While there have been some important improvements in safety, material technology and equipment, little else has changed in building construction in the last 100 years or more. With skilled labor shortages, economic pressures, rising material costs and the urgent need for buildings to do their part to reduce global climate impacts, the construction industry is ripe for disruption. Off-site construction, especially comprehensive volumetric solutions like modular construction, is one of the most promising means to modernize the building industry and reduce its environmental footprint.
Off-site construction means shifting a portion of construction processes from construction sites to remote manufacturing facilities, and includes panel fabrication, assembly of building components, and modular construction. Modular construction involves the complete fabrication of building volumes off-site, typically with interior finishes and building systems installed. These modules are transported to the site and stacked like blocks on a site-built foundation to form complete buildings. Modular construction has a reputation for cookie-cutter forms, lacking character and customization, but the industry has evolved, supporting creativity and elaborate designs.
The various off-site construction options offer similar benefits, but modular, being the most complete solution, maximizes those advantages. The advantages accrue to building owners, occupants, builders, tradespeople, the communities where projects are constructed, and the environment. These include:
Owners–Developers and owners gain significant advantage from a 30% to 50% reduction in the construction schedule, giving them a significantly faster time from design to occupancy. The shortened schedule can reduce financing costs, and reduced risks and other efficiencies may cut costs further, for an average savings of up to 25%. Once occupied, the enhanced quality and durability of modular buildings can minimize operation and maintenance costs as well. Finally, because modular volumes are designed to be individually stable for transport and placement, they can increase the resilience of buildings subject to hazard events such as earthquakes and high winds.
Occupants–The occupants of modular buildings benefit from healthier and more comfortable indoor environments. Construction in a fabrication plant can deliver enclosures with better thermal and acoustic performance, as well as preventing moisture exposure of interior elements during construction that could lead to air quality problems later. Additionally, modular construction can provide greater consistency and rigor in procurement and use of low-emitting materials and finishes, reducing occupant exposure to volatile organic compounds, formaldehyde and other air contaminants.
Builders–Modular building rewards contractors with reduced risks from weather delays, labor availability and other typical disruptions. The process also lends itself to optimized labor utilization and better coordination of trades with multiple projects executed in a common fabrication facility, which cuts costs and shortens schedules. Efficient procurement, storage and utilization of materials across multiple projects can reduce material purchase costs and waste. Builders can also retain many of these advantages while overcoming geographic limitations with pop-up fabrication plants closer to building sites.
Tradespeople–Construction workers may benefit from shorter travel time to work and a consistent commute to a single fabrication plant, avoiding remote construction sites and congested urban centers. One of the biggest advantages is a safer and more comfortable work environment. A fabrication plant will typically have better illumination, limited fall risks, fewer confined work environments and less heavy equipment to work around. Without exposure to extreme and variable weather, workers are also safer and more comfortable.
Community–The limited duration and intensity of on-site construction activities associated with modular construction reduces community exposure to these noise pollution and air quality impacts. Also, with fewer material deliveries (~90%), reduced construction worker commutes (~75% shorter), and less off-road construction vehicle use, neighbors suffer fewer air quality and traffic congestion impacts.
Environment–The local and global environment may see some of the greatest benefits. While modular volumes may contain additional material to give them stability for transport and lifting into place, that is more than offset by improved material use efficiency and the significant waste reduction (up to 98%) that can be realized. Thanks to the greater precision and quality control achievable in a fabrication facility, the building envelope can be tighter with reduced infiltration and thermal bridging, delivering 15% to 20% energy efficiency and reduced operational carbon emissions. Additionally, reduced vehicle usage (on- and off-site) means fewer air emissions (CO2, particulate matter, etc.) Finally, modular buildings are more adaptable over time, easier to relocate and reuse.
It is time to change the way we build. Off-site construction, especially modular building, provides multiple triple-bottom-line benefits to primary stakeholders in the construction industry. They cut costs, speed schedules, improve quality and performance, and reduce environmental and climate impacts. At the same time, they preserve the designer’s creative freedom and the owner’s need for customization. Modular represents the type of disruption we need to meet the demand for high-performance, low-carbon buildings.
Alan Scott, FAIA, LEED Fellow, LEED AP BD+C, O+M, WELL AP, CEM, is an architect with over 30 years of experience in sustainable building design. He is a senior consultant with Intertek Building Science Solutions in Portland, Ore. Ryan Knowles has over 20 years of experience in the modular buildings industry and is an industrialized buildings manager with Intertek. To learn more, follow Scott on Twitter @alanscott_faia.