Insulation reduces energy costs by slowing the transfer of heat between the conditioned space inside a building or enclosed space and the outside. Adding insulation is a cost-effective way to the improve the energy efficiency of an existing building. Below are a few key considerations when applying for insulation incentives through Energy Trust’s Existing Buildings program.

Standard (prescriptive) insulation incentives are only available for conditioned spaces. To receive an incentive for adding insulation to an existing commercial space, the space must be considered conditioned by code. Energy Trust recommends checking the with property owner for permit information if the space conditioning type is unclear.

Building codes permit a space as conditioned, semi-heated, or unconditioned as defined by ASHRAE. The space conditioning type determines what energy and building codes are applicable to that space. There are different code requirements for insulation when the space is considered “conditioned” vs “unconditioned”. See this article published by the US Department of Energy for details on space conditioning types.

Commercial building insulation comes in all forms, from traditional batts to advanced roofing systems. It can be difficult to understand how these different insulation options fit within Existing Buildings incentives. Existing Buildings refers to ASHRAE Standard 90.1 to promote clarity and follow industry standards.

The definitions of attic insulation and roof insulation have been expanded in 2025 to more clearly align with ASHRAE Standard 90.1. See the chart below for details:

If you would like to learn more about incentives for commercial or multifamily projects please reach out to your dedicated trade ally coordinator. You can also reach out to Portia Eaton at peaton@trccompanies.com.