{"id":208125,"date":"2024-02-12T12:00:15","date_gmt":"2024-02-12T17:00:15","guid":{"rendered":"https:\/\/www.constructionspecifier.com\/?p=208125"},"modified":"2024-02-09T15:58:27","modified_gmt":"2024-02-09T20:58:27","slug":"analyzing-impact-of-building-materials-to-address-climate-change","status":"publish","type":"post","link":"https:\/\/www.constructionspecifier.com\/analyzing-impact-of-building-materials-to-address-climate-change\/","title":{"rendered":"Analyzing impact of building materials to address climate change"},"content":{"rendered":"
\"Photos<\/a>
Photos courtesy Cunningham Baron <\/em><\/span><\/figcaption><\/figure>\n

By Bill Bellico<\/strong><\/p>\n

The construction industry is equipped with many tools to further its mission of fostering sustainable building practices. Assessing the carbon footprint of a building is one major tool aimed at addressing concerns regarding climate change.<\/p>\n

Embodied carbon has emerged as a critical consideration in measuring the carbon footprint of building materials. However, this is only a part of a material\u2019s total carbon footprint. The material\u2019s contribution to reducing operational carbon must also be considered.<\/p>\n

To fully understand the carbon dioxide (CO2) emissions associated with a particular material requires considering the CO2 generated during the material\u2019s entire lifecycle, as outlined below. It is important to understand the differences between cradle-to-gate versus cradle-to-grave lifecycle calculations. Some might be surprised to hear that the one more commonly used only gives a partial picture of a material\u2019s true carbon footprint. Whereas embodied carbon accounts for the CO2 emissions during only the cradle-to-gate portion of the material\u2019s lifecycle, operational carbon measures a material\u2019s effect on reducing CO2 emissions during the operation of the building, which coincides with the use stage of a full cradle-to-grave lifecycle assessment.<\/p>\n

Reducing the carbon footprint of construction should focus on building products that are long-lasting and resilient, can reduce CO2 emitted during the operation of the building, and are made or partially made of recycled content. A case in point is roofing. By understanding all the contributions to the total carbon footprint of various roofing material choices, construction specifiers are equipped with valuable knowledge to make informed decisions that align with carbon reduction goals while ensuring optimal roofing performance and longevity.<\/p>\n

Here is information that can help specifiers navigate the complex landscape of sustainable building and foster a greener built environment through conscious material selection and design decision-making.<\/p>\n

What is embodied carbon? <\/strong><\/p>\n

Embodied carbon refers to the total amount of CO2 emitted during the cradle-to-gate portion of the lifecycle of tangible goods of a particular building material. It encompasses the CO2 created from gathering raw materials, transporting them to the site of manufacture, as well as manufacturing. CO2 is generated in all manufacturing processes, including all roofing materials such as polyvinyl chloride (PVC) membranes.<\/p>\n

<\/p>\n

\"Embodied<\/a>
Embodied carbon refers to the total amount of carbon dioxide (CO2) emissions released during a portion \u2028of the lifecycle of tangible goods.<\/span><\/figcaption><\/figure>\n

However, the energy used by a building after it is constructed also contributes to carbon emissions. This is called operational carbon. Taking into account embodied carbon, the material\u2019s contribution to reducing operational carbon, and the end-of-life stage is the most accurate way to get a full picture of a building product\u2019s complete carbon footprint.<\/p>\n

EPDs: An incomplete picture <\/strong><\/p>\n

To manage carbon, most building and construction experts make decisions based on disclosures made through lifecycle assessments (LCAs) and related International Organization for Standardization (ISO) Type III ecolabels such as Environmental Product Declarations (EPDs). These documents use international standards (e.g.<\/em> ISO 14040 and ISO 14044) developed by ISO Technical Committee 207 on environmental management. LCAs collect environmental information throughout a product\u2019s lifecycle\u2014from raw material extraction to its final use and ultimately to its disposal. Since these documents are often lengthy, they usually include a summary page of the results. EPDs are one such standardized summary of an LCA.<\/p>\n

\"Operational<\/a>
Operational carbon refers to the energy used by a building after it is constructed.<\/span><\/figcaption><\/figure>\n

An EPD for a given material is created within boundaries described in a product category rule (PCR), as defined by ASTM. The PCR for single-ply roofing membranes, such as PVC, permits the use of information from either extraction, transport to factory, and manufacture, called a declared unit (\u201ccradle-to-gate\u201d) or all of that plus service life and recyclability, called a functional unit (\u201ccradle-to-grave\u201d).<\/p>\n

Since there is no requirement in the PCR to include the functional unit in their EPDs, many manufacturers elect to use the declared unit, the cradle-to-gate method, to derive content for their EPDs. When there are tools in the marketplace pulling portions of the cradle-to-gate modules, it is important for users to understand the limitations on comparability when important product attributes, such as durability and recyclability, are not being considered. The absence of these factors may result in fewer sustainable product selections. Purchasers should consider this when making purchasing decisions.<\/p>\n

Most, if not all, PCRs for construction materials draw from ISO 21930: 2017. For example, the PCR for single ply roofing membranes notes in section 5.5, comparability of EPDs for construction products:<\/p>\n