A home energy audit is the first step to assess how much energy your home consumes and to evaluate what measures you can take to make your home more energy efficient.

You can easily conduct a home energy audit yourself ( DIY ). With a simple but diligent walk-through, you can spot many inefficiencies in any type of home. You should keep a checklist of areas you inspect and problems you find as you go. This list will help you prioritize your energy efficiency upgrades.
Air Leaks
First, make a list of obvious drafts. This will indicate where air is leaking. Check for indoor air leaks, such as gaps along the baseboard or edge of the flooring and at junctures of the walls and ceiling. Check to see if air can flow through these places:
√Electrical outlets
√Switch plates
√Window frames
√Baseboards
√Weather stripping around doors
√Fireplace dampers
√Attic hatches
√Wall/window-mounted air conditioners.

If you can see daylight around a door or window frame, you have an air leak. All of these cause you to use more energy.
DIY Basic Building Pressurization Test:
==>Close all exterior doors, windows, and fireplace flues.
==>Turn off all combustion appliances such as gas burning furnaces and water heaters.
==>Turn on all exhaust fans (generally located in the kitchen and bathrooms).
This test increases infiltration through cracks and leaks, making them easier to detect.
TIP: Use incense sticks to locate leaks. Moving air will cause the smoke to waver.
OUTSIDE: Check the exterior of your home by inspecting all areas where two different building materials meet.
Insulation
You will need to find out how much insulation you have in your home and where. For energy efficiency, your home should be properly insulated from the roof down to its foundation. Inspect the following areas:
√Attic spaces
Attic access doors to unfinished attics
(If the attic hatch is located above a conditioned space, check to see if it is at least as heavily insulated as the attic, is weather stripped, and closes tightly.)
Knee walls in finished attics
√Ducts in unconditioned spaces
√Cathedral ceilings
√Exterior walls
√Floors above unheated garages
√Foundations
Basements
Crawl spaces
√Slab-on-grade floors

R-value indicates insulation’s resistance to heat flow. The higher the R-value, the greater the effectiveness.

When calculating the R-value of a multilayered installation, add the R-values of the individual layers.

√ While you are inspecting the attic, check to see if there is a vapor barrier under the attic insulation.
√Make sure that the attic vents are not blocked by insulation.

√Interior walls
Select an exterior wall and turn off the circuit breaker. Be sure to test the outlets to make certain that they are not "hot." Remove the cover plate from one of the outlets and gently probe into the wall with a thin, long stick. If you encounter a slight resistance, you have some insulation there. Ideally, the wall cavity should be totally filled with some form of insulation material.
Unfortunately, this method cannot tell you if the entire wall is insulated, or if the insulation has settled. Only a thermographic inspection can do this.
√Basement
Your water heater, hot water pipes, and furnace ducts should all be insulated.
Heating/Cooling Equipment
√Check furnace filters
√Check your ductwork for dirt streaks, especially near seams.
(This indicates air leaks)
√Insulation R-Value (6 is recommended for ductwork)
Lighting
√Wattage size of light bulbs. (You may have 100-watt bulbs where 60 or 75 watts would do.)
If your are not a DIY’er, professional auditors use a variety of techniques and equipment to determine the energy efficiency of a structure. Thorough audits use equipment such as blower doors, which measure the extent of leaks in the building envelope, and infrared cameras, which reveal hard-to-detect areas of air infiltration and missing insulation. Many help you find government programs that help with financing too.

Source: With Permission from the U.S. Department of Energy – Energy Efficiency and Renewable Energy