Energy efficiency is a little more technical, but the basics are a tight building envelope and passive solar design. Next comes efficient heating and cooling appliances and lighting. High end air source heat pumps with variable speed indoor and outdoor units are standard. Also standard are heat pump water heaters which produce hot water using about 25% the energy of a standard electric water heater. They also dehumidify the home. We use 95-100% LED lighting. And we install induction cooking appliances. We use heat recovery ventilation for exhaust and fresh air. The average HERS score for our homes is under 50 and the typical annual conditioning cost of our homes is under $200. All of our homes can be net zero energy with a limited amount of solar electric production.