Meeting Climate Change Expectations

by Stacy Rinella | December 12, 2023 8:41 am

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The imperative of the worsening climate crisis, and the public policy and private investment response to it are placing new expectations on buildings. Building codes, standards, and practices are evolving rapidly to meet these expectations, with an emphasis on performance and resilience. The new expectations require a dual focus on climate change mitigation (reducing greenhouse gas emissions), and climate change and natural hazard adaptation (reducing risks and vulnerabilities). This includes energy performance and carbon emission reduction, healthier indoor environments and indoor air quality (IAQ), and resilience in the face of increasing natural hazards. Here is how building science research and practice is evolving in each of these areas.

Energy and carbon

Emerging energy code updates will emphasize net-zero energy and decarbonization, favoring system performance over prescriptive requirements. This includes moving beyond prescribed thermal resistance (R-values) for building enclosure assemblies, with new mandates for reduction of thermal bridging and increase in air tightness. Manufacturer innovation and performance testing of new products and assemblies will be needed to meet new standards. Architects will also need greater focus on detailing and specifying building enclosure assemblies, and contractors must enhance field quality control to ensure enclosures meet these demanding performance requirements.

Project teams will no longer be able to trade off poorly performing enclosures with higher efficiency lighting and HVAC systems, as all systems will have high performance expectations. A few examples include:

• Lighting power density thresholds will continue dropping with new requirements for daylight and occupancy responsive controls added, and efficiency requirements for domestic hot water and HVAC equipment and controls will become more stringent.
• Research and development of heat pump refrigerants is ongoing in support of new HVAC efficiency requirements and building electrification. Current common refrigerants are potent and enduring greenhouse gases and are scheduled to be phased out and new options are needed.
• Additionally, as innovation continues to make renewable energy more affordable and efficient, both ASHRAE 90.1 and the International Energy Conservation Code (IECC) will include minimum requirements for on-site renewable energy.
• Increasingly, reducing embodied carbon in buildings is taking its place next to energy efficiency and operational carbon reduction. In additional to more states and municipalities adopting “buy clean” mandates with embodied carbon limits for materials in public projects, the State of California recently approved a new building code requirement, setting embodied carbon requirements for private development. Other states will likely follow.

Healthy indoor environments

The long-running healthy indoor environment trend accelerated with the pandemic. While indoor environmental quality has many facets, indoor air quality is central to this trend, with the recognition that it profoundly affects occupant performance (problem solving, cognitive function, etc.) and is closely linked to limiting the spread of airborne pathogens (COVID-19, influenza, rhinovirus, etc.). We have learned that the assumed tradeoff between energy efficiency and indoor air quality is a false choice. There is no need to choose between reducing outside air and saving energy or increasing ventilation and diluting pollutants. Through research and development, smarter, high-performance options are being made possible.

One of the key areas of innovation is in continuous IAQ monitoring and smart ventilation controls. Traditionally, outside air ventilation rates were based on fixed occupancy during regular occupied hours, with fresh air provided at a set ratio to
dilute concentrations of carbon dioxide (CO2) from occupant respiration. Two things have changed.

• In a post-pandemic world, building occupancy is more variable.
• New science is revealing the individual and compounding health impacts of multiple indoor environmental parameters, including temperature and humidity, CO2, particulate matter, volatile organic compounds (VOCs), ozone, and bioaerosols.

High-quality, low-cost sensors allow continuous air monitoring of multiple IAQ parameters in the breathing zone, and artificial intelligence (AI) can then signal the HVAC system to respond with appropriate interventions. Likewise, when low pollutant concentrations are detected, ventilation can be reduced to save energy while maintaining healthy indoor conditions.

Another emerging indoor environment innovation overlaps with resilience, for pandemics and natural hazards.

• When COVID-19 hit, the public health crisis demanded an increase in ventilation and the upgrading of filters, without regard to the energy penalty. ASHRAE recently released Standard 241P, that guides proactive preparation for another infectious disease outbreak. With a better understanding of how airborne pathogens spread, HVAC systems can be prepared with a “pandemic” mode to effectively control transmission risks while avoiding unnecessary energy use.
• Similarly, with much of the country now aware of the potential for distant wildfires to create local hazardous air quality, buildings will need a new operating mode when outdoor air quality is poor to maintain the best possible IAQ by reducing outdoor air, and deploying temporary pre-filters, supplemental air cleaning, and other measures.

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Beyond IAQ, interesting studies are revealing the critical importance of the multi-sensory connection to the outdoors and natural forms, patterns, and elements. Research provides concrete evidence of the mental and physical health benefits and improved human achievement when biophilic design is applied, including faster surgery recovery times in hospitals, and improved student engagement, learning, and test scores in schools.

Structure resilience

By August 2023, the year had already surpassed the previous record for billion-dollar-plus disasters, and this past summer was also officially the hottest ever recorded. While building codes play an important role in protecting the health and life safety of building occupants during a hazard event, the increasing frequency and severity of natural hazards demonstrates the need for more resilient buildings, as the disruption of disaster damaged buildings and infrastructure persist long after, putting social and economic strains on communities. Proposed rules under consideration by the Securities and Exchange Commission (SEC) and recent State of California legislation (Senate Bill 261) will require companies to disclose climate-related financial risks, including the increasing physical risks to their buildings from natural hazards. The demand for resilient structures is increasing. Some innovations in this area include:

• The same reduced thermal bridging and increased air tightness requirements coming in the code also increase the thermal resilience of buildings, reducing air conditioning demand during extreme heat events and helping to maintain safe indoor conditions even when the power is out. New research into super reflective paints and coatings, once commercialized for roofing and cladding, will also reduce heat islands, and increase thermal resilience.
• The increased frequency and severity of natural hazards will lead to new design considerations. For example, the American Society of Civil Engineers (ASCE) is adding a new chapter (Chapter 32) to ASCE 7-22 dedicated to tornado design, requiring engineers to consider EF0-EF2 tornadoes in the wind design of a significant portion of Risk Category III and IV buildings. This will lead building designers to look for components and cladding with higher design pressure ratings.
• Post-disaster damage assessments are revealing weakness with some materials and assemblies. For example, improved self-adhered membranes are becoming more common to resist wind-uplift and keep buildings dry during hurricanes and other high wind and rain events. Likewise, products like stamped metal roofing are proving to be more resilient to wind and hail and easier to replace when damage occurs.
• Flooding is one of the most common and costly of hazard events. New floodproofing products are being introduced, and along with them new dynamic testing methods are being developed to assure performance in expected conditions, like powerful storm surge, or flowing water combined with impacts from floating debris. In addition to shedding water in rain events, architects and engineers now need to consider wall assemblies on lower floors that can resist lateral forces and keep buildings dry in high-water conditions.
• In recent years, as whole communities have been wiped out by wildfires, post-fire investigations and research are providing new insights into building design to reduce wildfire risks. The recently published 2024 International Urban Wildland Interface Code (IWUIC) includes fire protection provisions that supplement the standard building and fire codes for fire prone areas. This code is spurring the development of fire-resistant building materials. The National Fire Protection Association (NFPA) Standard 285 is also becoming a critical standard for exterior wall assemblies. Research by the National Institute of Standards and Technologies (NIST) and other organizations is providing new guidance on hardening structures in the wildland urban interface (WUI), addressing threats from both airborne embers and flames. Additionally, important research is being conducted on the human health impacts of wildfire smoke that includes high concentrations of toxic compounds from incinerated structures. This will inform the development of less toxic building materials.

In the fast-evolving arena of building science for materials and building design, the topics of energy, occupant health, and resilience are intertwined. While development, testing, and regulation often focus on one issue or another, it is necessary for architects and building owners to apply systems thinking, understanding that many components and assemblies of a building must work together to address multiple demands. Understanding and optimizing these interrelated systems is the key to creating higher performing buildings at a lower cost.

Alan Scott, FAIA, LEED Fellow, LEED AP BD+C, O+M, WELL AP, CEM, is an architect and consultant with more than 35 years of experience in sustainable building design. He is director of sustainability with Intertek Building Science Solutions in Portland, Ore. To learn more, follow Scott on LinkedIn at www.linkedin.com/in/alanscottfaia.

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