Moisture brings durability and air quality problems with it, and myriad green products are designed to manage it and keep it out. Given the variety of products available, we look for those that meet key performance standards and that make sense in a whole building assembly—such as vapor-permeable weather-resistive barriers that not only prevent moisture from entering the building envelope but also allow drying when the envelope gets wet.
Proglaze Engineered Transition Assembly
These products are environmentally attractive because they need to be replaced less frequently or their maintenance has very low impact, both of which can reduce costs as well as environmental impact.
Robust answers on typical service life of products can be hard to come by, however. In GreenSpec we reserve this criterion for products where the material is clearly more durable than alternatives, such as an exceptionally traffic-resistant polyurethane floor finish. We refer to standardized tests for durability when they are available and appropriate.
We also consider “appropriate durability”: long life is more important in a building envelope than in interior finish materials that will be replaced for aesthetic reasons. Here, reduced maintenance can be particularly important. An example is resilient flooring that doesn’t require regular waxing: an unnecessary use of resources and a health hazard.
Before specifying efficient heating and cooling equipment, it’s important to do what we can to reduce heating and cooling loads. Insulation is one of the key products to consider here, but because there are so many insulation products on the market, we look for additional benefits. Examples include cellulose insulation with recycled content, mineral wool insulation with no flame retardants, and fiberglass insulation with no formaldehyde binders. Other products in this area are high-performance windows and glazings, products that contribute to building airtight envelopes, products that reduce thermal bridging, and window-retrofit products.
With products in this area under constant development, we are always refining our approach. For example, as we have learned about insulation products with hazardous flame retardants and blowing agents that have high global warming potential, we have removed those products from GreenSpec, pending manufacturing changes. We encourage building professionals to pressure manufacturers for those changes through specification language and purchasing decisions.
Just how low the VOC level needs to be for a given product to qualify for inclusion in GreenSpec depends on the product category. For most products, we require certification to California’s health-based emissions standard, CDPH Std Method v1.1 standard (also referred to as California Section 01350), which tests a product’s resultant VOC concentrations in the space after a given period of time. For wet-applied products like paints, caulks, and adhesives, we still also look for VOC content instead of, or in addition to, verified low emissions; this is because emissions testing doesn’t adequately test initial offgassing, and VOC content is currently the only widely available proxy.
Tremco's Proglaze Engineered Transition Assembly (ETA) is a complete system comprised of sealants, membranes, primers, and flashings (all its own products) and insulation and sheathings (from other manufacturers) designed to integrate well together. These aluminum and silicone components are designed to bridge between windows and other wall openings and another continuous air barrier. The system is designed to last 50–100 years. Tremco works with design firms to ensure proper use of the ETA and offers an industry-first warranty on the performance of the air and water barrier. Third-party testing shows that air leakage through the assembly is 0.004 cfm/ft2 and water vapor transmission is 2.59 perms. The system has 0 g/l VOC content and all components are Greenguard Children & Schools certified for low emissions. Tremco has eliminated phthalates from all elements in the ETA. The aluminum components are 60% recycled, 55% of which is pre-consumer.
An air barrier is made up of materials and components that are integrated into a system to restrict air flow through the building envelope.
Any material that has an air permeance equal to or less than 0.02L(s•m2) @ 75Pa (equal to the air permeance of drywall) can form part of an air barrier system. However, just having air barrier materials in a building does not create an airtight building. These materials and components must be joined into air barrier assemblies, which are then tied together with additional air barrier components to create a complete air barrier system.
According to the Air Barrier Association of America (ABAA), air barrier materials must be integrated to create assemblies with maximum air leakage no more than 0.20 L(s•m2) @ 75 Pa (per ASTM E2357). Note that the air leakage rate for enclosures is about 10 times greater than the air leakage standard for materials.
Air barriers may or may not also act as a vapor retarder or weather barrier. The air barrier can be on the exterior, the interior of the assembly, or both. Air barrier products listed here are sheet or fluid-applied products designed to limit air infiltration through discontinuities in the building envelope while meeting the ABAA standard.
GreenSpec lists products here that contribute to an air barrier assembly by providing key connections where two materials or systems meeting, or filling holes at common weak points in an air barrier assembly. For more products that contribute to air barriers, see specific sections such as Foamed-in-Place Insulation and Weather Barriers.
Sheet waterproofing is usually made from rubberized asphalt, isobutylene-isoprene rubber, or EPDM. Products listed here are manufactured using alternative materials, such as the more environmentally benign HDPE.
The driving environmental attributes of a liquid sealant are durability and chemical constituency.
The durability of liquid sealants is a function of their appropriate field application and designed service life. After nearly 10 years of research and development, the National Institute of Standards and Technology (NIST) is currently spearheading a true field service life prediction ASTM standard for liquid sealants: ASTM C1589 (being reballoted to include the new field test developed by NIST). GreenSpec is monitoring the development of that standard and plans to adopt it as one of its criteria for sealants.
Currently, GreenSpec lists caulk joint sealants with low VOCs, reduced chemicals of concern compared with industry norms, and other green attributes. GreenSpec also focuses on proper installation and performance: for more on this, see our GreenSpec Insights blog series.
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