LCA results & interpretation Exterior Dimension Stone Cladding
Scope and summary
- Cradle to gate
- Cradle to gate with options
- Cradle to grave
Product description
Stone cladding is applied to a building exterior to separate it from the natural environment and provide an outer layer to the building. It not only provides a control to weather elements but also a durable, aesthetically pleasing building appearance. Natural stone makes up 100% of the total mass of natural stone cladding, and the different stone types included in this study are granite, marble, quartzite, limestone, and sandstone. It is used in commercial, residential, and public sector buildings.
Functional unit
The functional unit is one square meter of installed natural stone cladding for a service life of 75 years. The natural stone cladding product system is an industry-average product, i.e., the product profile represents the weighted average of NSI’s natural stone cladding based on NSI’s industry-average quarrying of stone specific to cladding and also includes the industry-average production of cladding. The product system in this study also includes the ancillary materials used in the installation of the product – mortar and masonry connectors. Materials needed to meet functional unit are:
Natural stone - 83.28 kg per m2
Mortar - 4.88 kg per m2
Masonry connectors - 0.62 kg per m2
Water - 1.00 liters per m2
Manufacturing data
The data for all stone products were collected from NSI members covering a period of two years: January 2019 to December 2020. Data for quarry operations were collected from twelve NSI quarry members covering 36 quarries across North America. The participant quarries in this study are Coldspring, Delgado Stone Distributors, Freshwater Stone, Independent Limestone Company, Polycor, Quality Stone Corporation, Royal Bedrock Inc., Russell Stone Products, Stony Creek Quarry, Vermont Quarries Corporation, and Vetter Stone Company.
After the stone is extracted from the quarry, it goes to a processing facility. Stone processor operations data were collected from six NSI member processors covering 17 facilities across North America. Cladding products were produced at all facilities which submitted data but one processor. The participant processors in this study producing cladding are Delgado Stone Distributors, Polycor, Russell Stone Products, Vetter Stone Company, and Continental Cut Stone. NSI resources and other literature data were used to develop estimates or assumptions for other upstream or downstream activities where necessary.
Industry-wide results calculation methodology
Based on data provided by the participating natural stone processors, limestone and granite represented much of natural stone cladding at 56.72% and 36.18%, respectively. Marble cladding covered 0.13% of the market share, while the rest (6.97%) was from other natural stones (including quartzite and sandstone).
For quarry data, an average inventory per kg of stone quarried for each stone category (granite, limestone, marble, and other natural stone) was developed, and later a weighted inventory per kg of stone quarried was generated using the quarry production share of each stone type among the participant quarries. After that, the inventory per kg of stone quarrying specific to stone cladding was developed using the market distribution of natural stone cladding by stone type as collected from participant stone processing facilities (56.72% limestone, 36.18% granite, 0.13% marble, and 6.97% other natural stone).
Similarly, the inventory for one square meter of processed stone cladding was developed. An average inventory per square meter of stone processed for each stone category (granite, limestone, marble, and other natural stone) was developed, and later a weighted inventory per square meter of stone processed was generated using the production share of each stone type using the stone processing share of each stone type among the participant processors. After that, the inventory per square meter of stone processing specific to cladding was developed using the market distribution of natural stone cladding (56.72% limestone, 36.18% granite, 0.13% marble, and 6.97% other natural stone).
Data quality
Primary data was collected for a time period of two years, which represents typical operations of quarry and processors across North America. Inventory data is considered to have a good precision and provide a representative depiction of the industry average. Data is also considered to be complete, as no know flows are deliberately excluded from this analysis other than those defined to be outside of the system boundary.
What’s causing the greatest impacts
All life cycle stages
For the natural stone cladding product, the cradle-to-gate stage (A1-A3) dominates the results for all impact categories. This study assessed a multitude of inventory and environmental indicators. In addition to the six major impact categories (global warming potential, ozone depletion, acidification, smog, eutrophication, and fossil fuel depletion), additional impact categories have also been included. These six impact categories are globally deemed mature enough to be included in Type III environmental declarations. Other categories are being developed and defined, and LCA should continue making advances in their development. However, the EPD users shall not use additional measures for comparative purposes. LCIA results are relative expressions and do not predict impacts on category endpoints, the exceeding of thresholds, safety margins or risks.
Overall results are consistent with expectations for stone cladding's life cycles, with most of the impacts being generated during cradle-to-gate stages, as cladding is not associated with energy consumption during its use stage.
The primary finding, across the environmental indicators, was that the cradle-to-gate stage dominates the impacts mainly due to the energy consumed at the quarries and processing plants. The processor operations (A3) stage is the highest contributor to most of the impact categories followed by the quarry operations (A1). In some of the impact categories, quarry operations make the highest contribution, followed by the processor operations stage. The cradle-to-gate stage (A1-A3) contributes to ~65% of the total impacts in all impact categories except for ozone depletion. The transportation of stone from quarries to processing plants, transportation of cladding from processing plants to the installation sites, and the use of mortar during installation also generate significant impacts in the overall life cycle impacts of stone cladding.
Quarry operations and transport to processors
Impacts generated at quarries (A1) are mainly because of the use of grid electricity and fuels in the quarries. Other material inputs generate little impact in comparison to the electricity and fuel consumed. The transportation of stone from quarries to processing plants also generates significant impacts in numerous impact categories.
Processor operations and transport to building sites
Manufacturing operations at processing plants make up the greatest share of all impact categories except for ozone depletion. Energy consumed at processors (both electricity and fuels) is responsible for the majority of impacts, while other material inputs have an insignificant contribution. The transportation of stone cladding manufactured in processor plants to the building sites also makes a significant impact on the overall life cycle impacts of natural stone cladding.
Other life cycle stages
Use of mortar during installation also generates significant impacts in the overall life cycle impacts of stone cladding. Under normal operating conditions, stone cladding will not require any cleaning. Due to the nature of natural stone, it is anticipated that the stone cladding products will last for the lifetime of the building. The reference service life (RSL) thus meets an ESL of 75 years, and cladding will need no replacements during its service life. The use stage, thus, is not relevant. End-of-life stages have lower contributions to the total life cycle impacts.
Variation analysis
A variation analysis was performed to study the environmental impacts variation between natural stone cladding from different stone types. Results were generated for both quarry operations and processor operations specific to various stone types (granite, limestone, marble, and other natural stone). One of the major parameters that influences the results is the amount of stone that needs to be quarried to produce one square meter of stone cladding, which varies per stone type.
The variation between weighted average, minimum, and maximum LCIA results is greater than 20% for all the impact categories. This is attributed to varying quarry and processor operations used by different quarries and processors.
Sensitivity analysis
Based on NSI's expert judgement, it was assumed that energy consumed for the processing of a square meter of stone cladding matches the average energy consumed for processing of different stone products. A sensitivity analysis was performed to check the robustness of the results when the energy consumed during processing is varied by +/-20% from the estimate used in this study. The resulting variation in the total life cycle impacts is less than 10%, implying that the system is not sensitive to this assumed value.
How we're making it greener
The natural stone industry is committed to making sure our inherently eco-friendly building material is produced efficiently and responsibly. Through the Natural Stone Sustainability Standard we have defined metrics for responsible production in the following categories:
- Energy
- Water
- Chemicals
- Land reclamation & adaptive reuse
- Site management
- Transportation
- Social governance
- Human health & safety
- Excess process materials
- Solid waste
- Innovation
Companies have the opportunity to third-party verify compliance with these metrics. As the industry’s leader in education, the Natural Stone Institute is also striving to build awareness about best practices for sustainability among all quarriers and fabricators globally.
LCA results
| Life cycle stage | Raw material Supply and transport | Manufacturing | Construction | Use | End of life |
|
Information modules: Included (X) | Excluded* (MND) |
A1 Quarry operations | A3 Processor operations | A4 Stone transport to building sites | B1 Use | C1 Deconstruction |
| A2 Transport to processors | A5 Installation | B2 Maintenance | C2 Waste Transport | ||
| B3 Repair | C3 Waste processing | ||||
| B4 Replacement | C4 Disposal | ||||
| B5 Refurbishment | |||||
| B6 Operational energy use | |||||
| B7 Operational water use | |||||
 |
 |
 |
 |
SM Single Score
Learn about SM Single Score results| Impacts of 1 square meter of installed natural stone cladding | 9.56E-01 mPts | 1.51E+00 mPts | 3.72E-01 mPts | 0 mPts | 5.49E-02 mPts |
| Materials or processes contributing >20% to total impacts in each life cycle stage | Energy consumed during stone quarrying (electricity and fuels). | Energy consumed during stone processing (electricity and fuels). | Truck transportation and use of ancillary materials (mainly mortar) for installation.. | NA | Waste transport to end of life centers. |
TRACI v2.1 results per functional unit
| Life cycle stage | A1-A2 Quarry operations and transport |
A3 Processor operations |
A4-A5 Stone transport to building sites |
B1-B7 Use |
C1-C4 End-of-life |
Ecological damage
Human health damage
Additional environmental information
| Impact category | Unit | |||||
| Fossil fuel depletion | MJ surplus Mega Joule, lower heating value Fossil fuel depletion is the surplus energy to extract minerals and fossil fuels. |
1.57E+01 | 1.72E+01 | 1.19E+01 | 0 | 2.62E+00 |
| Ecotoxicity | CTUe Comparative Toxic Units of Ecotoxicity Ecotoxicity causes negative impacts to ecological receptors and, indirectly, to human receptors through the impacts to the ecosystem. |
46.5 % | 41.4 % | 10.1 % | 0 % | 2.0 |
References
LCA Background Report
NSI Natural Stone Cladding LCA Background Report (public version), NSI 2022; SimaPro Analyst 9.4; Ecoinvent 3.4 and US ecoinvent (US -EI 2.2) database; TRACI 2.1
ISO 21930:2017 serves as the core PCR along UL Part A.
ULE PCR Part A: Life Cycle Assessment Calculation Rules and Report Requirements v3.2
December, 2018. Technical Advisory Panel members reviewed and provided feedback on content written by UL Environment and USGBC. Past and present members of the Technical Advisory Panel are listed in the PCR.
ULE PCR Part B: Cladding Product Systems EPD requirements v2.0
April 2021. PCR review conducted by: Jim Mellentine (Thrive ESG); Christopher White (NIST), Ph.D.; and Philip S. Moser, P.E.(MA) (Simpson Gumpertz & Heger).
UL Environment General Program Instructions v2.5, March 2021 (available upon request)
ISO 14025, “Sustainability in buildings and civil engineering works -- Core rules for environmental product declarations of construction products and services”
Download PDF SM Transparency Report, which includes the additional EPD content required by the UL Environment PCR.
SM Transparency Reports (TR) are ISO 14025 Type III environmental declarations (EPD) that enable purchasers and users to compare the potential environmental performance of products on a life cycle basis. Environmental declarations from different programs (ISO 14025) may not be comparable. Comparison of the environmental performance of Cladding Product Systems using EPD information shall be based on the product’s use and impacts at the building level, and therefore EPDs may not be used for comparability purposes when not considering the building energy use phase. Full conformance with the PCR for stone cladding allows EPD comparability only when all stages of a life cycle have been considered, when they comply with all referenced standards, use the same sub-category PCR, and use equivalent scenarios with respect to construction works. However, variations and deviations are possible.
Example of variations: Different LCA software and background LCI datasets may lead to differences results for upstream or downstream of the life cycle stages declared
SM Transparency Report (EPD) 