Life Cycle Assessment of Pervious Pavements: Integrative Review and Novel Ideas of Analysis

Abstract

Life Cycle Assessment (LCA) and Life Cycle Cost Assessment (LCCA) are essential tools for environmental and economic assessment and decision-making in an evolving world with continuous climate change. In the same conditions, one of the most used and assessed solutions for facing climate change is using pervious pavements, with many papers proving its benefits. However, the literature has shown a need for more research on the LCA methodological aspects in the context of new green infrastructure. This research aims to review pervious pavements, LCA and LCCA combined, while discussing possible differences in boundaries, functional units, and other parameters. Thus, a string search was performed, leading to 89 documents. The main results indicate LCA is usually scope-bounded in the field of pervious pavements, with different benefits and characteristics, such as traffic impact, urban heat island effects, and carbonation. As for LCCA, private and public cost differentiation provide a scope definition and monetisation difficulties. In conclusion, both tools offer promising applications in pervious pavements. As a significant deliverable and recommendation of this paper, both LCA and LCCA theoretical frameworks were provided based on the benefits and specific characteristics included in the literature. These frameworks introduce novel ideas and perspectives, inviting further exploration and discussion.

1. Introduction

City planners must design and deliver systems resilient to climate change in the urban environment. Engineering concepts such as Green Infrastructure (GI), Best Management Practices (BMP), and Low Impact Development (LID) are examples of fundamentals applicable to engineering projects and decision-making focused on sustainability and resilience [1,2]. By using GI, for example, one can decrease runoff from roads, control diffuse pollution, and even sequester carbon [3]. Such benefits are essential for mitigating climate change and preparing for changes in rainfall patterns. Also, GI presents an alternative for urbanisation that better meets the urban resilience, adaptability, and sustainability requirements.

The increased frequency and intensity of rainfall in regions of Brazil [4] and the world is also a worrying factor that the government and public policies must address. Different nations have expressed their desire to establish adaptive actions to restrict the impacts of natural disasters under future climates. For example, Almeida et al. [5] researched a Disaster Risk Indicator in Brazil (DRIB), assessing water-related natural disasters such as drought, flooding, landslides, and sea-level rise. Many cities presented high exposure to natural disasters, including 778 cities, constituting about 14% of the Brazilian population, with very high vulnerability conditions. Other parts of the world have also experienced recent extreme events that validate the fear of future disasters, including the flooding experienced by Germany and China [6,7].

Another problem arising from climate change is the increase in temperature in urban centres, especially related to the effects of urban heat islands. Urban heat islands are an effect that occurs in urban centres and are related to the increase in temperature compared to the surrounding rural conditions [8]. These effects have increased with the continued climate change, and may also expect a further increase in cities that experience urban growth due to urbanisation [9]. All these factors contribute to the necessity of researching mitigation and adaptation methods for cities. Some techniques are good possibilities for this topic, such as using reflective materials, cool roof technologies, green roofs, parks, and pervious pavements [8,10].

The use of pervious pavements has been studied worldwide for decades, with advantages and benefits pointed out by researchers. The reduction of surface runoff, pollution control at the source, reduction of aquaplaning and noise from the passage of vehicles, and the improvement of some qualitative parameters are some of the benefits [11]. Given the characteristics of the technique, pervious pavements have also been included in the Sustainable Urban Drainage System (SUDS) classification. SUDSs are based on the premise of local stormwater treatment to reduce the impact of additional impervious areas on current drainage systems. In this way, urban drainage systems will need to be optimised to reduce the occurrence of flooding, which is expected to increase as the frequency of heavy rainfall increases [4]. SUDSs stand out as a pathway for the optimisation of these systems.

Given the complexity of SUDSs and GI systems, one can state that it is controversial which technology and design to prioritise. For pervious pavements, many authors have researched different types of surfaces in different metrics, such as water quality [12,13,14,15], clogging effects [16,17], urban heat island mitigation [18], environmental burden [19,20] and cost analysis [19,21,22]. One of the principal methodologies of assessing the environmental burden of systems and products is the Life Cycle Assessment (LCA). This framework aims to compare burdens corresponding to all life cycle stages. The LCA of pervious pavements is a recent topic, with less than 20 years of research experience and much more recent interest and potential [23].

Based on pervious pavements’ LCA, one can compare different approaches to paving and all the benefits and processes necessary for the system, such as the impact of different materials and use aspects [20,24,25,26]. Also, a Life Cycle Cost Assessment (LCCA) can explain the different costs and money-wise benefits during a pavement life cycle [27]. The urban heat island effect, stormwater quality improvement, and fuel consumption due to increased pavement roughness are possible analyses within this context.

This paper investigates the approaches used in the literature to perform LCA and LCCA studies considering pervious pavements. The main question used to define the integrative review is: “What framework of LCA/LCCA is the most comprehensive in a pervious pavement study?”. The question aims to answer which elements should be addressed in an LCA/LCCA of pervious pavements, including different stages, impact assessment methods, material, and other definitions.

2. Materials and Methods

The method proposed for this research consists of an integrative review of pervious pavements focusing on the life cycle assessment and cost analysis. The authors have used a systematic protocol to conduct the integrative review, with searches of papers, reviews, conference papers, technical reports, and other types of material in different databases, as further explained in the following sections. We used the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement to better report the results and criteria.

2.1. Research Questions and Criteria

The eligibility criteria were proposed to be wide-ranging to obtain as many studies as possible that have carried out a LCA or LCCA of pervious pavements. Any studies that include life cycle assessment concepts with environmental burdens or cost estimates were considered in the analysis. Also, any studies that mentioned LCA were included in the analysis if they addressed some other significant benefit points during the life cycle of pervious pavements. For example, some review papers that addressed how LCA and LCCA should be used were included.

Two databases were included in the screening process. Both are among the most complete engineering databases globally, from which journals with the highest impact factors are included. The first is Scopus, from the Elsevier group [28]. According to Elsevier, Scopus is the largest abstract and citation database, containing peer-reviewed journals on many areas of knowledge, including engineering and sustainability. As of 2020, Scopus had more than 24,000 indexed journals, including books, conference papers and other materials [29]. The second database is the Web of Science (WOS), maintained by Clarivate [30]. WOS is a multidisciplinary database that indexes peer-reviewed journals and other materials. As of 2022, WOS had more than 21,000 indexed journals. The matchup of both databases is believed to cover most of the papers that were highly cited in the proposed screening.

The searching strategy used was the following: (TITLE-ABS-KEY (“life cycle”) OR TITLE-ABS-KEY (“life-cycle”) OR TITLE-ABS-KEY (“lifecycle”) AND TITLE-ABS-KEY (“permeable pavement”) OR TITLE-ABS-KEY (“pervious pavement”) OR TITLE-ABS-KEY (“porous pavement”) OR TITLE-ABS-KEY (“permeable concrete”) OR TITLE-ABS-KEY (“pervious concrete”) OR TITLE-ABS-KEY (“porous concrete”) OR TITLE-ABS-KEY (“permeable asphalt”) OR TITLE-ABS-KEY (“pervious asphalt”) OR TITLE-ABS-KEY (“porous asphalt”)). The search protocol was performed on 13/12/2023. It is believed that the search protocol covers the essential material about pervious pavements, from which LCA or LCCA are the main goals of the screening. Figure 1 shows how many papers were obtained in each process step, containing the identification, screening and inclusion criteria. In total, 60 papers were excluded because they appeared in both databases, 45 were excluded because the abstract did not match the study’s goal and purpose, and 15 were excluded because the full text was unavailable.

The first part of the screening process had inclusion criteria based on the eligibility criteria. Papers should show LCA, LCCA or similar methodologies that compare pervious pavements to other systems, such as conventional drainage and paving or other types of GI. Also, other papers, such as review papers that discussed overall improvements in pervious pavements using LCA, were retrieved for analysis. Results were grouped within similar comparison metrics and overall conclusions.

2.2. Data Collection and Variables

Papers were divided into major groups to obtain general conclusions. The three groups of comparison assessed were:

• Life Cycle Assessment comparisons;
• Life Cycle Cost Assessment comparisons;
• Reviews and simple comparisons.

Within each of the groups, four different types of documents were obtained. There are comparisons of pervious pavements with other types of GI, pervious pavements with conventional pavements, comparisons of different types of pavements, and other types of documents such as reviews and analyses. Among these combinations, we discussed each result in each group. Other grouping options, such as surface materials used for the pervious pavements, stand out as exciting topics, being selected as one of the variables in comparison.

As for the variables analysed in each group (LCA, LCCA and reviews), we grouped the specific variables according to the type. For example, in LCCA studies, parameters such as the discount rate were assessed, while the specific impact assessment method was analysed for LCA studies. Phases, materials, and processes used in each study were also assessed. Other specific topics such as software used, impact assessment method, databases, financial parameters, and biased terms were also included in the analysis to explain potential differences. No meta-analysis was further performed, and the researchers compared the possibilities and differences among the results.

As for the questions proposed to each group, four categories were chosen. First, an LCA grouping was performed to understand the general framework that could consider pervious pavement comparisons holistically. Second, the same approach was performed for LCCA studies. Third, the specific details exclusive to some articles, mainly as benefits of pervious pavements, were grouped and discussed. The goal was to understand how specific assessments were made and how they would match the general framework. Lastly, specific questions about the surface materials were asked, such as using asphalt or Portland cement and new novel ideas. A flowchart outlining the method is shown in Figure 2.

3. Results and Discussion

3.1. Regional Productions and Metadata on Selected Documents

One can quickly notice trends in research in the LCAs/LCCAs of pervious pavements. Figure S1 in the Supplementary Data shows the geographic distribution of the 89 selected papers worldwide. China and the USA represent almost half of the publications, with Europe in third place. Europe represents approximately 25% of all the documents selected, with a broad application of the technique. Italy presented the highest number of studies on the continent, with nine papers published. Altogether, China and the USA presented dominance over other potential application sites. For instance, Brazil and Australia included only six papers on the theme, but they represent a considerable research centre for GI, pervious pavements and sustainability assessment. Also, language barriers can be a biased consideration, as the selected documents were only written in English.

The top two citation papers have 279 and 239 citations, respectively, with many links made by documents also contained in the retrieved papers. The most cited paper was written by Chandrappa and Biligiri [31], who studied the state of the art of pervious concrete as a sustainable material regarding design, durability, performance, and other topics. The second paper was written by Montalto et al. [32], who developed a simple model for the cost-effectiveness of GI solutions, creating a base for further studies. Many of the documents that cited both papers conducted further research on the life cycle approach, with cost or environmental impacts, regarding possible solutions and improving decision-making.

Table S1 in the Supplementary Data shows each selected document’s title, DOI, and authors. Figure 3, produced via Litmaps [33], shows how the selected papers have been interconnected and cited in the group. Within the selected studies, one can observe a growth in research with more recent interest and several publications.

Overall, one can divide the four major cited publications into three groups: LCA studies, LCCA studies and reviews or comparisons of “sustainable” materials. The following sections cover the main findings of the publications in the first two groups and the general conclusions obtained. No meta-analysis was performed in the research, although we conducted a few comparisons to understand the similarities and differences better.

3.2. LCA Frameworks of Pervious Pavements

Regarding the LCA frameworks, one can conclude that no standard analysis method exists. Although most authors cite ISO 14040 [34], the standardisation for Life Cycle Assessment frameworks, most works present different approaches regarding the stages, impact assessment methods, databases, and other definitions. This difference is easily explainable, as each publication focuses on a specific topic, although it remains essential that a framework is used to aim at unbiased comparisons.

3.2.1. Analysis Horizon

The “analysis horizon” varies between the different approaches proposed. For example, some of the studies compared different GI with pervious pavements, and thus have a much higher life cycle expectancy than comparisons made only on materials, for example. For these approaches, the horizon ranged from 8 to 50 years, depending on the level of detail, project size, and considered stages. Sousa et al. [35] compared a combination of green technologies to end-of-pipe solutions that aim to store or treat stormwater. The authors used 50 years as a basis for the comparison mainly because of the lifespan of some of the trees used.

Otherwise, Liu et al. [20] compared pervious and dense-graded asphalt through a framework based on LCA and performed an LCCA. The authors defined the design life according to Chinese standards, which is considered twelve years for dense asphalt and nine years for pervious asphalt. However, LCA needs an equal evaluation period for an equivalent number of processes, maintenance, and other specifications. Thus, the authors defined 36 years as the analysis horizon.

Other authors have used intermediary time horizons. For example, Antunes et al. [24] used 20 years to compare the conventional and pervious pavement systems. Wang et al. [36] developed an initial evaluation methodology addressing some of the use stage benefits, such as urban flooding mitigation, water recycling, and water purification. The authors used 12 years as the analysis horizon for a four-lane secondary road in China.

3.2.2. Design Storm Duration and Recurrence Period

Another selected topic is rainfall intensity. Most publications discussed rainfall and its parameters, as GIs are mainly used for stormwater attenuation and peak flow reduction. For example, Antunes et al. [37] and Vaz et al. [21] discuss that Brazil uses Intensity–Duration–Frequency curves. This type of curve has parameters such as the duration of the design storm and recurrence period, where the first is responsible for an estimation of the design storm duration (average time of a peak rainfall), and the recurrence period is responsible for assessing the probability of an event surpassing the rainfall amount.

Other publications followed a similar path of analysis, depending on the country and the goal of the research. However, no standard for the recurrence period was found. Figures range between 2 and 100 years, with the second value representing a much less probable event. For example, Hengen et al. [38] used a recurrence period of two years when comparing traditional stormwater retention systems with other possibilities, which included pervious pavements. Chen and Wang [39], in a study in New Jersey, USA, applied a 100 year recurrence period based on the stormwater BMP manual. Hammes et al. [13] commented that the Brazilian standard recommended a five-year recurrence period for micro-drainage systems used in their study.

The duration of the design rainfall also varies in the selected documents. For instance, a runoff peak reduction study focuses on a fast and high volume of rainfall, usually considering durations of less than 60 min [21,26,37]. Other studies calculated the total volume of stormwater available after infiltration in the pervious pavement system for non-potable purposes. In this type of research, the duration is usually higher, i.e., between 60 min and 24 h. Still, in many of the papers, it is not even commented on, with the only information being the annual rainfall in the case study performed.

Nevertheless, assessing the different rainfall patterns worldwide is crucial considering today’s and future climates. For example, using the IPCC interactive atlas [40], the Maximum 1 day Precipitation (RX1day) parameter ranges between 0 and 100 mm/day. As of 2020, Western and Central Europe presented a median RX1day of 28 mm/day; and such a median was 63 mm for southeastern South America and 58 mm for eastern North America. These values change to 32, 80 and 70 mm, respectively, considering climate change and a future 4 °C warming (SSP5-8.5).

3.2.3. Functional Unit

The functional unit is also an essential parameter in LCA studies, as it defines the deliverable metric that different systems have in common [34]. Authors can define different values in water LCA studies, such as delivered water volume, area of the drainage system, area of rainfall harvest, and the whole system, among other possibilities. Finnveden et al. [41] comment that the functional unit serves as a basis to quantify inputs and outputs, so it is essential for similar comparisons and equal analysis.

Among the possible functional units, the area is the most used. This variable is usually coupled with the amount of rainwater received as a function of rainfall. Examples include road construction or GI areas, often including drainage functions. The second most used functional unit is water volume, which represents a more quantitative result towards the productivity of the drainage/harvesting systems. One cubic meter of stormwater is used as a reference for material quantification in the different types of infrastructure, normalising the impacts. Besides construction area and water volume, other functional units include the volume of pervious concrete, a usual metric in material LCA studies; the volume of pervious pavements, including all layers; the mass of bituminous material; and the volume of GI in stratigraphy.

3.2.4. Databases

Databases are fundamental, as data quality is required for transparency and replicability. For example, the Brazilian standard for LCA [42], which is based on ISO 14040 [34], requires that data are assessed for temporal, geographical, and technological coverage, as well as for accuracy, completeness, representativeness, consistency, reproducibility, and definition of data uncertainty. All the required characteristics aspire to decrease the bias and misconceptions of the analysis.

Of the documents selected, 47 performed LCA frameworks with many different databases. Database selection criteria ranged from location necessities to availability and coverage. The most used was Ecoinvent, a popular LCA database with over 18,000 datasets [43]. Ecoinvent was used in fifteen studies, followed by Gabi and Simapro databases, used in eight and seven selected studies, respectively. Gabi’s database contains approximately 13,500 datasets, including engineering, energy, metals, and plastic, among other materials. Also, other sources, such as the US Life Cycle Inventory and specific company or local databases, were used when relevant.

3.2.5. Software and Life Cycle Impact Assessment

The software does not present differences in results, being a middle tool to organise and perform an LCA. Simapro (15 times), Gabi (5 times), OpenLCA (1 time), Umberto (1 time), and Athena calculator (1 time) were the pieces of software used in the publications. Other publications did not present the software or perform a simpler LCA via spreadsheets and direct calculations. Among the characteristics stated as a reason for choosing the software was the ease of use, databases directly obtained via software and results visualisation.

Another topic in the framework analysis is the Life Cycle Impact Assessment (LCIA) method. LCIA is the LCA phase responsible for defining the magnitude of the potential environmental impacts and organising each impact in a pre-defined category. According to the standardisation of LCIA, one must define the impact categories, categorisation methods and factors. Many LCIA methods address different categories in different approaches, such as global warming, eutrophication, and material depletion.

Among the studies selected, many LCIA methods were used. The most used was ReCiPe, i.e., 17 times, between the 2008 and 2016 versions of the LCIA. In 2017, Huijbregts et al. [44] updated the ReCiPe LCIA method with new characterisation factors, including an approach more representative of the global assessment. The authors proposed seventeen midpoint impact categories and three endpoint categories. Authors have also acknowledged the potential for further improvement in the LCIA method regarding the regionalisation of analysis and the further assessment of future pathways of environmental impact.

IPCC 2007 and Traci, versions 2.0 and 2.1, come in second and third place, with a corresponding number of five and four publications, respectively. In other documents not presented in the publications selected for this integrative review, some authors studied the impact of the LCIA on the results. For example, Cherubini et al. [45] assessed the uncertainty corresponding to the LCIA method and discussed how it might affect the research outcome. For the authors, the LCIA choice presented a significant change in eutrophication, acidification and freshwater ecotoxicity but did not change the final ranking of the comparison made in general conclusions. Bueno et al. [46] also assessed the difference that LCIA presents on an LCA. The authors concluded that midpoint categories presented similar and diverging results in all the five LCIA methods studied, depending on the impact category assessed. Also, for endpoint categories, both LCIA methods of ReCiPe and Impact 2002+ presented different results, with different conclusions for decision-makers.

Although one can conclude that there is yet to be a consensus on which LCIA method to use, it is comprehensive that the same types of categories have been analysed in most of the studies. Among the selected documents that used LCIA, categories such as global warming, acidification, eutrophication, ecotoxicity, material depletion and human toxicity were mainly used.

Table 1. The most analysed LCIA categories and main results about pervious pavements.

Category	Docs.	Main Results
Global warming/Greenhouse gases/Climate change	42	Positive impact on reducing greenhouse gas emissions by enabling water infiltration, mitigating urban heat island effect, and supporting carbon sequestration. The use of pervious pavements also reduces the need for energy-intensive drainage systems. The extent of greenhouse gas reduction depends on pavement type, local conditions, and proper maintenance. However, few studies found significant emissions differences between pervious and traditional pavements.
Eutrophication	25	Positive impact on reducing eutrophication, as pervious pavements allow stormwater to infiltrate the soil, naturally filtering out pollutants and nutrients before reaching water bodies. In the studies, factors such as soil type, proper maintenance, and overall stormwater management practices influence the effectiveness of pervious pavements in reducing eutrophication.
Acidification	23	Most studies indicate that pervious pavements positively impact the reduction of acidification by infiltrating stormwater into the soil, where acids are naturally neutralised. This minimises the acidic load that reaches water bodies and helps recharge groundwater, acting as a natural buffer to reduce soil acidification further.
Ecotoxicity	22	Studies have observed that through the filtration of pollutants such as heavy metals, oils, and other chemicals, pervious pavements reduce the harm to aquatic life and ecosystems, positively reducing ecotoxicity. Effectiveness depends on pavement type, soil composition, local conditions, and proper maintenance.
Resource depletion	20	Some studies indicate that, depending on the scenario, pervious pavement has a more significant impact on the resource depletion category. This is mainly due to the larger number of materials used in the layers, which often have greater thickness than traditional pavement, such as the reservoir layer. However, some authors have incorporated recycled materials, reducing the demand for virgin resources.
Human toxicity	20	By enabling stormwater infiltration into the soil, pervious pavements naturally filter out pollutants, reducing the potential for human exposure to toxic substances. This results in a positive impact on reducing human toxicity. Some researchers incorporated extra filtration layers like activated carbon or geopolymers to enhance pollutant removal further.
Ozone depletion	17	Most studies show that pervious pavements do not directly impact ozone depletion since it is primarily caused by releasing ozone-depleting substances such as chlorofluorocarbons (CFCs). However, they can indirectly reduce harmful chemicals and promote sustainable stormwater management.
Fine particulate formation	16	Studies indicate that pervious pavements effectively act as filters, trapping and retaining fine particles from stormwater. This prevents their release into the air, resulting in improved air quality.
Photochemical oxidant creation	15	Most studies have observed positive impacts in this category, as pervious pavements reduce the number of runoff-carrying pollutants in urban areas. This leads to fewer chemical reactions and less formation of harmful photochemical oxidants in the air.
Energy	14	Studies indicate that pervious pavements have a neutral or slightly positive impact on energy consumption compared to traditional pavements. While they may require more energy during construction, they reduce energy consumption over time. Factors include reduced need for public lighting due to lower reflectivity, decreased demand for air conditioning due to less heat retention, and less reliance on drainage and stormwater pumping systems. The impact may vary depending on local conditions and the type of pavement.
Land use	13	The central positive aspect of this category is the reduction in the need for drainage systems. The reduction leads to a decreased requirement for areas solely dedicated to water drainage, allowing for a more efficient use of urban space. Another point indicated in some studies is the contribution to groundwater recharge.
Ionising radiation	11	Studies have observed an indirect impact in this category, as pervious pavements reduce exposure to ionising radiation by minimising the runoff of contaminated water. This effect is achieved through stormwater filtration, which retains and removes harmful substances before they can reach water bodies.
Water	10	Pervious pavements replenish groundwater and maintain water availability by infiltrating stormwater, reducing evaporation and the need for additional irrigation. Some authors studied pervious pavements with water retention systems, further conserving water and minimising water depletion.

shows the most analysed LCIA categories in the selected articles and the main results obtained in the studies.

3.2.6. System Boundaries

The system boundaries defined among the publications ranged from simple cradle-to-gate analysis to a circular approach considering recycling and reuse. Figure 4 shows the life cycle stages considered in the selected publications. To define the life cycle stage naming and characteristics, one used the standard EN 15804 [47] along with specific details of the benefits. The labels A1 to EX_10 correspond to the product category rules for Type III Environmental Declaration of Construction Products to EN 15804+A1. Five studies presented nine or more LCA stages, assessing different parts, effects and influential details in pervious paving. The holistic investigations were performed by Bhatt et al. [25], Lu et al. [48], Antunes et al. [37], Liu et al. [20] and Hung et al. [49]. Before 2018, no study had assessed the benefits of pervious paving within an LCA scope besides water quality improvement. Further discussion is presented in each of the five studies’ overviews.

Antunes et al. [37] performed an LCA for different scenarios of water supply systems in a Brazilian public building. The authors aimed to analyse how the stormwater harvesting system via pervious pavements performed compared to the usual supply and drainage systems. The systems’ manufacturing, operation, maintenance, and end-of-life effects were considered concerning the LCA boundaries. Bhatt et al. [25] assessed the performance of a few LID installations implemented in a parking lot in Canada. An improvement observed in the previous studies is the construction stage analysis, with fuel consumption and on-site equipment emissions. Also, the authors considered the impact of the quality improvement of the stormwater after infiltration.

Lu et al. [48] investigated the GHG emissions of two pervious and one non-pervious pavements through an LCA framework. The authors included the impacts of the pavement roughness increase in the use stage and the consequent higher fuel consumption. Liu et al. [20] also studied the environmental impacts of pervious asphalt pavement, intending to compare it to dense pavement. Regarding the use stage, the authors aimed to include most of the benefits cited in the literature, considering rolling resistance, pavement albedo, urban heat island mitigation, urban flooding and vehicle detour, stormwater quality improvement, water recharge or reuse and even carbonation reactions.

Finally, Hung et al. [49] presented the newest study, until the screening process, that outlined a holistic approach and an assessment of use stage characteristics. For the use stage, the authors considered the impacts of the pavement–vehicle interaction and rolling resistance, traffic deviation, albedo and urban heat island mitigation, pavement pathologies (deflections) and improved stormwater quality. Hung et al. [49] assessed traffic deviation differently than Liu et al. [20], considering road closeness due to maintenance and repairs. Regarding the thermal effect on buildings, a recent study by Cascone and Leuzzo [50] made a framework for assessing thermal comfort in a square, including GI. Such a comparison may be extended and included in LCA studies.

3.2.7. Framework Suggestion for Future LCA Studies

The different approaches of the selected documents can be gathered through a theoretical boundary system that considers all the different effects in the stages of pervious pavements. Figure 5 shows the boundary system of the union of the boundary systems of the selected documents.

Annex B in the Supplementary Data gathers specific details of all ten benefits, including equations, LCA inventory addition and calculation methods. Studies relevant to each specific benefit were assessed and discussed. Overall, there are different methods for assessing and including the benefits phase in LCA studies; thus, Annex B serves as a collection of new ideas and ways to include the benefits in pervious pavements’ LCAs. It is important to reinforce that new methodologies may arise, and this document serves as a starting point in including specific aspects of the framework.

The other methodological elements should follow the state-of-the-art best practice. For instance, the analysis horizon should comprehend the least common multiple of all assessed systems. Also, it must consider all necessary processes to rehabilitate or reconstruct the systems. As for the design storm parameter, local characteristics, including climate change, must be addressed. Sensitivity and uncertainty assessments may help understand how the design storm influences the LCA and other technical outputs from the pervious pavement use.

The LCA practitioner must select the functional unit, database, software, and LCIA method according to the study’s scope. Local characteristics influence the selection of these parameters and will vary highly. However, a recommendation is set to use the most recent data and to comply with ISO 14040 in the transparency of the selection criteria. The analysis contexts cited in this review may serve as a basis for other similar studies and criteria for LCA applications.

3.3. LCCA Frameworks of Pervious Pavements

Among the selected documents, 45 papers considered the LCCA of pervious pavements and at least one alternative design: GI or conventional drainage/road. LCCA stands as a money-wise life cycle approach, focusing mainly on comparing the monetary gains and costs during the different stages of a product or system. Therefore, it has the same time-referenced assessment and pre-defined restraints as an LCA, with boundary definition, scope selection and quality assurance. Figure 6 shows all the stages considered in the LCCA studies.

Three main types of economic comparisons were performed:

• Pervious pavement with other GI;
• Pervious pavement design options;
• Pervious pavements and non-pervious traditional alternatives.

The following papers serve as an example of each comparison. Yuan et al. [51] assessed the costs of producing pervious and non-pervious concrete bricks. Mei et al. [52] compared different GI strategies for sponge city applications in China. Chen et al. [53] analysed different design options for pervious and non-pervious sidewalk applications.

Most of the conclusions obtained in the selected documents corroborate the idea that pervious pavements present a viable and economically attractive alternative. Twenty-two studies concluded that pervious pavements are economically feasible, while fifteen did not conclude about the feasibility or compare pervious pavements with other alternatives. Eight studies concluded that pervious pavements would be more expensive than a non-pervious alternative. Many papers have also commented on the difficulty of assessing the financial benefit of pervious pavements, such as the ones shown in the theoretical LCA framework.

Among the documents, only six included the stormwater treatment in the LCCA, and thirteen included the beneficial effects of pervious pavements. For example, the study by Zhan and Chui [54] proposed a monetary quantification for the economic, environmental and social benefits of LID alternatives in Hong Kong. Besides the monetary quantification of pervious pavements, the authors included the reduction in stormwater treatment costs and the monetary benefits of social improvement. Between our selection of documents, none of the 45 papers analysed monetary benefits other than water quality valuation. This means that the costs for water treatment and the final water quality are the only monetary benefits considered in the LCCAs. Therefore, there is potential for other monetary gains that could yield an even better financial result for pervious pavements.

Xu et al. [55] performed an LCCA of different coupled green and grey scenarios, considering the differences between the purchaser and real estate monetary fluxes. The costs of GI were higher than the construction costs of a grey alternative, which is considered the traditional option, but overall, the life cycle presented a smaller net cost. For real estate, green alternatives can lead to savings of up to 94%, while for purchasers, the benefit obtained was a reduction of 13% in loan interest. Also, no flood occurred in the simulations, resulting in an economically better resilient and effective system in extreme weather. The final model had 20% of its area modelled considering pervious pavements, presenting an optimal solution for the local conditions.

Many documents also assessed pervious pavements within the GI [27,56,57,58,59], from which pervious pavements usually present an intermediary cost per square meter among the alternatives. Usually, pervious pavements are good performers in runoff reduction and are more expensive than natural alternatives, such as bioretention and swales. However, pervious pavements are less expensive than green roofs.

Lastly, one should also comment on the differences among the parameters for the LCCA. As stated before in LCA studies, the analysis horizon varies widely, depending on the systems, materials, and design choices. Lifespans from 8 to 50 years were used in the LCCA studies. Also, the interest rates, inflation and minimum attractive rate of return vary among the selected documents, depending on the country of assessment, currency and usual costs for GIs. Such parameters influence how one should assess the feasibility of a system and make it harder to compare among different research. As an example, Peterson et al. [60] used a discount rate of 5%, Kourtis et al. [56] used 6%, and Xing et al. [14] used 8% per year. Wang et al. [61] used 2% per year as a discount rate practised in China.

In conclusion, LCCA frameworks vary vastly among different studies. For instance, studies that analyse the economic benefits of using pervious pavements are unusual and usually focus on performing a cradle-to-grave LCCA with the addition of stormwater quality treatment costs. Other effects, such as the benefits in the LCA theoretical framework, were not found in the documents, leading to an unequal comparison between pervious and non-pervious pavements. Figure 7 shows a theoretical framework for LCCA studies based on selected documents. Further framework detailing depends on local parameters, as discussed in this section.

3.4. Surface Materials and Pervious Pavement Design

Comparisons among the different materials are essential to provide engineers and designers with decision-making tools for sustainable choices. In the following sections, we discuss some of the main features of selected surface materials and comment on using by-products and recycled material.

3.4.1. Choice between Asphalt and Concrete Surfaces

Based on the selected documents, 28 analysed pervious pavements made with asphalt, 33 analysed pavements made with concrete (using Portland cement) and 7 compared asphalts with concrete. In some of the studies, the authors did not mention the material used on the surface [52,54,58,62]. Significant differences exist between the material types, including lifespan, permeability, maintenance, construction, and maintenance costs. All these differences can influence both the LCA and the LCCA.

Vares and Pulakka [63] assessed two fully pervious pavements made with asphalt and concrete, considering 30 years of operation. The surfaces responded to 65–80% of the pavement structures’ carbon footprint. The pervious pavement structures showed less carbon footprint than conventional solutions, mainly because it was assumed that the structure did not need conventional drainage systems. In the comparison between asphalt and concrete, the lowest carbon footprint was achieved for the structure made with a concrete surface.

Mccartney [64] assessed using pervious blocks, porous concrete, and porous asphalt pavement systems for pedestrian and occasional light vehicle applications. A cradle-to-grave with a 20-year design life was considered for the LCA. The porous concrete pavement was the optimum solution for reducing life cycle environmental burdens, while porous asphalt exhibited higher impacts. This result is mainly due to the reduced lifespan of the porous asphalt surface layer compared to porous concrete and permeable blocks, in which deconstruction and replacement of the surface layer were incorporated in the LCA.

Asphalt and concrete have specific differences regarding the benefits of the use stage of pervious pavements. The quality of the stormwater infiltrated through the structure is influenced by the type of surface [12,13,65]. Also, the route deviation due to the maintenance of the surface layer is an important matter that should be discussed more in LCA studies [64]. Thus, the maintenance details of different surface layers are also important. Different albedos of asphalt and concrete highly influence the urban heat island and thermal effects, making the concrete material more reflective and beneficial [49]. The surface’s albedo also influences road illumination [66]. Carbonation is also a benefit of the use stage, which is highly influenced by the surface type since it occurs in pervious concrete made with Portland cement and is not observed in asphalt structures [67]. The groundwater recharge, reuse of stormwater, and route deviation due to floods are minor or not influenced by the material of the pervious surface because the infiltration rates of pervious asphalt and concrete are similar.

In general, the studies found in the literature show that permeable concrete pavements have a lower carbon footprint than asphalt pavements [63], which have higher energy consumption [53]. Additionally, the shorter lifespan of asphalt significantly contributes to its more significant potential impacts [32,64]. In conclusion, pervious asphalt and concrete offer unique benefits for stormwater management. Pervious asphalt is suitable for low-traffic areas and provides good permeability, while pervious concrete offers higher structural strength and durability [39]. The choice between the two materials should be based on the specific project requirements, expected traffic loads, maintenance, and desired aesthetic appearance.

3.4.2. Use of By-Products and Recycled Materials

Among the studies selected in this review article, nine analysed the environmental impacts, on an LCA overview, of the replacement of natural aggregates or binders with recycled materials or by-products. Chen et al. [68] evaluated the engineering properties and environmental impacts of pervious concrete with fly ash and blast furnace slag, comparing them to pervious concrete with regular Portland cement. The authors use mass and economic allocation methods to allocate the environmental burdens from primary production associated with fly ash and steel slag (two industry by-products). When no allocation was considered, the mixtures with fly ash or slag had lower energy consumption and GHG emissions than the regular mix, ranging from 14% to 22% reduction. Considering the economic allocation, the fly ash and slag mixtures showed 6–9% lower energy consumption and 11–19% GHG emission reduction. When the mass allocation approach was considered, the energy and environmental impacts of fly ash and slag dramatically increased, which means that fly ash and slag caused more energy and environmental burdens than Portland cement. The results show the great importance of allocation methods.

Chen and Wang [39] also analysed the use of fly ash in pervious concrete pavements. The replacement ratio of fly ash ranged from 15% to 50%. The authors concluded that fly ash could cause a greater or lesser environmental impact depending on mechanical properties and the required surface layer thickness to achieve equivalent structural performance. The results were similar to those of Chen et al. [68] regarding the allocation method.

Electric Arc Furnace (EAF) slag was also assessed as a component in the pervious surface mixtures. Anastasiou et al. [69] assessed the use of EAF slag in pervious concrete paving blocks compared to concrete with natural limestone aggregates (current construction practice). In a cradle-to-gate overview, using EAF slag reduced CO₂ emissions by 13.8% (from 19.5 to 16.8 kg CO₂ eq/m²) and costs by 9.8% (from €2.55/m² to €2.30/m²). Chen et al. [70] also studied porous asphalt courses using steel slag as an existing pavement surface. The results demonstrated the cost-saving of porous asphalt with steel slag in both low and medium price ranges. According to statistical analysis, the mixture had a 78% and 92% chance of being more cost-effective than the regular open-graded friction course and porous asphalt with natural aggregates.

Other authors studied the effects of replacing natural aggregates with recycled concrete aggregates (RCA) or reclaimed asphalt pavement (RAP) in the production of pervious pavements. For example, Paula Junior et al. [71] investigated the effect of replacing 100% of natural aggregates with RCA in pervious concrete. The RCA production presented a lower potential environmental impact when compared to the production of natural aggregates. However, the authors state that the potential environmental impacts can worsen when RCAs’ transportation distance exceeds the gravel’s. Yap et al. [72] assessed the GHG emissions of pervious concrete made with different amounts of RCA. The CO₂ emission of the 100% RCA mix was 24% lower than the control mix. However, increasing RCA content reduced the compressive strengths for RCA replacement above 20%. The conclusion is that mixes developed with effective RCA content are appropriate for pedestrian trials and walkways, reducing CO₂ emissions. Other recent studies also show that recycled content decreases environmental impact [73].

Bizarro et al. [74] analysed a cradle-to-gate carbon footprint of porous asphalt mixtures with increasing RAP content. The results show a potential carbon footprint reduction between 55% and 64% for asphalt containing 93% RAP and produced at 105 °C compared to the regular mixture (0% RAP) produced at 175 °C. Pascale et al. [75] assessed different scenarios of pervious pavements with virgin aggregates, EAF, and EAF with RAP. As one of the conclusions, the authors found that both alternative scenarios provided better mechanical properties. However, there is an interest in using rejuvenating agents to limit the stiffening in high-content RAP mixtures. As for the environmental assessment, both EAF and RAP improved the LCA results.

Other more specific examples include Wu et al. [76] assessing ecological concrete with plant-compatible properties; Ibrahim et al. [77] analysing the CO₂ emissions of palm oil clinker aggregate as a replacement for the natural aggregates in producing pervious concrete; Huang and Wang [78] assessing the environmental aspects of a pervious pavement made with geopolymer concrete under three conditions: the addition of metakaolin, fly ash, and pervious concrete only (baseline); and El-Hassan and Kianmehr [79] assessing the carbon footprint of pervious concrete pavement incorporating ground-granulated blast furnace slag. All the results of this subsection show the great potential of by-products and recycled materials in alleviating the impacts caused by pervious pavement constructions. Attention must be given to the allocation methods used and the mechanical properties of the pavement.

4. Hotspots and Decision-Making

LCA and LCCA are exciting tools with many application pathways in pervious pavements. An essential part of LCA is determining which stages of a system’s life cycle cause the most significant environmental impacts. In this way, it is possible to establish improvements in the so-called hotspots (i.e., processes with more significant environmental damage). In the studies reviewed, extracting raw materials, manufacturing, and transporting products to the construction site (cradle-to-gate) were responsible for 50–100% of GWP impact. The high impact of the initial stage is also noted for most categories, mainly due to the large number of materials and equipment required to implement the pervious paving system. Using a high volume of material generates many extractions, impacting categories related to resource depletion.

The use and maintenance stages accounted for 1–50% of impacts. Such a significant variation in the use stage is mainly due to the different horizon analysis, lifespan and aspects considered during the system’s operation. According to Wang et al. [80], extending the lifespan of the pervious pavement system analysed in their study from 25 years to 40 years could lead to an annual reduction of 30% in life cycle GHG emissions. This reduction is mainly due to a decrease in effective annual material use. Therefore, LCA studies of pervious pavements must be standardised to avoid heterogeneity in the results obtained.

Maintenance activities, such as cleaning the pavement (generally two to four times a year) or pavement repairs also contribute to the impacts. The end-of-life stage also contributes to the environmental burdens, accounting for 0–12%. Most of the studies consider the simple disposal of materials in landfills as the destination of the system, generating gas emissions without capture and treatment. One solution to mitigate the end-of-life impacts would be to consider the recovery, reusing or recycling of the ended-lifespan materials in other systems.

Attention must also be given to the comparisons of LCAs. Some authors compared the life cycle of different GIs and concluded that pervious pavements yielded the highest GHG emissions among the options. Such higher impact is usually caused by the production of construction materials (primarily concrete manufacturing) and intensive installation and maintenance processes. However, using similar functions is critical to comparing pervious pavements with other GIs. For example, for a driveway, parking lot or sidewalk, a bioretention base (a green roof or a grass swale) would not be adequate for the necessary function (bearing loads of vehicles, bicycles, or people). Thus, considering the wide range of GI functions, comparing systems with significant differences is sometimes unfair.

Other topics, such as Social LCA (SLCA) and aesthetics, can be used as parameters for decision-making. A SLCA is responsible for assessing the social impacts of a system, such as how employment and community factors are affected by a technical decision. Aesthetics can also be an essential factor. As stated in the SUDS manual [81], one should and could design for amenities, including urban environments that are attractive, pleasant and useful. These topics should be assessed in urban and building plans, with optimal allocation of pervious pavements and other GIs, considering local characteristics and space use. Nevertheless, this synergy and optimisation should not be neglected in an LCA, as it is an essential step towards better stormwater management and resilient cities.

Thus, integrating a LCA, LCCA, SLCA, or other types of studies is interesting. This type of assessment has been performed in recent studies, mainly using weighting mathematical processes, such as the Analytic Hierarchy Process (AHP). AHP takes part in a discipline focused on aiding decision-making in problems with more than one dimension, called Multiple Criteria Decision Making (MCDM). The AHP method uses weight factors, decided by specialists in each area, to select the best alternative. In our example, all the different life cycle results (LCA, LCCA, SLCA) could be shown to a panel of specialists who weigh how the different methods affect the decision-making process. One may debate whether a specific impact is valuable or if the amenity or the aesthetics are worth it. Other MCDM methods are also found in the literature, such as TOPSIS, ELECTRE and fuzzy-MCDM alternatives [82,83].

Only three out of the selected studies performed AHP in overall comparison. Joshi et al. [84] used AHP to select the best site to implement pervious pavements concerning the imperviousness, land use, slope, elevation and end-point combined sewer overflow. Xu et al. [55] also used AHP as a comparison technique, including the life cycle cost and some benefits of pervious pavements. Yao et al. [58] used the AHP and regret decision theory to analyse multiple GI under hydrological and cost parameters. Future studies may gather AHP details with the frameworks proposed herein to provide broader comparisons, including pervious pavements. Also, some studies [59,61] used the NSGA-II algorithm to find optimal Pareto solutions under hydrological, economic and environmental parameters (which include LCA elements).

5. Conclusions

Through an integrative review, this paper assessed the state of the art of LCA and LCCA documents of pervious pavement designs and applications. The necessity of assessing the state of the art arose from the lack of a standard framework proposition. Therefore, the study’s goal was to present a general LCA/LCCA configuration that contains the pervious pavement’s potential benefits and present the conclusions obtained from the literature. Also, trends in the research were observed, including novel ideas for assessment, different materials and sustainable practices.

As the main deliverable, this paper produced two theoretical frameworks, one for LCA and one for LCCA, containing all major points within the already produced research. One can use such frameworks as a basis of assessment, producing more reliable studies with a more unbiased comparison that considers the plurality of functions affected by pervious pavements. Also, future research may assess each feature for a more reliable valuation of the benefits or environmental burdens.

Other conclusions obtained in the integrative review are listed below:

• LCAs and LCCAs of pervious pavements identify hotspots and offer opportunities for environmental and cost-benefit improvements. There is an increasing interest in using LCA and LCCA to obtain optimal urban layouts.
• Raw material extraction, manufacturing, and transport contribute to significant environmental burdens in a cradle-to-gate LCA of pervious pavements. Optimising materials and designing pervious pavements may diminish the environmental impacts.
• Use phase and maintenance stages vary in their contributions to environmental impacts due to different lifespans and operational considerations.
• End-of-life considerations contribute to environmental burdens and should not be disregarded in LCA studies. Future studies should address this phase and consider the recommendations of this review and other examples from the literature.
• Comparisons of pervious pavements with other GIs should consider different functions and avoid unfair environmental impact assessments. The benefits shown in this study are a starter for complex elements that should be regarded.
• The boundaries of LCAs and LCCAs should be expanded to include additional factors such as noise reduction and social or aesthetic parameters. A Social LCA (SLCA) may also be used as another comparison in further studies.
• Integrating multiple parameters in LCAs and LCCAs facilitates decision-making for stormwater management and resilient cities. However, the plurality of MCDM methods hinders the comparison of metrics and parameters. Future studies should address decision-making and pervious pavements, considering the different MCDM alternatives.
• Further benefits and studies should be analysed and incorporated to improve the frameworks of this paper. Understanding all synergies in pervious pavements still needs further research; thus, it is a work in progress.

The main recommendation to LCA practitioners is to consider all functions and benefits addressed under pervious pavements and GI solutions. The frameworks and considerations of the literature were assessed in this review and serve as inspiration. However, one is reminded that transparency and science-based principles are foundation points for ISO 14040 and should always be considered in LCA studies. Thus, by correctly stating all the LCA methodological considerations and comparing all functions provided by pavements, one may unbiasedly prove the sustainability of the pervious alternatives.