The Carbon Emissions Impact of Demand Flexibility

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Traditionally, a building acts as a relatively unsophisticated consumer of power from the electrical grid, paying a particular price for the electricity it uses (kWh) and a charge for its peak power (kW). A building consumes energy whenever needed, without regard to potential generation costs or emissions.

Emerging demand flexibility strategies enable buildings to manage their electric demand to provide grid services. Grid services could include capacity reduction (similar to demand response efforts), avoiding renewable curtailment, avoiding high-cost generation resources, or reducing emissions.

Laws setting building performance targets exist across the country, but Local Law 97 (LL97) in New York City is notable because it defines performance expectations based on carbon emissions.

This report provides context for the potential impact of using time-of-use emission factors to reduce emissions associated with electricity use in buildings. It evaluates the technical potential of optimally deployed demand flexibility in an office building and a multi-family building. The results of our analysis isolate the potential emissions savings provided by demand flexibility.

Key Findings
  1. Emissions Reductions over the Continuum of Decarbonization: Demand flexibility in buildings can provide limited emissions reductions based on the electricity generation mix in the current grid—up to 3% in New York City. However, demand flexibility in an all-electric office building could reduce emissions up to ~10% from buildings relying on grids similar to the expected generation supplying NYC by 2030, when more variable renewable generation will be included in the mix. And it could reduce emissions up to ~40% as the grid approaches full decarbonization.
  2. Benefits across Grid Conditions: Demand flexibility could provide benefits across different grid conditions that Zone J may see in its transition to a decarbonized future grid. Regardless of the type of variable renewable generation resources added to Zone J, demand flexibility can provide increasing fractions of emissions reductions for buildings.
  3. Selection of Emissions Signal Matters: The important characteristics of a time-of-use emissions signal are type, timestep, and level of advance notice. The selection of these criteria will define the demand flexibility response of a building. This analysis shows that the highest emissions reductions come from a marginal emissions signal with the shortest possible timestep and shortest level of advance notice.