About

Professor Arpad Horvath has been elected a Distinguished Member of the American Society of Civil Engineers (ASCE), the highest honor bestowed on civil engineers, recognizing individuals who exemplify innovation and practice in the profession. He is one of only 269 individuals to have received this distinction since 1852, and the first UC Berkeley faculty member in 25 years to be honored with this recognition. Professor Horvath's contributions are primarily in research and environmental life-cycle assessment (LCA) of infrastructure systems. He is recognized as one of the founders of a movement within civil engineering that emphasizes rigorous analytical evaluation of the life-cycle environmental and economic impacts of the built environment. His work has introduced new foundational theories and concepts, along with innovative applications, utilizing extensive data from various fields to analyze the environmental impacts of infrastructure in unique ways. At UC Berkeley, he leads research in life-cycle assessment and directs the Energy, Civil Infrastructure and Climate graduate program. He is also a member of the U.S. National Academy of Engineering and the National Academy of Construction, being one of only 17 individuals worldwide to hold all three distinctions.

Research topics

• Computer Science
• Environmental science
• Economics
• Engineering
• Geography
• Environmental resource management
• Environmental economics
• Environmental protection
• Natural resource economics
• Environmental engineering
• Business
• Agricultural economics
• Food science
• Agricultural science
• Agricultural engineering
• Chemistry
• Water resource management
• Agronomy
• Environmental planning
• Waste management

Selected publications

• Can agglomerated tall buildings reduce carbon emissions compared to a low-rise urban sprawl?

  Environmental Research Infrastructure and Sustainability · 2025-02-26 · 1 citations

  articleOpen accessSenior author

  Abstract The building sector is a significant source of greenhouse gas (GHG) emissions globally. A city’s urban form and building typology can influence and even determine what strategies are implemented for GHG reductions. An important consideration for new construction is whether agglomerated mixed-use high-rises have the potential to reduce overall carbon emissions relative to a sprawl of low-rise dwellings. This study aims to contribute to that discussion by carrying out a comparative environmental assessment of the Burj Khalifa, the tallest building in the world, and Al Hudaiba, a nearby low-rise neighborhood in Dubai, United Arab Emirates. The aim of this exercise is to identify takeaways that can inform sustainable building construction and housing typologies. A life-cycle framework is used to analyze the annual per capita CO 2 e emissions of both systems, where material production, construction, building use, and end-of-life phases are considered. A baseline scenario is established in which certain benefits an agglomerated system of tall buildings would provide are realized, including having buildings with longer service lives and reducing transportation demand. Baseline results show that the Burj Khalifa has 11%–37% lower annual per capita life-cycle emissions, depending on the assumed electricity grid mix. Despite the higher operation emissions, reductions are achieved due to the Burj Khalifa’s relatively lower embodied carbon and transportation emissions. Monte Carlo simulation (MCS) is used to assess some of the uncertainties associated with baseline assumptions in each building phase. The MCS reveals that the Burj Khalifa leads to 5%–66% less annual GHG emissions per capita across all emission distribution percentiles, again depending on the electricity generation mix. Meanwhile, a sensitivity analysis shows that life-cycle emissions are mostly dependent on the energy use intensities of both systems. Had the Burj Khalifa been built as a low-energy use building, it would have been more CO 2 e efficient than 95% of Al Hudaiba’s MSC realizations, with a mean difference of 4.3 tonnes CO 2 e person −1 yr −1 . Overall, our findings demonstrate that agglomerated tall building systems can reduce building life-cycle emissions when they are intentionally designed to do so, especially if paired with a cleaner grid mix.

  PublisherDOI

• Environmental Justice and Systems Analysis for Air Quality Planning in the Port of Oakland in California

  Environmental Science & Technology · 2024-05-02 · 7 citations

  articleOpen accessSenior author

  Many frontline communities experience adverse health impacts from living in proximity to high-polluting industrial sources. Securing environmental justice requires, in part, a comprehensive set of quantitative indicators. We incorporate environmental justice and life-cycle thinking into air quality planning to assess fine particulate matter (PM2.5) exposure and monetized damages from operating and maintaining the Port of Oakland, a major multimodal marine port located in the historically marginalized West Oakland community in the San Francisco Bay Area. The exposure domain for the assessment is the entire San Francisco Bay Area, a home to more than 7.5 million people. Of the more than 14 sources included in the emissions inventory, emissions from large container ships, or ocean-going vessels (OGVs), dominate the PM2.5 intake, and supply chain sources (material production and delivery, fuel production) represent between 3.5% and 7.5% of annual intake. Exposure damages, which model the costs from excess mortalities resulting from exposure from the study’s emission sources, range from USD 100 to 270 million per annum. Variations in damages are due to the use of different concentration–response relationships, hazard ratios, and Port resurfacing area assumptions. Racial and income-based exposure disparities are stark. The Black population and people within the lowest income quintile are 2.2 and 1.9 times more disproportionately exposed, respectively, to the Port’s pollution sources relative to the general population. Mitigation efforts focused on electrifying in-port trucking operations yield modest reductions (3.5%) compared to strategies that prioritize emission reductions from OGVs and commercial harbor craft operations (8.7–55%). Our recommendations emphasize that a systems-based approach is critical for identifying all relevant emission sources and mitigation strategies for improving equity in civil infrastructure systems.

  PublisherOA PDFDOI

• Assessing uncertainty in building material emissions using scenario-aware Monte Carlo simulation

  Environmental Research Infrastructure and Sustainability · 2024-04-19 · 11 citations

  articleOpen accessSenior author

  Abstract Global greenhouse gas emissions from the built environment remain high, driving innovative approaches to develop and adopt building materials that can mitigate some of those emissions. However, life-cycle assessment (LCA) practices still lack standardized quantitative uncertainty assessment frameworks, which are urgently needed to robustly assess mitigation efforts. Previous works emphasize the importance of accounting for the three types of uncertainties that may exist within any quantitative assessment: parameter, scenario, and model uncertainty. Herein, we develop a quantitative uncertainty assessment framework that distinguishes between different types of uncertainties and suggest how these uncertainties could be handled systematically through a scenario-aware Monte Carlo simulation (MCS). We demonstrate the framework’s decision-informing power through a case study of two multilevel ordinary Portland cement (OPC) manufacturing scenarios. The MCS utilizes a first-principles-based OPC life-cycle inventory, which mitigates some of the model uncertainty that may exist in other empirical-based cement models. Remaining uncertainties are handled by scenario specification or sampling from developed probability distribution functions. We also suggest a standardized method for fitting distributions to parameter data by enumerating through and implementing distributions based on the Kolmogorov–Smirnov test. The level of detail brought by the high-resolution parameter breakdown of the model allows for developing emission distributions for each process of OPC manufacturing. This approach highlights how specific parameters, along with scenario framing, can impact overall OPC emissions. Another key takeaway includes relating the uncertainty of each process to its contributions to total OPC emissions, which can guide LCA modelers in allocating data collection and refinement efforts to processes with the highest contribution to cumulative uncertainty. Ultimately, the aim of this work is to provide a standardized framework that can provide robust estimates of building material emissions and be readily integrated within any uncertainty assessment.

  PublisherOA PDFDOI

• Exploring the significance of transportation emissions in upfront embodied carbon in buildings

  Building and Environment · 2024-12-14 · 13 citations

  articleOpen accessSenior author

  • Upfront embodied GHG emissions (A1-A4) from a multi-family residential building in the San Francisco Bay Area in California are estimated. • An improved method for considering transportation emissions from material delivery (A4) in whole-building life-cycle assessments is considered. • A4 emissions account for anywhere from very little (close to 0 %) to over 80 % of total upfront embodied carbon, depending upon the specific material and manufacturing location. • Results suggest that policies promoting use of locally-sourced materials can reduce A4 emissions, but not yield lowest A1-A4 impacts. Addressing embodied carbon associated with building materials is urgent. Transportation (A4) emissions are sometimes neglected (or incorrectly calculated) in relation to the materials' “product stage” (A1-A3) and a building's “use stage” (B1-B7) emissions. We present a comprehensive model for considering transportation emissions in individual building projects to determine their significance in upfront (here A1-A4) embodied carbon. Transportation scenarios are presented for an illustrative case study of a multifamily residential building in Oakland, California, although the methods described herein are applicable to any location. Material emissions are extracted from site-specific environmental product declarations (EPDs) and are compared to transportation emissions calculated based on direct operational emissions from transporting the goods from the EPD's stated manufacturing location to the project site and embodied emissions from transporting the goods, from manufacturing the delivery modes (vehicles, freight trains, cargo/container ships) and constructing the delivery infrastructure (roadways, railways, port terminals). Relative to three defined scenarios (Lowest Materials Emissions, Closest to Project Site, Furthest from Project Site), transportation emissions account for anywhere from very little (close to 0 %) to over 80 % of upfront embodied carbon, depending upon the specific material and manufacturing location. Results differ when transportation is electrified or uses biofuel. A blanket policy on demanding locally produced materials might actually increase A1-A4 emissions. This study serves to refine how different life-cycle stages are considered in Whole Building Life-cycle Assessments (WBLCAs). Future research should continue to explore the efficacy of current WBLCA methodologies, particularly in estimating upfront embodied carbon.

  PublisherDOI

• Uncertainty in determining carbon dioxide removal potential of biochar

  Environmental Research Letters · 2024-12-03 · 7 citations

  articleOpen accessSenior author

  Abstract A quantitative and systematic assessment of uncertainty in life-cycle assessment is critical to informing sustainable development of carbon dioxide removal (CDR) technologies. Biochar is the most commonly sold form of CDR to date and it can be used in applications ranging from concrete to agricultural soil amendments. Previous analyses of biochar rely on modeled or estimated life-cycle data and suggest a cradle-to-gate range of 0.20–1.3 kg CO 2 net removal per kg of biomass feedstock, with the range reported driven by differences in energy consumption, pyrolysis temperature, and feedstock sourcing. Herein, we quantify the distribution of CDR possible for biochar production with a compositional life-cycle inventory model paired with scenario-aware Monte Carlo simulation in a ‘best practice’ (incorporating lower transportation distances, high pyrolysis temperatures, high energy efficiency, recapture of energy for drying and pyrolysis energy requirements, and co-generation of heat and electricity) and ‘poor practice’ (higher transportation distances, lower pyrolysis temperatures, low energy efficiency, natural gas for energy requirements, and no energy recovery) scenarios. In the best-practice scenario, cradle-to-gate CDR (which is representative of the upper limit of removal across the entire life cycle) is highly certain, with a median removal of 1.4 kg of CO 2 e/kg biomass and results in net removal across the entire distribution. In contrast, the poor-practice scenario results in median net emissions of 0.090 kg CO 2 e/kg biomass. Whether this scenario emits (66% likelihood) or removes (34% likelihood) carbon dioxide is highly uncertain. The emission intensity of energy inputs to the pyrolysis process and whether the bio-oil co-product is used as a chemical feedstock or combusted are critical factors impacting the net carbon dioxide emissions of biochar production, together responsible for 98% of the difference between the best- and poor-practice scenarios.

  PublisherDOI

• Considerations for estimating operational greenhouse gas emissions in whole building life-cycle assessments

  Building and Environment · 2024-03-11 · 35 citations

  articleOpen accessSenior author

  Building operations, which include the energy from electricity and natural gas account for about 28% of global greenhouse gas (GHG) emissions. Stakeholders need accurate assessments of building operations in whole building life-cycle assessments (WBLCA), at both the individual building and building stock-level, to inform mitigation strategy selection, policy development, and progress tracking of building sector GHG emission mitigation targets. This review provides an overview of building energy estimation methods (measured, building energy modeling, representative empirical and modeled databases) and electricity emission factors (average versus marginal, regional versus utility, direct combustion versus life-cycle values) for estimating building operational GHG emissions in WBLCAs. An investigation of the most commonly used approaches in WBLCAs, especially in the context of emerging considerations including grid decarbonization, non-constant building and energy supply loads, and embodied and operational GHG trade-off decisions, reveals that there is no standard practice for justifying method or dataset selection. While many of the datasets and tools discussed in this study are developed for the United States, the overarching methods for quantifying building energy use and emissions are applicable for global audiences. Based upon the literature survey and the utility of each building energy estimation method and emission factor dataset, we identify recommended approaches for quantifying building operational GHG emissions in WBLCAs under various policy goals including establishing benchmarks, choosing mitigation strategies, implementing on-site renewable generation, and forecasting emission reductions in the building sector.

  PublisherDOI

• Exploring the Significance of Transportation Emissions in Upfront Embodied Carbon in Buildings

  SSRN Electronic Journal · 2024-01-01 · 1 citations

  preprintOpen accessSenior author
  PublisherDOI

• What are the energy and greenhouse gas benefits of repurposing non-residential buildings into apartments?

  Resources Conservation and Recycling · 2023-08-09 · 29 citations

  articleOpen accessSenior author

  This study examines the potential strategies for reducing embodied energy and greenhouse gas emissions through adaptive reuse of non-residential buildings for residential purposes, as compared to new construction of apartment buildings. Such an approach can address housing crises in urban areas with an abundance of underutilized non-residential buildings, promoting sustainable housing growth. A comprehensive assessment of repurposing in California reveals approximately 510 million m² of floor space across 230,000 non-residential buildings in the current building stock. The potential reduction in embodied energy and CO2eq emissions ranges from 0.14 to 1.4 billion GJ and 5.0–70 million metric tons for the state, respectively, contingent upon the percentage of repurposed floor space (10–100%) and adaptive reuse scenario (retaining structural components and façade or solely the structure). A repurposed building avoids about 56% of embodied energy, 34-48% of CO2 eq emissions, and 72% of materials by mass compared to building a new apartment building. However, various technical, financial, and regulatory challenges may hinder emissions reductions, necessitating proactive policy measures. Cities can potentially expedite the process by streamlining approvals for mixed-use adaptive reuse projects involving both commercial and residential spaces.

  PublisherDOI

• Modular Construction's Capacity to Reduce Embodied Carbon Emissions in California's Housing Sector

  SSRN Electronic Journal · 2023-01-01 · 7 citations

  preprintOpen accessSenior author
  PublisherDOI

• Modular construction's capacity to reduce embodied carbon emissions in California's housing sector

  Building and Environment · 2023-05-24 · 58 citations

  articleOpen accessSenior author

  Demand for new housing construction must be balanced with minimizing embodied greenhouse gas (GHG) emissions from building materials, logistical operations, and construction activities. This study examines the potential embodied GHG benefits that an innovative housing production method, factory-built modular construction, might have in meeting the multifamily housing needs, with California as a case study. A model is developed to quantify the embodied GHG emissions from materials, transportation, and construction for representative modular housing projects, contrasting results to scenarios where housing is constructed with conventional methods. Results are scaled from single building prototypes to meeting housing demand for lower income residents in California, representing 1.1 million housing units in all 58 of the state's counties. Statewide, compared to all housing units being stick-built, most modular types achieve emission reductions of 2–22%, with potential benefits depending upon structural framing material and factory location. A parametric sensitivity analysis reveals additional key modeling variables: module size and capacity of the module delivery vehicle. A Monte Carlo analysis is conducted for each county, comparing a random allocation of modular types from all factory locations to conventionally constructed housing. Counties farthest away from module factories experience GHG emission gains, while all other counties experience emission benefits of 1–14% (removing one of the modular types increases benefits to 4–20% for all counties). While the results are California-specific, the modeling framework is applicable to any location and relevant for regions assessing the embodied carbon impacts of rapid housing construction methods.

  PublisherDOI

Recent grants

• INFEWS/T1: Reducing the Environmental Impacts of FEW Systems In and Around Cities

  NSF · $2.4M · 2017–2023

• CAREER: Re-engineering of Construction Processes and Education for Sustainable Development

  NSF · $375k · 2001–2007

Frequent coauthors

• Chris Hendrickson

  Carnegie Mellon University

  36 shared

• Eric Masanet

  University of California, Santa Barbara

  35 shared

• Olivier Jolliet

  Technical University of Denmark

  34 shared

• Wolfram Krewitt

  30 shared

• Uwe Klann

  30 shared

• Gregory Norris

  26 shared

• Gjalt Huppes

  Leiden University

  25 shared

• Hiroki HONDO

  Yokohama National University

  25 shared

Awards & honors

• ASCE Distinguished Member