In seeking to create a built environment based on regenerative principles, one goal often cited is to create closed loop systems of water and waste. Net-positive Water is the sole Imperative for the Living Building Challenge’s Water Petal, for instance. The idea is that we ought to be able to supply all our potable water needs using filtered and sterilized rainwater that falls on the site; wastewater recycling is another option but using it for drinking water complicates matters even more.
In our pursuit of lower construction costs and greater efficiency in energy, materials and land use, we often work very hard to reduce the geographic footprint of the project. This is especially true in the residential sector, and doubly so in affordable housing projects. Greater density is often heralded as a basic groundrule of sustainable design (at least in urban settings).
But as we will discuss, density also presents serious challenges to developing projects that are net-zero in energy and water.