December 5, 2013

A deep energy retrofit is a building energy upgrade that reduces energy consumption by 50% or more.

There seems to be a lot of confusion over the meaning of a "deep" energy retrofit. The confusion hinges on the difference between a basic or shallow energy retrofit versus a deep energy retrofit? 

Let's begin by defining "energy retrofit," which is a package of improvements or upgrades that reduce a building's energy consumption. The effectiveness of a retrofit is typically based on the amount of energy saved, expressed as a percentage, which is the direct result of the home improvements. 

So, where is the line between a deep energy retrofit and a basic or shallow retrofit? To be frank, I don't exactly know. Some set the bar quite low for a deep energy retrofit, somewhere in the neighborhood of a 30% reduction. There seems to be much more consensus among experts, such as the Rocky Mountain Institute and Green Building Advisor, that a deep energy retrofit must result in at least a 50% energy reduction. Yet, some purists argue a 70% reduction is required in order to justify the tag of deep energy retrofit. 

If I had to vote on this matter, I'd say a deep energy retrofit must result in at least a 50% reduction in a building's energy consumption. However, I think the more important distinction is between those projects that embrace the concept of a "home as a system" versus single measure improvements, such as replacing windows or swapping out incandescent bulbs in favor of CFL's. Achieving a 50% reduction in energy usage is unlikely unless you address the house as a whole, making improvements to the building envelope, mechanicals, etc.  

What do you think?

What percentage of energy reduction is required of a "deep" energy retrofit? Please leave your thoughts in the comments below.