There are hundreds of things you can do to make your home more efficient, ranging from simple, free adjustments to major, long-term investments. Which ones you should do in your home will depend on a number of factors—where you live, the size and style of your house, how efficient it already is, which direction it faces, and so on.

Nevertheless, let one principle be your guide: go for the best buys first. Often it will be the cheapest, easiest projects that make the biggest dents in your utility bills. Then, with the money you're saving each month on energy and water, you can tackle further projects.

Some utilities and state energy offices offer great information and financing programs to encourage their customers to invest in energy efficiency and renewables. Ask yours about rebate programs and energy-saving technologies.

The following tips are excerpted from the RMI book and modified for Australia: Homemade Money: How to Save Energy and Dollars in Your Home.

Getting Started

1. Collect your fuel and electric bills for the past 12 months. Divide their total by the square metres of your home—but don't include garages and unheated basements. Most annual bills range from $6.45 to $9.68 per square metre. If your bills fall in this range, or are even higher, you have many cost-effective opportunities to dramatically reduce your bills.
   
2. Measure the thickness of insulation in the roof cavity, basement, and walls. Note the age and condition of your home's major heating and cooling equipment, appliances, the type of windows, and if your water heater is wrapped with an insulating jacket. How does your home feel? Is it drafty on windy days? Are you comfortable?
   
3. Call for help. Most state energy offices have useful consumer information booklets, and can refer you to local weatherization agencies and other energy experts who can help you (Homemade Money's appendix contains an extensive list). Many electric utilities offer free or discounted water heater blankets, new showerheads, or compact fluorescent lamps; many also offer financial incentives for the purchase of more efficient appliances or heat pumps.
   
4. You may want to have a comprehensive audit done on your home, in which case the auditor should list, in order of importance, what should be done. We can send an auditor to your home, typically cost $60 to $150, but if your home energy bills are high it will most likely be worth it.
   
5. Make a plan of action. The following priority lists are a useful place to start. Feel free to substitute your own priorities, since only you, and the professionals who may be helping you, know your situation. Each of the measures listed is discussed in detail in Homemade Money. 

Free—Things That Cost Nothing and Save Cash

• Turn down water heater thermostat to 60°C.
  
• Turn off lights when leaving a room.
  
• Set thermostats to 20°C in winter when you're home, and down to 13°C when you go to bed or when you're away. (Programmable thermostats do this automatically—see below).
  
• Use energy-saving settings on washing machines, clothes dryers, dishwashers, and refrigerators.
  
• Don't waste water, hot or cold, inside or outside your home.
  
• Clean your refrigerator's condenser coils once a year.
  
• Air-dry your clothes.
  
• Close heating vents in unused rooms.
  
• Repair leaky taps and toilets (5 percent of water "use" is leakage).
  
• Close drapes (and windows) during sunny summer days and after sunset in the winter.

Simple and Inexpensive—
Things That Will Pay for Themselves in Lower Energy Bills in Less Than a Year

• Install a water-saving low flow showerhead.
  
• Install water-efficient tap heads for your kitchen and bathroom sinks.
  
• Install a programmable thermostat.
  
• In the roof space and basement, plug the air leaks a cat could crawl through, and replace and re-putty broken window panes.
  
• Clean or change the air filter on your warm-air heating system during winter and on air conditioning units in the summer.
  
• Insulate the hot and cold water pipes.
  
• Install compact fluorescent light bulbs in the fixtures you use the most.

Getting Serious —
Measures That Collectively Will Cost Up to $500 and Have Paybacks of One to Three Years

• Get a comprehensive energy audit, including a blower door test, to identify sources of air infiltration.
  
• Caulk and weatherize all leaks identified by the test. Start with the roof space and basement first (especially around plumbing and electrical penetrations, and around the framing that rests on the foundation), then weatherize windows and doors.
  
• Seal and insulate warm-air heating (or cooling) ducts.
  
• Have heating and cooling systems tuned up every year or two.
  
• Install additional faucet aerators, efficient showerheads, and programmable thermostats.
  
• Make insulating shades for your windows, or add insulating storm windows (or, in a northern climate, shade sunny windows or add solar gain control films).
  
• Insulate hot water pipes in unheated basements, walls, ceiling or crawlspaces.

Going All the Way—Measures That Will Save a Lot of Energy and Money, But Will Take Three to Fifteen Years to Pay for Themselves

• Foundation: insulate inside rim joist and down the foundation wall to below frost-line to at least R-3.5 in cold climates and to R-2 or better in moderate climates. Remember to caulk first.
  
• Basement: insulate the ceiling above crawlspaces or unheated basements to at least R-3.5 in cold climates. If your basement is heated, insulate the inside of basement walls instead to R-3.5 or more above grade and to R-2 or more below grade. Basement or foundation insulation is usually not needed in hot climates.
  
• Roof space: increase roof space insulation to R-8.5 in cold climates, R-6.5 in milder climates, and R-5 plus a radiant barrier in hot climates.
  
• Walls: adding wall insulation is more difficult and expensive, but may be cost-effective if your house is uncomfortable.
  
• Install more compact fluorescent bulbs. Put them in your most frequently used fixtures, including those outdoors.
  
• Replace exterior incandescent lights with compact fluorescents and put them on a timer or motion sensor if they're on more than a couple of hours a night.
  
• Install a radiant barrier in your roof if you live in the Sunbelt states.
  
• Convert to solar water heating, and perhaps also supplementary solar space heating.
  
• Upgrade your water heater, furnace, boiler, air conditioners, and refrigerator to more efficient models. Newer units are far more efficient. Upgrading is often cost-effective, and definitely so if you need to replace failing units anyway. Also, if you've weatherised and insulated, you'll be able to downsize the heating and cooling system.
  
• Upgrade to super insulating or at least low-emissivity windows in cold climates, or low solar transmittance windows in hot climates, if replacement is needed.
  
• Replace high-flow toilets with modern water-efficient dual-flush toilets that use 50–80 percent less water.
  
• Install awnings or build removable trellises over windows that overheat your home in the summer.
  
• Plant a tree to shade your largest west window in summer. You won't save any money for years, but you'll get an A+ for long-range vision.