Structural Imbalance and Life-Cycle Cost Coverage in Vertical Greenery Systems: A Systematic Literature Review

Abstract

Vertical greenery systems (VGS), including vertical gardens (VG) and green façades (GF), are increasingly promoted as nature-based solutions for sustainable urban development. Despite their environmental benefits, economic evaluation remains fragmented, particularly within a life-cycle cost (LCC) perspective. This study conducts a systematic literature review to examine the structural configuration of cost-related research on VGS within an LCC framework. Following the PRISMA protocol, 136 peer-reviewed articles published between 2021 and 2025 were identified through a structured search of the ScienceDirect database and retained as the analytical dataset. Bibliometric mapping, thematic classification, and co-occurrence analysis were applied to assess publication patterns, the distribution of cost components, and reporting structures. Five principal cost categories were identified: Installation and Operation, Maintenance, Consumables, Materials and Manufacturing, and Design. The results reveal a pronounced concentration on installation and maintenance costs, while design-phase economics and comprehensive LCC integration remain marginal. Most studies address only one or two cost categories, indicating structural fragmentation. In addition, heterogeneous reporting units and inconsistent contextual descriptors constrain cross-study comparability and cumulative synthesis. Collectively, the findings demonstrate that although cost research on VGS is expanding, it has not yet achieved methodological maturity within a standardized LCC framework. Advancing harmonized cost-reporting protocols and integrated life-cycle modeling is therefore essential to support robust economic evaluation and informed implementation of VGS in sustainable built environments.

1. Introduction

Over the past several decades, accelerated urban growth has emerged as a major global phenomenon [1,2,3,4,5,6,7]. This expansion has led to the progressive reduction in urban green spaces, which have increasingly been replaced by impervious surfaces [4,5,6,7]. Such transformations disrupt the urban energy balance and intensify the urban heat island (UHI) effect [8,9,10], resulting in significantly higher temperatures in urban areas compared with surrounding rural regions [10,11,12]. Simultaneously, cities have become major contributors to greenhouse gas emissions [1,2,3]. Although urban green spaces are widely recognized as an effective strategy for mitigating these environmental pressures, horizontal green areas in dense urban environments are frequently constrained by limited land availability and are often insufficient to adequately improve air quality [13,14,15,16,17,18]. These structural limitations highlight the need for alternative, spatially efficient solutions capable of enhancing environmental performance within built-up contexts.

Extensive research demonstrates that urban green spaces substantially reduce urban heat and improve environmental quality [13,19]. Specifically, they lower air temperature and UHI intensity [11,14,15], decrease building heat gain [20,21,22], and capture particulate matter while absorbing airborne pollutants [16,23,24]. However, in high-density cities characterized by physically intensive development [6,7], the expansion of ground-level green spaces is severely restricted by land scarcity and intense competition for urban land use [6,25,26]. Indeed, more than 60–70% of urban land is typically occupied by buildings, roads, and infrastructure [6,27], thereby limiting the potential for increasing horizontal greenery [27,28,29]. In response to these constraints, vegetation has increasingly been integrated into building envelopes and structures [13,19,30], particularly through the application of vertical greenery systems (VGSs) [5,31,32].

Vertical greenery systems were developed to address spatial scarcity in high-density urban areas [31,32]. By utilizing vertical building surfaces as substrates for vegetation [31,32], VGS expand green surface area vertically [33] and provide environmental benefits comparable to those of horizontal green spaces while requiring substantially less land [34,35]. Empirical evidence indicates that VGS reduce building surface and ambient air temperatures [20,36,37], mitigate UHI intensity [38,39,40], and capture particulate matter while absorbing air pollutants [16,17,23,24,41]. Consequently, VGS are widely recognized as an integral component of urban green infrastructure [13,19], a nature-based solution supporting sustainable urban development [5,42,43], and a strategy that enhances climate resilience in the built environment [1,44].

Despite their documented environmental performance, the broader adoption of VGS remains constrained by economic considerations. While environmental benefits have been extensively investigated, the economic feasibility of VGS in architectural applications remains less systematically examined [22,33,39,40]. Numerous studies report that VGS entail higher costs than conventional horizontal green spaces due to requirements for supporting structures, irrigation and drainage systems, specialized planting materials and systems, labor-intensive installation processes, and customized design solutions [31,35,36,39]. Furthermore, long-term maintenance costs remain uncertain and context-dependent [33,36,37,45]. The absence of comprehensive and consistently structured cost data further complicates economic evaluation [5,35,40,42,46].

From a sustainability transition perspective, economic feasibility constitutes a decisive factor influencing the implementation of nature-based solutions in the built environment. Without structured and comparable life-cycle cost (LCC) information, environmental performance alone is insufficient to support evidence-based decision-making. However, existing cost-related research on VGS is fragmented, inconsistently reported, and methodologically heterogeneous. Previous systematic reviews have acknowledged cost barriers related to installation and maintenance [33,35,36,40], yet they also indicate that cost data vary in unit specification, reporting format, and analytical scope, and that no standardized framework currently enables transparent comparison across studies [32,35,40]. This lack of methodological coherence restricts cumulative knowledge development and weakens the integration of cost evidence into life-cycle-based decision processes in architectural practice.

To address these limitations, this study conducts a systematic literature review that rigorously, transparently, and reproducibly collects, screens, and synthesizes scholarly evidence on the financial cost components of vertical greenery systems. By organizing dispersed cost information within a structured life-cycle cost framework, this research aims to clarify how cost components are distributed across different life-cycle stages, evaluate the consistency and comprehensiveness of existing cost-reporting practices, and identify conceptual and methodological gaps that constrain robust economic assessment. Through this integration, the study seeks to strengthen the foundation for life-cycle-based evaluation, support policy formulation, and facilitate more informed implementation of VGS in sustainable architectural practice [31,32,40,47,48,49].

Accordingly, this study addresses the following research questions:

RQ1: How are cost components of vertical greenery systems structured and distributed across different life-cycle stages within the existing literature?

RQ2: To what extent do current studies provide consistent, comparable, and comprehensive life-cycle cost (LCC) reporting for vertical gardens and green façades?

RQ3: What methodological and conceptual gaps limit the integration of cost evidence into life-cycle-based decision-making for VGS implementation?

In response to these gaps, this study conducts a systematic literature review to examine the structural configuration of cost-related research on vertical greenery systems (VGS), including vertical gardens (VG) and green façades (GF), within a life-cycle cost (LCC) framework. Specifically, the review addresses three questions: (1) What is the structural landscape of cost-related publications on VGS? (2) How are cost components distributed across life-cycle stages? and (3) To what extent are cost data reported in a standardized and comparable manner? By synthesizing bibliometric trends, thematic cost classifications, co-occurrence patterns, and reporting structures, this study moves beyond descriptive enumeration to identify methodological fragmentation and theoretical misalignment within the field. In doing so, it contributes a structured analytical foundation to support more coherent life-cycle economic evaluation of VGS. The remainder of this article is organized as follows: Section 2 outlines the materials and methods; Section 3 presents the results; Section 4 discusses the findings in relation to life-cycle cost theory and existing literature; Section 5 concludes the study; and subsequent sections address limitations and directions for future research.

As shown in Figure 1, the background and significance of this study are illustrated.

2. Materials and Methods

This study was designed to examine the structural configuration of cost-related re-search on vertical greenery systems (VGS), including vertical gardens (VG) and green fa-çades (GF), within a life-cycle cost (LCC) perspective. The objective was not merely to quantify publication output, but to identify how cost components are distributed, interrelated, and reported across life-cycle stages. Specifically, the review sought to achieve the following: 1 map the structural landscape of cost-related publications, 2 classify cost components within an LCC framework, and 3 evaluate the consistency and comparability of reported cost data. To achieve these objectives, a systematic literature review was conducted.

2.1. Data Collection

The review was conducted in September 2025 using the ScienceDirect database. ScienceDirect was selected due to its extensive coverage of peer-reviewed journals in engineering, environmental science, and building-related disciplines, which are central to VGS research. The review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines [50] (shown in Supplementary Material) to ensure transparency, reproducibility, and methodological rigor [51,52] (Figure 2).

2.1.1. Identification

The search strategy targeted studies explicitly addressing cost aspects of VGS. The following search strings were applied: (“cost”) AND (“vertical garden”), (“cost”) AND (“green façade”) [53,54,55,56,57,58,59].

Searches were conducted within titles, abstracts, and keywords to capture studies where cost constituted a central analytical component.

The search was limited to the following: English-language publications and articles within architecture, building, and built environment contexts

Publications between 2021 and 2025. This process yielded 774 records. All records were exported and independently screened at the title and abstract level. Articles clearly unrelated to economic or cost aspects were excluded, resulting in 294 articles retained for further screening [60,61,62,63].

It should be acknowledged that the search strategy focused on explicit cost-related terms combined with “vertical garden” and “green façade”. Although this approach ensured that retrieved studies directly addressed economic aspects of vertical greenery systems, it may have excluded studies discussing cost-related implications using alternative terminology such as “economic assessment”, “financial evaluation”, or “cost–benefit analysis”. Consequently, some relevant studies might not have been captured. This limitation is acknowledged and should be considered when interpreting the results.

2.1.2. Screening

During screening, full-text accessibility was verified. Sixteen records were excluded due to unavailable full texts, leaving 278 articles for eligibility assessment.

2.1.3. Eligibility Phase

Full-text review was conducted to confirm explicit relevance to cost-related analysis of VGS. Studies were excluded if they addressed environmental or performance outcomes without economic analysis; mentioned cost superficially without analytical treatment; or did not provide identifiable cost components or discussion. Following this evaluation, 142 articles were excluded.

2.1.4. Inclusion Phase

A total of 136 peer-reviewed articles met the inclusion criteria and were included in the final analytical dataset. These studies formed the basis for the subsequent structural and thematic analyses conducted within a life-cycle cost (LCC) framework.

For transparency, the complete list of screened and included studies is provided in Appendix A (

Table A1. The list of selected articles from a systematic review.

NO	Title	Year	Authors	First-Author-Affiliation Country	Publication	Citation Indexes
[84]	Internet of Things and autonomous control for vertical cultivation walls towards smart food growing: A review	2021	Malka N. Halgamuge, Alexe Bojovschi, Peter M.J. Fisher, Tu C. Le d, Samuel Adeloju e, Susan Murphy	Australia	Urban Forestry & Urban Greening	78
[85]	Water consumption of felt-based outdoor living walls in warm climates	2021	Luis Pérez-Urrestarazu	Spain	Urban Forestry & Urban Greening	10
[86]	Towards smart green wall maintenance and Wallbot technology	2021	Sara Wilkinson, Marc Carmichael, Richardo Khonasty	Australia	Property Management	12
[60]	Are green wall technologies suitable for major transport infrastructure construction projects?	2021	Reina Iligan, Peter Irga	Australia	Urban Forestry & Urban Greening	15
[87]	Stakeholders’ perceptions of appropriate nature-based solutions in the urban context	2021	Vera Ferreira, Ana Paula Barreira, Luís Loures, Dulce Antunes, Thomas Panagopoulos a	Portugal	Journal of Environmental Management	39
[63]	Green walls: A form of constructed wetland in green buildings	2021	Olivia Addo-Bankas, Yaqian Zhao, Jan Vymazal, Yujie Yuan, Jingmiao Fu, Ting Wei	China	Ecological Engineering	60
[88]	Assessment of the environmental loads of green façades in buildings: a comparison with un-vegetated exterior walls	2021	Ileana Blanco, Giuliano Vox, Evelia Schettini, Giovanni Russo	Italy	Journal of Environmental Management	31
[89]	A comparative life cycle assessment between green walls and green facades in the Mediterranean continental climate	2021	Marta Chàfer, Gabriel Pérez, Julià Coma, Luisa F. Cabeza	Italy	Energy and Buildings	36
[90]	Development of microclimate modeling for enhancing neighborhood thermal performance through urban greenery cover	2021	Mohamed Dardir, Umberto Berardi	Egypt	Energy and Buildings	37
[91]	Evaluation of the suppressive effects on solar radiation for a building façade covered with green layers in the Kathmandu valley	2021	Aakriti Shrestha, Takafumi Shimizu	Japan	Environmental Challenges	9
[73]	Trends and gaps in global research of greenery systems through a bibliometric analysis	2021	Marta Chàfer, Luisa F. Cabeza, Anna Laura Pisello, Chun Liang Tan, Nyuk Hien Wong	Italy	Sustainable Cities and Society	53
[75]	Holistic analysis and prediction of life cycle cost for vertical greenery systems in Singapore	2021	Ziyou Huang, Chun Liang Tan, Yujie Lu, Nyuk Hien Wong	Singapore	Building and Environment	22
[57]	Economics of green roofs and green walls: A literature review	2021	Inês Teotónio, Cristina Matos Silva, Carlos Oliveira Cruz	Portugal	Sustainable Cities and Society	107
[92]	In situ experimental evaluation of a novel modular living wall system for industrial symbiosis	2021	Patricia Kio, Ahmed K. Ali	India	Energy and Buildings	16
[93]	A review of the impact of the green landscape interventions on the urban microclimate of tropical areas	2021	Udayasoorian Kaaviya Priya, Ramalingam Senthil	India	Building and Environment	120
[94]	Evaluation of thermal comfort and building form attributes in different semi-outdoor environments in a high-density tropical setting	2021	Juan Gamero-Salinas, Nirmal Kishnani, Aurora Monge-Barrio, Jesús López-Fidalgo, Ana Sánchez-Ostiz	Spain	Building and Environment	33
[95]	Making bioreceptive concrete: Formulation and testing of bioreceptive concrete mixtures	2021	M. Veeger, M. Ottelé, A. Prieto	Netherlands	Journal of Building Engineering	24
[96]	Green infrastructure for air quality improvement in street canyons	2021	Mamatha Tomson, Prashant Kumar, Yendle Barwise, Pascal Perez, Hugh Forehead, Kristine French, Lidia Morawska, John F. Watts	United Kingdom	Environment International	234
[97]	A physically-based model of interactions between a building and its outdoor conditions at the urban microscale	2021	Martin Miguel, Wong Nyuk Hien, Ignatius Marcel, Hii Daniel Jun Chung, He Yueer, Yu Zhonqi, Deng Ji-Yu, Srivatsan V Raghavan, Nguyen Ngoc Son	Singapore	Energy and Buildings	34
[98]	Psychological and physiological effects of a green wall on occupants: A cross-over study in virtual reality	2021	Seungkeun Yeom, Hakpyeong Kim, Taehoon Hong	South Korea	Building and Environment	139
[99]	Effect of space layouts on the energy performance of office buildings in three climates	2021	Tiantian Du, Sabine Jansen, Michela Turrin, Andy van den Dobbelsteen	China	Journal of Building Engineering	31
[100]	Perceptions of urban heat island mitigation and implementation strategies: survey and gap analysis	2020	Chenghao Wang, Zhi-Hua Wang, Kamil E. Kaloush, Joseph Shacat	United States	Sustainable Cities and Society	59
[54]	Feasibility of vertical ecosystem for sustainable water treatment and reuse in touristic resorts	2021	Miquel Estelrich, Josephine Vosse, Joaquim Comas, Nataša Atanasova, Jordi Castellano Costa, Heinz Gattringer, Gianluigi Buttiglieri	Austria	Journal of Environmental Management	22
[62]	A comparative study on green wall construction systems, case study: South valley campus of AASTMT	2022	Adel Samy El Menshawy, Abdelaziz Farouk Mohamed, Nayera Mahmoud Fathy	Egypt	Case Studies in Construction Materials	36
[55]	Ecosystem services and well-being dimensions related to urban green spaces—A systematic review	2022	Luís Valença Pinto, Miguel Inácio, Carla Sofia Santos Ferreira, António Dinis Ferreira, Paulo Pereira	Lithuania	Sustainable Cities and Society	130
[65]	Rethinking greening the building façade under extreme climate: Attributes consideration for typo-morphological green envelope retrofit	2022	Tzen-Ying Ling	Taiwan	Cleaner and Circular Bioeconomy	8
[101]	Dynamic heat transfer model of vertical green façades and its co-simulation with a building energy modelling program in hot-summer/warm-winter zones	2022	Yu Zhang, Lei Zhang, Qinglin Meng	China	Journal of Building Engineering	20
[102]	Heat transfer reduction in building envelope with green façade system: A year-round balance in Mediterranean climate conditions	2022	Giuliano Vox, Ileana Blanco, Fabiana Convertino, Evelia Schettini	Italy	Energy and Buildings	26
[103]	Evapotranspiration rates and evapotranspirative cooling of green façades under different irrigation scenarios	2022	Reza Bakhshoodeh, Carlos Ocampo, Carolyn Oldham	Australia	Energy and Buildings	43
[104]	Perspective of using green walls to achieve better energy efficiency levels. A bibliometric review of the literature	2022	Dorin Maier	Romania	Energy and Buildings	37
[74]	Knowledge mapping of research progress in vertical greenery systems (VGS) from 2000 to 2021 using CiteSpace based scientometric analysis	2021	Muhammad Mubashir Ahsan, Wei Cheng, Aqsa Bilal Hussain, Xuefeng Chen, Basit Ali Wajid	Pakistan	Energy and Buildings	33
[105]	The passive cooling effect of window gardens on buildings: A case study in the subtropical climate	2021	Jing Ren, Mingfang Tang, Xing Zheng, Xia Lin, Yanan Xu, Tingting Zhang	China	Journal of Building Engineering	11
[56]	Use of double skin façade with building integrated solar systems for an energy renovation of an existing building in Limassol, Cyprus: Energy performance analysis	2022	Christos Italos, Michalis Patsias, Andriani Yiangou, Stylianos Stavrinou, Constantinos Vassiliades	Cyprus	Energy Reports	37
[82]	A hydroponic vertical greening system for disposal and utilization of pre-treated Blackwater: Optimization of the operating conditions	2022	Xiangyu Li, Jin Zhou, Yingqi Tang, Yiqing Li, Zhan Jin, Hainan Kong, Min Zhao, Xiangyong Zheng, Ke Bei	China	Ecological Engineering	15
[106]	Review of key factors that affect the implementation of bio-receptive façades in a hot arid climate: Case study north Egypt	2022	Rewaa Mahrous, Emanuela Giancola, Ahmed Osman, Takashi Asawa, Hatem Mahmoud	Egypt	Building and Environment	17
[107]	Energy retrofit analysis for an educational building in Mumbai	2022	Vallary Gupta, Chirag Deb	India	Sustainable Futures	14
[108]	Home gardening in Singapore: A feasibility study on the utilization of the vertical space of retrofitted high-rise public housing apartment buildings to increase urban vegetable self-sufficiency	2022	Shuang Song, Jia Chin Cheong, Joel S.H. Lee, Jonathan K.N. Tan, Zhongyu Chiam, Srishti Arora, Karl J.Q. Png, Johanah W.C. Seow, Felicia W.S. Leong, Ankit Palliwal, Filip Biljecki, Abel Tablada, Hugh T.W. Tan	Singapore	Urban Forestry & Urban Greening	30
[109]	What’s behind the barriers? Uncovering structural conditions working against urban nature-based solutions	2021	Hade Dorst, Alexander van der Jagt, Helen Toxopeus, Laura Tozer, Rob Raven a, Hens Runhaar	Netherlands	Landscape and Urban Planning	123
[110]	Cable-driven parallel robot for curtain wall module installation	2022	K. Iturralde, M. Feucht, D. Illner, R. Hu, W. Pan, T. Linner, T. Bock, I. Eskudero, M. Rodriguez, J. Gorrotxategi, J.B. Izard, J. Astudillo, J. Cavalcanti Santos, M. Gouttefarde, M. Fabritius, C. Martin, T. Henninge, S.M. Nornes, Y. Jacobsen, A. Pracucci, J. Cañada, J.D. Jimenez-Vicaria, R. Alonso, L. Elia	Germany	Automation in Construction	69
[111]	Greywater treatment in a green wall using different filter materials and hydraulic loading rates	2023	M. Sami, A. Hedström, E. Kvarnström, D.T. McCarthy, I. Herrmann	Sweden	Journal of Environmental Management	31
[52]	Economical sustainability of vertical greeneries in tropical climate	2023	G.D.C. Jayakody, K.G.N.H. Weerasinghe, G.Y. Jayasinghe, R.U. Halwatura	Sri Lanka	Energy and Buildings	16
[112]	Nature-based solutions in informal settlements: A systematic review of projects in Southeast Asian and Pacific countries	2023	Erich Wolff, Hanna A. Rauf, Perrine Hamel	Netherlands	Environmental Science & Policy	39
[113]	Understanding the drivers of green roofs and green walls adoption in Global South cities: Analysis of Accra, Ghana	2023	Benedict Essuman-Quainoo, C.Y. Jim	Hong Kong	Urban Forestry & Urban Greening	18
[114]	Green walls and health An umbrella review	2023	Marcel Cardinali, Alvaro Balderrama, Daniel Arztmann, Uta Pottgiesser	Germany	Nature-Based Solutions	19
[58]	Early-stage design of a low-embodied carbon and cost-effective green facade system	2023	Maricruz Solera Jimenez, João Cortesão, Sanda Lenzholzer, Ralf Walker	Netherlands	Journal of Building Engineering	6
[115]	Nutrient treatment of greywater in green wall systems: A critical review of removal mechanisms, performance efficiencies and system design parameters	2023	Moeen Gholami, Aisling D. O’Sullivan, Hamish R. Mackey	New Zealand	Journal of Environmental Management	26
[68]	Global technological advancement and challenges of glazed window, facade system and vertical greenery-based energy savings in buildings: A comprehensive review	2023	M. Washim Akram, M. Hasannuzaman, Erdem Cuce, Pinar Mert Cuce	United States	Energy and Built Environment	114
[116]	Models and methods for quantifying the benefits of engineered heat mitigation initiatives: A critical review	2023	Ghiwa Assaf, Rayan H. Assaad	United States	Urban Climate	6
[81]	Trans-functional green wall’s developed predesign model as a first stage to designers to understand the design and potential performance aspects of green walls	2023	Tamer Refaat, Marwa El-Zoklah	Egypt	Open House International	-
[117]	Botanical filters for the abatement of indoor air pollutants	2023	María Sol Montaluisa-Mantilla, Pedro García-Encina, Raquel Lebrero, Raúl Muñoz	Spain	Chemosphere	30
[66]	Bio-colonization layered concrete panel for greening vertical surfaces: A field study	2023	Ronaldas Jakubovskis, Jurgita Malaiškienė, Viktor Gribniak	Lithuania	Case Studies in Construction Materials	8
[59]	The Nature Smart Cities business model: A rapid decision-support and scenario analysis tool to reveal the multi-benefits of green infrastructure investments	2023	Wito Van Oijstaeijen, Maíra Finizola Silva, Phil Back, Alexandra Collins, Kris Verheyen, Robbe De Beelde, Jan Cools, Steven Van Passel	Belgium	Urban Forestry & Urban Greening	14
[118]	Quantifying the influence of nature-based solutions on building cooling and heating energy demand: A climate specific review	2023	Q. He, F. Tapia, A. Reith	China	Renewable and Sustainable Energy Reviews	33
[119]	Thermal performance of vertical greenery systems (VGS) in a street canyon: A real-scale long-term experiment	2023	Noa Zuckerman, Itamar M. Lensky	Israel	Building and Environment	22
[120]	Monitoring and performance evaluation of a green wall in a semi-arid Mediterranean climate	2023	Salvatore Carlucci a, Magdalene Charalambous a, Julia Nerantzia Tzortzi b	Italy	Journal of Building Engineering	19
[121]	Social housing as focus area for Nature-based Solutions to strengthen urban resilience and justice: Lessons from practice in the Netherlands	2023	Robbert P.H. Snep, Judith Klostermann, Mathias Lehner, Ineke Weppelman	Netherlands	Environmental Science & Policy	17
[122]	Use of climbing and ornamental plants in vertical flow constructed wetlands treating greywater	2023	Aimilia Stefanatou, Spyridoula Schiza, Ioanna Petousi, Anacleto Rizzo, Fabio Masi, Athanasios S. Stasinakis, Nikolaos Fyllas, Michail S. Fountoulakis	Greece	Journal of Water Process Engineering	27
[123]	Experimental analysis to assess the hydrological efficiency and the nutrient leaching behavior of a new green wall system	2023	Stefania Anna Palermo, Gaspare Viviani, Behrouz Pirouz, Michele Turco, Patrizia Piro	Italy	Science of The Total Environment	8
[124]	Systematic review of carbon-neutral building technologies (CNBTs) by climate groups and building types	2023	Gyueun Lee, Nadia Avelina, Donghyun Rim, Seokho Chi, Hyeunguk Ahn	South Korea	Journal of Building Engineering	14
[125]	The multifunctionality concept in urban green infrastructure planning: A systematic literature review	2023	Maria Korkou, Ari K.M. Tarigan, Hans Martin Hanslin	Norway	Urban Forestry & Urban Greening	91
[126]	Diagnosing the cause-effect relationship among deterrents to intensive green roof adoption: A hybrid EFDM-FDEMATEL approach	2023	Sepideh Motamedpooya, Mojtaba Ashour, Amir Mahdiyar, Elmira Jamei	Poland	Sustainable Cities and Society	6
[127]	Socioeconomic disparities in cooling and warming efficiencies of urban vegetation and impervious surfaces	2023	Jian Lin, Hongsheng Zhang, Min Chen, Qiang Wang	China	Sustainable Cities and Society	39
[128]	Citizens’ preferences and valuation of urban nature Insights from two choice experiments	2023	J.A. Papineau Salm, Marija Bočkarjova, W.J.W. Botzen, H.A.C. Runhaar	Netherlands	Ecological Economics	23
[129]	Exploring the evolving landscape Urban horticulture cropping systems–trends and challenges	2024	M.A. Nethmini Sashika, H.W. Gammanpila, S.V.G.N. Priyadarshani	United Kingdom	Scientia Horticulturae	29
[130]	Economic evaluations of urban green and blue space interventions: A scoping review	2024	Christopher Tate, Ngan Tran, Alberto Longo, John Barry, Tim Taylor, Ciaran O’Neill,Ruth Hunter	United Kingdom	Ecological Economics	9
[80]	Integrating vertical farm into low-carbon high-rise building in high-density context A design case study in Hong Kong	2024	Yuxin Bao, M.K. Leung, Dicken Poon, Changying Xiang	Hong Kong	Journal of Building Engineering	8
[131]	Achieving net zero neighborhoods: A case study review of circular economy initiatives for South Wales	2024	Jacob Edwards, Hanbing Xia, Qian Jan Li, Peter Wells, Jelena Milisavljevic-Syed, Alberto Gallotta, Konstantinos Salonitis	United Kingdom	Journal of Cleaner Production	10
[132]	Empowering vertical farming through IoT and AI-Driven technologies: A comprehensive review	2024	Ajit Singh Rathor, Sushabhan Choudhury, Abhinav Sharma, Pankaj Nautiyal, Gautam Shah	India	Heliyon	63
[133]	A systematic analysis on the efficiency and sustainability of green facades and roofs	2024	Thácia Danily de Oliveira Santos, Fernando António Leal Pacheco, Luís Filipe Sanches Fernandes	Portugal	Science of The Total Environment	22
[134]	Unlocking energy and economic benefits of integrated green envelopes in office building retrofits	2024	Rui Guo, Yunran Min, Yafeng Gao, Xiangjie Chen, Huizhong Shi, Changqiao Liu, Chaoqun Zhuang	Denmark	Building and Environment	11
[135]	Methodological framework for impact evaluation of Building-Integrated Greenery (BIG-impact)	2024	Gabriel Pérez, Marcelo Reyes, Julià Coma, Aleix Alva, Fanny E. Berigüete, Ana M. Lacasta	Spain	MethodsX	3
[76]	Evaluating the economic sustainability of commercial complex greening based on cost-benefit analysis A case study of Singapore’s Shaw center	2024	Yimeng Wu, Hao Wang, Zhendong Wang, Jessica Ann Diehl, Siyuan Xue	Singapore	Ecological Indicators	13
[81]	Retrofit strategies to improve energy efficiency in buildings: An integrative review	2024	Candi Citadini de Oliveira, Igor Catão Martins Vaz, Enedir Ghisi	Brazil	Energy and Buildings	54
[64]	Assessing vertical green walls for indoor corridors in educational buildings and its impact outdoor: A field study at the universities of Canada in Egypt	2024	Nisreen Abdeen, Tamer Rafaat	Egypt	Results in Engineering	14
[136]	Dynamic facades for sustainable buildings: A review of classification, applications, prospects and challenges	2024	Garkuwa Jamilu, Adel Abdou, Muhammad Asif	Saudi Arabia	Energy Reports	22
[137]	Research trends and gaps in experimental applications of phase change materials integrated in buildings	2024	Mariela Vega, Paula E. Marín, Svetlana Ushak, Stan Shire c	Chile	Journal of Energy Storage	21
[138]	Fire safety performance of functional vegetated green building systems A comprehensive review	2024	Zhen Ni, Danyang Zhao a 1, Lik-ho Tam b, Denvid Lau a, Cheuk Lun Chow a	Hong Kong	Journal of Building Engineering	3
[108]	Exploring the potential for nature-based solutions to cool the streetscapes of a densely urbanised Mediterranean city	2024	Mark D.C. Mansoldo, Claudia de Luca, Mario V. Balzan	Malta	Nature-Based Solutions	3
[71]	Photobioreactors for building integration A overview of designs and architectural potential	2024	Ruma Arora, K. Sudhakar, R.S. Rana	India	Heliyon	12
[139]	Implementing biophilic design in architecture through three-dimensional green spaces: Guidelines for building technologies, plant selection, and maintenance	2024	Weijie Zhong, Torsten Schröder, Juliette Bekkering	Netherlands	Journal of Building Engineering	22
[140]	Microalgae bio-reactive façade: System thermal–biological optimization	2024	Victor Pozzobon	France	Renewable Energy	4
[141]	Understanding citizens’ willingness to contribute to urban greening programs	2024	Antonia Elisabeth Schneider, Tatjana Neuhuber, Wojciech Zawadzki	Austria	Urban Forestry & Urban Greening	17
[142]	Comparative summer thermal performance analysis between open ventilated facade and modular living wall	2024	Zaloa Azkorra-Larrinaga, Naiara Romero-Anton, Koldobika Martin-Escudero, Gontzal Lopez-Ruiz, Catalina Giraldo-Soto	Spain	Case Studies in Thermal Engineering	9
[143]	A review on the mechanisms behind thermal effect of building vertical greenery systems (VGS): methodology, performance and impact factors	2024	Meifang Su, Pengyu Jie, Peixian Li, Feng Yang, Zishuo Huang, Xing Shi	China	Energy and Buildings	28
[144]	Strategies to reduce air pollution emissions from urban residential buildings	2024	Robiel Manzueta, Prashant Kumar, Arturo H. Ariño, César Martín-Gómez	Spain	Science of The Total Environment	22
[145]	Influence of façade orientation, floor height, substrate pH, and microbial inoculation on woody plants’ performance in vegetated façades in Southern Finland	2024	Xi Shu, Long Xie, D. Johan Kotze, Miia Jauni, Iiris Lettojärvi, Taina H. Suonio, Ayako Nagase, Susanna Lehvävirta	Finland	Urban Forestry & Urban Greening	2
[146]	Bioinspired technology in society: Ethical and architectural innovations for sustainable development	2024	Siddharth Chaudhary, Rickwinder Singh, Amit Shamrao Zore, Apoorva Upadhyay, Christoph Lindenberger, Vivekanand Vivekanand	India	Technology in Society	12
[147]	Vertical greening systems serve as effective means to promote pollinators: Experimental comparison of vertical and horizontal plantings	2024	Manuel Treder, Vera Joedecke, Karsten Schweikert, Peter Rosenkranz, Ute Ruttensperger, Kirsten Traynor	Germany	Landscape and Urban Planning	11
[148]	Measures, benefits, and challenges to retrofitting existing buildings to net zero carbon: A comprehensive review	2024	L.N.K. Weerasinghe, Amos Darko, Albert P.C. Chan, Karen B. Blay, David J. Edwards	Hong Kong	Journal of Building Engineering	32
[149]	Achieving carbon neutrality at single and multi-building complex levels—A review	2024	Saeed Rayegan, Liangzhu (Leon) Wang, Radu Zmeureanu, Ali Katal, Mohammad Mortezazadeh, Travis Moore, Hua Ge, Michael Lacasse, Yurong Shi	Canada	Energy and Buildings	14
[150]	Review Urban heat mitigation by green and blue infrastructure: Drivers, effectiveness, and future needs	2024	Prashant Kumar, Sisay E. Debele, Soheila Khalili, Christos H. Halios, Jeetendra Sahani, Nasrin Aghamohammadi, Maria de Fatima Andrade, Maria Athanassiadou, Kamaldeep Bhui, Nerea Calvillo, Shi-Jie Cao, Frederic Coulon, Jill L. Edmondson, David Fletcher, Edmilson Dias de Freitas, Hai Guo, Matthew C. Hort, Madhusudan Katti, Thomas Rodding Kjeldsen, Steffen Lehmann, Giuliano Maselli Locosselli, Shelagh K. Malham, Lidia Morawska, Rajan Parajuli, Christopher D.F. Rogers, Runming Yao, Fang Wang, Jannis Wenk, Laurence Jones	United Kingdom	The Innovation	202
[151]	Research progress on functional, structural and material design of plant-inspired green bionic buildings	2024	Xiaoqing Mei, Chajuan Liu, Zhixiu Li	China	Energy and Buildings	15
[152]	The improvement of wind comfort and natural ventilation in high-rise building vertical gardens with adjustable louver angles	2025	Xiaoliang Teng, May Lwin Oo, Jian Ge, Nyuk Hien Wong, Yifan Fan	China	Building and Environment	2
[153]	Growing sustainability Analysis of socioecological drivers of urban and peri-urban agriculture (UPA) under multiple framework assessments. A review	2025	Jairo Guzman-Molina, Ramoudane Orou Sannou, Serena Caucci a	Germany	Journal of Urban Management	1
[77]	Cost-Benefit analysis of urban nature-based solutions: A systematic review of approaches and scales with a focus on benefit valuation	2025	Alessia Chelli, Luke Brander, Davide Geneletti	Italy	Ecosystem Services	19
[69]	Smart city technologies for sustainable urban planning: Evidence and equity lessons from Shenzhen	2025	Wenxuan Zhao	China	Sustainable Futures	4
[154]	Nature where we live: Receptivity to context-sensitive nature-based solutions in African cities	2025	Michael Osei Asibey, Cyndi Adwoa Appiah, Emmanuella Abena Bemah Okyere, Maxwell Adu Bilson	Ghana	Cities	1
[155]	Sustainable construction based on green roofs designed to retain rainwater and provide food: An LCA compared to conventional roofs	2025	Florence Rezende Leite, Maria Lúcia Pereira Antunes, Diogo Aparecido Lopes Silva	Brazil	Sustainable Production and Consumption	1
[156]	Prerequisites for the adoption of nature-based solutions in local communities using the NbS Assessment Tool (NAT) A case study of Lahore, Pakistan	2025	Aimen Feroz, Irfan Ahmad Rana	Pakistan	Environmental Impact Assessment Review	3
[83]	From energy-intensive buildings to NetPlus targets: An innovative solar exoskeleton for the energy retrofitting of existing buildings	2025	Roberto Stasi, Francesco Ruggiero, Umberto Berardi	Italy	Energy and Buildings	9
[70]	Multi-criteria assessment of vegetated walls: a scientific approach to nature-based solutions	2025	Marco Bellomo, Simona Colajanni	Italy	Energy and Buildings	1
[157]	Plasticity in Dendrobium floral structure and physiological response under different drought stress levels	2025	Yi Zhou, Yi-Yi Meng, Qiang-Yu Long, Jia-Wei Li	China	Scientia Horticulturae	-
[158]	Influence of balcony greenery on indoor temperature reduction in tropical urban residential buildings	2025	Udayasoorian Kaaviya Priya, Ramalingam Senthil	India	Energy and Buildings	4
[159]	Ten questions concerning the role of urban greenery in shaping the future of urban areas	2025	Rengin Aslanoğlu, Jan K. Kazak, Szymon Szewrański, Małgorzata Świąder, Gustavo Arciniegas, Grzegorz Chrobak, Agnieszka Jakóbiak, Ethemcan Turhan d	Poland	Building and Environment	34
[160]	Urban agriculture and sustainability A systematic review and thematic trends	2025	Muhammad Noor E Elahi Mirza, Hassam Bin Waseem, Irfan Ahmad Rana	Pakistan	World Development Sustainability	1
[161]	Guidelines for the convergence of bio-architecture and neuroarchitecture based on the WELL building standard	2025	Elton Lima, Hilma Ferreira, Luís Mateus, Amilton Arruda	Portugal	Energy and Buildings	2
[79]	Achieving socio-economic resilience in neighborhood through nature-based solutions A systematic review	2025	Basem Hegazy, Laila Khodeir, Fatma Fathy	Egypt	Results in Engineering	4
[162]	Numerical simulation of the effect of solar chimneys on NOx-O3 photochemical reaction and ventilation in urban street canyon	2025	Hanbing Xiong, Tianhao Shi, Yongjia Wu, Ruiyue Xia, Xitong Yuan, Renaud de Richter, Wei Li, Yueping Fang, Nan Zhou, Wenyu Li, Chong Peng, Tingzhen Ming	China	Urban Climate	2
[163]	Systematic review of plant selection in vertical greenery systems for urban sustainability: Current research, knowledge gaps, and future directions	2025	Miktha Farid Alkadri, Aprilia Yolanda, Raisa Putri Alifa, Ricky Purbaya, Dalhar Susanto, Noor Fajrina Farah Istiani, Muhammad Suryanegara	Indonesia	Energy and Buildings	2
[164]	The impact of green walls on outdoor thermal comfort in residential areas under warm weather conditions: A case study	2025	Małgorzata Kozak, Tomasz Lipecki	Poland	Urban Climate	1
[165]	Synergistic carbon sequestration and emission reduction of green facades climate-specific analysis for office buildings	2025	Junru Yan, Lihua Zhao, Zichuan Nie, Sisi Chen	China	Energy and Buildings	0
[51]	Experimental evaluation of the thermal behavior of a green facade in the cold and warm seasons in a subtropical climate (Cwa) of México	2025	W.G. Baez-Garcia, E. Simá, M.A. Chagolla-Aranda, L.G. Carreto-Hernandez, J.O. Aguilar	Mexico	Journal of Building Engineering	5
[49]	Innovative design, fabrication, and evaluation of an integrated smart green facade and photovoltaic: A double-layer air circulation system for air retention time expose to plants and PV cooling to enhance air purification	2025	Shamsedin Tajik, Mohammad Hossein Jahangir	Iran	Energy Reports	4
[72]	Integrating Bi-facial photovoltaics and photosynthesis in a green facade: An experimental study	2025	Wei Wan, Chunying Li, Junyi Tan, Haida Tang, Guanrong Huang, Jixing Xie, Xiaojiao Zhu, Kaiwen Shi	China	Journal of Building Engineering	2
[166]	Development and environmental evaluation of magnesia-based bioreceptive panels for vertical green facades	2025	Jae Heun Lee, Sung Rok Oh, Neung Won Yang	South Korea	Construction and Building Materials	-
[167]	Benefits and monetary values of vertical greening systems: A semi-systematic review	2025	Sini Chen, Francesca Olivieri, Liping Peng, Jing Li	Spain	Building and Environment	1
[168]	BIM-based parametric energy analysis of green building components for the roofs and facades	2025	Felippe Pereira Ribeiro, Olubimbola Oladimeji, Marcos Barreto de Mendonça, Dieter Boer, Rashid Maqbool, Assed N. Haddad, Mohammad K. Najjar	Brazil	Next Sustainability	-
[169]	A framework for integrated assessment of blue-green infrastructure: A decision support tool for evaluating climate adaptation and social benefits in relation to construction and maintenance costs	2025	Sofia Thorsson, Oskar Bäcklin, Joanna Friberg, Sofia Frisell Eriksson, Salar Haghighatafshar, Janina Konarska, Shelly Kotze, Fredrik Lindberg, Claes-Anders Malmberg, David Rayner, Jutta Schade f, Lisa Ström, Björn Sundén, Barbro Sundström, Nils Wallenberg, Peter Ylmén	Sweden	Cities	4
[170]	Next-generation building envelopes: Smart materials, energy efficiency and environmental impact	2025	Salim Barbhuiya, Bibhuti Bhusan Das, Dibyendu Adak, Aditya Singh Rajput	United Kingdom	Next Materials	1
[171]	Multi-criteria-decision-making framework using ecosystem-services for an integral design of vertical greenery systems	2025	Dieuwertje Bakker-den Hartog, Martijn Lugten, Marc Ottelé b d	Netherlands	Urban Forestry & Urban Greening	2
[172]	Mechanical structure, plant selection, and environmental impacts of vertical greenery systems (VGSs): a review	2025	Xiaowen Li, Junxiao Chen, Yugang Lai, Weiqin Zhu, Ying Ding	China	Energy and Buildings	1
[173]	The optimal buffer for urban features to impact outdoor thermal comfort	2025	Ye Xia, Weisheng Lu, Ziyu Peng, Jianlei Niu	Hong Kong	Sustainable Cities and Society	2
[174]	A systematic review of retrofitting buildings for sustainability from a lifecycle perspective	2025	Sai Yang, Wen Yi, Haiyi Zong	Hong Kong	Sustainable Cities and Society	4
[175]	Thermal modeling of living walls: A review	2024	Eva Zavrl, Tej Žižak, Primož Poredoš, Ciril Arkar	Slovenia	Renewable and Sustainable Energy Reviews	3
[176]	Optimizing green space-building landscape characteristics of key urban functional zones for comprehensive thermal environment mitigation	2025	Zhifeng Wu, Ying Wang, Yin Ren	China	Landscape and Urban Planning	18
[177]	Sustainability nexus in high-rise buildings: Insights from topic modeling and systematic review	2025	Usman Mehmood, Uznir Ujang, Muhammad Imran Qureshi	Malaysia	Sustainable Futures	33
[178]	PSAT: A knowledge-based decision support tool for selecting passive energy consumption optimisation strategies in buildings	2025	Amirhossein Balali, Akilu Yunusa-Kaltungo	United Kingdom	Energy and Buildings	1
[179]	Biophilic street design for urban heat resilience	2025	Yiqun Li, Bao-Jie He	China	Progress in Planning	1
[180]	Development and performance evaluation of a hybrid louver window system using natural light and LED for energy-efficient vertical farming building	2025	Youngsub An, Kieu Ngoc Minh, Hong-Jin Joo, Kyoung-Ho Lee, Wang-Je Lee, Min-Hwi Kim, Hyun-Hee Lee, Seoyong Shin, Sae-Byul Kang	South Korea	Building and Environment	1
[181]	Measuring pedestrian-level street greenery visibility through space syntax and crowdsourced imagery: A case study in London, UK	2025	Mingze Chen, Yuxuan Liu, Fan Liu b, Trishla Chadha, Keunhyun Park	Canada	Urban Forestry & Urban Greening	13
[182]	How does green infrastructure (GI) influence urban thermal environments? A systematic literature review of trends, gaps, and future directions (2014–2024)	2025	Shiyao Liu, Xiaohang Jin	Malaysia	Sustainable Cities and Society	3
[183]	A novel climate assessment framework for integrating adaptation into planning and design interventions on public real estate	2025	Carmela Apreda, Guglielmo Ricciardi, Alfredo Reder, Paola Mercogliano, Gianluca Capri, Matteo Mariotti, Diana Giallonardo, Giacomo Antonino, Simona Domini, Claudia Scaramella	Italy	Urban Climate	1
[184]	Exploring the effects of street canyon morphology on LST within different street types using causal inference and machine learning	2025	Ziyi Liu, Hong Yuan, Jianing Luo	China	Sustainable Cities and Society	2
[185]	Energy performance assessment on vertical greening systems with green roof in hot summer and cold winter regions based on long-term experimental data	2025	Xunxing Song, Xiaoli Hao, Yaolin Lin, Guole Ai, Wei Yin a, Jinhua Hu a, Shaobo Zhang	China	Urban Forestry & Urban Greening	10
[186]	Useful daylight illuminance for ornamental plants in buildings—The method to design the green interior	2025	Eliza Szczepańska-Rosiak, Jerzy Sowa, Katarzyna Mastalerz, Dariusz Heim	Poland	Energy and Buildings	3
[187]	Selection of passive energy consumption optimisation strategies for buildings	2025	Amirhossein Balali, Akilu Yunusa-Kaltungo	United Kingdom	Renewable and Sustainable Energy Reviews	9

). All 136 studies forming the analytical dataset are documented in this appendix. Not all studies included in the dataset are necessarily cited in the main text; only those directly discussed in the analytical narrative are included in the reference list. This approach is common in systematic literature reviews, where the analytical dataset may exceed the number of studies explicitly cited within the discussion.

2.2. Data Analysis

To align with the research objectives, a multi-layered analytical strategy was employed.

2.2.1. Bibliometric and Descriptive Mapping

Descriptive analysis was conducted to map the following: publication trends over time, journal distribution, disciplinary classification, geographic distribution of first-author affiliations [62,63,64].

This stage addressed the structural landscape of cost-related research rather than merely reporting frequency.

2.2.2. Thematic Classification Within an LCC Framework

A deductive coding approach was applied to classify cost components into five life-cycle categories: 1. Installation and Operation, 2. Maintenance, 3. Consumables, 4. Material and Manufacturing, and 5. Design.

The categorization was informed by established life-cycle cost (LCC) principles and prior cost-structure literature. Each article was coded according to whether it explicitly addressed one or more of these categories [58,59,60,61,62,63,64].

This step enabled assessment of distributional imbalance across life-cycle stages.

2.2.3. Co-Occurrence and Structural Fragmentation Analysis

To evaluate the degree of integration across life-cycle stages, co-occurrence analysis was conducted. This analysis examined the following: how frequently cost categories appeared jointly, whether studies adopted partial or comprehensive life-cycle coverage, structural coupling between cost phases. The resulting heatmap and co-occurrence matrices were used to assess fragmentation patterns within the literature.

2.2.4. Cost-Reporting Structure Analysis

Finally, reported numerical cost data were examined to identify the following: units of measurement (e.g., per area, per year, per module), presence or absence of contextual descriptors, and consistency of reporting formats.

This analysis enabled evaluation of methodological harmonization and comparability across studies.

3. Results

Following the PRISMA-based methodology described in Section 2, the findings are structured into four analytical domains: (1) research landscape characteristics, (2) structural distribution within the life-cycle cost (LCC) framework, (3) fragmentation of cost coverage, and (4) heterogeneity in cost reporting and detailed component structures. This organization enables interpretation beyond frequency reporting and reveals the structural configuration of cost-related research on vertical greenery systems (VGS).

3.1. Research Landscape Structure

3.1.1. Temporal Development

A total of 136 eligible articles published between 2021 and 2025 were included in the final analytical dataset. The publication output demonstrates a fluctuating yet overall upward trajectory over the observed period.

In 2021, the field produced 23 publications (16.91% of the dataset). This number temporarily declined to 16 publications in 2022 (−30%), followed by a renewed increase to 24 publications in 2023 and 29 publications in 2024. By 2025, publication output reached 44 articles (32.35% of the dataset), despite the year not being complete at the time of data collection. As shown in Figure 3, the annual publication distribution of cost-related vertical greenery system (VGS) studies between 2021 and 2025 (n = 136) fluctuates but shows an overall increasing trend; the line represents yearly publications, while the shaded area indicates the overall growth trend.

The temporal pattern indicates increasing research attention to cost-related aspects of vertical greenery systems (VGS). However, the growth in publication volume does not necessarily imply methodological consistency. As demonstrated in the following sections, the literature remains characterized by structural imbalances in life-cycle cost coverage and reporting practices.

This upward trend indicates increasing scholarly interest in vertical greenery systems, particularly in relation to sustainability, urban climate adaptation, and life-cycle performance considerations. The acceleration of publications after 2023 may also reflect growing policy attention toward nature-based solutions and climate-responsive urban design.

3.1.2. Publication Sources and Disciplinary Distribution

The 136 articles included in the analytical dataset were published across 46 different academic journals. Approximately half of the publications were concentrated within the top five outlets, indicating a moderate level of journal concentration within the field.

As shown in Figure 4, the distribution of publications across journal sources indicates that a substantial proportion of studies are concentrated within a few leading journals.

Energy and Buildings contributed the highest number of publications (22 articles; 16.18%), followed by Journal of Building Engineering (13 articles) and Urban Forestry & Urban Greening (13 articles). This pattern suggests that research on vertical greenery systems (VGS), particularly studies addressing cost-related aspects, is strongly embedded within journals focusing on building performance, environmental systems, and urban sustainability. As shown in

Table 1. Distribution of publications by primary subject area classification.

Subject Area and Category	Frequency	Percentage
Environmental Science	16	23.19%
Engineering	12	17.39%
Energy	8	11.59%
Social Sciences	8	11.59%
Business, Management and Accounting	5	7.25%
Agricultural and Biological Sciences	4	5.80%
Economics, Econometrics and Finance	3	4.35%
Chemical Engineering	2	2.90%
Decision Sciences	2	2.90%
Multidisciplinary	2	2.90%
Others	2	2.90%
Biochemistry, Genetics and Molecular Biology	1	1.45%
Chemistry	1	1.45%
Earth and Planetary Sciences	1	1.45%
Materials Science	1	1.45%
Medicine	1	1.45%
Total	69	100.00%

, the distribution of publications across subject areas highlights the dominance of environmental and engineering disciplines.

From a disciplinary perspective, Environmental Science (23.19%), Engineering (17.39%), and Social Sciences and Energy (11.59%) together account for more than 63.76% of all subject classifications. In contrast, fields traditionally associated with economic evaluation—such as Economics, Business, and Decision Sciences—remain comparatively underrepresented.

This disciplinary distribution indicates that cost-related VGS research is primarily framed within environmental and technical performance discourses rather than within rigorous financial or economic modeling traditions. Consequently, although cost considerations are increasingly discussed in the literature, they remain only partially institutionalized within established economic evaluation frameworks.

Environmental Science (23.19%), Engineering (17.39%), and Social Sciences and Energy (11.59.%) emerged as the most frequently represented primary subject categories in the dataset.

When analyzed based on occurrence frequency (multiple classifications per article), Engineering emerged as the dominant disciplinary domain.

As shown in

Table 2. Occurrence-based distribution of subject areas and categories.

Subject Area and Category	Frequency	Percentage
Engineering	65	31.71%
Environmental Science	54	26.34%
Energy	21	10.24%
Agricultural and Biological Sciences	17	8.29%
Social Sciences	11	5.37%
Business, Management and Accounting	8	3.90%
Economics, Econometrics and Finance	5	2.44%
Medicine	5	2.44%
Decision Sciences	4	1.95%
Earth and Planetary Sciences	4	1.95%
Chemical Engineering	2	0.98%
Chemistry	2	0.98%
Materials Science	2	0.98%
Multidisciplinary	2	0.98%
Others	2	0.98%
Biochemistry, Genetics and Molecular Biology	1	0.49%
Total	205	100.00%

, the occurrence-based distribution further emphasizes the dominance of engineering and environmental disciplines across multiple classifications.

Engineering (31.71%), Environmental Science (26.34%), and Energy (10.24%) together account for more than 68.29% of all subject classifications. In contrast, fields traditionally associated with economic evaluation—such as Economics, Business, and Decision Sciences—remain comparatively underrepresented.

The occurrence-based distribution further reinforces this pattern, highlighting the dominance of engineering and environmental disciplines across multiple classifications. In contrast, economic-related fields remain marginal, indicating limited integration of formal economic evaluation approaches within the existing literature

This imbalance suggests that while the technical and environmental performance of VGS has been extensively studied, the economic dimension of life-cycle cost analysis remains comparatively underdeveloped.

3.1.3. Geographical Distribution of Publications

First-author affiliations span 42 countries. As shown in Figure 5, the geographical distribution of publications highlights the global research contributions across countries.

At the regional level: As shown in Figure 6, the regional distribution of publications indicates that Europe and Asia dominate the research output.

Europe accounts for 44.12% of publications, while Asia represents 39.71%, exhibiting the strongest growth in 2025. Publication trends among the five most productive countries further reveal uneven growth dynamics. Figure 7 presents publication trends among the five most productive countries.

Although output is geographically diverse, publication growth is concentrated within a limited number of countries. Nearly half of the represented countries contributed only one publication during the study period, indicating regional clustering rather than globally balanced methodological development. Collectively, the research landscape demonstrates expanding volume but uneven disciplinary and geographic integration.

3.1.4. Collaboration Patterns Among Authors

To complement the structural overview of the research landscape, a descriptive bibliometric analysis was conducted to examine collaboration patterns among the studies included in the dataset. The analysis focused on the number of authors per publication as an indicator of research collaboration within the vertical greenery systems (VGS) research field.

The results indicate that most publications were produced by small- to medium-sized research teams, typically consisting of two to four authors. Single-author publications were relatively limited, while only a small proportion of studies involved larger collaborative teams. This pattern suggests that research in the VGS domain is generally conducted within compact research groups rather than large multi-institutional collaborations.

The observed collaboration structure also reflects the interdisciplinary nature of VGS research, which often requires the integration of expertise from architecture, environmental engineering, horticulture, and sustainability science. However, the relatively fragmented collaboration networks may also contribute to the heterogeneous methodological approaches observed in the literature, particularly in the reporting and evaluation of life-cycle cost components. These findings provide additional insight into the collaborative structure of the research field and complement the structural analysis of cost-related research presented in the following sections.

3.2. Structural Distribution of Cost Components Within the LCC Framework

Content analysis was conducted to classify cost components identified in the reviewed studies into five principal categories aligned with the life-cycle stages of vertical greenery systems (VGS): (1) Installation and Operation, (2) Maintenance, (3) Consumables, (4) Materials and Manufacturing, and (5) Design. This classification framework provides a structured basis for examining the distribution of life-cycle cost components across the existing literature. (Figure 8).

3.2.1. Installation and Operation

Installation and operation costs represent the expenditures associated with the establishment and activation of vertical greenery systems. These costs typically include structural installation, irrigation systems, supporting infrastructure, and initial system com-missioning. Among the reviewed studies, installation and operation costs appear in 82.35% of the articles (112 studies), making this category the most frequently reported cost component. The high prevalence of installation-related costs reflects the construction-oriented nature of many VGS studies, which often focus on technical implementation and system performance.

3.2.2. Maintenance

Maintenance costs refer to the ongoing expenditures required to sustain the functionality and long-term performance of vertical greenery systems. These costs generally include plant care, pruning, irrigation system servicing, replacement of vegetation, and routine inspections. Maintenance costs are reported in 108 of the reviewed studies, making them the second-most frequently documented cost category. The prominence of maintenance in the literature reflects the biological and operational nature of vegetation-based systems, which require continuous management to ensure system viability and environmental performance.

3.2.3. Consumables

Consumable costs include materials and resources that must be periodically replenished during system operation. These typically involve fertilizers, nutrients, water, and minor horticultural inputs required to maintain plant health. Compared with installation and maintenance costs, consumables receive more limited attention in the literature, appearing in 26 studies. In many cases, consumable costs are incorporated within broader maintenance categories or reported only qualitatively, resulting in limited transparency regarding their contribution to overall life-cycle cost structures.

3.2.4. Materials and Manufacturing

Materials and manufacturing costs encompass the production and procurement of structural and technical components used in vertical greenery installations. These may include modular planting panels, supporting frames, substrate systems, and irrigation equipment. A total of 40 studies explicitly address material and manufacturing costs. However, detailed cost breakdowns are often limited due to proprietary technologies and variations in system design. As a result, the economic implications of material production and fabrication processes remain inconsistently documented across the reviewed literature.

3.2.5. Design

Design costs refer to professional services involved in the planning and conceptual development of vertical greenery systems. These costs may include architectural design, landscape planning, structural engineering consultation, and project documentation. Despite the critical role of design in determining system feasibility and long-term performance, this category is represented in only eight studies. The limited reporting of design-related costs indicates that early-stage economic considerations remain marginal within the existing literature.

Overall Structural Distribution: Installation and Operation appears in 82.35% of the reviewed studies (112 articles), followed closely by Maintenance (108 articles). Materials and Manufacturing (40 articles) and Consumables (26 articles) receive moderate attention, while Design is represented in only eight studies. This distribution demonstrates a pronounced concentration on capital and operational expenditure stages, whereas early-stage design economics and comprehensive life-cycle integration remain marginal. The observed imbalance suggests that cost-related research on vertical greenery systems (VGS) is predominantly operational rather than strategically integrated within comprehensive life-cycle cost (LCC) frameworks.

3.3. Structural Fragmentation of Life-Cycle Cost Coverage

While Section 3.2 examined the distribution of individual cost components reported in the literature, a deeper analysis reveals a more fundamental structural issue: the fragmented integration of these components within comprehensive life-cycle cost (LCC) frameworks. Although installation and maintenance costs are widely discussed across the reviewed studies, the overall coverage of cost elements across the full life-cycle remains uneven and incomplete.

In many cases, studies report only selected cost categories—most commonly installation or maintenance expenditures—without situating them within a complete LCC structure that incorporates design, production, operation, and long-term system performance. As a result, cost assessments frequently remain partial rather than systematically integrated. This selective reporting creates methodological inconsistencies that complicate comparisons across projects, technologies, and geographical contexts.

The analysis further indicates that early-stage cost components, particularly those associated with design decisions and system planning, are rarely incorporated into economic evaluations. Yet these early decisions often determine long-term operational costs, maintenance intensity, and overall system feasibility. The underrepresentation of design-related cost considerations suggests that economic assessments of vertical greenery systems remain largely reactive—focusing on operational expenditures after system implementation—rather than proactively integrated into strategic planning and design processes.

This imbalance highlights a structural gap in the current body of research. Although vertical greenery systems are increasingly promoted as nature-based solutions for sustainable urban development, the economic dimension of their implementation has not yet been fully aligned with established life-cycle cost assessment methodologies. Consequently, existing studies provide valuable insights into individual cost elements but often fall short of delivering integrated economic evaluation frameworks capable of supporting long-term decision-making.

Overall, the findings suggest that future research should move beyond isolated cost reporting toward more comprehensive LCC-based evaluation models that incorporate design, construction, operation, maintenance, and end-of-life considerations. Such integrated approaches would enhance comparability across studies and provide stronger evidence for policymakers, designers, and urban planners seeking to evaluate the economic viability of vertical greenery systems.

3.3.1. Partial Life-Cycle Coverage

Co-occurrence analysis examined the number of cost categories jointly addressed within individual studies.

As shown in Figure 9, the most frequent pattern involves studies addressing two cost categories (44.12% of articles).

The most frequent pattern involves studies addressing two cost categories (44.12% of articles). Studies examining a single or three categories are less common. Only twelve studies address four categories, and merely two studies cover all five categories simultaneously.

This confirms that comprehensive life-cycle modeling remains rare. Instead, research tends to adopt segmented or pairwise cost perspectives, limiting holistic LCC assessment.

3.3.2. Inter-Category Coupling

To further explore structural relationships among cost categories, a co-occurrence heatmap was constructed. As shown in

Table 3. Co-occurrence matrix of cost categories in vertical greenery system (VGS) studies.

	Installation and Operation	Maintenance	Consumable	Material and Manufacturing	Designing
Installation and Operation		87	22	34	8
Maintenance	87		24	29	6
Consumable	22	24		12	3
Material and Manufacturing	34	29	12		5
Designing	8	6	3	5

, installation and operation most frequently co-occurs with maintenance.

Installation and Operation most frequently co-occurs with Maintenance (87 instances; 63.97%), indicating strong analytical coupling between initial capital expenditure and ongoing operational costs. The second-most frequent linkage occurs between Installation and Operation and Material and Manufacturing [65,66,67].

Design exhibits weak integration across categories, confirming its marginal presence within broader cost frameworks. The clustering pattern reveals operational cost pairs as the dominant analytical structure rather than full life-cycle integration.

3.3.3. Structural Implications for Life-Cycle Cost Assessment

The combined evidence from the distribution analysis (Section 3.3.1) and the inter-category coupling analysis (Section 3.3.2) highlights a structural fragmentation in the way life-cycle cost components are addressed in the existing literature. Although certain cost categories—particularly installation, operation, and maintenance—are frequently analyzed together, other stages such as design and material production remain weakly integrated within the analytical structure of most studies.

This pattern indicates that current research tends to prioritize operational perspectives rather than adopting a fully integrated life-cycle cost assessment framework. As a consequence, critical upstream decision variables, including design strategies and material system selection, are seldom incorporated into economic evaluation models. The observed fragmentation therefore limits the ability of existing studies to support comprehensive life-cycle cost decision-making for vertical greenery systems.

3.4. Heterogeneity in Cost Reporting

The structural fragmentation identified in Section 3.3 is further reinforced by substantial heterogeneity in cost-reporting formats across the reviewed studies. In addition to differences in the number of cost categories considered, considerable variation also exists in how cost data are measured and reported.

Installation costs are typically expressed per unit area (e.g., USD/m²), although significant regional variation in reported values can be observed. Maintenance costs are commonly reported on an annual basis (e.g., USD/m²·yr), reflecting the operational nature of vegetation-based systems. However, consumable and material-related costs are reported using diverse and inconsistent units, including €/kWh, €/m³, €/module, or €/unit, and in some cases without clearly defined measurement standards.

Design-related costs are rarely quantified using standardized units and are frequently embedded within aggregated project expenditures or overall construction budgets. This lack of standardized measurement makes it difficult to isolate the economic contribution of design decisions within life-cycle cost assessments.

Overall, the heterogeneity in reporting practices significantly constrains cross-study comparability and prevents robust quantitative synthesis within an LCC framework. The absence of standardized cost-reporting protocols therefore represents a structural methodological limitation in the current body of vertical greenery systems research.

3.5. Detailed Cost Component Analysis

3.5.1. Detailed Aspects of Installation and Operation

Structural and supporting systems represent the largest share of detailed aspects (26 occurrences), followed by construction processes (21), irrigation systems (15), labor (12), and computational or technological components (8). This distribution indicates a strong emphasis on physically tangible and performance-driven cost elements during system implementation. As shown in Figure 10, structural and supporting systems represent the largest share of detailed cost components, followed by construction processes, irrigation systems, and labor.

3.5.2. Detailed Maintenance Components

Plant replacement (35.48%) constitutes the most frequently reported maintenance aspect, followed by irrigation, nutrient management, place maintenance, and technical maintenance. The prominence of biologically driven cost components highlights the operational vulnerability and performance dependency of VGSs.

3.5.3. Detailed Consumable Components

Water accounts for the largest share of consumable-related cost details, followed by nutrient and substrate components. Energy-related aspects represent the smallest proportion. This pattern reflects operational resource dependency, particularly water intensity in vertical systems.

3.5.4. Material and Manufacturing

Structural elements dominate this category, followed by material production, plant components, equipment, and planter systems. The concentration on structural elements reinforces the engineering-oriented framing of cost analysis within the literature.

Structural Synthesis of Findings

Collectively, the findings reveal a structurally imbalanced cost research landscape in vertical greenery system (VGS) studies. Although publication volume demonstrates a clear upward trajectory, analytical attention remains disproportionately concentrated on installation and maintenance expenditures. In contrast, design-phase economics and fully integrated life-cycle cost (LCC) modeling are marginally represented, both in frequency and in co-occurrence structure. Moreover, substantial heterogeneity in cost-reporting units and measurement formats constrains cross-study comparability and impedes cumulative methodological development. These patterns indicate that while cost-related scholarship on VGS has expanded quantitatively, it has yet to consolidate into a standardized and systematically integrated LCC framework. This structural immaturity underscores the need for methodological harmonization and deeper economic integration in future research.

4. Discussion

4.1. Expansion Without Consolidation: Structural Characteristics of the Research Landscape

The findings of this review demonstrate a clear expansion of cost-related research on vertical greenery systems (VGS) in recent years. The noticeable increase in publications between 2023 and 2025 reflects growing recognition that economic feasibility is a critical determinant for the large-scale adoption of vertical gardens (VGs) and green façades (GFs). Within contemporary sustainable construction discourse, environmental performance alone is no longer sufficient to justify implementation; economic validation has become an equally decisive factor [67,68,69,70,71,72,73].

Despite this quantitative growth, the present analysis reveals limited methodological consolidation. As shown in the research landscape analysis (Section 3.1), the literature remains structurally concentrated within engineering and environmental disciplines, while formal economic modeling, financial evaluation techniques, and decision science frameworks remain comparatively underrepresented.

Consequently, cost analysis is frequently embedded within performance-oriented technical studies rather than developed as an independent analytical dimension grounded in economic theory. This structural configuration indicates that VGS cost research is currently in a transitional phase: awareness of economic considerations has expanded, yet institutional integration into standardized and theory-driven evaluation paradigms remains incomplete [74].

4.2. Partial Convergence with Life-Cycle Cost (LCC) Theory

Life-cycle cost (LCC) theory—formally structured in international standards such as ISO 15686-5—emphasizes comprehensive economic evaluation across planning, construction, operation, maintenance, and end-of-life phases. A fundamental principle of LCC scholarship is that early-stage design decisions exert a disproportionate influence on long-term financial performance and operational expenditure trajectories [68,75].

However, the findings of this review indicate only partial convergence between existing VGS cost studies and this theoretical framework. As demonstrated in the structural distribution analysis (Section 3.2), installation and operation–maintenance costs dominate the reported cost components, while design-related economic considerations remain marginally represented.

This imbalance is particularly significant because system configuration, structural integration, irrigation strategy, and material selection—decisions typically made during the design-phase—directly influence downstream maintenance intensity, operational energy demand, and replacement cycles.

Thus, although many studies adopt life-cycle terminology, empirical practice often reflects segmented cost enumeration rather than integrated LCC modeling. The resulting structural misalignment between theoretical life-cycle principles and applied analytical methods limits predictive robustness and reduces cross-study comparability.

4.3. Fragmentation and the Limits of Analytical Coupling

The co-occurrence analysis presented in Section 3.3 reveals strong analytical coupling between installation costs and operation–maintenance expenditures. This relationship reflects practical project realities, as initial capital investment and long-term upkeep are financially interdependent.

Nevertheless, the limited number of studies addressing all five identified cost categories indicates substantial methodological fragmentation. Most investigations adopt partial analytical frameworks, focusing on one or two life-cycle phases rather than modeling cost interdependencies across the entire system life-cycle [66,67,76,77].

Such segmentation restricts the evaluation of strategic economic trade-offs—particularly scenarios in which higher initial investment may reduce long-term operational burdens. Without comprehensive modeling structures, decision-makers lack the analytical basis necessary to assess cost optimization across extended service horizons.

This pattern is consistent with developmental trajectories observed in emerging sustainability research fields, where descriptive cost listing typically precedes methodological standardization. The evidence therefore suggests that VGS cost research is progressing toward structural synthesis but has not yet achieved full analytical integration.

4.4. Reporting Heterogeneity and Barriers to Knowledge Accumulation

Another structural limitation identified in this review concerns the heterogeneity of cost-reporting formats. As shown in Section 3.4, installation and maintenance costs are often expressed using relatively standardized metrics such as cost per square meter or annual maintenance expenditure. These formats allow limited cross-study comparison.

However, other cost categories—particularly material consumption, irrigation energy, and system components—are reported using diverse and inconsistent units (e.g., €/kWh, €/m³, €/module, €/unit). Design-related expenditures are frequently embedded within aggregated project costs without explicit disaggregation.

This variability constrains cumulative knowledge development. Even when numerical cost values are reported, insufficient specification of contextual variables—including climatic zone, façade orientation, system typology, building scale, and regional labor conditions—reduces transferability and limits benchmarking potential.

The primary methodological constraint; therefore, is not the absence of cost data but the lack of harmonized reporting protocols. Without standardized measurement frameworks and contextual descriptors, meta-analytic synthesis and comparative economic evaluation remain methodologically restricted [72,78].

4.5. Implications for Research and Implementation

The structural patterns identified in this review generate implications at both academic and professional levels.

From a research perspective, future investigations should aim to the achieve the following: adopt fully integrated life-cycle cost frameworks encompassing all cost phases, explicitly quantify design-stage economic implications, standardize reporting units and contextual metadata, integrate financial modeling and decision-analysis methodologies, develop comparable benchmarking protocols across climatic and geographic contexts [70].

From a professional standpoint, harmonized cost modeling is essential for architects, engineers, developers, and policymakers evaluating the adoption of vertical greenery systems. Improved economic transparency can reduce perceived investment risks, strengthen policy justification, and facilitate long-term strategic planning.

Methodological standardization therefore represents not merely an academic refinement but a practical prerequisite for scaling VGS implementation within sustainable urban development strategies [77,79].

4.6. Toward Methodological Maturity

Collectively, the findings of this review indicate that VGS cost research has entered a phase of quantitative expansion but has not yet reached methodological maturity. The field demonstrates growing recognition of economic relevance, yet integration within standardized and theory-driven life-cycle evaluation frameworks remains incomplete. Progress therefore requires a shift from fragmented cost enumeration toward harmonized, model-based economic assessment. Achieving such integration would enhance predictive capacity, strengthen interdisciplinary coherence, and increase the economic credibility of vertical greenery systems within both sustainable construction research and professional practice [71,80,81,82,83].

5. Limitations

Several limitations should be acknowledged when interpreting the findings of this review.

First, the literature search was restricted to a single major academic database (ScienceDirect) and conducted in September 2025. Although ScienceDirect provides extensive coverage of peer-reviewed journals in engineering, environmental science, and building-related disciplines, relevant studies indexed in other databases (e.g., Scopus, Web of Science) or published in regional outlets may not have been captured. This restriction may introduce disciplinary and geographic bias, potentially underrepresenting research from non-English-speaking regions, local technical reports, or practitioner-oriented publications.

Second, although the review successfully identified and classified cost components within a structured life-cycle cost (LCC) framework, substantial challenges were encountered in synthesizing comparable numerical cost data. Significant heterogeneity in reporting units, aggregation levels, and contextual descriptors limited the feasibility of systematic quantitative comparison across studies. Many publications lacked detailed specification of climatic conditions, system typologies, façade orientations, or regional market variables, thereby constraining cross-study transferability and benchmarking.

Third, the analysis primarily focused on structural patterns in cost reporting rather than producing a unified quantitative cost model. While this approach allows the identification of methodological gaps and fragmentation patterns across the literature, it also means that the study emphasizes qualitative structural interpretation rather than numerical cost estimation.

These limitations do not undermine the structural findings of the review but instead reflect broader methodological constraints currently present in VGS cost research.

6. Future Research

The structural imbalance and reporting heterogeneity identified in this review point to several priorities for future investigation.

First, future studies should adopt comprehensive life-cycle cost (LCC) frameworks that explicitly integrate all major cost categories, including design-phase economics, installation, operation, maintenance, consumables, and material considerations. Explicit modeling of interdependencies across life-cycle stages would enable more robust evaluation of long-term cost trade-offs and system performance.

Second, methodological harmonization is essential. Standardized reporting units, clearer contextual descriptors, and consistent cost breakdown structures would significantly enhance comparability across studies and facilitate cumulative knowledge development. Establishing shared reporting protocols would support benchmarking across climatic zones, building typologies, and regional markets.

Third, empirical research should expand beyond short-term cost estimation toward longitudinal monitoring and real-world implementation studies. Field-based data collection, comparative regional analyses, and integration with financial modeling and decision-analysis methods would strengthen the evidentiary basis for policy and design decision-making.

Finally, interdisciplinary collaboration between engineering, environmental science, architecture, and economics is necessary to advance the methodological maturity of VGS cost research. Integrating technical performance evaluation with economic modeling would enable more comprehensive and policy-relevant assessments of vertical greenery systems.

7. Conclusions

This systematic literature review provides a structured evaluation of cost-related research on vertical greenery systems (VGS), including vertical gardens (VG) and green façades (GF), through a life-cycle cost (LCC) perspective. The study addressed three central questions concerning the research landscape, the distribution of cost components across life-cycle stages, and the degree of standardization in cost reporting.

First, the findings indicate that although publication output has increased markedly between 2023 and 2025, this quantitative expansion has not been accompanied by equivalent methodological consolidation. The research landscape remains concentrated within engineering and environmental disciplines and geographically clustered in Europe and Asia, with limited integration of formal economic modeling and decision science methodologies.

Second, five principal cost categories were identified: (1) Installation and Operation, (2) Maintenance, (3) Consumables, (4) Materials and Manufacturing, and (5) Design. The distribution of analytical attention is structurally imbalanced. Installation and maintenance dominate the literature, while design-phase economics and fully integrated life-cycle modeling remain marginal. Most studies address only one or two cost categories, indicating that current research only partially operationalizes established life-cycle cost theory.

Third, substantial heterogeneity in reporting practices was observed. Cost data are expressed using diverse and inconsistent units, and contextual variables are often insufficiently specified. As a result, cross-study comparability, benchmarking, and cumulative synthesis remain limited. The central methodological constraint in the field is therefore not the absence of cost information, but the absence of harmonized analytical and reporting standards.

Collectively, these findings reveal a structurally imbalanced and methodologically fragmented research landscape. While economic aspects of VGS implementation are increasingly recognized, their integration into coherent, theory-informed LCC frameworks remains incomplete.

This review contributes the following to the field:

(i) Systematically mapping the structural configuration of cost components in VGS research;

(ii) Identifying fragmentation patterns in life-cycle coverage and inter-category coupling;

(iii) Clarifying the divergence between theoretical LCC principles and empirical reporting practices.

By framing the analysis within a structured LCC perspective, the study advances methodological understanding beyond descriptive frequency reporting and provides a foundation for future standardization of cost evaluation approaches.

In conclusion, cost research on vertical greenery systems has entered a phase of rapid expansion but has not yet achieved methodological coherence. Advancing toward standardized, theory-informed life-cycle modeling will be essential for enabling rigorous economic evaluation and supporting the large-scale integration of VGS as nature-based solutions within sustainable built environments.