Energy
Retrofits

Building Decarbonization

Which mix meets the emissions target at the lowest cost once the cheap retrofits hit their installation limits?

Optimized portfolio

Least-cost compliant mix

Eff 1,500 · HP 2,500 · Solar 600 · Gas 931 · Green 469 MWh

Minimum cost to target

~$356k/year

What binds

Retrofit caps + carbon target (not budget)

Portfolio model

Least-cost portfolio

Why this mix

Efficiency, heat pumps, and solar all reach their installation limits. The carbon target limits gas to 931 MWh and requires 469 MWh of green power.

Situation

The portfolio must serve 6,000 MWh and meet its carbon target. Efficiency, heat pumps, and solar each have installation limits.

Model logic

Chooses the lowest-cost supply and retrofit mix that meets demand and the emissions cap.

Portfolio logic

Efficiency, heat pumps, and solar all reach their installation limits.

The carbon target limits gas to 931 MWh and requires 469 MWh of green power.

Budget still has headroom; retrofit capacity and carbon set the plan.

Takeaway

Use the least-cost compliant mix: 1,500 MWh efficiency, 2,500 heat pumps, 600 solar, 931 gas, and 469 green power.