View source for Decarbonization During Predevelopment of Modular Building Solutions

{{Report
|Image=DecarbonizationModularBuilding.jpg
|Published=2021-12-31
|Organization=National Renewable Energy Laboratory
|poc=Noah Klammer, Zoe Kaufman, Ankur Podder, Shanti Pless, David Celano, and Stacey Rothgeb
|Where=Golden CO
|Summary=Affordable, zero carbon emissions is an important climate-performance target for the future of
multifamily housing, and the multifamily construction industry holds an essential position in
achieving this goal in the United States. Building construction and operation accounts for 37% of
global energy-related carbon emissions (UN Environment Programme 2021). Meanwhile, an
additional 3.8 million housing units are needed to address the shortage in the United States.
|Link=https://www.nrel.gov/docs/fy22osti/81037.pdf
|sector=Buildings
|Tag=Modular Building
|Release=81037.pdf
}}
To date, net zero energy (NZE) has served as a tangible preliminary target for high-performance
building in both voluntary certification programs and, now, building energy codes. Industrialized
construction is one approach to efficiently achieve affordable housing that implements NZE
strategies. These dwelling units are often all-electric and outfitted with rooftop solar arrays, and
they produce at least as much energy through on-site renewable resources as they consume each
year, enhancing energy affordability. However, the full potential of affordable, NZE housing has
not yet been tapped, due in part to incremental costs of NZE strategies surpassing traditional
budgets for affordable housing projects. Additionally, as new construction becomes more energy
efficient, the greenhouse gas (GHG) emissions from the construction industry play a
proportionately larger role in environmental impact and must be considered when evaluating
methods of construction. There has been limited investigation into the trade-offs between sitebuilt and industrialized construction buildings from the perspective of reducing the incremental
cost of NZE strategies and reducing GHG emissions resulting from upfront and operational
emissions that are “embodied” in the building’s life. '''This report details actionable pathways
for the industry to leverage advanced building construction, reduce NZE incremental costs,
and achieve significant GHG emissions reduction by 2030.'''

This effort demonstrates a pathway to affordability and emissions reduction via specific
strategies within the framework of industrialized construction. Various decarbonization strategies
were compared in “what-if” scenarios at each development stage, using cost, energy, and
emissions modeling, with the most impactful and viable strategies proposed in the resulting
pathway. The primary audience, stakeholders, and beneficiaries for this methodology are
productized modular builders and associated investors who are interested in (1) NZE incremental
cost reduction and (2) GHG emissions reduction. “Productized” here refers to the repeatable,
solutions-based, packaged design that a manufacturer commits to developing, evolving, and
producing and delivering at scale, over time. The case study is analyzed over the years 2016–
2030, where the production builder begins instituting the analysis and intervention 5 years after
initial product development.

The unique contributions from this framework are two methodologies:
#Methodology I is focused on cost reduction through learning effects and experience
curves applied to NZE productized modular construction. 
#Methodology II is focused on reducing GHG emissions per unit of housing, evaluated
via a life cycle assessment (LCA). The reductions come from a variety of strategies,
including: the bill of materials, learning effects on production waste, learning effects on
logistics, decarbonization of the electrical grid, and energy demand management.
As the primary stakeholders, productized modular builders can leverage this framework as a
development road map for strategic planning to invest and allocate necessary resources in their
facilities that (1) encourage labor learning and increased productivity, and (2) continuously
increase the annual production of dwelling units to reach a goal of 10,000 dwelling units
annually by 2030. This framework introduces three development phases that modular builders
can plan to follow to achieve financially viable high-performance projects: Pre-Build Product
Development Phase (years 1–5), Industrialized Construction Phase (years 6–10), and Advanced
Manufacturing Phase (years 11–15 and beyond).