Sustainable Design

Approaching Decarbonization Through Forward-Thinking Strategies

by Justin Koscher, President of the Polyisocyanurate Insulation Manufacturers Association

The design industry is rapidly adopting strategies to embrace high-impact energy and climate policies, design practices, and building materials.  For example, in a forward-thinking move to reduce carbon emissions, California became the first state to make embodied carbon targets a mandatory component of its green building code.  This landmark measure will be included in the latest updates to the California Green Building Standards Code, also known as CALGreen, effective this summer.  Beginning July 1, 2024, commercial projects over 100,000 sq.ft. and school buildings over 50,000 sq.ft. will be required to adhere to one of three pathways: building reuse, performance, or prescriptive means through environmental product declarations.  Architects and designers who work in California will need to stay abreast of this policy and ensure compliance where applicable. 

         While California is setting the precedent, more Western states are sure to follow in its footsteps as the need for sustainable design becomes more urgent.  One proven way architects can decarbonize and comply with green policies is through building reuse and energy efficient retrofits to the building envelope.

Reducing Carbon Footprint Through Building Reuse

         As the focus on reducing embodied carbon emissions increases, examples of building reuse have gained attention in the media over the last several years.  For example, many pandemic-shuttered office spaces in California’s largest cities were converted into multi-use housing projects to help address the State’s affordable housing crisis. 

         Looking ahead, one of the three compliance options in the recent CALGreen code amendment requires buildings to reuse at least 45% of their existing structure and exterior.  While progressive, such policies can present critical performance challenges for older commercial buildings, a majority of which were constructed before modern energy codes were in place.  Consequently, these buildings often lack adequate insulation and air sealing, compromising thermal integrity and placing additional strain on the HVAC systems. 

         According to reports, this shortfall in building performance could lead to a 23% increase in electricity use by 2050 nationwide.  This would undermine efforts to reduce carbon consumption.  However, the same analysis indicates that aggressive energy upgrades could reverse this trend, potentially reducing energy use by 33% and electricity use by 13%.  Such upgrades could also significantly decrease the cost of grid decarbonization by one-third. 

         Emphasizing the opportunity presented by building reuse and retrofits, a panel of experts has authored letters to the United States General Services Administration on the topic of building decarbonization.  They urge the agency to accelerate federal building retrofits and prioritize envelope upgrades to achieve carbon reductions, emphasizing these strategies even before considering mechanical upgrades.  This showcases the opportunity for Western architects to closely evaluate existing building envelopes and implement retrofits that offer substantial carbon and energy savings.

Efficiency-First Approach With Roof Alterations

         Data from the United States Energy Information Administration’s Commercial Building Energy Consumption Survey found that existing low-sloped roofs in commercial building envelopes can be under-insulated by 50% or more compared to current energy code requirements.  Further, a recent report by the same organization indicates that roof replacements are not only the most common envelope-specific alteration but also the most prevalent building alteration affecting energy use. 

         Western architects looking to reduce carbon emissions can adopt an efficiency-first approach by prioritizing roof replacements to improve thermal efficiency in existing commercial buildings and schools.  Evaluating the effectiveness of this approach, the Polyiso Insulation Manufacturers Association commissioned a third-party study to quantify energy savings potential from roof replacements in various climate zones and building types.  Of note, the results reported that energy-compliant roof replacements in climate zone five can reap about 9-10% whole-building energy savings in primary schools. 

Bolstering Performance Using Polyiso Roof Insulation Boards

         To enhance the energy efficiency performance of the roof system, Western architects can integrate proven solutions like polyiso insulation boards during replacements.  With one of the highest R-values per inch compared to other insulation options, polyiso roof insulation boards provide excellent resistance to heat gain and loss.  This, in turn, helps lower space heating and cooling requirements and minimize energy consumption to maintain consistent indoor temperatures.  The thinner profile of polyiso products also allows re-roofing project teams to install higher levels of R-value when existing rooftop conditions create space constraints for the replacement system.  Furthermore, design teams should always specify polyiso roof insulation boards in a multi-layered system with staggered insulation joints to reduce the potential for airflow and thermal bridges in their re-roofing projects.  

         Sharing insights on the potential benefits of this approach, Greg Sagorski, Director of Technical Services at Atlas Roofing Corporation, reported, “Given the high-temperature differentials often experienced across different parts of the Western United States, architects should carefully consider the envelope insulation, particularly in the roof assembly.  Additionally, retrofits often require teams to fit the insulation system within the space provided by the existing rooftop conditions such as door and window thresholds or mechanical equipment.  To meet these dual requirements, polyiso roof insulation boards make it possible for architects to work within the existing building layout while improving the roof systems’ overall thermal performance.”

Key Considerations for Western Architects

         By specifying code-compliant levels of polyiso insulation during roof replacements, Western architects can offer their clients a proven, long-lasting solution to enhance energy efficiency in their building envelopes.  These measures lead to substantial reductions in carbon emissions and building operation costs while ensuring compliance with stringent energy codes common in Western states. By capitalizing on the opportunities presented by commercial building re-roofing projects, architects who work in the Western United States can meet long-term decarbonization goals that align with the broader sustainability objectives of the industry, paving the way for a more efficient built environment.

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