passive solar design : Building design that takes advantage of the fact that the summer sun is higher than the winter sun. Overhangs shade the building from the summer sun and allow the lower winter sun to enter the building and heat it.

petrochemicals : Chemicals derived from petroleum.

phantom load; standby power: Energy drawn by a plugged-in appliance even when the appliance is turned off.

plastic identification code : A triangle with a number from 1 to 7 inside indicating what type of plastic an item is made from.

PV cell: A photovoltaic cell; a cell with a thin semiconductor that converts solar power into electricity.