Stakeholders’ Awareness of the Benefits of Passive Retrofit in Nigeria’s Residential Building Sector

Abstract

There is a growing global interest in making existing buildings more energy-efficient. However, stakeholders seem to have differing views on the matter, especially in developing countries, thus raising the issue of awareness amongst key stakeholders at the operational stage of existing buildings. This study aimed to examine stakeholders’ awareness of the benefits of passive retrofit in residential buildings using a convergent mixed-methods approach. Quantitative data were collected from 118 property managers and 163 owners of residential buildings, and qualitative data were collected from six government officials in Lagos State, Nigeria. The quantitative data collected were analysed using fuzzy synthetic evaluation, which addresses the fuzziness in judgement-making on multi-criteria phenomena. The results revealed that property managers and owners had a moderately high level of awareness of the environmental, economic, and social benefits of the passive retrofitting of residential buildings. However, while property managers generally had a higher level of awareness than owners, a significant gap was found in their awareness of environmental benefits. Conversely, the qualitative analysis results showed that government officials demonstrated a strong awareness of environmental benefits (energy reduction, air quality, and natural lighting) and economic advantages (cost savings and lower implementation costs). In contrast, their awareness of social benefits was limited to health improvements. The findings have practical implications for policy development and awareness campaigns. Building agencies need to further reinforce their targeted awareness programmes for owners, who demonstrated fair awareness of environmental benefits while leveraging the intermediary role of property managers in promoting home retrofit practices. Economic benefits should also be an integral part of policy frameworks to drive wider adoption across all stakeholder groups.

1. Introduction

Approximately 40% of global energy consumption and 33% of greenhouse gas emissions (GHGs) are generated by buildings, making them a major focus in tackling climate change in rapidly developing countries [1,2]. Many of these countries, particularly those in the tropics, experience multiple challenges, including rising cost of living, inadequate electrical infrastructure, and extreme climatic conditions, leading to reliance on inefficient cooling solutions [3].

Within this global context, Nigeria, with its tropical climate, has some unique characteristics, including intense heat, which presents buildings with distinct challenges [4]. External heat enters buildings through gaps in their envelopes, while internal heat generated from occupant behaviours, design elements, and the use of home appliances further compound indoor thermal management challenges, especially in densely populated areas of the country [5]. Furthermore, the unreliability of electricity supply in Nigeria has caused an estimated 60% of households to depend on fuel-powered generators, which are not environmentally friendly [6].

While the National Climate Change Policy (NCCP) recommends retrofitting existing buildings, most other policies focus on developing new ones. However, around 80% of today’s buildings will still exist by 2050. Replacing them with new ones could take over 65 years to recover the embodied energy loss [7,8]. Retrofitting can be achieved using active (mechanical) and/or passive (non-mechanical) measures [9]. Within this context, however, passive retrofitting presents a feasible solution for reducing heavy dependence on electricity, while improving indoor air quality [10]. This is particularly crucial in Nigeria where residential buildings account for approximately 65% of Nigeria’s total annual energy consumption [11]. Passive retrofit measures include the use of measures, which include improving envelope insulation, installing external shading, enhancing natural ventilation, using reflective roofing, and upgrading windows to reduce heat gain [12]. Implementing these measures can provide buildings with substantial climate resilience against the risks of extreme weather [13].

Stakeholders’ awareness of the benefits of passive retrofitting is a critical success factor for its effective implementation [14]. This is to ensure that retrofit implementation is performed in a way that the benefits do not contradict one another [15]. However, research shows that awareness levels vary across contexts. Studies such as [16,17,18] indicate substantial awareness of retrofit benefits in parts of Southeast Asia, Europe, and Australia. Conversely, other studies (for example, [19,20,21]) reveal significant deficiencies in awareness, particularly regarding the passive retrofitting of existing residential buildings. However, little is known about the awareness of stakeholders in Nigeria’s residential building sector, where extreme climatic conditions and inconsistent access to reliable electricity make retrofitting particularly relevant. This constitutes a significant research gap, given Nigeria’s distinct energy context compared to developed countries.

Addressing this gap not only helps to understand awareness level but also to comprehend its behavioural dimensions, thereby justifying the study’s use of a mixed-methods approach. The urgency of this study is underscored by two factors: increasing heat waves necessitating eco-friendly thermal comfort solutions in Nigeria and the country’s commitment to reducing carbon emissions by 20% by 2030. Therefore, this study examined stakeholders’ awareness of the benefits of passive retrofitting of residential buildings in Lagos State, Nigeria. The Lagos State planning and regulatory framework specifically outlines the need for energy efficiency and conservation initiatives [22]. Given its dynamic urban landscape and rising energy demand, Lagos State represents an economic powerhouse with a pressing need for sustainable development initiatives that can be scaled to other parts of the country.

To achieve the aim of this research, the following research questions were addressed:

• How aware are the stakeholders of the benefits of passive retrofitting of residential buildings in Lagos State, Nigeria?
• What dimensions of the benefits do the stakeholders consider important?

The study considers the benefits of the passive retrofitting of residential buildings in terms of the environmental, social, and economic dimensions of Elkington’s [23] Triple Bottom Line framework, which aligns with Sustainable Development Goals (SDGs) 11 (Sustainable Cities and Communities) and 13 (Climate Action) [24]. The three interconnected stakeholder groups serve distinct roles in the retrofitting ecosystem: homeowners initiate retrofitting efforts motivated by economic benefits [25,26]; property managers balance economic, social, and environmental considerations through professional oversight; and government agencies prioritise social and environmental impacts. Understanding awareness across these stakeholder groups is crucial for fostering the required collaboration to achieve net-zero emission (NZE) targets. The findings of this study will inform policymakers, professionals in the built environment, and researchers seeking to accelerate Nigeria’s transition to energy-efficient homes amid the country’s unique challenges.

2. Literature Review

The decision to implement the passive retrofitting of residential buildings is increasingly being appreciated in achieving energy efficiency. While the benefits of retrofitting, including environmental, social, and economic [27,28] are well established, critical gaps remain in understanding the stakeholders’ awareness of them. A wide range of existing literature was systematically reviewed to identify, categorise, and analyse the dimension-based awareness analysis of retrofit benefits within the context of stakeholders in the residential sector. Existing frameworks such as the Healthy and Efficient Retrofitted Buildings (HERB) tool by C40 Cities also categorised retrofit benefits into three, namely, health benefits, socio-economic benefits, and climate and pollution benefits. These benefits relate to the triple bottom line’s emphasis on social, economic, and environmental issues, which the following subsections discuss extensively to identify gaps in the existing literature.

2.1. Environmental Benefits

The environmental benefits of building retrofitting are enormous. Retrofitting reduces carbon emissions, improves energy security, enhances resource management, and mitigates climate change issues [16,29]. Studies by Jafari et al. [30] and Kabeyi and Olanrewaju [31] corroborated these findings, with operational-phase retrofitting estimated to halve carbon emissions. Ahn et al. [32] and Pacheco-Torgal [33] emphasised the improvement in air quality as another significant environmental benefit of retrofitting buildings. Passive measures such as green roofs can reduce energy consumption in rooms under them by 22% to 45% [34,35], and insulating ceilings can increase a dwelling’s rating by 2.2 stars [36]. These measures can reduce over-reliance on cooling systems [29,31,37], which is commonplace for homes in tropical climates.

However, while the benefits of implementing passive retrofitting are enormous, demand is an urgent issue that needs to be addressed in tropical climates; awareness of these benefits appears to be inconsistently distributed amongst decision-making stakeholders, including homeowners, property managers, and the government. Ensuring consistency amongst these stakeholders is critical to ensure that the environmental outcomes of retrofit implementation align with national energy-efficiency standards (see [38,39]).

2.2. Economic Benefits

Retrofitting buildings can be viewed from two significant economic perspectives: microeconomic and macroeconomic [29]. At the micro level, the retrofitting of buildings has emerged as a vital contributor to economic gains across various geographical contexts. Specifically, the microeconomic perspective on residential building retrofits highlights the potential for cost reductions, particularly in labour and materials, driven by market dynamics and enhanced competitiveness within the energy efficiency domain [40].

Studies highlight increased property values as a major direct economic benefit of residential retrofitting. Retrofitting yields between 6 and 14% property-value premiums: 13.5% for green buildings [41], 6.6% for high-efficiency labels [42], and two-star energy upgrades in the Australian Capital Territory (mandatory since 1999) raise sale and rental values [36].

In terms of payback and operating-cost savings, studies have reported rapid payback and savings: Australian ceiling insulation pays back within five years (average benefit to cost ratio = 3.9–5.6) [36], German single-family homes cut operating costs by 15–62% [43], and passive measures further lower lifecycle expenses [33,44]. These results consistently show that retrofitting substantially reduces operating costs for homeowners. In pursuit of cost-effective pathways to net-zero buildings, Ferreira et al. [45] posited that selecting optimal retrofit measures can significantly reduce transition costs. This is especially relevant in the Nigerian context, where residential buildings heavily rely on fuel-powered mechanical cooling amid epileptic power supply and rising electricity costs [46].

At the macro level, building retrofitting can drive national competitiveness by boosting energy productivity and sector-wide synergies. Retrofits enhance output per non-energy input [47], reduce industrial energy use and GHGs [48], and improve firms’ and nations’ competitive positioning [49]. Building retrofitting can also translate into higher disposable incomes, improved provider efficiency, lower energy prices, and reallocated public funds [29]. However, these outcomes are often supported by government policy, leading to downstream benefits such as reduced energy prices and the reallocation of financial resources to other public sectors.

According to Ahn et al. [32] and Ma’bdeh et al. [50], retrofitting of buildings fosters energy access and affordability—increasing disposable income and thermal comfort of households. Furthermore, Hirvonen et al. [29] documented broader global impacts, where energy-importing countries reduced their dependency, while energy-exporting nations increased exports, contributing to overall GDP growth. Su et al. [51] compared the lifecycle costs of conventional, passive, and green buildings and concluded that, although passive and green buildings incur higher initial construction and operational costs, these are offset by significant long-term energy savings. Applying these principles to Nigeria’s residential building sector could lower energy demand, reduce environmental levies, and improve the sector’s market competitiveness.

2.3. Social Benefits

The social benefits of any sustainability initiative are often considered to surpass the financial benefits for individual investors [52]. From this perspective, the social benefits of building retrofitting encompass better indoor thermal comfort, lower mortality rates, and reduced healthcare costs due to fewer hospital visits and less time off work due to illness [53,54,55]. These health and comfort gains can also boost tenant satisfaction and, consequently, enhance the social standing of housing projects while improving living conditions and alleviating energy poverty [56,57].

Lower energy costs from retrofitting can increase access to affordable energy in regions with limited energy availability, which in turn promotes socio-economic growth. Retrofitting can create between 12 and 17 jobs for every EUR one million invested, decreasing fuel use and generating both direct and indirect employment [37,40,58,59], thus supporting community development [60,61]. The flexibility of passive retrofitting strategies also fosters positive relationships between tenants and owners, encouraging active involvement in sustainable building practices [38]. Active engagement in these efforts is key to ensuring that retrofit projects meet both NZE goals and the SDGs.

From the foregoing discussion, there is a need to find a balance between comfort and health benefits, particularly for low-income families who may struggle with initial costs. This is especially relevant in developing nations where there are significant socio-economic differences amongst investors of varying income levels. In Nigeria, the integration of retrofit projects with wider development goals and SDGs could significantly enhance public awareness and encourage the uptake of these sustainable practices.

These benefits are summarised in

Table 1. Summary of the benefits of retrofitting.

Dimensions	Key Benefits	Code	References
Environmental	Reduction in heavy reliance on non-renewable energy consumption	Env1	Hirvonen et al. [29], Hurley et al. [37], Kabeyi and Olanrewaju [31].
	Reduction of carbon emissions and household energy consumption	Env2	Ahn et al. [32], Alcazar and Bass [34], Alkhateeb and Hijleh [62], Clinch and Healy [40], Coyne et al. [27], Hirvonen et al. [29], Hurley et al. [37], Insulation Council of Australia and New Zealand [ICANZ] [36], Jafari et al. [30], Luddeni et al. [63], Niachou et al. [35].
	Enhancement of air quality	Env3	Ahn et al. [32], Pacheco-Torgal [33].
	Mitigation of climate change	Env4	Ab. Azis et al. [16].
	Enhancement of energy security	Env5	Ahn et al. [32], Oguntona et al. [38].
	Increases the energy star rating of existing residential dwellings	Env6	ICANZ [36].
	Reduction in solar radiation and glare	Env7	Shahdan et al. [39].
Economic	Improves competitive positioning in the property market and attracts more willing tenants	Eco1	Ahn et al. [32].
	Increases property value	Eco2	Brounen et al. [42], Hirvonen et al. [29], ICANZ [36], Pivo and Fisher [41], Sameh and Kamel [64].
	Energy savings and reduction in consumption cost	Eco3	Clinch and Healy [40], Hirvonen et al. [29], Ma’bdeh et al. [50], Mayer et al. [43], Pacheco-Torgal [33], Rhoads [44], Su et al. [51].
	Improvement of the real estate’s contribution to national economic growth in the long run	Eco4	Hirvonen et al. [29], Proskuryakova and Kovalev [49], Tuominen et al. [65].
Social	Enhancement of homeowners’ social reputation	Soc1	Ahn et al. [32], Liang et al. [56], Wang et al. [57].
	Reduction in illness and healthcare expenditures and guarantees good health and well-being	Soc2	Causone [54], Clinch and Healy [40], Coyne et al. [27], Howden-Chapman et al. [53], Jafari and Valentin [28], Payne et al. [55].
	Improvement of indoor thermal comfort, tenants’ satisfaction, and productivity	Soc3	Causone [54], Clinch and Healy [40], Liang et al. [56], Payne et al. [55].
	Creation of local jobs and drives community growth	Soc4	Bell [60], Clinch and Healy [40], Hurley et al. [37], Meijer et al. [58], Mikulić et al. [52], Oyedepo [61], Ürge-Vorsatz et al. [59].
	Foster positive tenant–owner relationship	Soc5	Oguntona et al. [38].

as follows:

2.4. Empirical Literature

A few empirical studies have covered areas related to retrofit awareness. These studies have shown that varying awareness patterns exist amongst stakeholders. In Finland [19] and Italy [66], tenants, architects, HVAC engineers, and energy service companies are aware of the benefits of retrofitting. Similarly, Rahman [17] found that clients and consultants in Brunei possessed a strong awareness of the benefits. Substantial awareness of environmentally sustainable retrofit benefits has been documented in Israel [18]. In Algeria, Djebbar and Mokhtari [67] also found that retrofit stakeholders understand the benefits of retrofitting buildings. However, many of them do not have access to expert advice on how to go about it. At the community level, Ab. Azis et al. [16] also revealed a heightened awareness of retrofitting in Malaysia.

While studies from Iraq [20] and Montenegro [21] revealed limited awareness amongst stakeholders, retrofitting of residential buildings is evolving with new assessment frameworks being developed. Recent tools like the HERB tool suggest growing international attention to comprehensive retrofit evaluation approaches. This tool emphasised three categories of benefits related to dimensions considered in this study: climate and pollution benefits, socio-economic benefits, and health benefits [68].

However, there remains a significant gap in the literature regarding retrofit awareness studies conducted in tropical climate regions, where unique environmental conditions such as high humidity and intense solar radiation create distinct challenges for building performance and energy efficiency. Most existing studies focus on a general awareness of building retrofitting in temperate climates, leaving a gap in understanding the multi-dimensional aspects of awareness of retrofit benefits from stakeholders’ perspectives in tropical contexts. This study addresses this gap by employing the Fuzzy Synthetic Evaluation (FSE) method and thematic analysis, which are discussed in the next section.

3. Materials and Methods

In this study, the convergent mixed-methods research design was employed. As shown in Scheme 1, the convergent mixed-methods research design allows the concurrent quantitative and qualitative data collection, separate analysis, and comparison and integration of the results to provide a comprehensive understanding of the research problem within a specific context of residential buildings in Lagos State, Nigeria (see [69]).

In this study, the mixed-methods approach features a combination of the FSE on the quantitative side and thematic analysis on the qualitative side. Details of this method for data collection and analysis are provided in the following subsections.

3.1. Data Collection

Data were gathered using both quantitative and qualitative methods to capture comprehensive insights from key stakeholders in the residential building retrofit process. On the one hand, quantitative data were collected using research questionnaires designed on Qualtrics and administered to property managers and building owners. This questionnaire contained statements related to the stakeholders’ awareness of the benefits of the passive retrofitting of residential buildings, which respondents were asked to rate on a Likert scale of 1 (strongly unaware) to 5 (strongly aware). On the other hand, qualitative data were obtained through structured interviews with government officials. The selection of these three stakeholder groups was based on their critical roles in retrofit decision-making: property managers serve as intermediaries who influence implementation through advisory roles, owners are the primary decision-makers who authorise and finance projects, and government officials establish regulatory frameworks that influence retrofit adoption.

The sampling of the property managers involved consulting the most recent Nigerian Institution of Estate Surveyors and Valuers’ (NIESV) directory, which contained the names, telephone numbers, and email addresses of property managers (financial members of the Institution for the year 2023) operating in Lagos State (see [70]). Out of the 853 property managers documented, 813 emails were available, and the questionnaire was sent to them. It is noteworthy, however, that only 796 of the emails were delivered, and 190 started the survey. After data cleaning, inadequate responses were excluded, and 118 complete responses were used for data analysis.

The second research questionnaire was administered to owners of residential buildings in Lagos State. Given the lack of a published database for the owners, convenience sampling was adopted by relying on selected Estate Surveying and Valuation Firms (ESVFs) who helped to send out the questionnaire to the residential property owners in their management portfolios. According to the updated website of the NIESV, 436 ESVFs were domiciled in Lagos State [71]. However, we selected nine of them that had a minimum of two branches in Lagos State. According to Hendriks [72], firms that manage large and geographically dispersed clients limit the distance by locating branches close to them, thus increasing the number of branches. A total of 235 owners filled out the questionnaire, of which 163 responses were used for data analysis. The sample sizes exceed the minimum of 30 recommended by Ott and Longnecker [73].

On the other hand, government officials, specifically those working with the two planning and building control agencies in Lagos State (Lagos State Building Control Agency—LASBCA, and Lagos State Physical Planning Permit Authority—LASPPPA), were purposively selected for qualitative data collection using structured interviews. The invitations sent were accepted by six of the officials of these government agencies. The profiles of the officials are presented in

Table 2. Profiles of the interview respondents.

Respondent	Profession	Agency	Years with Agency
LAS001	Civil Engineer	LASBCA	5 years
LAS002	Town Planner	LASBCA	24 years
LAS003	Town Planner	LASPPPA	11 years
LAS004	Architect	LASPPPA	16 years
LAS005	Civil Engineer and Geographic Information System (GIS) Analyst	LASBCA	8 years
LAS006	Architect	LASPPPA	15 years

.

The study acknowledges that the sampling technique may introduce specific biases; however, the authors employed various strategies to improve representativeness for each stakeholder group. In the case of property managers, the utilisation of the NIESV directory has enabled the incorporation of a wide range of qualified professionals who are actively engaged in Lagos State. While selecting homeowners through ESVFs creates a bias towards homeowners who use property management services, this limitation was reduced to some extent by the diversity of the firms’ residential portfolios, which include properties owned by a range of socioeconomic groups across Lagos State. Responses were received from owners of different types of residential buildings: 48 tenement buildings, 34 detached houses, 23 semi-detached houses, 15 terraced houses, 2 maisonettes, and 55 apartments. This distribution captures the range of common residential properties within the high-density types (e.g., flats and tenement buildings) associated with middle and low-income owners and low-density types (e.g., detached, semi-detached buildings, terraced houses, and maisonettes), which are often owned by higher-income earners.

3.2. Data Analysis

3.2.1. Validity and Reliability of Data Collection Instruments

To guarantee the reliability and validity of the research tools, a validation procedure was implemented. The face/content validity of the questionnaires was established through an expert review by two researchers and five Estate Surveyors and Valuers (ESV), each possessing at least 10 years of practical experience in property management in Lagos State. These experts evaluated the clarity, relevance, and suitability of the research questions by ensuring that the instruments were thorough in capturing stakeholders’ awareness of retrofitting. Their feedback was incorporated to refine the instrument before data collection.

The reliability of the Likert scale items was also tested using Cronbach’s alpha coefficients. The results indicated excellent internal consistency for both stakeholder groups examined. Cronbach’s alpha values for the responses provided by the property managers and the owners were 0.925 and 0.892, respectively, across the 16 items measured. These reliability scores are well above the 0.70 threshold recommended for reliable measurement instruments by Nunnally and Bernstein [74].

3.2.2. FSE

Quantitative data can often involve complex personal perceptions, leading to subjectivity, ambiguity, and imprecision, which binary Boolean logic (i.e., True/False or Yes/No) may not adequately capture [75,76]. The FSE was selected for this study because awareness measurement involves subjective judgements that exist on a continuum rather than discrete categories. The method’s hierarchical approach to aggregating multi-dimensional data (economic, environmental, and social benefits) was expected to provide more nuanced insights than simple averaging approaches. This method has been increasingly adopted in building research to solve similar complex issues (see [77,78]).

The procedure for the FSE is explained as follows in six steps:

• Step 1: Definition of the factor set.

The factor set (U) in this study is given as

{f₁, f₂, …, f_n},

(1)

where f represents the list of all the retrofit awareness statements.

• Step 2: Establishment of the evaluation sets.

  R = {r₁, r₂, r₃, r₄, r₅},

  (2)

The respondents were asked to rate the criteria based on a 5-point Likert scale, where r₁ represented “strongly unaware”, r₂ represented “not aware”, r₃ represented “neither aware nor unaware”, r₄ represented “aware”, and r₅ represented “strongly aware” as shown in Equation (2).

Each qualitative category is assigned a fuzzy weight from 0 to 1 for computation.

• Step 3: Definition of the dimension sets.

B = {b₁, b₂, …, b_m},

(3)

where each bj groups thematically related awareness statements (e.g., economic, environmental, and social benefits); each dimension b_j consists of a subset of awareness statements f_i ∈ b_j.

• Step 4: Establishment of the set of criteria and dimension weights.

In deriving the criteria and dimension weights, the mean scores (w_i) for each criterion f_i were divided by the total mean scores in each dimension. In the same way, the derived mean scores of each dimension (W_j) were divided by the aggregate mean scores. This approach normalises the criteria and dimension mean scores so that the sum of their weights equals one.

The weights (w) for each criterion fi within a given dimension of benefits are computed using the following equation:

$${\mathrm{C}}_{\mathrm{i}}={\mathrm{w}}_i/\left({\sum }_{i\in bj}wi\right), 0\le {\mathrm{C}}_i\le 1$$

(4)

Similarly, the weight of each dimension bj is determined as:

$${\mathrm{D}}_j={\mathrm{W}}_j/\left({\sum }_{j=1}^{m}Wj\right), 0\le {\mathrm{D}}_{\mathrm{j}}\le 1$$

(5)

where C_i represents criteria weight; w_i is the mean score of each criterion f_i; W_j is the aggregate mean score of each dimension b_j; D_j is the dimension weight.

• Step 5: Establishment of the membership function for criteria—Level 3.

The membership function at this level captures the distribution of responses across all grade categories, preserving the uncertainty in respondents’ opinions rather than collapsing to a single average score. The membership functions were derived as a proportion of total ratings per criteria to the total number of responses for that criterion. For each awareness statement f_i, the number of responses falling under each grade r_j (i.e., SU to SA) is used to compute a membership vector:

MF_i = (a_i1/T_i, a_i2/T_i, a_i3/T_i, a_i4/T_i, a_i5/T_i)

(6)

where a_ij is the number of respondents who selected grade r_j for criterion f_i; Ti = $\sum _{j=1}^{5}aij$ represents the total number of respondents for that statement

This produces a fuzzy evaluation matrix for each criterion.

• Step 6: Computation of fuzzy scores for criteria and aggregate to higher levels

The membership functions from Step 5 serve as weights in calculating the fuzzy scores, allowing the preservation of response variability throughout the hierarchical aggregation process.

• Fuzzy score for each criterion f_i.
  The membership function from Step 5 is used to weigh the numerical scores, ensuring that the final score reflects both the grade values and the distribution of responses. The fuzzy score for each awareness statement f_i is calculated as:

$${\mathrm{FS}}_i={\sum }_{j=1}^5({\displaystyle \frac{aij}{Ti}}·{\mathrm{s}}_j)$$

(7)

where s_j ∈ {1,2,3,4,5} is the numerical score for grade r_j.

b.

Fuzzy score for each dimension b_j—Level 2.

Aggregate the criteria scores under each dimension using their normalised weights:

$${\mathrm{DS}}_j=({\sum }_{i\in bj}Ci·{\mathrm{FS}}_i)$$

(8)

This produces a dimension-level fuzzy score for each benefit category.

c.

General awareness score—Level 1

Finally, the general awareness score (GAS) is computed as the weighted sum of dimension scores, calculated as the product of dimension weight and the level 2 membership function.

$$\mathrm{GAS}={\sum }_{j=1}^m(D_{\mathrm{j}}·{\mathrm{DS}}_j)$$

(9)

This single-scale value reflects the general level of awareness of retrofit benefits amongst the respondents.

These steps are summarised in a flowchart presented as Scheme 2.

The analysis was completed using MS Excel^® (Office 16).

Decisions on the level of stakeholders’ awareness were made based on the following linguistic terms and measurement scale adapted from Pimentel [79]: not at all aware—1.00–1.79; not aware—1.80–2.59; fairly aware—2.60–3.39; moderately high awareness—3.40–4.19; and high awareness—4.20–5.00.

3.2.3. Thematic Analysis

Thematic analysis was used to uncover and explain themes of retrofit benefits to the passive retrofitting of residential buildings, following Braun and Clarke‘s [80] six-step recommendation. The following are the steps recommended by the authors: (1) Review and familiarisation with the transcript; (2) Code development and highlighting of key analytical concepts; (3) Grouping of related codes; (4) Evaluation of themes for the entire dataset and the coded data. A theme map can help to structure the research and clarify the links between subjects; (5) Name and define topics; and (6) Reporting. The analysis was performed using the NVivo Software (Version 12).

4. Results and Discussion

4.1. Quantitative Results

4.1.1. Multi-Dimensional Analysis of Property Managers’ and Owners’ Awareness

The results reveal important patterns in how property managers and owners perceive retrofit benefits across three dimensions, with each dimension’s awareness score providing deeper insights into their broader understanding.

Environmental Dimension

The awareness scores of 3.88 and 3.27 for property managers and owners, respectively, indicate moderately high and fair awareness levels regarding the environmental benefits of the passive retrofitting of residential buildings. The relatively higher scores amongst property managers could be attributed to the roles they play in compliance with environmental standards, property maintenance, and frequent engagement with sustainability professionals. In contrast, the lower awareness score from the perspective of property owners may be due to the intricate technicalities related to issues such as carbon emissions and energy security, which are often not communicated in accessible terms to homeowners. While the comparatively lower level of awareness regarding environmental benefits, especially amongst owners, corresponds with insights gathered from stakeholders in Iraq [20] and Montenegro [21], the Nigerian context reveals a more pronounced gap between professional and lay stakeholder groups. Unlike the uniformly low environmental awareness reported in Iraq and Montenegro, Nigerian property managers demonstrate substantially higher environmental awareness compared to owners, suggesting that professional training and regulatory exposure create distinct awareness tiers that are less evident in other developing contexts. Moreover, Duan et al. [81] argued that the recognition of environmental benefits varies with economic conditions, which further explains the relatively lower awareness scores in resource-constrained contexts.

Economic Dimension

The economic benefit dimension received moderately high awareness scores from both property managers (4.03) and owners (3.99). For property managers, this reflects their operational role as intermediaries between homeowners and tenants who are tasked with maximising property value and operational efficiency. For owners, initiatives such as retrofitting require some cost, and they are more likely to subscribe if assured of increased return on investment, property value increases, and operational savings. These observations support Duan et al.’s [81] assertion that economic incentives are the primary drivers behind environmentally friendly decisions and align with the research of Mangialardo et al. [82], which found that financial considerations frequently impact owners’ decisions.

Social Dimension

The results showed that property managers (3.78) and owners (3.80) were moderately aware of the social benefits of the passive retrofitting of residential buildings. Unlike economic and environmental aspects, social benefits like improved interactions between owners and tenants and community development are challenging to quantify. The slightly higher score amongst owners reflects their direct engagement with tenants and their long-term presence in the community where they live. These results are consistent with Ab. Azis et al. [16], who reported a growing recognition of the social dimension of building retrofitting within Malaysian communities.

The results discussed above are summarised in

Table 3. FSE of property managers’ perception of retrofit benefits.

Retrofit Benefits	Criteria Mean	Level 3 Membership Function (% of Response)					Criteria Weight (Ci)	Dimension Weight (Di)	Level 2 Membership Function					Level 2 Membership Function/Likert Scale					Awareness Scores
		SU	SLU	N	SLA	SA			SU	SLU	N	SLA	SA	SU	SLU	N	SLA	SA
Environmental								0.437	0.019	0.120	0.068	0.546	0.246	0.019	0.241	0.205	2.185	1.228	3.88
Env4	3.96	0.000	0.102	0.102	0.534	0.263	0.1460
Env5	3.96	0.017	0.110	0.042	0.559	0.271	0.1460
Env2	3.95	0.034	0.102	0.042	0.525	0.297	0.1456
Env1	3.92	0.008	0.144	0.034	0.551	0.263	0.1445
Env3	3.92	0.042	0.068	0.068	0.568	0.254	0.1445
Env6	3.75	0.017	0.153	0.068	0.585	0.178	0.1382
Env7	3.67	0.017	0.169	0.127	0.500	0.186	0.1353
Economic								0.259	0.021	0.089	0.075	0.473	0.342	0.021	0.177	0.226	1.891	1.710	4.03
Eco2	4.13	0.008	0.085	0.059	0.466	0.381	0.2565
Eco3	4.12	0.034	0.059	0.025	0.517	0.364	0.2559
Eco4	3.95	0.025	0.110	0.110	0.398	0.356	0.2453
Eco1	3.9	0.017	0.102	0.110	0.508	0.263	0.2422
Social								0.304	0.027	0.118	0.128	0.501	0.226	0.027	0.236	0.384	2.003	1.130	3.78
Soc3	3.97	0.025	0.068	0.076	0.568	0.263	0.2102
Soc4	3.76	0.017	0.110	0.178	0.483	0.212	0.1990
Soc2	3.75	0.017	0.169	0.102	0.475	0.237	0.1985
Soc1	3.74	0.042	0.119	0.136	0.466	0.237	0.1980
Soc5	3.67	0.034	0.127	0.153	0.508	0.178	0.1943

Note. SU = 1; SLU = 2; N = 3; SLA = 4; and SA = 5. Level 2 membership function = Level 3 membership function × criteria weight.

and

Table 4. FSE of owners’ perception of retrofit benefits.

Retrofit Benefits	Criteria Mean	Level 3 Membership Function (% of Response)					Criteria Weight (Ci)	Dimension Weight (Di)	Level 2 Membership Function					Level 2 Membership Function/Likert Scale					Awareness Scores
		SU	SLU	N	SLA	SA			SU	SLU	N	SLA	SA	SU	SLU	N	SLA	SA
Environmental								0.397	0.101	0.255	0.072	0.422	0.151	0.101	0.509	0.216	1.686	0.756	3.27
Env7	3.39	0.055	0.239	0.098	0.472	0.135	0.1483
Env6	3.39	0.055	0.282	0.080	0.387	0.196	0.1483
Env3	3.37	0.117	0.202	0.037	0.485	0.160	0.1474
Env4	3.28	0.104	0.245	0.074	0.423	0.153	0.1435
Env5	3.23	0.086	0.282	0.092	0.399	0.141	0.1413
Env2	3.15	0.135	0.264	0.061	0.399	0.141	0.1378
Env1	3.05	0.160	0.270	0.061	0.380	0.129	0.1334
Economic								0.276	0.032	0.105	0.057	0.451	0.355	0.032	0.210	0.172	1.805	1.773	3.99
Eco2	4.29	0.031	0.043	0.025	0.405	0.497	0.2703
Eco4	4.13	0.025	0.067	0.061	0.448	0.399	0.2602
Eco1	3.95	0.037	0.098	0.031	0.546	0.288	0.2489
Eco3	3.5	0.037	0.233	0.123	0.405	0.202	0.2205
Social								0.327	0.039	0.124	0.109	0.450	0.278	0.039	0.247	0.327	1.800	1.389	3.80
Soc4	4.25	0.012	0.049	0.061	0.429	0.448	0.2261
Soc1	4.15	0.018	0.055	0.067	0.472	0.387	0.2207
Soc3	3.77	0.031	0.135	0.074	0.558	0.202	0.2005
Soc5	3.44	0.031	0.184	0.233	0.423	0.129	0.1830
Soc2	3.19	0.123	0.233	0.135	0.350	0.160	0.1697

Note. SU = 1; SLU = 2; N = 3; SLA = 4; and SA = 5. Level 2 membership function = Level 3 membership function × criteria weight.

.

4.1.2. General Awareness Amongst Property Managers and Owners

With respective GAS of 3.89 and 3.64, the results revealed a moderately high awareness of the passive retrofit’s benefits amongst property managers and owners. These results are nearly identical to those of simple arithmetic means (approximately 3.89 and 3.66). This close convergence demonstrates that both methods can sometimes lead to the same practical conclusions about stakeholder awareness levels. This suggests that people are starting to pay more attention to sustainable building practices in the Nigerian property sector. The relatively higher awareness amongst property managers could be because they have encounters with sustainability and building performance regulations more often. On the other hand, property owners’ awareness could have been shaped by their individual experiences, money-saving reasons, and what they learn from people around them.

These scores suggest more differentiated awareness levels between stakeholder groups compared to Malaysia’s more uniform community-wide awareness (see [16]). This difference reflects less developed retrofit awareness campaigns and the greater institutional distance between property professionals and homeowners in Nigeria. Similarly, the findings align with Zhang et al.’s [83] observation that awareness stabilises above the midpoint of measurement scales following sustained exposure to energy efficiency campaigns in China and that awareness gaps between stakeholder groups tend to widen without systematic campaigns.

While there is a growing awareness amongst the stakeholders, significant room exists for improvement. Like in most parts of the world, the pronounced emphasis on economic benefits, as revealed in this study, often overshadows long-term environmental considerations. This prioritisation becomes particularly understandable considering energy poverty in many developing countries, which particularly affects over 75% of Nigerians [84]. However, the environmental awareness gap between property managers and owners suggests that technical knowledge has not yet fully permeated from professional to general audiences, a pattern that distinguishes Nigeria from countries with more established retrofit awareness campaigns.

In summary, these results revealed different awareness levels, with property managers and owners placing more priority on economic benefits than on environmental and social benefits. However, because quantitative analysis alone cannot sufficiently explain the reasons for these varying patterns, it was supported with a qualitative method to gain deeper insight from government officials’ perspectives.

4.2. Qualitative Results

This section discusses the results of the analysis of qualitative data collected during interviews with six respondents (LAS001 to LAS006) from government agencies to understand their perception of the environmental, economic, and social benefits of passive retrofitting of residential buildings in Lagos State, Nigeria. Questions were also asked to help understand how the agencies promote awareness of the benefits of the passive retrofitting of residential buildings. The qualitative results are organised into themes of benefits as identified in the interviews. The thematic analysis followed a systematic approach where interview transcripts were initially coded using open coding to identify emerging concepts. These initial codes were then grouped into broader categories through axial coding, which revealed the three main benefit themes. The coding process was conducted using NVivo Software (Version 12), and sub-themes within each main category were identified through pattern recognition across multiple respondent interviews.

4.2.1. Environmental Benefits of Passive Retrofitting

The interview respondents identified four important environmental benefits of passive retrofitting, which include a reduction in energy consumption and carbon footprint, climate resilience, natural lighting and ventilation, and reduced dependence on power generators.

Reduction in Energy Consumption and Carbon Footprint

One of the key environmental benefits emphasised by respondents was the reduction in the consumption of energy. As LAS001 explained: “Passive retrofitting would put in place standards and measures that will ensure that the energy being used in a building is efficiently utilised.” This directly contributes to carbon footprint reduction, as noted by LAS005: “If we can reduce the amount of energy consumed, then in turn we can reduce the carbon footprint of that building… The carbon footprint of that building is reduced because the generation of electricity also contributes to carbon footprint.”

These perspectives align with Rahman [17] and Ürge-Vorsatz et al. [59], who reported that retrofitting significantly lowers residential energy demand. This statement was further reinforced by LAS001, who stated: “You are naturally trying to have less carbon footprint just going to the atmosphere.”

Climate Resilience

Respondents suggested that retrofitted buildings would also be more resilient to climate extremes, with LAS001 noting that implementing passive solutions “would naturally help build resilience in the end.”

Natural Lighting and Ventilation

Natural lighting and ventilation were frequently emphasised as key benefits. LAS003 appreciated the strategic placement of windows, stating that if “every dwelling unit is climate facing, there will be illumination and there will be aeration.” The energy savings potential was articulated by LAS002: “Instead of using your bulb in the day, you want to use the natural lighting to illuminate your building,” with LAS003 adding: “You don’t need to switch on light at least till nighttime.”

Cross ventilation was another area that the respondents emphasised. LAS006 observed that “most of their buildings don’t have cross ventilation,” a design flaw that passive retrofitting can help correct. LAS005 added, “When natural ventilation is improved, we may not be needing much energy for cooling.” These findings are consistent with Liang et al. [56], who emphasised the role of passive airflow in reducing cooling load and increasing tenant satisfaction.

Reduced Dependency on Power Generators

Finally, the respondents highlighted that passive retrofitting could lessen reliance on fuel-powered generators. This is critical in Nigeria due to persistent grid instability. As LAS003 noted: “To the barest minimum, you don’t need to use your power-generating sets.” This theme supports the argument by Oyedepo [61] that energy self-sufficiency through passive design is a strategic pathway towards reducing national fossil fuel dependence.

4.2.2. Economic Benefits of Passive Retrofitting

The economic benefits of passive retrofitting were a central focus during discussions with government officials, who demonstrated a high awareness of how these interventions can foster more economical and sustainable construction practices. The three important aspects were highlighted as follows: energy cost savings, lower implementation costs, and implementation feasibility.

Energy Cost Savings

Most of the respondents acknowledged that a significant economic benefit of passive retrofitting is the reduction in operational costs, particularly in energy consumption. Elements of passive design, such as improved natural ventilation, adequate insulation, and increased natural light, were identified as crucial methods for lowering utility expenses. The financial impact was articulated most clearly by LAS001: “Your costs of consumption or costs of energy or costs of living would drastically reduce.” LAS004 also further emphasised that “the number one advantage or benefit is that you are going to make savings on your cooling bills,” while LAS005 emphasised the broader utility impact: “If we can save energy, it reduces cost. That’s on utility bill.”

These perspectives are consistent with Ürge-Vorsatz et al. [59], who reported that implementing passive energy retrofitting substantially lowers household energy costs, especially in tropical regions with high cooling demand. In a similar vein, Santamouris et al. [85] noted that utilising passive cooling in hot climates can provide lasting financial benefits by reducing reliance on mechanical systems.

Lower Implementation Costs

Respondents stated that passive retrofit measures are more cost-effective than active systems, with LAS003 stating: “It’s cheaper, it’s less cumbersome, it’s cheaper, it’s less expensive, then it’s not too sophisticated.” This perception was reinforced by LAS004, who noted that “Upfront cost is reduced compared to the active retrofit. It’s a lot reduced.”

This reflects the financial accessibility of passive strategies such as shading devices, ventilated roofs, or louvre windows—solutions that typically require lower capital investment compared to installing HVAC systems or photovoltaic panels. However, Nguanso et al. [86] highlighted that, depending on the materials used, some passive designs may involve higher upfront costs compared to conventional materials. The officials’ emphasis on affordability suggests that local material availability and labour costs may create different economic dynamics compared to other contexts. This divergence indicates that cost perceptions of passive retrofitting are highly context-dependent, with Nigerian stakeholders potentially benefiting from locally available materials and construction techniques that reduce implementation barriers.

Implementation Feasibility

The final economic sub-theme explored the feasibility of implementing passive retrofit measures at the level of individual homes and communities. The respondents believed that many approaches are possible given the financial and technical resources available to homeowners and community members. As LAS003 noted: “Many things that you’d do are within your capacity.”

This viewpoint regards passive retrofitting as a cost-effective strategy appropriate for households with middle and lower incomes, thereby enhancing the potential for expanding these initiatives throughout a varied housing sector in Nigeria. This aligns with the conclusions drawn by Mastroberti et al. [87], who posited that the effectiveness of retrofitting methods frequently hinges on their economic feasibility and their ability to adjust to regional financial circumstances.

4.2.3. Social Benefits of Passive Retrofitting

Although less frequently discussed than the environmental and economic dimensions, social benefits emerged as a noteworthy theme in the interviews. The social benefits identified were air quality and health improvement and indoor thermal comfort enhancement.

Air Quality and Health Improvement

The respondents widely recognised improvements in indoor air quality and occupants’ health. LAS003 provided a detailed account:

“There have been cases of people sleeping in tenements with their generator set behind their windows. And they have reports of cases of a medical challenge that by the time they are analysed (diagnosed) in the hospital, they’d be told to shift the location of their generating sets that pollute the air they breathe in directly… The less time we use those artificial interventions, the better for us because of the air we will be breathing in. Even for some cases of respiratory tract infections or respiratory issues.”

This health-focused perspective is complemented by LAS001’s broader environmental view: “It would also promote healthy living because we’re looking at reducing carbon emissions as well.” Howden-Chapman et al. [53] also reported a strong link between building energy performance and reduced respiratory illness.

Indoor Thermal Comfort Enhancement

Related to health improvement is the issue of indoor thermal comfort. LAS006 noted that with passive measures, “the indoor air comfort is improved… to make the people living there to be healthy so that they will be free from some health issues.” This perspective reflects the awareness that inadequate indoor comfort poses serious health risks, particularly given Nigeria’s widespread reliance on fuel-powered generators for cooling.

The health implications of excessive heat were further highlighted by the same respondent, who articulated that “even people that are living in my environment, some of them are complaining of that heat.” The concern is particularly relevant because of the increased risk of heat-related illnesses such as meningitis in parts of sub-Saharan Africa during the dry season. As a solution, LAS002 believed that the roof should be designed in a way that allows the heat collected on the roof to be “re-radiated back into the sky instead of coming in so that you can enjoy cooling effect within your building.”

These findings correspond with studies by Causone [54], Hirvonen et al. [29], and Pacheco-Torgal [33], who demonstrated that passive roof retrofits reduce temperatures in low-income housing.

Collectively, these results revealed that respondents were generally aware of the environmental, social, and economic benefits of passive retrofitting, with greater emphasis on the environmental benefits. Despite ongoing efforts by the planning and building control agencies of the government, targeted actions remain important to raise awareness and the adoption of passive retrofitting of residential buildings.

Scheme 3 depicts the result of the frequency of relevant words used in the interviewees’ responses. At a maximum of 500 words, the most frequent word was building with 147 occurrences (weighted percentage = 2.71%), while the second-most frequent word, with 97 occurrences and a weighted percentage of 1.79% was passive. Ranking third, “energy” occurred 83 times with a weighted percentage of 1.53%. The fourth most occurring word was buildings, occurring 66 times with a 1.22% weighted percentage. Other prominent words include Lagos (62 times), people (55 times), retrofitting (45 times), state (43 times), and code and residential (41 times), among others. These, amongst others, are the expected words, suggesting a vast understanding of the questions the respondents answered. Therefore, it can be inferred that the respondents agreed with the results of past studies such as [88] that passive retrofitting can reduce the energy consumption and carbon footprint of buildings.

A further text search was conducted with a focus on the most recurring word, “building.” The result (see Scheme 4) shows that most of the other recurring words are used in connection with building.

4.3. Promotion of Awareness

The final part of the discussion focused on how government agencies in Lagos State promote awareness of the benefits of passive retrofitting. Respondents described the existing framework:

“There’s a PAU unit that’s in charge of advocacy and sensitisation … the sensitisation is still on, but it’s not as expected for now.”

[LAS003]

“They’ve a lot of campaigns and since we are talking of the existing building now, I think what they are doing is just like sensitisation, education, and advocacy for now on the issue of retrofitting, and some lectures and seminars on it.”

[LAS006]

Respondents also highlighted room for improvement. LAS006 noted: “LASBCA is doing well on the campaign … they are doing well, but you know, they still need to do more.”

LAS002 further expressed optimism about future awareness activities, particularly as the Lagos State Building Code advances towards formal adoption: “By the time the code is passed, there will have to be sensitisation and every other thing … concerning the passive energy saving and efficiency.” Practical implementation approaches were also identified, with one respondent suggesting that “during the clearing of drawings, they will create it that you have to include it in your drawings” [LAS002].

The analysis of interview data reveals that while awareness promotion regarding passive retrofitting is progressing in Lagos State, there remains a significant opportunity to strengthen these efforts as the building code implementation advances.

To assess how stakeholder awareness aligns with internationally recognised retrofit benefits,

Table 5. Results vs. HERB framework’s three benefit categories.

HERB Benefit Categories	HERB Specific Benefits	Study Findings: Awareness Level	Stakeholder Group Performance	Key Gaps Identified
Health benefits	Reduced excess heat Reduced cold Reduced asthma from damp and mould Improved daylight Reduced nighttime noise	Social Dimension (Health-related) Property Managers: 3.78 Building Owners: 3.80 Government Officials: 2 themes identified	Moderate awareness across all groups	Limited recognition of specific health impacts like respiratory benefits
Socio-economic Benefits	Jobs supported Reduced energy poverty Net Present Value, payback time and productivity savings	Economic Dimension Property Managers: 4.03 Building Owners: 3.99 Government Officials: 3 themes identified	Highest awareness—Strong alignment	Good understanding of cost savings but limited awareness of broader socio-economic impacts
Climate and Pollution Benefits	Reduced GHG emissions Reduced indoor air pollution Reduced outdoor air pollution	Environmental Dimension Property Managers: 3.88 Building Owners: 3.27 (lowest) Government Officials: 4 themes identified	Significant gap for building owners	Critical awareness gap in climate benefits, especially amongst owners

compares the study findings against the HERB framework’s three benefit categories to reveal the strengths and critical gaps in stakeholders’ awareness.

This comparison highlights the need for targeted awareness campaigns that explicitly connect economic benefits (where awareness is high) to health and environmental outcomes (where awareness lags).

Scheme 5 presents a conceptual model demonstrating how awareness might translate into action across stakeholder groups. The model recognises that property managers, owners, and government officials each have different levels of environmental awareness and require tailored intervention strategies, and so suggests different actions based on the research findings: awareness bridging, pilot implementation, and scaling and replication. With the recommendations put forward in this model, the awareness of the stakeholders can be improved towards achieving the widespread implementation of the passive retrofitting of residential buildings.

4.4. Integration and Implications of Results

These findings contribute to the growing body of knowledge on retrofit awareness in developing tropical economies. While international frameworks for retrofit assessment continue to evolve, this study provides specific insights into stakeholder awareness patterns in a context characterised by energy poverty, unreliable electricity supply, and extreme heat conditions—factors that may not be fully addressed in frameworks developed primarily for other geographic and economic contexts.

The Nigerian context reveals a distinctly different awareness landscape compared to international studies. Unlike the uniformly high awareness levels reported in developed contexts such as Finland and Italy [19,66], where tenants, architects, and energy service companies demonstrate a comprehensive understanding of retrofit benefits, the research findings show significant stratification between professional and lay stakeholder groups. While government officials demonstrate a substantial environmental awareness (four themes identified), the 0.25-point difference between the general awareness among property managers and owners suggests that awareness dissemination mechanisms effective in developed countries may not translate directly to developing tropical contexts.

This pattern contrasts sharply with limited awareness contexts such as Iraq [20] and Montenegro [21], where studies reported generally low awareness across all stakeholder groups. The Nigerian case suggests that planning and building control agencies’ attempts to raise awareness through seminars and climate action programs have been more effective for professional stakeholders than for property owners. This indicates a need to shift from general awareness campaigns toward more targeted educational programs specifically designed for owners. Liu et al. [89] suggested that providing targeted knowledge and policy tools can help increase awareness about retrofitting amongst the stakeholders involved.

The HERB framework comparison (Table 5) reveals awareness gaps not previously identified in the literature. While previous studies have noted general awareness deficits, this systematic comparison against internationally recognised benefit categories shows that Nigerian stakeholders have relatively strong economic awareness but critical gaps in understanding health and environmental benefits. This pattern differs from studies in temperate climates, where environmental benefits often receive greater emphasis due to heating-related energy costs and established environmental consciousness.

The tropical climate context introduces unique factors not adequately addressed in the existing literature. For example, retrofitting priorities such as natural ventilation, shading, and thermal comfort reflect the solar heat in Lagos, which is different from the heating solutions usually found in temperate climates. Consequently, this indicates the necessity for climate-specific frameworks that can encompass the complete range of stakeholder awareness across various environmental settings.

These findings have several important implications for both policy and practice. First, awareness plans need to be designed for different groups rather than adopting one-size-fits-all approaches. Second, the strong economic awareness among Nigerian stakeholders suggests that retrofit promotion should leverage economic arguments while gradually building an understanding of health and environmental benefits.

Third, planning and building control agencies should leverage the strong economic awareness foundation by explicitly connecting economic benefits to environmental and social outcomes in their promotional materials and incentive programs. A deliberate emphasis on how energy efficiency measures simultaneously reduce costs and environmental impact could help bridge the environmental awareness gap [29,33] as evidenced in Australia, where retrofit subsidies provided by different tiers of government helped to improve homeowners’ awareness of environmental issues [90]. Fourth, the development of climate-specific retrofit frameworks is essential for tropical contexts where cooling rather than heating dominates energy concerns. Finally, the successful engagement of professional stakeholders demonstrates that institutional capacity building can be effective but requires different approaches for reaching property owners who make the ultimate retrofit decisions.

5. Conclusions

This study addressed a significant research gap in stakeholders’ awareness of the benefits of passive retrofitting of residential buildings in tropical developing regions, particularly in Nigeria, where older structures significantly impact the nation’s energy consumption. While previous studies have examined retrofit awareness in various areas, there has been limited assessment of awareness amongst key decision-makers in residential retrofitting, specifically property managers, owners, and government officials. The study employed a convergent mixed-methods approach, with quantitative analysis focusing on property managers and owners, while government officials were examined qualitatively. This involved the integration of the FSE method and thematic analysis to measure awareness levels and delve into the qualitative aspects of understanding.

Property managers achieved a GAS of 3.89, while building owners recorded 3.64, both demonstrating moderately high levels of awareness across all three retrofit benefit dimensions. The dimensional analysis showed that economic awareness scored 4.03 for property managers and 3.99 for owners, social awareness scored 3.78 for property managers and 3.80 for owners, while environmental awareness scored 3.88 for property managers and 3.27 for owners. Both groups prioritised economic benefits, followed by environmental and social benefits for property managers, while owners ranked social benefits second and environmental benefits lowest. Property managers need targeted environmental education, while owners require campaigns emphasising environmental benefits that build on their social awareness.

The qualitative results revealed that government officials demonstrated a strong awareness of environmental and economic benefits, with thematic analysis identifying four key environmental themes (energy reduction and carbon footprint reduction, climate resilience, natural lighting and ventilation, and reduced generator dependency), three economic themes (energy cost savings, lower implementation costs, and implementation feasibility), and two social themes (air quality and health improvement, and indoor thermal comfort enhancement). Therefore, government policies need to focus on quantifying health and air quality improvements to translate their awareness into actionable regulations.

Awareness-building should connect economic benefits to environmental and social outcomes rather than treating these as separate dimensions. Given the research findings, there is potential for stakeholders to collaborate by setting up regular roundtable discussions led by planning and building control agencies, creating retrofit advisory committees with input from key stakeholders, and partnerships between the public and private sectors targeted at contributing resources for retrofitting homes. Awareness could also be enhanced using a combination of communication strategies including traditional media, online platforms, and community outreach to speak widely to the needs of each stakeholder group.

The limitations of this study prevent the generalisation of its results in other contexts. The study did not empirically test the conceptual model designed, and the cross-sectional design could limit the application of its results to an evolving awareness scenario. Therefore, future research should investigate how awareness patterns influence actual retrofit implementation decisions and explore whether targeted educational interventions can effectively address the identified awareness gaps, particularly regarding environmental benefits amongst property owners who manage their properties independently without professional services. Furthermore, comparative studies across tropical developing regions could inform more effective sustainability strategies.