Eagle County’s Building Decarbonization Master Plan
Project Overview
Eagle County, Colorado, a county of about 55,000 people that stretches from resort communities like Vail and Beaver Creek to working ranch land, is building a decarbonization master plan for every building and vehicle it operates. The county’s goal is to eliminate fossil fuel use in its operations by 2050, with a 50% reduction required by 2030. Protecting the mountain ecosystem is one of the county’s strategic priorities, so the plan has full support from leadership and connects directly to the community-wide climate action plan.
The county had already made real progress on efficiency, renewables, and electrification, including a geothermal project that decarbonizes a 75,000 square foot campus and cuts about 140 tons of emissions a year. But staff concluded that one-off projects would not scale to the size of the challenge. They needed a practical, step-by-step roadmap that was cost-effective, lined up with existing capital improvement and equipment replacement schedules, and had buy-in from other departments.
To get there, the county inventoried everything under its control (buildings, fleet, and equipment), then brought several departments together to write an RFP, review proposals, and select a consultant. They chose Millig Design Build, which scored highest and works as an energy performance contractor with a design-build approach, so its cost estimates are reliable enough to put into a budget. Millig’s team included CLEER, the firm that has prepared the county’s annual greenhouse gas inventories for years and already held its historical data.
Eagle County’s portfolio is 21 buildings totaling about 550,000 square feet. In its 2023 baseline year the county emitted a little over 1,700 tons of carbon. Projects completed or underway since then cut about 390 tons, a 22% reduction, leaving another 28% to reach the 2030 goal. Millig identified a priority project list of about $6 million that closes that gap, while also producing a net energy cost savings of about $20,000 a year. That savings is modest, but significant given that poorly planned electrification can multiply utility bills. Counting work already done, the county expects to reach its 50% reduction for roughly $13 to $15 million over about seven years.
Priority projects include replacing the natural gas boiler plant at the Justice Center with a heat pump plant tied into the geothermal system, replacing infrared gas heaters at the airport (a simple, cost-effective step), reusing airport terminal exhaust air as makeup air for a partly enclosed baggage handling area, and swapping packaged rooftop equipment at community centers for heat pumps. Building on this internal plan, Eagle County plans to develop a companion community-wide decarbonization plan in 2026 to define its role in meeting community climate goals.
What decarbonization costs: Millig’s benchmarks
Millig has produced decarbonization master plans for about 22 million square feet of buildings across North America over the past five years, including a plan for the 3 million square foot Washington State Capitol campus built around an ambient temperature loop with geothermal exchange. A meta-analysis of its completed plans produced a useful rule of thumb: the installed cost to eliminate one ton of annual carbon emissions.
For energy-intensive facilities that run around the clock, such as hospitals and pharmaceutical plants, that cost can be as low as about $3,000 per ton. For the buildings most towns and counties own (offices, courthouses, jails, schools, and community facilities), the range is wide but averages about $20,000 per ton. The first half of the reductions tends to be cheaper, about 15% below that average, while the second half runs about 15% above it. Communities with a greenhouse gas inventory can use these figures to estimate the rough scale of investment ahead.
Lessons Learned
Base the plan on data and whole-building analysis
Many master plans rely on rules of thumb or cost per square foot, or only look at central plant equipment, which leaves them too vague to act on. Energy modeling and a holistic understanding of each building prevent costly one-for-one swaps. Millig described a mountain client that replaced a gas boiler with an electric boiler and saw utility bills triple or quadruple. At average Colorado rates, moving from gas to electric resistance heat raises bills by about 400%, while a well-designed heat pump approach can bring costs close to even.
Reduce loads before you electrify
If a building wastes 30% of its energy, electrifying it as-is means oversized, more expensive equipment and bigger electrical upgrades. Load reduction is the foundation of the plan. Electrifying both buildings and vehicles also adds demand on a property’s electrical capacity, so the two need to be planned together.
Phase the work alongside existing capital needs
Over a 35-year horizon, nearly all building equipment will be replaced anyway. Timing decarbonization upgrades to coincide with planned replacements turns them into a small incremental cost rather than a standalone expense. Front-load a few high-impact projects to build momentum and public support, and prioritize equipment that is at the end of its life.
Pursue every outside funding source
Eagle County’s geothermal well field was more than 50% funded by outside sources, which made it much easier to secure the local match. Pairing decarbonization with co-benefits like deferred maintenance, comfort, lower operating costs, and resilience also helps projects win funding.
Ask for detail when you hire a partner
Climate action plans are often too broad to act on. A useful decarbonization plan specifies which equipment gets replaced, with what, and when. When writing an RFP, ask for work samples and look for partners who model buildings holistically, reduce loads first, phase work with capital plans, and actively pursue external funding.
Program Contacts
Kate Kirkman, Resiliency Department, Eagle County
Lauren Donley, Co-Founder and Vice President, Millig Design Build