Older building can have materials that are potentially poisonous. When the materials and building structure degrade, it can lead to serious occupant health problems or building-related illnesses.

Certain windows (particularly older, metal-frame, single pane ones) transmit a lot of warmth out of your space in the winter, and a lot of coolness in the summer. This can be prevented by replacing them with multipaned and insulated frame windows.

Some stoves do not make efficient use of energy;

Some freezers lose much of the coolness they make and do not make efficient use of the electricity they consume. This is especially true of older models, and important in homes with large numbers of people.

Let the warm sunlight in through south-facing windows to lower the heating bill and reduce the need for additional lighting.

Keep direct sunlight from shining into rooms and you'll not only keep everyone cooler, you'll also lower your utility bill.

Skylights can lose heat in the winter, and gain heat in the summer. This can be reduced by replacing them with multipaned and insulated skylights.

Most electronic equipment draws small amounts of power, even when they are in the 'off' state. Unfortunately, when many devices are in such a state, for 24 hours for every day in the year, the amount of power consumed is actually very significant.

A cool roof will significantly reduce the loss of coolness in the summer. This is especially important in areas where air conditioning is used a lot.

If you are currently heating your home with electric resistance heat (such as electric baseboards), or you have a heating system that runs off of propane or fuel oil, you should consider installing an ground source heat pump (GSHP). GSHPs, also known as geothermal heat pumps, use electricity to move heat from a heat exchange loop buried underground or in water to inside your house providing heating in the winter. Because the technology moves heat rather than generating heat, and the ground remains a relatively constant temperature throughout the year, GSHPs are often two to four times more efficient than conventional electric heating systems and are also much cheaper to operate than fuel oil, propane, and some natural gas systems. They are also more efficient than other types of air conditioning systems providing additional savings during the summer. GSHPs can be used with an existing ducted or hot water heating/cooling systems by using a water to air or a water to water GSHP respectively.