All homes use energy Energy is used in myriad ways in our homes, but in most homes, energy use tends to follow a fairly simple 60-40 rule. About 60% of your home's energy is consumed by space heating, cooling, and water heating. The other 40% goes to power lighting and appliances.
Reduce with energy efficiency Replacing your home's older inefficient equipment, and improving the home's insulation and air tightness, reduces energy use. This is called energy efficiency, and it's typically the first thing to do - because it not only pays for itself through savings on utility bills, it also increases home comfort and occupant health.
	Replenish with rooftop solar The right energy efficiency improvements can decrease a home's energy usage anywhere between 20% - 60%. Adding rooftop solar can make up for the remaining energy use.
Net-Zero Energy! A home whose energy use is first reduced with energy efficiency, and the remaining energy is made up by energy produced by rooftop-solar is deemed a "Net-Zero Energy" home.