It may be surprising that just these three systems — mechanical, electrical and plumbing (MEP) — can make up as much as 15% of the total environmental footprint of a building's materials. Even more important is the operation of these systems, particularly mechanical and plumbing. In many cases, pipes and ducts are run willy-nilly after a home has been designed. The frequent result: high energy and water bills. These details are examples of how MEP systems must be integrated into a home's design and then installed according to the design for optimal performance.

The toughest details are those that have to match up with someone else's work, or those done — even done well — when energy was really cheap. These details are a collection of some common — and tough — dovetails of existing work with retrofits or additions. Bear in mind that green remodeling means creating a new operating regime that is better, not worse, than the one that may well have been working just fine before. Integration of energy efficiency, moisture management, and indoor air quality is much more important and challenging in remodeling than in new construction.

If you set your tank water heater temperature to the recommended 120°F and the space it is in is 70°F, that is a 50 F° difference. That is equal to the difference between the inside and outside of your house in the winter when it is 20°F outside! We should be insulating tank water heaters with just as much insulation as we do our walls. Wrapping your tank water heater with extra insulation is easy, inexpensive, and essential. Of course, insulation should never block the air intake opening for a gas water heater.