КАРТИРОВАНИЕ ИССЛЕДОВАТЕЛЬСКОГО ЛАНДШАФТА ЭНЕРГОЭФФЕКТИВНЫХ ЗДАНИЙ: БИБЛИОМЕТРИЧЕСКИЙ АНАЛИЗ ПУБЛИКАЦИЙ SCOPUS

УДК: 697.1/.7 : 502.174.3

Аннотация

Усиление урбанизации, быстрое экономическое развитие и деградация окружающей среды обострили потребность в энергоэффективных зданиях (ЭЗЗ). В данном исследовании используется библиометрический анализ 594 публикаций из базы данных SCOPUS (2021–2025) с помощью программы VOSviewer 1.6.20 для картирования текущего исследовательского ландшафта и выявления новых тенденций в технологиях ЭЗЗ. Из первоначального набора данных, состоящего из 21 098 записей, был получен уточненный набор данных путем применения фильтров по тематическим категориям и анализа совместной встречаемости ключевых слов (пороговое значение: 11 совместных встречаний; 121 ключевое слово; 5 кластеров; 2937 связей; общая сила связей: 7513). Было выделено пять исследовательских кластеров: (1) интеграция возобновляемой энергии в системы ОВКВ; (2) моделирование и имитация энергопотребления; (3) стратегии «зеленого» строительства и экологически чистые материалы; (4) тепловой комфорт жильцов и качество воздуха в помещении; (5) структурная прочность и эксплуатационные характеристики ограждающих конструкций энергоэффективных жилых зданий. Публикации после 2022 года показывают заметный сдвиг в сторону устойчивости на протяжении всего жизненного цикла, энергетического моделирования с использованием ИИ и стандартов зданий с нулевым потреблением энергии (ЗНЗЭ). Полученные результаты обеспечивают структурированную доказательную базу для определения приоритетов исследований, разработки политики и отраслевой стратегии в секторе зданий из углеродистой стали.

Abstract

Increased urbanization, rapid economic development, and environmental degradation have intensified the need for energy-efficient buildings (EEBs). This study employs bibliometric analysis of 594 publications from the SCOPUS database (2021–2025) using VOSviewer 1.6.20 to map the current research landscape and identify emerging trends in EEB technologies. From an initial pool of 21,098 records, a refined dataset was obtained by applying subject-category filters and keyword co-occurrence analysis (threshold: 11 co-occurrences; 121 keywords; 5 clusters; 2,937 links; total link strength: 7,513). Five research clusters were identified: (1) renewable energy integration for HVACR systems; (2) energy demand modelling and simulation; (3) green building strategies and sustainable materials; (4) occupant thermal comfort and indoor air quality; (5) structural durability and building envelope performance of residential EEBs. Post-2022 publications show a marked shift towards whole-lifecycle sustainability, AI-assisted energy modelling, and net-zero energy building (NZEB) standards. The findings provide a structured evidence base for research prioritization, policy development, and industry strategy in the EEB sector.

Ключевые слова: энергоэффективное здание, библиометрический анализ, VOSviewer, интеграция возобновляемых источников энергии, тепловой комфорт, характеристики ограждающих конструкций здания, здание с нулевым потреблением энергии.

Keywords: energy-efficient building, bibliometric analysis, VOSviewer, renewable energy integration, thermal comfort, building envelope performance, net-zero energy building.

1. Introduction

The construction and operation of buildings account for approximately 36% of global final energy use and nearly 40% of total CO₂ emissions [1]. The emergence of sustainable, green, and energy-efficient building (EEB) concepts in the 1980s was driven by the energy crisis and the mounting ecological burden of conventional construction methods [2]. EEBs encompass a variety of design philosophies, all centred on resource-efficient solutions applied across the full building life cycle [3]. Research output in this domain has grown substantially: a SCOPUS query using the term “energy-efficient building” returns 21,098 publications for the period 1985–2025, with more than 60% of records published after 2015 (Fig. 1). China, the USA, and Hong Kong lead in publication volume, collectively accounting for over 45% of the global output (Fig. 2). In Azerbaijan, 2024 was designated the “Year of Solidarity for the Green World”, mandating the integration of clean eco-technologies across all economic sectors, including construction [6,7,8]. This policy context reinforces the importance of mapping the global scientific frontier so that national research and regulatory efforts can be strategically aligned [9].

Despite the growing literature, no recent bibliometric study has systematically mapped EEB research trends using SCOPUS data filtered to the Construction Technologies category for the 2021–2025 period. Prior reviews either cover broader sustainability topics or rely on older datasets, leaving a gap in evidence for current practitioners and policymakers.

Figure 1. Annual publication count for the subject area “energy-efficient building” in SCOPUS (1985–2025). Publication volume grew at an average annual rate of ~14% between 2015 and 2023, with a record high in 2022 (approx. 1,800 papers). Post-2022 output stabilises, suggesting field maturation alongside emergence of new sub-topics

Figure 2. Countries with the highest publication output on EEB technologies (SCOPUS, 1985–2025): 1-China, 2-USA, 3-Hong Kong, 4-Malaysia, 5-Australia, 6-England, 7-Taiwan, 8-Italy, 9-Canada, 10-South Korea, 11-India, 12-Germany. China, the USA, and Hong Kong together account for over 45% of total records

The present study aims to: (i) identify the dominant research clusters in EEB science using keyword co-occurrence analysis; (ii) trace the temporal evolution of research priorities from 2022 to the present; and (iii) highlight emerging topics — particularly AI-assisted modelling, NZEB standards, and whole-lifecycle carbon accounting — that represent high-growth frontiers for future investigation.

2. Methods. 2.1 Data collection

A structured search of the SCOPUS database was conducted using the following primary keyword: “energy-efficient building”, supplemented by: energy-efficient building technologies, performance, thermal comfort, sustainability, HVAC, eco-system, building envelope, renewable energy, green building, sustainable science technology, alternative energy, low-carbon energy, environmentally friendly energy, sustainable energy, technology. The initial query returned 21,098 publications (1985–2025). The dataset was subsequently restricted to the period 2021–2025 and filtered to the SCOPUS subject category “Energy Efficient Science and Technology / Construction Technologies”, yielding 1,647 records. After applying inclusion criteria (peer-reviewed articles, review papers, conference papers; English-language; complete metadata), 594 publications were retained for analysis. The full data-processing sequence is presented in Table 1.

Table 1. Data collection and processing workflow

Limiting the search query to the Scopus database is justified by its comprehensive interdisciplinary coverage and stringent indexing criteria for peer-reviewed literature in construction technologies. While the integration of Web of Science and Dimensions databases is planned for future stages to expand the scope, Scopus currently provides a representative and internally consistent sample, avoiding potential metadata duplication issues associated with merging different platforms.

2.2 Bibliometric mapping. Records were imported into VOSviewer 1.6.20 as a Tab-Delimited file in Full Record format. The map was constructed using bibliographic data with keyword co-occurrence as the unit of analysis and Full Counting as the weighting method. From 4,422 unique keywords, those appearing in at least 11 publications (threshold selected to balance network density against interpretability, following van Eck & Waltman, 2014 [15]) were retained, producing a set of 121 keywords grouped into 5 clusters. To examine temporal dynamics, a separate overlay visualisation was generated for publications from 2022 to the present, enabling identification of recently emerging topics (Fig. 4). This two-map approach — static co-occurrence network plus temporal overlay — is consistent with best practice in bibliometric reviews [12,13,14].

Keyword co-occurrence analysis was deliberately selected as the primary method, as this study focuses on the conceptual and thematic evolution of the terminology ("research landscape") rather than institutional ties. However, to partially address the limitation regarding collaboration mapping, a quantitative analysis of country-level publication output is provided in Section 1. Advanced co-citation analysis and author/country collaboration mapping are designated as immediate priorities for the next phase of this research project.

3. Results and Discussion.

3.1 Overview of the keyword co-occurrence network. The 121 retained keywords form 5 thematically coherent clusters (Fig. 3). The most frequently co-occurring terms across the entire network are: performance (n=312), energy efficiency (n=287), optimization (n=231), thermal comfort (n=198), and building envelope (n=176). The network contains 2,937 links and a total link strength of 7,513, indicating a well-connected research field with significant interdisciplinary overlap.

Figure 3. VOSviewer keyword co-occurrence network for 121 terms (threshold ≥11 co-occurrences; 5 clusters; 2,937 links; total link strength 7,513). Node size proportional to keyword frequency; line thickness proportional to co-occurrence strength

3.2 Cluster analysis. Cluster 1 — HVACR systems and renewable energy integration (46 terms; red). The dominant terms in this cluster are heat pump (link strength: 412), ventilation (389), solar energy (341), and energy recovery (298). Publications in this cluster highlight that high-performance HVAC equipment — particularly variable-speed heat pumps and heat-recovery ventilation units — can reduce building energy demand by 25–40% compared to conventional systems [16,7]. Integration of photovoltaic panels with HVACR controls emerges as a cross-cutting theme, consistent with EU Directive 2023/1791 on energy efficiency [8,9].

Cluster 2 — Energy demand modelling and digital simulation (31 terms; green). Key terms include EnergyPlus (link strength: 321), machine learning (287), building information modelling (BIM) (265), and digital twin (198). This cluster reflects the rapid uptake of data-driven and AI-assisted approaches for predicting building energy consumption at the design stage. Machine learning models (LSTM, random forests, ANNs) are reported to improve prediction accuracy by 15–30% over physics-based baselines [4]. The growing presence of “digital twin” as a keyword (first appearing in 2021, rising to top-20 by 2024) signals a major emerging trend.

Cluster 3 — Green building strategies and sustainable materials (29 terms; blue). Dominant terms: LEED certification (link strength: 356), life-cycle assessment (LCA) (312), green roof (276), and recycled materials (241). This cluster spans both design strategies (passive cooling, bioclimatic design) and material innovation (aerogel insulation, bio-based composites). A notable sub-theme is the distinction between embodied carbon and operational carbon — a topic gaining traction as net-zero targets require accounting for full life-cycle emissions [7].

Cluster 4 — Occupant thermal comfort and indoor environmental quality (9 terms; yellow). Core terms: PMV/PPD index (link strength: 187), indoor air quality (IAQ) (165), post-COVID ventilation (143). Although this is the smallest cluster by keyword count, it exhibits the highest average link strength per term (20.8 vs. network average 14.7), suggesting tight thematic cohesion. Post-pandemic research has reinforced the importance of IAQ as a health outcome, not merely a comfort parameter.

Cluster 5 — Structural durability and building envelope performance (6 terms; purple). Key terms: durability (link strength: 156), U-value (148), airtightness (134). Though the smallest cluster, it represents a foundational constraint: EEBs must maintain structural integrity and envelope performance over multi-decade lifespans without generating additional environmental impact. Recent work from our group demonstrated that ventilated façades under extreme wind conditions (case study: Baku) can maintain thermal performance within 4% of design values.

The temporal overlay (Fig. 4) reveals three categories of keyword evolution:

• Emerging terms (first entering top-20 after 2022): digital twin, embodied carbon, NZEB (net-zero energy building), reinforcement learning for HVAC control, post-COVID IAQ.
• Stable high-frequency terms: energy efficiency, thermal comfort, building envelope, renewable energy.
• Declining terms: passive house (peak 2019–2021), BIPV as a standalone topic (now absorbed into broader renewable integration cluster).

This pattern suggests that the field is moving from component-level optimisation towards system-level and whole-lifecycle approaches, with AI and digital tools as key enablers.

Figure 4. VOSviewer temporal overlay for publications 2022–present. Warmer colours (yellow–green) indicate terms with higher mean publication year, signalling recently emerging research priorities. Notable emerging nodes: “digital twin”, “embodied carbon”, “net-zero energy building”.

3.3. Research gaps identified. Despite the breadth of the literature, the bibliometric analysis reveals several under-represented topics that represent high-priority research opportunities:

• AI-driven predictive maintenance integrated with building energy management systems (BEMS) — identified in <3% of reviewed papers.
• Whole-lifecycle embodied carbon accounting for EEBs in emerging economies, including the South Caucasus region.
• Long-term field performance data for novel insulation materials (aerogel, vacuum insulation panels) under real climate conditions.
• Social equity dimensions of EEB adoption: affordability, access, and displacement effects in low-income urban areas.
• Integration of EEB metrics into national building codes of post-Soviet countries — a significant policy gap given the region’s ageing building stock.

4. Conclusion

 This bibliometric study of 594 SCOPUS publications (2021–2025) provides a structured map of current research in energy-efficient building technologies. The main findings are:

• Five research clusters dominate the EEB literature: HVACR and renewable energy integration; energy demand modelling; green building strategies; occupant thermal comfort; and structural/envelope performance.
• Post-2022 publications show a clear shift toward AI-assisted modelling (digital twins, machine learning), net-zero energy building standards, and whole-lifecycle carbon accounting — topics that will likely define the next research cycle.
• Five research gaps were identified, of which embodied carbon accounting and AI-assisted BEMS represent the most actionable near-term priorities for both academics and policymakers.
• The findings are directly relevant to Azerbaijan’s national green-economy agenda and can inform evidence-based updates to building energy codes and public procurement standards.

Future work should expand the dataset to include Web of Science and Dimensions databases, incorporate co-authorship network analysis to map international collaboration patterns, and conduct a citation-based influence analysis to identify the most foundational works in each cluster.

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