As the global focus on sustainability intensifies, the construction industry is being called to rethink traditional methods and embrace innovative, eco-friendly alternatives. Modular construction, with its strategic advantages, stands out as a powerful solution. From waste reduction to energy efficiency, modular building has the potential to transform how we build in four key areas:
Significant Waste Reduction
Lower Carbon Footprint/Embodied Carbon
Relocate, Renovate, and Repurpose
Greater Energy Efficiency/Tighter Building Envelope
Waste Reduction
The Environmental Protection Agency considers construction waste and debris is one of the largest contributors to landfills annually. While construction demolition
of existing structures represents about 90 percent of this landfill waste, new
construction activity accounts for nearly fifty-seven million tons of landfill waste.
But it doesn’t have to be this way.
There have been several studies and reports conducted globally on the impact
modular and prefabrication have on overall waste reduction. From the groundbreaking “Prefabrication and Modular Construction 2020” report by In terms of academic research, the results are also undeniable.
RESEARCH SPOTLIGHTS
Quantifying Advantages of Modular Construction: Waste Generation –
L. Loizou, K. Barati, X. Shen ORCID, B. Li
This paper focuses on modular construction as an off-site production system, where a framework to compare waste generation of modular and conventional, in-situ construction methods is proposed. This paper aims to quantify these differences. The framework relies on a comprehensive literature review to estimate the waste rates of building materials, which are then applied to realistic case studies in order to determine the differences in waste generation. Overall, modular construction reduces the overall weight of waste by up to 83.2%, for the cases considered. This corresponds to a 47.9% decrease in the cost of waste for large structures.
Qualitative comparisons asserting that prefabrication reduces waste have also been verified. For quantitative comparisons, the results show greater waste reductions than most previous studies. Quale et al., Jaillon et al., Kim, Jaillon and Poon, and Hosseini et al., showed waste reductions of 20.1%, 52%, 60%, 65%, and 92%, respectively.
Onsite vs. Offsite: Comparing Environmental Impacts - Quale, et. al.
The University of Virginia conducted a study (Quale, et.al.) using life cycle assessment to quantify the environmental impacts of constructing a typical residential home using two methods, based on data from several modular construction companies and conventional homebuilders. The study, peer-reviewed and published in the Journal of Industrial Ecology, included impacts from material production and transport, off-site and on-site energy use, worker transport, and waste management.
In terms of materials usage and waste, homes constructed using a modular process were found to use about 20 percent less material overall. This included greater material use for modular mate lines and transportation but significantly less material waste for modular. In fact, the modular homes sent about 75 percent less wood and drywall waste to the land fill per project (1,380 lbs. for modular vs 5,500 lbs. for conventional). Worker transport to the jobsite daily had a negative impact for conventional construction while energy use in the factory reduced the environmental impact of modular construction projects.
LOWER CARBON FOOTPRINT / EMBODIED CARBON
While carbon footprint measurements have long been a popular way of evaluating the carbon needed to operate a building, they can be misleading since they don’t consider the structure’s entire life cycle and the materials used to construct it. Embodied carbon measurements, on the other hand, look at the carbon usage inherent to the materials—and the project-related transportation and maintenance thereof—used in a building project. Still, both metrics provide valuable insights into the overall environmental impact of any given building, and modular construction techiniques have been shown to reduce both.
In fact, as mentioned in the Quale, et. al., research referenced above, the environmental impacts from modular construction are, on average, lower than those from on-site construction with total greenhouse gas emissions about 30 percent less by using modular construction.
RESEARCH SPOTLIGHTS
North Ridge CO2 Analysis Report - Comparison between Modular and On-Site Construction - M. Al-Hussein, J.D. Manrique, D. Mah
This study, conducted by the University of Alberta, comparing modular and on-site construction noted significant advantages for modular construction, specifically noting a compressed site schedule, minimized waste, fewer workers on-site (and for less time), fewer materials stored on-site, and a tighter building envelope. The research found that by using modular construction, the overall schedule was shortened by four months on an 11-month project and CO2 emissions were reduced by 43 percent.
Comparison of the Embodied Carbon Emissions and Direct Construction Costs for Modular and Conventional Residential Buildings in South Korea - H. Jang, Y. Ahn, S. Roh.
This study analyzed the embodied carbon emissions and direct construction costs incurred during the production phase of a modular residential building and provides comparison to an equivalent conventional residential building. Major drawings and design details for a modular residential building in South Korea were obtained, and the quantity take-off data for the major construction materials were analyzed for a modular construction method and a conventional construction method using a reinforced concrete structure under the same conditions. Focusing on major construction materials during the production phase, the embodied carbon emissions assessment revealed that adopting a modular construction approach reduced the environmental impact by approximately 36%, as compared to the conventional reinforced concrete method. This result was significantly affected by the large input of ready-mix concrete, with its high embodied carbon emissions, utilized in RC construction and not modular construction.
GREATER ENERGY EFFICIENCY / TIGHTER BUILDING ENVELOPE
According to the National Renewable Energy Lab (NREL) “Industrialized construction has immense potential to address the growing need globally to build and upgrade the building stock to be affordable, energy-efficient, and resilient. It can also help achieve the United States’ goal of a 50% reduction in U.S. greenhouse gas (GHG) emissions by 2030. The industrialized construction of Net Zero Energy (NZE), low-carbon modular buildings is an essential step for developing a transformational pathway for our clean energy future.”
RESEARCH SPOTLIGHT
Modular Construction: Energy-Efficiency Field Study in Commercial and Multifamily Buildings - July 9, 2020. University of Nebraska-Lincoln,
Colorado State University, and New Buildings Institute.
A multiyear field study targeting four climate zones in three states {CA, PA and WA}, documenting energy performance of 45 modular projects with a focus on multifamily buildings. Prefabrication in a controlled, factory setting has the
potential to improve energy efficiency and performance while streamlining related code-compliance processes and better enabling the integration of
advanced technologies. When integrated, this approach may reduce total
energy use by 50 percent when compared to comparable site-built construction.
CONCLUSION
Modular construction is a more environmentally-friendly building method than traditional on-site construction. By utilizing modular techniques, building developers can lower their projects’ overall environmental impact through reduced emissions, reduced waste, material reusability, and increased energy efficiency.
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