Recently, Home Innovation had a chance to discuss resilience in the context of sustainability and building performance with James M Williams PE, CE, SE, AIA, who authored the resilience section of the 2020 NGBS.
James Williams, president of J.M. Williams and Associates (JMWA) and AE URBIA, has over 30 years of professional experience. He is a licensed professional engineer, civil engineer, structural engineer, architect, and LEED accredited professional. Notable projects include: the tallest water slide in the world; the tallest manmade waterfall in the western hemisphere; the world's longest gondola; the steepest funicular; the largest museum of natural history in North America; Jurassic Park at Universal Studios Orlando; and the water features for the Atlantis Resort in the Bahamas and on Palm Island in Dubai. His company JMWA is noted for its structural engineering, architectural design, and building code expertise, and design solutions that are creative, cost effective, and sustainable.
Resilience is increasingly an issue for policy makers. Do you think developers are starting to think about how to design their projects to be more resilient? If so, how?
Most local developers are having buildings constructed, to sell. Their objective is to be competitive in the market and to maximize their profit, so they typically have buildings constructed in compliance with minimum building code requirements. Developers who hold their buildings to manage and lease are more sensitive to operation and maintenance costs. They want buildings that are more durable, require less maintenance, and are more energy efficient. Currently, most developers are not yet thinking in terms of resilience. As renters and owners become more informed and start demanding resilience, then developers will respond. For example, when owners’ interest in solar power increased, more developers began to provide PV panels, or at least they engineered their buildings to support the additional weight for future solar panels.
Is resilience valued by building developers? Owners? Investors?
With the dramatic effects we are seeing from climate change and other factors – such as the increased number of tropical storms, hurricanes, tornados, earthquakes, wildfires, and flooding every year ꟷ building developers, owners, and investors, as well as planning, zoning, and building departments, are starting to require more resilient designs and construction techniques. As developers, owners, and investors become more knowledgeable about resilience, they will require it even more. Performance-based codes will continue to replace prescriptive codes in the future, which will also result in more resilient buildings.
How do architects and project teams approach resilience in the design process?
Architects and design teams rely on codes and standards to define minimum design resilience. Cost constrains most architects and engineers to design buildings that meet zoning and code minimums. Increasingly, local building ordinances are beginning to address designing for hazards such as flooding, fire, landslides, liquefaction, etc. However, while more project contracts include sustainability, most do not yet address resilience. Resilience is a lively AIA topic, so active members are familiar with the issue and contemporaneous debates, but unless the client specifically requests resilience, it is not driving building design. Occasionally, resilience objectives are client-driven.
You submitted the resilience practice that was ultimately adopted into the 2020 NGBS ꟷ what went into your proposal?
Building codes have historically been based on life safety. The earthquake provisions of codes and standards were designed to save lives, not buildings. The objective was to ensure a building stands long enough for occupants to exit, prior to collapsing, either totally or partially. If no lives were lost, the building performed, even if ultimately it had to be demolished and replaced. More recently, insurance companies and others have begun to recognize that costs associated with business loss or disruption can exceed the actual building’s replacement cost. Also, there is a terrible cost for the families who lose their homes, must rebuild, and potentially end up with two mortgages (or a consolidated mortgage).
My NGBS resilience proposal was designed to codify tangible resilience metrics and incentivize resilient design and construction via the NGBS Green certification program. How to quantify resilience has always been a challenge, and to the best of my knowledge, it has not been done previously. I think the NGBS approach is sensible and corresponds well to established performance levels already in the building code for earthquake design.
How does the NGBS resilience practice correspond to building codes?
The building code assigns “importance factors” to essential structures, such as fire departments, police stations, hospitals, water storage facilities, or power-generating stations, that need to remain standing and operational after a major natural disaster. These buildings have importance factors that range from 1.0 to 1.5 based on the risk category and the type of risk (i.e., snow, wind, or seismic). A 1.5 importance factor means that the design seismic forces will be increased 1.5 times or 50% more than the base code minimum design forces.
The NGBS resilience practice uses the same principle. Using the 2018 IRC and the 2018 IBC as the baseline, the NGBS minimum base design is set as the same for buildings with an importance factor of 1.0 and the maximum is set to an importance factor of 1.5 (50% increase of code design forces). To allow and incentivize various resilience levels, the design forces in the NGBS range from 10% to 50% and increase in increments of 10% above the base design. Certification points are assigned to the different levels of resilience, ranging from two points for the base design, up to 15 for an enhanced resilience of 50% above the base design.
What are the benefits of the enhanced importance factors?
If a multifamily building is designed and constructed with an importance factor of 1.5 for seismic (earthquake) resilience, meaning the design earthquake forces were increased 50%, then those apartments would have the same resistance to earthquakes as an essential facility like a hospital. That would ensure the building would be operational after an earthquake. The building may need minor repairs, but the apartments would be safe to occupy, and there would be little to no disruption to the inhabitants.
How does the NGBS help facilitate building resilience?
The NGBS is a standard that is readily available for design professionals and builders to use. It is a simple and direct approach to green construction, which is directly associated with resilience.
As mentioned previously, an owner can select the building code minimums, which are intended to save lives (not necessarily buildings), or the owner can design to forces which are 10%, 20%, 30%, 40%, or 50% higher than the code minimums. Lateral load design forces that are 50% higher than code minimums are used for essential buildings that need to remain in operation after a natural disaster. The NGBS now addresses structural resilience in sections 613 for new construction and section 11.613 for remodels or renovations. For the first time, structural resilience is quantified in the building standard.
In addition to these new sections in the 2020 NGBS, resilience to climate change or extreme temperatures is indirectly addressed in the NGBS through the sections on Energy Efficiency and Indoor Environmental Quality. The sections on Site Design & Development and Lot Design, Preparation, and Development directly address wildfires and indirectly address resilience to flooding, landslides, and resilient transportation, etc. Resilient electric power systems and resilient water and wastewater systems are also indirectly addressed in the NBGS.
Have product manufacturers been responsive to the industry’s needs related to resilience or are they lagging in product design?
Most manufacturers have been responsive to the industry’s needs for resilience in materials, products, and building systems; but undoubtably, building materials, products, and building systems will be more resilient in the future than they are today. In fact, there are many manufacturers who drive or lead the building industry by producing more resilient products and building systems that are more efficient and economical. Building innovation is growing exponentially in this country and throughout the world.
Does the process of seeking a green building certification like NGBS Green help a building be more resilient?
Yes, I believe the process of seeking a green building certification like the NGBS does, in and of itself, result in single-family homes, multifamily buildings, and communities being more resilient.
Home builders, architects, engineers, designers, and owners should all communicate and work together through the process to identify areas where resilience can be improved or enhanced. Many improvements in resilience can be achieved at little or no additional cost, while others do come at an additional cost, but may be something an owner desires and is willing to pay for.
Find out more about NGBS Green certification and the NGBS Green+ RESILIENCE badge on the Home Innovation website. Questions? Contact us.***