What is a deep energy retrofit (DER)?
A deep energy retrofit is a renovation to an existing building whose owner seeks to reduce energy consumption by a significant percentage – often 50% or more. Deep energy retrofits typically focus on adding significant levels of insulation to basements, walls and roofs, aggressive air sealing to stop leaks of warm air, replacing leaky windows with high performing units, upgrading the mechanical system to the most efficient, appropriately sized unit available and adding mechanical ventilation. Many sites on our Resources and Links page discuss deep energy retrofits in more detail.
