Building Decarbonization Calculator

Overview

Synapse’s Building Decarbonization Calculator (BDC) is a tool for modeling the energy consumption of space and water heating systems in residential and commercial buildings across the country. As federal, state, and local governments and organizations seek to decarbonize energy use, energy consumption in the buildings sector will need to be transitioned to more sustainable sources. Policymakers, advocates, and other stakeholders will need to understand how accelerating the adoption of new technologies impacts the broader space and water heating market and impacts greenhouse gas (GHG) emissions and electricity consumption. The BDC can provide the quantitative, state-level projections of future scenarios that jurisdictions need to make informed building decarbonization decisions.

How We Use BDC

The model uses a stock turnover framework to evaluate how installations of various heating system technologies impact space and water heating energy consumption over time. It also calculates emissions impacts from changes in heating system market share and evaluates how various trajectories of heat pump installations can help meet GHG reduction goals. Synapse uses the BDC to develop intermediate and long-term heating electrification benchmarks to help states decarbonize building energy consumption.

The BDC uses state-specific data on existing buildings from the U.S. Census Bureau’s American Community Survey along with the U.S. Energy Information Administration’s Residential and Commercial Buildings Energy Consumption Surveys (RECS and CBECS) to develop estimates for the characteristics of current building heating system stock. To further calibrate the model, Synapse uses data on annual changes in the number of homes heated by each fuel type as reported by the American Community Survey. For future years, the BDC develops heat pump technology adoption curves based on user inputs to calculate annual system sales by fuel type for each state, sector, and end-use. The BDC also accounts for improvements in appliance efficiency, heating system survival curves, changes in building shell quality, and new construction buildings over the study period.

One of the challenges of achieving complete building sector electrification is the long lifetime of fossil-fuel-based heating systems. A new natural gas furnace installed in the coming years may need to be replaced before the end of its useful life in order to achieve complete decarbonization by 2050. This “early retirement” of still-functioning equipment can be more costly than planning ahead and installing low-carbon heating systems in the first place. By quantifying required early retirements to achieve zero emissions by a certain target year, the BDC can demonstrate the consequences of delaying action on building electrification.