Updated (03/25/25)
What is the LEAN Deep Energy Retrofit Pathway?
An incentive pathway for a retrofit to an income eligible multifamily building that meets a 40% reduction in site EUI compared to existing building conditions. The incentive is $350 per million BTU (MMBTU) savings, as calculated through a whole building energy model.
- Projects must include higher-than standard weatherization and other energy efficiency measures to reach the 40% reduction target.
- Projects may include electrification of space heating and water heating.
- Renewable electric systems do not count toward 40% savings.
- Projects are client-managed, and clients must do the upfront work of designing and selecting the scope.
- The incentive is paid out at the end of installation, after LEAN inspection.
- The pathway includes a free building performance review within 12 months.

What is the Process?
The LI DER process is distinct from the standard LEAN program, however, both use the same application form. Because much of the work is client-managed, including the design, scoping, and contractor selection, LEAN’s role is to establish the projected savings and then conduct an inspection, issue the incentive payment, and oversee the building performance review.
Submission
Client: Stage 1 - LEAN application; any known DER details;
Stage 2 - audit or equivalent if done, scope details, modeling if any, costs & sources.
Discovery & Validation
LEAN: Stages 1 & 2 - reviews materials, conducts audit if needed, estimates incentive;
Stage 3 - sends for final energy model when ready, calculates incentive.
Reviews & Approvals
LEAN: Stage 3 - conducts completeness review of final energy model, submits for internal & PA approval;
Post-Stage 3 - sends incentive documents to client
Client: Signs incentive documents.
Construction & Invoicing
Client: Manages construction, submits invoice(s) to LEAN.
Inspection, Payment, Cx
LEAN: Manages inspection & building performance review, issues payment.
What to Know Before Getting Started
We use clients’ energy models to gauge the feasibility of a project meeting our 40% EUI savings threshold. We do not use client energy models to establish the MMBTU savings the incentive is based on. For more information, review page 6 in the Participation Guide linked below and contact us if you need more information.
Key things to know:
- We have detailed modeling guidelines available for clients on request.
- Clients are not expected to follow our guidelines during their own energy modeling and should be aware that their results may differ from ours.
How to Get Started:
Submit the LEAN application here and indicate “yes” in the DER question.