One of the basic principles of permaculture is catching and conserving resources when they are abundant so you have access to them when they are unavailable. For instance, a greenhouse can catch and store the sun’s energy to keep plants warm. With clever placement, a greenhouse can even provide passive solar heat for other buildings. Canning abundant summer produce for lean winter months is a way of storing food energy. Harvesting rainwater or recycling greywater from the house prevents valuable irrigation water from being lost to runoff or the sewage system, and provides water energy during dry months. With the extended drought in California, saving our scarce rainwater so that we can water our gardens later is a great idea!