City of Sunnyvale staff told the Sustainability Commission that the city's 2024 greenhouse gas inventory shows higher emissions than expected but that much of the increase is driven by changes in state models and a temporary change in the electricity supply mix, not by a sudden surge in local activity.

The inventory, which measures emissions relative to 1990 levels and supports the city's Game Plan 2028 target of 56% below 1990 by 2030, showed large increases in the transportation and electricity sectors for 2024. Staff said those increases reflect two main drivers: an updated California Air Resources Board (CARB) modeling assumption that reduced fleet fuel-efficiency inputs, and a short-term change in Silicon Valley Clean Energy's (SVCE) power purchases that increased emissions factors for electricity in 2024.

City staff emphasized the differences between model outputs and on-the-ground programs and listed recent and planned actions intended to reduce local emissions and increase resilience. They also described steps the city will take to clarify measurements and improve future reporting.

Staff's explanation and context

Presenters told commissioners the CARB model update lowered assumed fuel efficiency for gasoline and diesel vehicles (staff reported an example change from roughly 24 mpg to about 20 mpg for gasoline cars in the underlying county fuel-use data), which increased the calculated fuel use when that efficiency was applied to Sunnyvale's vehicle-miles-traveled (VMT) inputs. Staff described a 17% increase in transportation-sector emissions in the 2024 inventory driven by that modeling change and said they have contacted CARB for more detail about the revised assumptions.

Separately, staff said SVCE could not deliver as much carbon-free power in 2024 because of tight renewable procurement markets and lower hydro availability in the Pacific Northwest. SVCE's board elected not to buy additional renewable energy certificates (RECs) to mask that mismatch and instead recorded the higher emissions in its 2024 supply mix; staff described the SVCE decision as a one-year effect they expect to reverse in future inventories as SVCE brings additional contracted resources online.

What city programs and results staff reported

- Buildings and electrification: Staff said the Game Plan's playbook attributes roughly 44% of modeled reductions to decarbonizing buildings (existing and new construction). The presentation noted nearly 300 HVAC upgrades completed, about 170 heat-pump water heaters installed, ongoing reach-code and green-building work, and municipal facility projects including the all-electric Lakewood Library planned to open in spring and Fire Station 2 designs that include solar and battery capacity.

- Transportation and EVs: Staff reported adding roughly 3,000 EVs registered in Sunnyvale in 2024 (a year-over-year increase the presentation summarized as about 14% in the EV share), 121 new EV chargers reported in local datasets, 22 chargers installed at city facilities, and municipal fleet growth from 22 to 56 electric vehicles after hiring a fleet manager. Staff said the city is participating in regional charging cohorts and planning supportive metrics for VMT and mode shift.

- Waste and food recovery: Sunnyvale is participating in a countywide edible-food recovery program; staff reported nearly 700,000 pounds recovered in Sunnyvale in 2024 and said countywide recovery is on the order of tens of millions of pounds. Staff also flagged that the Smart Station material-transfer facility will receive a major investment (presented as approximately $60 million) expected to raise on-site diversion rates from roughly 39% toward about 55%.

- Grants, staffing and shoreline planning: Staff described several grants and funding items, including a $100,000 electrification engagement grant to fund an electrification liaison for commercial and multifamily outreach, and a regional multi-jurisdiction shoreline adaptation grant of $2.6 million to support planning. Staff said five positions authorized with Game Plan 2028 were hired and onboarded to support implementation.

Data questions, commission concerns and next steps

Commissioners repeatedly pressed staff on data clarity. The most acute concerns centered on (1) the reliability of VMT as reported (Sunnyvale currently interpolates year-to-year VMT from a baseline and a 2035 projection) and (2) how to reflect the CARB model change and the SVCE supply anomaly when showing multi-year trends. Staff said they are seeking CARB clarification, exploring alternative or supporting metrics (such as counts of people walking and biking, shuttle ridership and charger installation), and considering whether to stop producing an annual inventory and instead issue a biennial inventory to reduce staff time spent reconciling model changes and to free capacity for program delivery. Staff also said they will complete a municipal (city operations) greenhouse-gas inventory in the coming fiscal year.

Commissioners asked for more granular, location- and sector-level data (for example, building-level energy use available from benchmarking, and specific breakdowns of commercial versus residential natural-gas reductions). Staff said the city is improving benchmarking compliance and expects better commercial data over time.

Public input and suggested measures

One member of the public, Charlene Liu, urged the city to adopt supportive or relative measures that better track mode shift (for example, bicycle miles or bicycle/vehicle counts and percent changes derived from automated counters or publicly available datasets) rather than relying solely on modeled VMT.

Why it matters and what to watch next

Sunnyvale's 2024 inventory highlights how changes in state-level modeling and in a third-party electricity supplier's procurement decisions can materially affect a city's annual accounting. Staff maintain that local program activity (electrification rebates, municipal fleet electrification, edible-food recovery, and infrastructure projects) is moving forward even as the inventory shows a one-year rise. The city plans to pursue better VMT and fuel-use data with CARB, to continue program implementation, to present an update to city council, and to complete a municipal inventory in the next fiscal year.

For readers interested in evidence in the record: commissioners asked staff to provide recalculations or comparable indicators, and staff said they will return with more analysis and continue coordination with regional and state partners.