications. Initially, research papers were screened based on titles, keywords, and abstracts (Step 1). For inclusion, studies needed to meet at least one of the three predefined criteria; those failing to do so were excluded (Step 2). In (Step 3), qualifying studies were examined in detail, with relevant data extracted to support the research objectives (Step 4). These data were then organized into summary figures and tables and analyzed in the final assessment (Step 5).

3. Publication Trends and VGS Development Stages

Due to the growing complexity of VGS research, 119 articles were identified and analyzed. Figure 3 illustrates the research trends in simulation, fabrication, and IoT applications within VGS studies. The trend shows a steady increase from 2018 to 2022, peaking at 17 articles in 2022. However, from 2023 to 2024, the number of publications declined, indicating a phase of research maturation. The articles originated from various journals and conferences, with most published in Energy and Buildings, followed by papers from Building and Environment. Other contributions came from Buildings, The Association for Computer Aided Design in Architecture (ACADIA), Construction and Material, and other relevant sources.

Figure 4 highlights the integration of various topics related to Vertical Greenery Systems (VGS), including simulation, the Internet of Things (IoT), and fabrication, based on the analysis of 119 journal articles. To identify the most frequently discussed topics in these studies, a content analysis was conducted using VOSviewer (version 1.6.20) software. The analysis results indicate that simulation is the most extensively covered topic, while fabrication and IoT remain less explored.

Additionally, the purple cluster, which includes terms such as “temperature” and “solar radiation”, highlights that thermal performance is the most frequently discussed aspect of VGS, particularly in relation to temperature reduction. This is influenced by various factors such as climate and material selection. The advancements in digital construction methods are reflected in the orange cluster. The linkage between “Fabrication”, “additive manufacturing”, and “mineral foam” further suggests an exploration of alternative sustainable materials. This visualization underscores the role of computational tools in VGS design and performance evaluation, the contribution of IoT to dynamic environmental monitoring, and the advancements in fabrication technologies that support sustainable building solutions.

Despite ongoing advancements, existing VGS research lacks a cohesive approach, with studies often focusing on specific technical aspects rather than exploring their interconnections. While technological innovations—such as recycled materials and modular walls—have been widely studied, there is still a need for a more structured framework that integrates design, construction methods, and performance monitoring to enhance VGS efficiency and long-term sustainability.

Most research on VGS focuses on evaluating facade performance, particularly how design variables influence final outcomes. However, fewer studies examine the integration of design methods, construction techniques, material selection, and maintenance strategies within a structured workflow. While previous reviews highlight technological innovations—such as recycled materials and modular walls to reduce carbon footprints—VGS development requires a comprehensive approach that incorporates form generation, simulation-driven optimization, fabrication, and long-term operational strategies.

Developing a VGS facade with multiple performance objectives involves three key stages: early design, preliminary design, and detailed design [25]. However, VGS design extends beyond construction methods and material choices; other critical aspects, such as multi-performance optimization, fabrication, and maintenance, also need further investigation.

The early design stage includes context analysis, form generation exploration, and defining performance objectives through simulation [26,27]. The detailed design stage focuses on fabrication and construction planning. Additionally, the operational stage—covering technical and maintenance aspects such as climate adaptation, water and irrigation systems, structural stability, and material durability—must be considered to ensure long-term effectiveness [28].

This review highlights the need for a more comprehensive approach to VGS design covering all stages, from context analysis to long-term maintenance. Future research should focus on integrating technological advancements across these stages to optimize VGS performance and sustainability.

4. Result

4.1. Context

The performance of Vertical Greenery Systems (VGS) is significantly influenced by contextual factors, particularly climate conditions. Different climates produce varying results in terms of energy efficiency, thermal regulation, and humidity control. The Mediterranean, humid subtropical, and hot desert climates are the most extensively studied due to their extreme summer and winter conditions. Studies indicate that VGS interactions during summer effectively reduce cooling loads, while their impact on heating load in winter depends on orientation [29,30,31]. However, there is only a little research that highlights differences in VGS effectiveness in heating and cooling loads. Moreover, research that analyzes tropical weather with a longer summer period is scarcer. However, limited research explores the effectiveness of VGS in both heating and cooling loads, and even fewer studies analyze VGS performance in tropical climates, which experience prolonged warm periods.

Beyond climate, urban morphology plays a crucial role in shaping local microclimate conditions. The height and density of buildings influence wind speed, air temperature, and humidity levels, often described through the street canyon concept, which is defined by the height-to-width ratio of urban spaces [32,33,34]. To assess these factors, microclimate data collection can be conducted through weather stations, on-site measurements, or preliminary urban-scale modeling of the built environment surrounding the study site.

4.2. Form Generation

Form generation is an iterative process that integrates design and performance simulation to optimize VGS effectiveness. A performance-driven approach relies on the relationship between building components, design variables, performance indicators, and performance objectives [35]. Despite its significance, research on form generation in VGS studies remains limited.

One notable example is the Weeping brick system, which incorporates evaporative cooling as its performance objective. This system consists of a water reservoir, evaporative surfaces, structural elements, and water vessels, all of which contribute to the component’s extrusion pattern [36]. The modular brick design has been further refined for both exterior and interior wall applications, demonstrating how parametric adjustments can enhance VGS efficiency. Such iterative processes highlight the importance of refining design parameters to achieve optimal performance outcomes.

4.3. Simulation

The integration of design, simulation, and optimization enables the identification of high-performing VGS solutions. Performance optimization depends on the dynamic relationship between design variables and performance objectives [37]. To achieve this, digital tools are employed in building performance optimization, categorized into design simulation and optimization tools [26,27]. However, achieving a comprehensive understanding of VGS performance requires improved methodologies for linking simulation results with design decisions.

Existing VGS simulation studies can be classified into three key areas based on their objective: (a) simulating performance objectives and design variables to understand their relationship, (b) exploring computational methods using different simulation tools, and (c) comparing various strategies between VGS and other design approaches. A review of 66 studies reveals that the majority focus on performance parameters (47 sources), followed by computational methods (7 sources) and comparative strategy analyses (14 sources) (Figure 5).

Investigations into performance parameters primarily focus on simulating different design variables to understand their impact on overall VGS performance. Numerous review papers have analyzed the simulation performance of VGS applied in building facades, classifying performance objectives into categories based on their benefits and functions [38,39,40,41]. Of the 47 research papers, most studies concentrate on environmental implications, such as thermal comfort, energy efficiency, humidity control, daylight availability, and acoustics. However, other performance objectives remain underexplored.

Limitations in simulation tools for certain performance objectives have led researchers to explore new tools and hybrid approaches. Many studies address performance aspects that cannot be simulated using conventional VGS simulation tools, including hygrothermal analysis [34,42,43], Physiologically Equivalent Temperature [44], and stormwater management [45]. Another explores 3D characterization using a LiDAR system to provide input data for further simulation [46].

Additionally, research on strategy comparisons evaluates different VGS types alongside other passive strategies, such as passive heating and cooling systems, green roofs, and other façade strategies. Dabaieh and Serageldin [29] compare VGS with Earth Air Heat Exchangers (EAHEs), which circulate air through underground pipes, and Trombe Walls, while other studies analyze its performance in relation to green roof systems [47,48,49,50,51,52,53]. Several studies also integrate multiple tools to enhance analytical accuracy.

This research identified several gaps in VGS simulation research:

• Previous VGS simulation literature has not addressed the iterative process of design–simulation–optimization, as most research focuses solely on the simulation phase.
• Performance objectives have primarily centered on thermal and energy aspects, while other quantifiable parameters—such as acoustics, economic feasibility, and life cycle assessment—remain underexplored
• The types of simulation and optimization tools used for VGS performance evaluation have not been comprehensively discussed despite their importance in ensuring accurate and valid results.

4.3.1. Relations Between Performance Objectives and Design Variables

VGS is widely recognized to be effective in mitigating the urban heat island (UHI) effect, reducing building energy consumption, and addressing urbanization-related issues. Its primary cooling mechanism operates through evapotranspiration, effectively lowering the external façade temperature [7,54]. Furthermore, VGS contributes to urban cooling by reducing ambient temperatures, particularly in densely populated areas, thereby alleviating UHI intensity [55,56]. Given the limited availability of green spaces due to rapid urbanization, integrating greenery through VGS presents an innovative approach to sustainable urban development [57].

Various factors influence the effectiveness of VGS, including building morphology (e.g., orientation, dimensions, and plant coverage area), plant properties (e.g., Leaf Area Index (LAI), plant type, and soil media), wall materials (e.g., thermal properties), façade layering configurations, and urban microclimate conditions. These variables interact to affect energy efficiency, thermal regulation, daylight availability, humidity control, and acoustic performance (Figure 6). To systematically analyze these relationships, a coding process was conducted using ATLAS.ti (version 24.1.1.30813), where relevant journal articles were examined to identify patterns and correlations based on predefined categories.

A study by Li et al. [53] showed that integrating greenery into building façades can significantly enhance occupant comfort while reducing energy consumption. Jiang et al. [58] showed that the cooling effects of different green wall designs varied, with Green Facades reducing the external surface temperature by up to 4.5 °C. Moreover, studies also found that cooling energy consumption in summer can be reduced by 11.2–24.9%, with winter heating demand decreasing by up to 25% [59,60,61].

The building morphology, including orientation, dimensions, and plant coverage area, plays a crucial role in VGS performance. The orientation of a building influences how much solar radiation is absorbed, with west- and south-facing facades proving most effective for cooling despite the latter receiving more sunlight [62,63]. These findings highlight the strong connection between building form, massing scale, and urban microclimate performance in thermal and energy regulation.

At the facade scale, wall materials, layering configurations, and plant properties significantly impact indoor thermal, energy, and humidity levels. Various studies show that different facade configurations incorporating VGS influence both indoor and outdoor air temperatures. Galagoda et al. [64] conducted simulations of various VGS types—including living walls and direct and indirect systems—and found that they effectively reduce indoor temperatures. Additionally, Djedig et al. [34] showed that the air gap between the facade and modular panels affects hygrothermal performance. Material properties and vegetation selection also play a key role in VGS effectiveness. Studies assessing VGS’s energy-saving potential analyze temperature reductions and heat flow through building walls, considering material thermal properties [65]. Heat transfer is heavily influenced by these material characteristics. Simulations of different wall materials and layers show their effects on indoor temperatures [66]. Additionally, plant properties, such as the Leaf Area Index (LAI) and soil media, impact VGS performance. Carlos [31] found that reducing LAI can increase a building’s heat load by 8–10%, highlighting how denser vegetation improves insulation and lowers energy demand. Substrate layers also influence indoor temperature regulation, underscoring their importance in VGS design [62].

Pragati et al. [67] found that buildings with VGS experienced a 4.62% increase in indoor humidity due to plant evapotranspiration. Gao et al. [68] further noted that seasonal and orientation-based variations impact humidity levels, with increased moisture near living walls during hot periods. Additionally, Li et al. [69] identified shading as a major contributor to cooling, accounting for approximately 53% of the total cooling effect of VGS.

Other environmental benefits of VGS include acoustic mitigation and life cycle efficiency. VGS has the potential to mitigate urban noise; for example, adding foliage and substrate layers to concrete walls can reduce sound pressure levels (SPL) and reverberation time (RT), effectively absorbing and diffusing noise [9,70]. The Life Cycle Analysis (LCA) of VGS highlights their considerable impact on energy efficiency and CO₂ emission reduction across various applications. Ramadhan and Mahmoed [71] evaluated living wall facades as a sustainable, energy-saving solution in hot, arid regions, demonstrating their effectiveness in reducing CO₂ emissions by enhancing building performance. The environmental impact of VGS installation can be assessed using methods such as eMergy analysis, which compares initial investment costs with long-term maintenance and energy savings [72].

4.3.2. Computational Tools

Computational tools used in VGS research can be categorized into three main types: 3D modelers, performance simulators, and optimization tools (

Table A1. Computational tools used for performance simulation.

No.	Software	Plugin	Computational Tools			Use in Study	Design Variables	Performance	Reference
			3D Modeler	Performance Simulation	Optimization
1	Autodesk Green Building Studio		v	v		Run building performance simulation by estimating building energy use and operating cost	Building Morphology, Facade Layering	Cost, Energy, Thermal	[6,129]
2	ANSYS			v		Simulate Computational Fluid Dynamics (CFDs) to investigate temperature distribution and flow uniformity	Wall Material, Building Morphology, Plant Properties	Energy, Thermal, Humidity, Cost	[10,29,33,44,130]
3	Design Modeler		v			CAD model and meshing	Plant Properties	Thermal	[130]
4	ENVI Met		v	v		Model and simulate the effect of VGS and surrounding environmental elements. Simulate outdoor microclimate and thermal comfort	Plant Properties, Wall Material, Building Morphology, Facade Layering	Humidity, Thermal, LCA, Urban Microclimate	[2,8,32,42,43,47,49,50,52,53,62,63,68,74,131,132,133]
5		Biomet		v		Calculate human thermal comfort from ENVI-met tools, including PET and UTCI	Wall Material	Thermal	[52]
6	CE3X			v		Calculate energy simulation to estimate energy demand	Building Morphology, Wall Material	Energy, Cost	[72]
7	Delphin			v		Calculate coupled heat and moisture in building materials	Facade Layering, Wall Material	Thermal, Humidity	[42,43]
8	Design Builder		v	v		Analyze using Computational Fluid Dynamics to investigate building performance. Used to create 3D models and simulate thermal and energy analysis. However, there are limitations in VGS modeling. Connected to EnergyPlus as a calculation engine	Building Morphology, Plant Properties, Wall Material, Facade Layering, Urban Microclimate	Thermal, Energy, Humidity, Cost	[7,13,29,30,33,48,49,53,54,56,57,64,66,67,71,134,135,136,137,138]
9		Energy Plus				Building energy simulation program to analyze thermal and energy use by calculating building component and material	Facade Layering, Wall Material, Plant Properties, Building Morphology, Urban Microclimate	Energy, Thermal, Cost, Humidity	[29,30,31,48,49,51,53,55,56,58,60,61,63,66,71,134,138,139,140]
10	FDS			v		To study fire spread along VGS	Plant Properties	Fire Spread	[1]
11	Rhinoceros		v			3D Modeling	Plant Properties, Wall Material, Building Morphology	Thermal	[69,73,123,124]
12	Grasshopper		v	v		Generate building geometry and computational simulation	Plant Properties, Wall Material, Building Morphology	Thermal	[69,73,107,123,124]
13		Honeybee		v		Simulations to evaluate human thermal comfort. Assign material characteristics to geometry to connect Grasshopper and Energyplus			[6]
14		Ladybug		v		Import and create weather data analysis	Plant Properties		[10]
15		DIVA-for Rhino	v			Modeling plug-in for Rhinoceros			[69]
16		Galapagos			v	Optimize a fitness function that produces numeric value	Plant Properties	Thermal	[73]
17	IES VE		v	v		Predict thermal efficiency of VGS facade	Wall Material	Daylight, Energy, Thermal	[6]
18	ODEON			v		Predict the acoustic effect of vegetation	Wall Material	Acoustic	[14]
19	Rayman Pro			v		To calculate PET from ENVI-met input data	Wall Material, Building Morphology	Thermal, Humidity	[74]
20	Revit		v	v		Three-dimensional modeling and simulation	Building Morphology, Facade Layering, Wall Material	Daylight, Humidity, Thermal, Cost, Energy, LCA	[66,124,136,137]
21		Revit Tally		v		Evaluate environmental impact from material selection and design	Wall Material	LCA	[2]
22	TRNSYS			v		Simulate transient system, such as thermal and energy	Plant Properties, Urban Microclimate, Wall Material, Building Morphology	Energy, Cost, Thermal	[11,12,29,34]
23	USEPA SWMM 5.1			v		Stormwater management	Plant Properties		[45]

). The 3D modelers are primarily used to create digital representations of buildings and VGS designs. While some 3D modeling software includes basic performance simulation features, additional plugins or external software are often required for more accurate calculations. performance simulators assess various aspects of VGS performance, including thermal behavior, energy consumption, humidity levels, and cost-effectiveness. In contrast, optimization tools refine simulation outputs by identifying the most efficient design configurations to maximize VGS performance. However, their application in VGS research remains limited.

Among the most frequently used performance simulators are ENVI-met and DesignBuilder, both of which are used for 3D modeling and performance simulation but serve different purposes. ENVI-met is recognized for its high-resolution microclimatic modeling, effectively simulating interactions between urban geometry, vegetation, and the outdoor environment [42]. It provides detailed insights into the temperature distribution, wind flow, and radiation balance, making it well-suited for evaluating the outdoor thermal performance of VGS. However, its computational intensity and long processing times limit its efficiency for large-scale simulations.

In contrast, DesignBuilder, powered by the EnergyPlus engine, offers a user-friendly interface for creating detailed energy models and has been validated for its accuracy in predicting energy performance [66]. Unlike ENVI-met, DesignBuilder focuses more on indoor thermal comfort and whole-building energy performance rather than detailed microclimatic interactions with vegetation. While it allows users to model the shading effects of VGS, it does not inherently simulate plant-related cooling mechanisms, such as evapotranspiration.

Other notable simulation tools include Grasshopper, a graphical algorithm editor for Rhino, which facilitates parametric design and allows for rapid iterations in modeling. While Grasshopper does not perform direct performance simulations, it integrates with Ladybug and Honeybee to conduct energy and daylight analysis, making it particularly beneficial for optimizing green facades [73]. Additionally, RayMan Pro utilizes ENVI-met outputs to calculate thermal indices such as PET (Physiological Equivalent Temperature), providing an essential link between microclimate simulation and human thermal comfort assessment [74]. For moisture-related studies, Delphin is applied to simulate humidity and water transport in façade materials, addressing a critical gap in existing tools that struggle with dynamic plant growth and moisture exchange [43].

Despite these advancements, most available tools prioritize energy and thermal performance, while fewer studies focus on acoustics, fire safety, and life cycle assessment (LCA) [1,2,14]. Additionally, several studies have explored numerical modeling approaches that combine field measurements with computational simulations [10,34,46,61]; however, such studies also remain limited. Furthermore, the lack of integrated VGS modeling in existing software has led researchers to adopt simplified modeling methods, often requiring hybrid approaches that combine different tools for a more comprehensive analysis.

4.4. Fabrication

As part of the approach, digital fabrication is increasingly used in the development of vertical greening systems (VGS). A key advantage of fabrication techniques lies in their capacity to exert precise control over dimensions, surface modifications, and various associated characteristics, thereby accommodating the use of diverse materials. This process harnesses cutting-edge technologies such as 3D printing, robotic fabrication, and laser cutting.

Digital fabrication has driven architectural innovation in façades and holds great potential for enhancing VGS. Beyond precise form-making, it optimizes material use and supports sustainability. As the building sector moves toward decarbonization, digital fabrication offers an efficient solution for creating site-specific, high-performance, and environmentally friendly façade components [75].

4.4.1. Digital Fabrication Tools in VGS

Among digital fabrication tools, 3D printing has emerged as a key technology, enabling the production of complex and large-scale structures with improved material efficiency, functional integration, and the use of recycled materials [76]. Tay [77] categorizes large-scale 3D concrete printing into two primary techniques: binder jetting and the material deposition method (MDM), each offering distinct advantages and limitations for VGS applications.

In the context of VGS, fabricating earthen and living ceramic biocomposites face various fabrication challenges, including printing scales, hydro-seed optimization, production costs, print orientation, and durability. These challenges directly impact VGS performance, particularly in regulating airflow, controlling indoor temperatures, and maintaining structural integrity. Curth et al. [78] and Barnes et al. [79] highlight scalability as a key issue, requiring further experimentation and industry collaboration due to budget constraints. Moreover, clay viscosity and print settings can cause cell growth inconsistencies, emphasizing the need for optimized hydro-seeding. The Fused Filament Fabrication (FFF) process is also prone to irregularities, requiring an experimental approach and optimized print orientation to improve wet clay adhesion and geometric compatibility [80]. Additionally, optimizing the print orientation could improve wet clay adhesion and geometric compatibility [81].

Material limitations extend beyond structural concerns to ecological performance. Current concrete formulations lack adequate moisture retention and nutrient delivery, limiting their effectiveness in living wall applications. Bae and Park [36] stress the importance of full-scale testing to assess durability and overall functionality.

Beyond 3D printing, robotic arms enhance VGS fabrication and maintenance. Automation has been explored in agriculture and urban greening, with Marchant and Tosunoglu [82] developing control algorithms for vertical farming, while Phillips et al. [83] and Sepulveda et al. [84] demonstrated robotic adaptability in specialized environments. In urban contexts, robotics is increasingly integrated into architecture and design to reduce labor-intensive maintenance [85]. Li et al. [86] and Gren [87] applied robotic arms for pollination and plant management. Biomimicry has also influenced robotic advancements, such as flexible robotic arms inspired by climbing plants [88] and autonomous climbing robots for garden maintenance [89,90].

Robotic arms are also used in fabrication, with Bae and Park [36] applying 3D robotic arm printing to create porous ceramics, while Xu et al. [91] designed concrete greening modules with integrated irrigation, and Xu and Huang [15] developed clay-based modular facades using complex geometries. These advancements showcase the potential of robotic automation in both the creation and upkeep of vertical greening systems, paving the way for more efficient urban green solutions.

4.4.2. Material Advantages and Disadvantages

Material selection in façade fabrication plays a crucial role in structural integrity, thermal performance, energy efficiency, and sustainability, particularly in VGS. Various materials, such as thermoplastics, concrete, metal, clay, bio-based materials, mineral foam, plastics, and wood, offer distinct advantages and limitations (

Table A2. Advantages and disadvantages of material used for VGS fabrication.

Tools	Material Category	Materials	Advantages	Disadvantages
Robotic Arm	Soil-based	Clay and sand [78] Sand [79] Clay [15,36,80,91,111]	• Offers balance of workability, low shrinkage rate, good cohesion, and low carbon impact, widely available and low carbon impact [78] • Potential for load-bearing structures and plant germination, efficient scaling up, and porosity behavior for effective water distribution and evaporative cooling [79] • Consistent performance with stable or improving fluorescence yield [80] • High plasticity and drying performance [111] • Improved material removability [91]	• Lower durability and weather resistance without additional reinforcement [78] • Repetition of drying cycles weakens structural strength; changes in soil–water characteristics affect watering schedule [36] • Inherent material irregularities and non-linear behavior during wet conditions [111]
3D Printers	Bio-materials	Algae filament [106] Bio-material substrate [17] Nylon [141]	• Improves thermal performance, reduces carbon emissions and energy production, enhances water quality, and minimizes material waste [107] • Widely available in Middle East [106]	• Need for annual tube maintenance costs and cleaning tube parts, costly for construction [107]
	Concrete	Concrete [16] Sulfur concrete mix, cork concrete [142] Portland cement [125]	•Enable the production of building components with detailed designs, offers aesthetic appeal and energy-saving features, provides soundproofing and thermal insulation, and maintains structural performance [16] • Improves energy efficiency [142] • Enhances plant growth with higher porosity and lower alkalinity cement [125]	• Larger aggregate mixture decreases mechanical strength, high alkalinity hinders plant growth, and higher porosity supports growth but reduces structural integrity [125]
	Foam	Foam [24,108] Cement-free, geopolymer-based mineral foam, Industrial fly ash [24]	• Simple foaming process and applicability at construction scale [104] • No need for sintering process; UHPFRC is high-performance load-bearing material, less energy-intensive than sintering, allowing for fabrication of larger elements with lower densities [104] • Light-weighted, environmentally friendly, recycled materials, low embodied carbon, and convenient to replace and assemble [24]	• Labor-intensive, time-consuming, and less accurate [104]
	Plastics	PETG [109]	• Lightweight, versatile, enables high-performance envelope solutions, energy-saving benefits, reduces construction industry carbon footprint, durable, and hard-wearing components [109]	• Derives from non-renewable resources [109]
Laser Cut	Wood	MDF [110]	• Fast, high precision for intricate design, and no manual adjustments needed. Clean process without coolants or lubricants [143,144]	•Burning risk in Laser Settings, improper adjustment can lead to burning, and toxic fumes can be produced during process [143,144]
	Steel	CNC extruded cells, steel, water-jet milled frame [145]	• Strength and versatility, ideal for convoluted designs, laser cut supports customization, provides precision and accuracy [146]	• High initial costs, energy consumption, noise, vibration during cutting, and environmental concerns [146]
	Foam	EPS blocks foam [147]	• Supports precision and customization of design form, lightweight, easy installation, high-performance building materials for sound and thermal insulation [126,127]	• Fungibility and weather resistance issues, poor life cycle performance, and limited structural integrity [126,127]

).

Thermoplastics are valued for their ability to create nearly transparent components, insulation, and recyclability [92,93,94], while clay provides strong insulation, mechanical strength, and low environmental impact with its low carbon footprint [95,96,97]. However, Xu et al. addressed challenges such as overhangs and printing speed, demonstrating geometric fidelity and sustainability [91].

Concrete remains widely used for its fire resistance and thermal properties, especially with lightweight shotcrete layers [98,99,100,101]. Additionally, concrete innovations, including dynamic insulation and digital fabrication, enhance energy efficiency when using PMV and PPD indices [16].

Despite its versatility, metal poses challenges due to high costs and slow production [102,103,104,105], while bio-based materials like algae offer sustainable alternatives, contributing to carbon sequestration and improved thermal regulation [106,107]. Mineral foams support intricate 3D-printed components but raise sustainability concerns due to resource-intensive production processes. Bedarf et al. [108] further introduce a scalable 3D printing procedure for mineral foam that streamlines the foaming process. Plastic materials such as Polyethylene Terephthalate Glycol (PETG) explored by Zidek et al. [109] offer durability and hydrophobic properties suitable for VGS but raise sustainability concerns due to their reliance on non-renewable resources.

Wood, particularly Medium-Density Fiberboard (MDF), is rarely used in VGS due to low water resistance but allows for high-precision fabrication and UAV-assisted irrigation [110]. Steel provides structural durability for VGS but involves high energy consumption and environmental impact. Foam, though lightweight and effective for thermal and acoustic insulation, lacks durability and weather resistance for VGS applications [24,108].

4.4.3. Material Selection Parameter

Material selection criteria must consider mechanical strength, environmental impact, and economic feasibility (

Table A3. Material selection parameters.

No	Material/Form	Material Selection Parameters															Vegetation Parameters				Form Design Parameters						Form Categories			References
		Mechanical Strength	Solar Radiation	Availability	Indoor Air Quality	Porosity	Permeability	Thermal Behavior	Design Flexibility	Aesthetic Functionality	Energy Consumption	Life Cycle	Cost Production	Printing Scale	Non-Toxic	Environmentally Friendly	Plant Growth	Alkalinity	Weather resistance	Moisture	Water reservoir	Evaporative surface	Structural elements	Water vessel	Printability	Vernacular Architecture	Basic Geometric	Curve Geometric	Complex/Irregular
1	Clay and sand cylindrical	v		v					v			v		v		v				v			v				v			[78]
2	Sand Dome	v		v												v	v								v			v		[79]
3	Clay Piramidal																v										v			[80]
4	Clay Irregular				v					v										v	v	v	v	v	v				v	[36]
5	Clay Interlocking masonry units									v													v				v			[111]
6	Clay Blocks with elliptical concave					v	v									v	v		v	v					v		v			[91]
7	Clay Extrusion of an equilateral hyperbolic paraboloid (hypar)															v									v				v	[15]
8	Algae filament Spiral		v	v	v								v	v	v	v			v						v			v		[106]
9	Bio algae Spiral		v	v	v			v		v		v			v				v						v			v		[107]
10	Biomaterial substrate Modular block with concave and convex shapes	v	v									v				v						v				v			v	[17]
11	Nylon Triangular tiles mesh			v					v					v											v				v	[141]
12	Concrete Sinusoidal							v			v			v			v		v						v			v		[16]
13	Sulfur concrete mix Rectangular							v											v						v		v			[142]
14	Low-Alkalinity Sulphoaluminate Cement (LSAC) Rectangular	v				v	v		v								v	v							v		v			[125]
15	Fly ash mixture Circle based cellular patterns									v						v									v		v			[108]
16	Foam Isostatic lines based on strength analysis	v				v										v							v						v	[108]
17	Cement-free, geopolymer-based m-neral foam. Industrial fly ash. Alcove-like geometry					v				v															v		v			[24]
18	PETG Pod with voronoi pattern			v					v	v							v	v	v	v				v					v	[109]
19	Laser cut MDF components Pigeonholes			v													v		v		v	v					v			[110]
20	CNC extruded cells, steel, water-jet milled frame Hexagonal			v					v								v		v						v		v			[145]
21	EPS blocks (Foam) Penrose tiling			v					v	v															v				v	[147]

). In 3D-printed structures, mechanical performance is crucial for supporting complex geometries and ensuring long-term durability. Properly formulated earth materials can achieve high compressive strength, while natural fiber reinforcements like straw enhance load-bearing capacity [78]. Additionally, the choice of binders in concrete mixtures influences printability and mechanical strength, ensuring the structural integrity of printed materials for supporting plant life and load-bearing requirements [106]. Therefore, a strategic focus on mechanical strength is essential for developing durable and functional structures in both traditional and 3D-printed applications [78,79].

Sustainability remains a key parameter in material selection, necessitating the use of eco-friendly, biodegradable materials. This aligns with the new device element, which repurposes algae as a local biopolymer—an environmentally safe, cost-effective solution that adds value to the project [107]. Moreover, 3D-printed earth provides recyclable, fire-resistant formwork for reinforced concrete, enhancing resource efficiency. Prioritizing life cycle assessments helps refine sustainable construction practices, maximizing earth materials’ low-carbon benefits while minimizing environmental impact [78].

Beyond mechanical and environmental performance, material selection impacts functionality and aesthetics in architecture. Adjusting the print orientation and loop configurations optimizes structural integrity and design flexibility, enhancing solar control, airflow, and efficiency. Wet clay’s unique texture enables dynamic façades that blend aesthetics with environmental benefits [36,111].

Cost and scalability further shape material feasibility in sustainable construction. The high cost and limited local availability of traditional filament polymers and plastics pose challenges, particularly in the Middle East, increasing expenses and restricting scalability. Algae-based biopolymers offer a cost-effective solution, reducing reliance on imported materials [106]. To support industry adoption, scalable material conveyance systems and on-site testing are essential, especially as demand for sustainable construction continues to grow [78]. Additionally, small-scale algal prototypes using wastewater can be developed into façade elements that provide watering, filtration, and aesthetic benefits, effectively addressing environmental challenges while meeting design needs.

4.4.4. Relationship Between Tools and Performance

The use of software plays a significant role in estimating various parameters of VGS, including plant growth, structural strength, substrate media, and airflow. However, while software can provide valuable simulations and predictions, the validation of structural strength and plant growth still requires measurement tools to collect initial data and ensure accuracy.

In addition to software applications, 3D printing and robotic fabrication contribute significantly to VGS production, particularly in assessing structural integrity. The selection of 3D printers, measurement tools, and software for VGS must prioritize the creation of strong and durable structures (Figure 7). This figure was generated by coding various tools and materials alongside the variables considered in multiple studies. Computational tools are primarily utilized for analysis and simulation, such as evaluating structure strength and plant growth. In contrast, fabrication tools, including 3D printing and robotic fabrication, are employed in the physical manufacturing process to enhance structural strength and durability.

A common challenge in the 3D printing process is structural deformation, which can compromise both integrity and functionality, underscoring the need for further optimization in fabrication techniques. Moreover, more comprehensive studies are needed to evaluate the impact of material selection and airflow on plant health and growth within VGS. Different structural designs influence airflow and ventilation, affecting the microclimate surrounding the plants. Understanding these interactions is essential to improving plant viability and overall system efficiency.

Another critical aspect that requires attention is the consideration of maintenance parameters in material selection for VGS fabrication. Ensuring that materials are not only structurally sound but also require minimal maintenance can enhance the long-term sustainability and effectiveness of these systems. By optimizing material choices and fabrication methods, VGS can become more resilient, resource-efficient, and environmentally sustainable.

4.5. Monitoring and Maintenance

Advancements in technology, including devices and wireless communication systems, enable the development of integrated systems that enhance computational efficiency, reliability, adaptability, and security [112]. The Internet of Things (IoT) is a concept where a range of devices with different functions communicate with each other, creating a global, dynamic network.

In the VGS context, effective monitoring and maintenance are essential to ensure optimal plant growth and system performance. Timely and accurate regulation of essential environmental factors, including air temperature, soil temperature, humidity, water levels, soil moisture, soil pH, and light intensity, can only be accomplished through real-time monitoring [113]. The implementation of IoT facilitates automated monitoring and control, improving overall VGS performance.

IoT enables automated maintenance, which is crucial for sustaining VGS functionality. Holschemacher et al. [18] highlight that an automated system reduces operational costs, minimizes dependence on environmental conditions, enhances maintenance quality through shorter care intervals, and allows for localized adjustments. Integrated IoT systems also provide accurate estimations of plant requirements. For instance, Sarfraz et al. [114] use temperature data from sensors to estimate the evapotranspiration rate across different orientations to help enhance water management for efficient irrigation.

There have been several reviews discussing the use of IoT for the maintenance of vegetation. Halgamuge et al. [113] investigate the essential parameters for automating sustainable vertical gardening systems based on the use of the IoT concept in smart cities. However, the current state of IoT applications in maintaining and monitoring vertical greening systems has not been thoroughly reviewed. Therefore, this presents an opportunity to explore its potential in optimizing system performance, such as maintaining plants through automated irrigation controls, real-time monitoring of environmental conditions, and analyzing the overall performance of VGS.

4.5.1. Function of Internet of Things in VGS

The IoT concept plays a vital role in maintaining VGS by automating and optimizing processes. IoT-based VGS maintenance is often implemented through automated irrigation systems. Holschemacher et al. [18] developed a large-scale rope-driven robot with nozzles and injectors to apply water and fertilizer precisely. Sensors, such as near-infrared spectroscopy, temperature and humidity probes (for air and substrate), and standard cameras, can be integrated for condition monitoring. By analyzing the data, measured values are evaluated to determine tailored actions for each plant.

Additionally, IoT can monitor the growth environment, enabling users to evaluate conditions and make necessary adjustments for optimal plant development. Dungca et al. [19] suggested that adding temperature and pH sensors enhances the system’s capabilities by helping users adjust to environmental conditions. Helman et al. [115] employed remote sensing to monitor CO₂ uptake using spectral data from the photochemical reflectance index (PRI), improving VGS management. Additionally, thermal data analysis helps evaluate water stress and optimize irrigation by estimating transpiration rates.

Beyond individual plant care, IoT contributes to overall VGS performance evaluation. This process involves analyzing a range of factors to determine the system’s efficiency, effectiveness, and sustainability. Key considerations include the impact of rain and irradiance, which affects heat absorption and overall wall temperature regulation [9]; the impact of temperature and humidity on the performance of wireless sensor systems that utilize plants as energy sources [116]; and parameters such as building geometry, vegetation density, and species selection, which play a crucial role in enhancing the cooling effect, improving air quality, and optimizing thermal comfort, especially in a hot and humid climate [117].

4.5.2. Relation of IoT Functions and Growth-Influencing Factors

Figure 8 illustrates the relationship between two coding groups: the functions of IoT for VGS and the factors influencing their growth. Different aspects, such as irrigation, daylight, temperature, and noise pollution, are interconnected with the purposes of IoT for VGS, including maintenance, monitoring systems, and performance analysis. Each flow represents how these factors contribute to or interact with the primary objectives of maintaining and optimizing VGS performance. To systematically capture these interactions, relevant studies were analyzed and categorized, resulting in a structured visualization of these connections.

Irrigation is one of the key factors managed through IoT in VGS to ensure optimal water supply and prevent over-irrigation by regulating both the frequency and quantity of water delivered. Santi et al. [23] introduced a system with humidity sensors and drips connected to an automatic electronic programmer for a consistent water distribution that is self-cleaning, self-compensating, and anti-draining. Similarly, Sarfraz et al. [114] developed an irrigation method for Living Green Walls (LGWs) by estimating evapotranspiration (ET0) using temperature data, employing sensors, electromechanical valves, and a gutter drainage system to improve efficiency.

Another crucial factor influencing plant growth and development is light. It regulates essential physiological processes, including photosynthesis, morphogenesis, metabolism, and gene expression. Heród and Malik [118] investigated the impact of an increased DLI (Daily Light Integral) on plant growth and development in vertical gardens. Using an LI-250A light meter with a Q50604 sensor to measure the photosynthetic photon flux density (PPFD), they assessed growth variables such as the plant height, diameter, number of leaves, leaf blade length, leaf width, leaf area, and the total area of leaf blades.

Comprehensive climate data, including solar radiation, wind speed, and air humidity, aids thermal monitoring. Fensterseifer et al. [119] investigated green facades’ impact on building wall thermal performance by placing automatic temperature sensors at internal and external wall positions. They used DHT22 sensors for internal temperatures and DS18B20 sensors for external ones, as they are waterproof and resistant to weather. Similarly, Liang et al. [120] found that VGS effectively reduces the mean radiant temperature in surrounding environments.

4.5.3. IoT Tools for VGS

The use of tools is an essential element in supporting research activities, with their selection determined by the specific objectives of the study (

Table A4. The use of IoT tools in various studies.

No	IoT Function			Tools		Tools						Categories					Parameter Input (V)/Output (X) Data																																Referensi
	Performance Analysis	Monitoring System	Maintain VGS		Sensor	Record	Actuator/Robot	Controller/Programming	Photovoltaic	Hardware	Software	Irrigation	Temperature	Daylight	Noise Pollution	Air Pollution/Carbon Sequestration	Fertilization	Water	Water Flow	Water Preassure	Water Volume	Water Speed	Water Frequency	Light Intensity	Solar Radiation	Duration of Light Exposure	Air Felocity/Wind Speed	Surface Temperature	Air Temperature	Room Temperature	Humidity	Pressure	Soil Density	Soil Moisture	Soil Substrate	Orientation	Location	Vegetation Type	Rain drops	CO2	Leaf Transpiration	Evapotranspiration	Spectral	LAI	Infrared - Spectroscopy	Air Quality	Energy Efficient	PM Mittigation
1	v			AGRI|gen Analysis	v			v		v	v			v										v		v										v	v	v											[122]
2.	v			Thermocube						v			v															v																					[120]
3.	v			Globe Thermometer						v			v
4.		v		SpecimIQ hyperspectral camera	v					v																																	v
5.	v			Air Temperature sensor	v								v																v
6.		v		2 Onset® Silicon Pyranometer Smart Sensor (Part # S-LIB-M003)	v					v				v										v																									[148]
7.		v		2 HOBO® U20 Fresh Water Level Data Logger 13 feet—U20-001-04	v					v		v																						v
8.		v		T/RH sensors of Xiaomi	v					v										v																													[115]
9.		v		LI-6800, LiCOR	v					v			v																v		v
10.		v		LI-600, LiCOR	v					v						v																								v	v
11.		v		FLIR T560	v					v						v																								v	v
12.	v			LI-3100 Leaf Area Meter		v				v			v			v																												v					[149]
13.			v	Automated drip irrigation	v		v	v		v	v	v						x			x	x	x																										[150]
14.			v	Soil moisture sensor	v					v		v																						v
15.		v	v	Control devices	v		v	v		v	v	v	v					x			x	x	x					v			v											v
16.			v	Automatic irrigation sprayer	v		v	v		v	v	v	v					x			x	x	x					v			v											v							[151]
17.			v	Temperature sensor	v					v		v																																					[114]
18.		v		Agronic				v			v	v
19.				Two-meter sensor	v					v		v											v
20		v		DHT22	v					v		v	v																v		v																		[19]
21.		v		pH Sensor	v					v
22.		v		Acoustic sensor	v										v																																		[152] [129]
23.		v		Smart Citizen kit v2.0 SCK				v			v	v						x	x	x	x	x	x											v
24.		v		INMET Weather Station		v					v		v											v			v		x		v															x			[119]
25.		v		Onset HOBO weatherproof temperature logger	v	v				v			v																v	x																			[153]
26.		v		Rope driven robot	v		v			v		v					x	x	x	x	x	x	x						v		v														v
27.			v		v					v				v										v		v																							[118]
28.	v	v			v											v											v		v		v					v				x						x		x	[154]
29.	v			RS 485 RTU-Modbus	v	v					v																		v	x									v										[20]
30.	v			Wireless sensor nodes	v					v						v											v		v	v										x						x		x	[155]
31.		v		Electronic automatic programmer				v			v	v						x			x	x	x								v																		[23]
32.			v	Campbell CS215	v	v				v		v						x			x	x	x											v	v														[38]
33.	v																																			v	v	v								x			[117]
34.	v			nRF52840-based Wireless sensor node	v																								v		v	v														v	x		[116]
35.			v	Arduino UNO	v			v			v	v																																					[121]
36.			v	Integrated Development Environment (IDE)				v			v	v
37.			v	ThingSpeak				v			v	v							v		v									v	v			v			v
38.			v	The FC-28	v					v		v						v															v	x
39.			v	The DHT22	v					v		v																		vx	vx
40.			v	Light Dependent Resistor (LDR) Photo-Resistor	v					v		v												vx
41.			v	The YL-83	v					v		v						x																					v
42.			v	The YF-S402	v					v		v							v		x

). In the context of IoT, tools play a crucial role in collecting data, which are then processed into valuable information for users. These tools can be categorized based on their respective functions within the IoT system, including data collection, transmission, processing, output, and storage (Figure 9), which were generated by coding and analyzing information from previous studies to identify key components and their interactions within the IoT framework for VGS.

In VGS, data collection primarily involves hardware. Sensors used for performance analysis include Wireless Sensor Nodes and Air Temperature Sensors, while monitoring utilizes devices like the SpecimIQ Hyperspectral Camera, Silicon Pyranometer Smart Sensor, Soil Moisture Smart Sensors, HOBO Data Logger, T/RH (Temperature/Relative Humidity) Sensors (DHT22), LiCOR, FLIR, pH Sensors, Acoustic Sensors, and HOBO Temperature Loggers. Maintenance relies on tools like Soil Moisture Sensors (FC-28), DHT22, Light-Dependent Resistors (LDR) Photo-Resistors, Rain Sensors (YL-83), and Water Flow Sensors (YF-S402).

Collected data are transmitted using tools such as RS 485 RTU-Modbus and LoRa Transceiver Radio Modules, then stored on internal SD cards in the main controller, which periodically uploads the data to a monitoring server for processing [20]. The data uploaded to the monitoring database are then processed using various software tools, such as the Smart Citizen Kit v2.0, Artificial Intelligence platforms, ThingSpeak, and Agronic, tailored to meet data output requirements.

The output data are the result of processing and are used as input for tools such as robots, automated irrigation sprayers, and drip irrigation systems, enabling efficient operation with minimal human intervention. Data are stored with timestamps on hardware like SD cards or software platforms such as ThingSpeak, providing a versatile storage solution [20,121].

4.5.4. Advantages and Disadvantages of IoT

The integration of IoT technology into rope-driven robotic systems for maintaining urban green facades offers significant advantages by enabling efficient, automated maintenance at great heights, regardless of weather or time of day, reducing costs and improving maintenance quality [18]. IoT-enabled VGS improves air quality by managing particulate matter (PM) removal and reducing CO₂, SO₂, and volatile organic compounds, leading to healthier indoor environments. These systems enhance occupant well-being by reducing stress and mental fatigue and improving productivity [115]. IoT-driven VGS also optimizes indoor thermal comfort and air purification, saving energy for heating and cooling [121]. In tropical climates, IoT-supported green walls help mitigate wall temperatures and improve urban microclimates, aiding sustainable construction and combating urban heat islands (UHIs) [23].

However, integrating IoT into VGS poses challenges, such as complexity and cost, limiting access to wealthier entities or large-scale projects [122]. Maintenance needs for IoT devices, including updates and monitoring, increase operational costs. Continuous monitoring often requires remote sensing technologies, complicating system integration [115]. Additionally, IoT reliance introduces vulnerabilities, with system failures or poor maintenance affecting performance, underscoring the need for reliable data systems [120].

Figure 10 illustrates the suggested workflow for VGS development, structured into an input–process–output framework. The input phase involves data collection through onsite performance measurements, climate analysis, and environmental assessment tools. The process phase integrates form finding, simulation, analysis, and fabrication, leveraging parametric design, structural performance analysis, and optimization techniques. The output phase focuses on installation, operation, and maintenance, with an emphasis on IoT-based monitoring for plant health, irrigation management, and structural integrity.

5. Discussion

Within the scope of this study, simulation is the most extensively researched area, while form-finding receives minimal attention. Most studies focus on evaluating existing VGS designs, particularly in terms of thermal and energy performance indicators. Despite growing interest in fabrication and architectural innovations, there remains a significant gap in form-finding, especially in its integration with performance simulation. This imbalance across VGS design stages highlights the need for a more integrated workflow.

As stated by Bustami et al. [25], several studies on VGS focus on reducing carbon footprints through recycled materials and modular forms. However, since VGS facades must meet specific performance objectives [27], further research is needed to optimize form generation and simulation-based performance evaluation.

Form-finding remains a key research gap, particularly in its integration with simulation tools. The limited focus on this stage suggests that current VGS designs may not be fully optimized for site-specific conditions. Incorporating an iterative form-finding–simulation–optimization process could enhance VGS performance, ensuring that design choices align with functional and environmental requirements. Furthermore, urban microclimates significantly impact VGS efficiency, yet few studies incorporate site measurements and microclimate simulations in the design phase. Bridging the gap between contextual analysis and form-finding methodologies is crucial for improving VGS adaptability.

Additionally, IoT applications for automated maintenance and real-time monitoring show promising advancements in long-term VGS efficiency. These technologies help ensure system reliability, allowing VGS to adapt to environmental changes and optimize resource use. Further research should explore how IoT-driven monitoring can be fully integrated into VGS lifecycle management, from initial design to long-term operation.

Furthermore,

Table 2. Existing studies, research gaps, and future directions.

Design Stages	Existing Studies	Research Gaps	Future Directions
Context	Focus on VGS cooling performance, with limited research on its effectiveness in heating load reduction [29,30,31].	Fewer research studies that highlight differences of VGS effectiveness in heating and cooling load	Analysis of VGS performance in response to different context conditions, climates, and microclimates
	Studies primarily evaluate the performance of VGS in Subtropical and Mediterranean climates [7,8,10,13,16,58,60,61].	Fewer research studies that analyze tropical weather with a longer summer period
Form Generation	Weeping Brick system, which demonstrates the potential of parametric adjustments in VGS design but rarely explores iterative form generation involving design variables, parameters, and performance indicators [36,67].	Very few studies of VGS explored the form generation stage that involves iterations from design variables, parameters, and performance indicators	Explore form generation based on multi-performance optimization
Simulation		The previous VGS simulation literature review has not mentioned the iterative process of design–simulation–optimization, where most research is only performed on the simulation phase	Integrate VGS form generation and simulation stages Explore more computational tools and performance objectives
	Existing research primarily evaluates VGS performance based on thermal and energy efficiency metrics [11,66,67,69].	Performance objective is still heavy on thermal and energy; however, there are other quantifiable parameters, such as acoustic, economic and life cycle parameters that can be determined using computational tools
	Using Grasshopper to generate building geometry and computational simulation [69,73,107,123,124].	Computational tools used 3D modeling and performance simulation tools, but rarely utilized optimization tools
Fabrication	Material selection in several studies focuses on performance, environmental impact, design, and production (cost and scale) [36,78,107].	Integration Challenges: Limited exploration of how materials can be optimized for plant growth, water management, and nutrient distribution within VGS	Develop hybrid materials that combine the thermal performance of clay and the structural integrity of concrete with bio-materials such as algae or bioplastics to enhance plant growth while maintaining durability Investigate the potential of low-carbon and recyclable materials, such as mineral foams and PETG, for lightweight, modular VGS applications Explore material modifications to optimize water retention, nutrient distribution, and root anchorage for various plant species commonly used in VGS Conduct studies on material interaction with microbial ecosystems to boost plant health and environmental performance Expand the use of robotic arms and 3D printing to achieve precise geometries that support plant integration while addressing challenges such as overhangs, material shrinkage, and geometric fidelity Explore adaptive fabrication methods that allow for on-site customization based on local environmental conditions
	There are few studies that have examined material properties like porosity, alkalinity, and thermal behavior on plant growth [125].	Material–Plant Interactions: Insufficient research on how material properties like porosity, alkalinity, and thermal behavior directly affect plant survival and growth
	Several studies highlight scalability as a key issue and require further experimentation and collaboration due to budget constraints [78,79].	Scalability and Cost Efficiency: A lack of studies addressing the economic feasibility and scalability of advanced fabrication techniques like 3D printing and robotic assembly for VGS in urban environments
	There are only a few studies that have assessed the environmental impact of VGS materials by evaluating their life cycle and carbon sequestration [58,126,127].	Sustainability Metrics: Few studies incorporate comprehensive life cycle assessments or carbon sequestration metrics to evaluate the long-term environmental benefits of materials used in VGS
Monitoring and Maintenance	Existing studies have not throughly reviewed the benefits of using IoT for maintaining and monitoring system [128].	The potential of IoT in maintaining and monitoring VGS has not been thoroughly reviewed	Enhance IoT-based real-time systems for monitoring and automating irrigation, light, and nutrients Develop IoT systems that can optimize VGS for both energy efficiency and plant health
	Existing studies primarily focus on using IoT for monitoring, maintaining, and analyzed the performance of VGS [114].	Current research has not fully addressed how IoT can be utilized to optimize the performance of VGS

summarizes the identified existing studies, research gaps, and future directions, emphasizing the need for interdisciplinary approaches integrating computational design, material innovation, and IoT-based performance monitoring.

However, potential biases in the study selection may include an overemphasis on fabrication, computational methods, or IoT integration, potentially overlooking traditional VGS design insights. Additionally, the exclusion of non-English studies may limit the diversity of perspectives and regional innovations.

6. Conclusions

VGS is a promising facade strategy in response to the development of urban areas, with their ability to reduce heat and energy consumption widely recognized. Current research on VGS focuses mainly on performance simulation and fabrication; limited attention has been given to other stages or the interconnectivity of these phases. This study breaks down the VGS creation process into several stages, including (a) context, (b) form generation, (c) simulation, (d) fabrication, and (e) maintenance and monitoring. This study highlights the technological advancements applied at each stage of creating VGS as a facade in the following ways:

• Technological advancements in computational tools and simulation enable the analysis and optimization of VGS performance in relation to climate and microclimate conditions. These tools help design more effective VGS systems tailored to specific environmental conditions.
• While research on form generation is limited, integrating this stage with simulation and optimization processes can generate more diverse and adaptable VGS forms. Technological advancements allow for the exploration of a wider range of VGS forms, enhancing the overall design flexibility.
• Computational tools enable detailed simulation of VGS performance, helping to predict its effectiveness in various climatic conditions. These advancements aid in optimizing the design before physical construction, ensuring better performance.
• Technological improvements in fabrication allow for the efficient production and precise construction of VGS elements. These advancements ensure that VGS systems can be implemented at scale while maintaining accuracy and reliability in their application to facades.
• IoT technology is increasingly utilized for the automation and maintenance of living vegetation within VGS. Real-time monitoring and automated care ensure the sustainability and long-term functionality of the system, reducing the need for manual intervention.

Moreover, future research should explore combinations of tools to expand VGS form exploration. This study emphasizes a broader framework for the VGS creation stages, highlighting potential areas for integration and development to optimize VGS design and performance as a facade in architecture.

Additionally, future studies should incorporate case studies or real-world applications to assess VGS performance across different climatic and urban contexts, enhancing the credibility and applicability of findings. A more comprehensive exploration of advanced digital tools, such as AI and digital twins, could further optimize VGS adaptability and automation. Furthermore, urban morphology and microclimate interactions should be examined in greater depth, as these factors significantly influence VGS efficiency in diverse built environments.

To strengthen practical applications, future research should develop standardized guidelines for integrating VGS into various architectural typologies, considering factors such as structural load, maintenance accessibility, and long-term sustainability. Additionally, incorporating IoT-based monitoring and automation will enhance system efficiency by enabling real-time performance tracking and adaptive maintenance, reducing manual intervention. Policymakers should also be encouraged to support VGS adoption through incentives, regulations, and urban planning strategies that promote green infrastructure. Addressing these aspects will provide a more holistic understanding of VGS implementation, ensuring its effectiveness as a sustainable facade strategy that contributes to energy efficiency and urban resilience.