SPONSOR CPD PROGRAMME Assessing phenolic foam ducts for reduced embodied and operational carbon Continuing professional development (CPD) is the regular maintenance, improvement and broadening of your knowledge and skills, to maintain professional competence. It is a requirement of CIBSE and other professional bodies. This Journal CPD programme can be used to meet your CPD requirements. Study the module and answer the questions on the final page. Each successfully completed module is equivalent to 1.5 hours of CPD. Modules are also available at www.cibsejournal.com/cpd This module considers the factors that determine whether it is appropriate to employ commercial phenolic foam ductwork systems Ductwork systems that are used to distribute air in ventilation systems are, in most cases, practically a lifetime investment for a building, so decisions made at the time of the ductwork design will directly impact the buildings life-cycle carbon impact and lifetime financial cost. Historically, the majority of ductwork distribution systems in commercial buildings have been constructed of galvanised steel, providing a robust, long-lasting, and effective solution. Alternative materials have increasingly been applied in appropriate applications, which in recent years have included ductwork made of faced phenolic foam insulation boards. This CPD will explore some of the significant factors that determine the appropriateness of employing phenolic foam ductwork systems in commercial buildings. Much of the change to traditional ductwork practices is being driven by the requirement to reduce the environmental impact of building services systems. CIBSE Guide Part L 2020 Sustainability discusses the two types of CO2 equivalent emissions associated with buildings: the embodied emissions of the products that make up the building, and the operational emissions that are mostly associated with the energy consumption of the day-to-day use of the building. The stages that are combined to provide a standardised measure of embodied carbon, as defined in BS EN 15978,1 are illustrated in Figure 1. CIBSE TM 652 notes that a large proportion of building services products carbon emissions is associated with extraction, transport and processing of materials, and the energy consumption used in the manufacture of the products (stages A1-A3), so the majority of the embodied carbon in mechanical services will be directly related to the product stage. Environmental product declarations (EPDs) are a standardised way of expressing embodied carbon and other environmental impacts throughout the life-cycle stages of a product. TM 65 notes that an EPD should be considered as the most reliable source of information about the environmental impacts of a product. In the discussion of the assessment methodologies, it is noted that maintenance, repair, deconstruction and transport to waste processing are often not included due to lack of data a challenge that affects current practical assessments and comparisons of products and the ability to determine an EPD, since that includes an assessment of the end of life stage (C1 to C4) and reuse, recovery and recycling (D). As noted by TM 65, very few manufacturers of building services products offer EPDs, mainly because of the complexity of mechanical, electrical and plumbing (MEP) products and their supply chain, but also because incentives from the market and regulation are missing. TM 65 provides basic and mid-level methodologies that are complementary to the EPD in order to be able to assess and compare environmental impact realistically with reduced reliance on stages C and no inclusion of stage D. As described by Densley Tingley et al in their very useful paper,3 phenolic foam has a closed cell structure that resists moisture and water vapour ingress, so providing a suitable core material for insulation boards (which are used in forming ductwork), with a low thermal conductivity of 0.020W.m-1K-1 (compared with expanded polystyrene (EPS) at 0.038W.m-1K-1, mineral wool at 0.036W.m-1K-1 and polyisocyanurate (PIR) at 0.027W.m-1K-1). In further work4 by Densley Tingley et al, they www.cibsejournal.com February 2022 49 CIBSE Feb22 pp49-52 CPD 191.indd 49 28/01/2022 16:25