Informing Vermont’s energy and climate policy with LEAP and NEMO

The Vermont Pathways Model is a model developed using SEI’s Low Emissions Analysis Platform (LEAP) and Next Energy Modeling system for Optimization (NEMO) to simulate greenhouse gas emissions across Vermont’s entire economy, including both energy and non-energy sectors. It uses existing data and projections of activity across a wide range of sectors, to model energy production and consumption, estimates emissions of greenhouse gases and other pollutants, and analyse the cost and impact of mitigation measures over time.

The model includes a baseline that projects future emissions based on the current policies, and a range of mitigation scenarios that explore the potential and costs of alternative policy and technological pathways for reducing Vermont’s emissions. It also provides estimates of key implementation indicators, such as the number of weatherized homes, heat pump and electric vehicle adoption, and sector-specific emission changes over time.

This model was initially developed in support to the 2020 Comprehensive Energy Plan and the 2021 Climate Action Plan. Since then, it has been substantially updated to analyze emission reduction policies in the buildings and thermal energy sectors, and to inform Vermont’s latest 2025 Climate Action Plan . Working with Vermont’s Agency of Natural Resources (ANR), the model now incorporates the most recent data and trends, including impacts of federal funding cuts and other policy shifts, such as the exclusion of the Advanced Clean Cars II and Advanced Clean Trucks regulations, helping improve the understanding of key components of climate action, as well as strengthen the recommendations that guide state decision-making processes.

Key findings from the recent 2025 CAP analysis include:

• Emissions under the baseline scenario are projected to decline over time, but not fast enough to meet anticipated long-term targets.
• Multiple mitigation scenarios were explored, incorporating 26 mitigation measures across all sectors. Results illustrate the difficulty of achieving Vermont’s current mitigation goals. Even in the most ambitious scenario – featuring significant transport electrification, widespread weatherization and heat pump adoption – emission reductions fall short without faster, broader adoption of mitigation strategies, as well as the introduction of additional measures.
• The modeled mitigation pathways demonstrate that deep decarbonization is technically achievable, but requires sustained policy support and accelerated implementation across sectors.
• Considering the social costs of greenhouse gases, the explored  mitigation scenarios result in net economic benefits, with total savings reaching up to USD 10 billion by 2050.
• Even without social accounting for social costs, scenarios that emphasize early, cost-effective action can still deliver net savings to Vermont residents while others may require public investment, but deliver larger emission reductions and broader environmental and health benefits.