A DER causes a home to leapfrog well beyond the level of performance typical for current building practices. DER extends the useful life of the building or the building component by positioning it to perform, and perform well, for another 50-100 years.

What is important to keep in mind is that significant changes to the building enclosure will have profound effect on the dynamics of water, air, vapor and heat flow within the home. What may have worked before the retrofit - e.g. a leaking window where the water was able to dry through an uninsulated wall - may not work after the retrofit. By virtue of the fact that the building is standing and people are living in it, we can guess that the building is working. But we may not know exactly how it is working. So one must approach DER with a healthy dose of humility. It is important to be aware of ways in which the DER could change the dynamics of the building. Modifications to the building must aim to always reduce known risks.