Technical committee tests EUI calculator, sets work plan for Evanston building targets

Members of Evanston’s technical committee spent the session testing a new spreadsheet calculator intended to translate percentage reductions into final site energy‑use intensity (EUI) targets and to help set interim steps toward 2050 goals.

The committee’s staff member led a walkthrough of the tool and noted it summarizes interim steps and produces a final column that “tabulates it all up so that you see what the total reduction is.” Participants repeatedly tested different percentage inputs and raised that, in some versions, the sheet showed zero buildings above target. The staff member said they would resend an updated version for troubleshooting: “I’ll send you updated version again. Maybe something happened, something calculated,” they said.

Why it matters: the spreadsheet will determine how many buildings must retrofit at each interim checkpoint and therefore which property types to prioritize. Committee members emphasized using local benchmarking: the baseline defaults use Evanston’s 2024 median data but can be switched to national medians for comparison. One member summarized the local approach plainly: “So we’re using actual data from our buildings here in Evanston.”

Committee discussion focused on three practical choices: whether to let users work “forward” by applying periodic percentage reductions or to let them enter a final EUI and have the tool compute required steps (a “work‑backwards” column); how granular building‑type categories should be; and how to treat outliers such as shared‑meter central plants. The group agreed a notes/comments column and a first tab with clear instructions or metadata would help internal collaboration and future public use.

Slipstream deliverable and timeline: staff reported Slipstream supplied the calculator and will produce a written methodology explaining assumptions (outliers, building‑type choices and baseline selection). The committee directed that Slipstream’s outputs and a revised spreadsheet be available for the next meeting; one participant noted the Slipstream tool is expected by the next session (noted in the meeting as the next meeting date).

Offsets, renewables and the Beam portal: members discussed whether allowable carbon offsets or renewable energy purchases should be restricted to local projects or permitted from external markets. Staff explained Beam and Portfolio Manager will capture site or source emissions and can be used to upload supporting documentation (power purchase agreements, offsets receipts) but that Beam may not automatically flag RECs/offsets today. The committee agreed the policy around what offsets are acceptable should be defined by its deadlines in September.

Alternative compliance form: staff presented a draft alternative compliance plan (ACP) form to request adjustments (time, target or other). Members recommended simplifying many financial categories into a single “financial hardship” box and requiring applicants to upload supporting documentation. The group suggested the form include clear prompts — building ID, address confirmation, verification year and ability to link to Beam data — so the city avoids repetitive follow‑ups.

Equity and verification: participants recognized a wide range of owner capacity — from sophisticated portfolios to small churches — and debated what verification or audit level to require for an ACP. The committee favored flexibility with clearer guidance on acceptable supporting documentation and follow‑up check‑ins tied to plans submitted for alternative compliance.

Next steps and action items: staff will circulate an updated spreadsheet, Slipstream’s methodology report and the draft ACP form; members will test the tool and meet again in approximately two weeks to advance consensus on interim EUIs and documentation standards. The meeting closed with members agreeing to use the summer to refine targets and to return with proposals for the next session.

Quotes in context are attributed to meeting speakers as recorded in the transcript and identified here by role rather than by name because the transcript labeled voices numerically rather than by self‑identification.