ABOUT EFFICIENT PLUMBING LAYOUT
Sound planning saves energy
Heat losses increase with the diameter of the line, the distance the water must travel, and inversely with the speed at which the water moves. A large volume of slow-moving water sheds more heat as it travels to its destination than a smaller amount of water moving quickly.
For that reason, zoned trunk-and-branch systems (also known as structured plumbing) save water and energy compared to conventional trunk-and-branch systems or home-run (manifold) systems.
Heat loss in conventional systems. A 3/4-in. dia. supply line in a trunk-and-branch system holds a lot of water. When a hot-water tap is opened in a bathroom far from the water heater, all the water sitting in the 3/4-in. pipe must flow through the system before any hot water reaches the user.
In a home-run system, the tubing is usually only 3/8 in. or ½ in., so less water is wasted before hot water reaches the faucet.
Structured plumbing. To reduce the time it takes hot water to reach a remote faucet, save energy, and save water, green builders should install a type of plumbing system called “zoned trunk and branch” or “structured plumbing.” For more information on structured plumbing, see these two articles:
- “Inefficient Hot Water Piping Layouts Waste Hot Water” by Gary Klein
- “Efficient Hot-Water Piping” by Gary Klein