The first step to making your house energy efficient is to do a home energy checkup to analyze how your household uses energy.
Energy efficiency and conservation can be achieved by installing an automatic setback or a programmable thermostat and resetting the thermostat when you are asleep or away from home. According to Every.gov, turning your thermostat lower by 10-15 degrees Fahrenheit for eight hours a day form its normal settings can save you 10% a year on heating and cooling. Setting the thermostat at 68% Fahrenheit or lower during the winter and 78% Fahrenheit during the summer is generally recommended.  During winter, energy conservation can be attained by turning down your heater when using your fireplace and closing the damper to block out cold air. Closing curtains and shades can prevent warm air from escaping. 
Turning off lights when they are not in use, and using LED lights are ways to decrease energy consumption. Insulating your house properly will also improve energy efficiency. Use of low flow fixtures for showers and bath is also recommended. The use  of renewable energy resources (Geothermal, Solar, Biomass, and Wind) can reduce the burning of fossil fuels, lessening the carbon output from the house.  In terms of location, the home should be located close to stores, school, work, and especially a mass transit facility, such as a  bus stop, or BART/train station.  Locally grown produce provide both fresh products and decrease energy consumption these good will not need to be transported long distances.