SWEPP-2026-0021 - Open-Source HVAC Decarbonization Web Tool

The Berkeley Decarb Tool (the “Tool”) is an open-source web platform that helps users evaluate the energy and carbon performance of different heating, ventilation, and air-conditioning (“HVAC”) systems and equipment, and hosted by UC Berkley’s Center for the Built Environment (“CBE”) at decarb.cbe.berkeley.edu. Users can select a building type, vintage, and climate zone to generate representative heating and cooling load profiles from pre-simulated Energyplus models, or select measured data from ~30 buildings, or upload their own data. They can then choose from a library of HVAC equipment combinations, including heat pumps, boilers, chillers, and hybrid systems, and apply multiple grid emissions scenarios that reflect different assumptions about grid region, year, and decarbonization trajectory. The Tool computes and visualizes how each combination of equipment and grid scenario performs in terms of energy use, operational carbon emissions, and other relevant factors, helping users understand trade-offs and sensitivities when planning HVAC retrofits or new designs.   

The proposed project will expand the Tool’s capabilities by adding functionality specific to California (“CA(s)”), new building loads, equipment and controls options (e.g., fuel switching & exhaust air heat recovery), and metrics such as utility costs and total system benefit (“TSB”). Enhanced visualization and user features will support more complete, transparent, and data-driven analyses. These improvements will align with CA(s) decarbonization goals via the built in decision making and accelerate the adoption of high-efficiency, low-global warming potential (“GWP”), HVAC solutions.  

These enhancements will directly support CalNEXT Technology Priority Maps (“TPMs”) on Commercial Hydronic Heat Pumps, Commercial Air-to-Air Heat Pumps, and Decarbonized Designs for Complex HVAC Systems. By improving access to standardized and transparent analysis, the Tool will help overcome key market barriers such as uncertainty about retrofit feasibility, limited understanding of electrical infrastructure implications, and inconsistency in analytical approaches used across the industry. Many analyses today omit key features or make overly simplified assumptions to the point that it substantially affects the estimated benefits and even the relative ranking of different solutions compared to one another.  For example, they may omit pre-combustion emissions estimates for electricity and/or natural gas, use average vs marginal emissions factors, use annual instead of hourly emissions factors, or omit refrigerant leakage emissions, or use estimates for these effects that are not based on the latest available scientific consensus – the current version of the Tool addresses these limitations. This project will support both research and market transformation by providing and extending a freely accessible, scientifically grounded resource for evaluating low-carbon HVAC solutions and comparing them to baseline solutions.  TRC’S overall project hypothesis is that this Tool will help practitioners and decision-makers assess how HVAC choices affect operating emissions and costs, along with the associated uncertainty, and that this will ultimately accelerate the adoption of high-efficiency, low-GWP, electrified systems. In the long term, the Berkeley CBE Decarb Tool aims to serve as a central, open-source platform for comparing the performance and emissions impacts of HVAC systems in CA(s) and beyond, contributing to more coordinated, informed, and cost-effective pathways toward building decarbonization.