These ones are for year-round use, though. Here we go.
- This one is obvious, but some people don’t get it. Lights. Turn them off when you’re leaving the room (unless you’re returning in the next couple of minutes). And change your light bulbs. When the regular incandescent bulbs you have in your lamps burn out, replace them with energy-saving compact fluorescent bulbs (CFL), or even better, LED bulbs. CFLs last ten times as long as regular bulbs and are four times more efficient, but LED bulbs last ten times as long as CFLs and are three times more efficient.1 Don't worry, the days of harsh fluorescent lighting are over—both CFLs and LEDs now come in “warm white” so as not to cause headaches and eye strain. CFLs and LEDs are more expensive than incandescents, but if you do the math, they’re worth it cost-wise and definitely environmentally. See Eartheasy’s page on Energy Efficient Lighting for additional important information about each type of bulb, including how to choose the right strength. Also, be sure to read their section on proper disposal of CFLs due to their mercury content.
- Vampire electronics: These are home electronics like computers and peripherals, video and stereo equipment, and kitchen appliances like coffee makers and toasters that suck juice even when they’re not being used. If there’s a light on it, it’s on and using electricity. Turn them off.
Some appliances and electronics now are made to never be completely off unless they’re unplugged. It’s hard to know which of your belongings do this and which don’t, so it’s best to use power strips. You can get a bunch of power strips inexpensively from a department or general store (even dollar stores often have them). Place them anywhere you have multiple electronics within cord distance from each other. This way, instead of going around unplugging and plugging back in each device, just get in the habit of flipping the power strip off whenever they’re not being used. Some power strips also contain surge protectors which are especially important for expensive devices as they can save them from being fried if there’s a sudden surge from lightning, downed power lines, equipment malfunction, etc.
The biggest perpetrator of all the vamps? Chargers, namely cell phone chargers. A lot of people leave their charger plugged in all the time and just attach their cell phones when they are running low. The bad news is that even when there's no phone connected to them, most phone chargers are sucking electricity. This goes for most chargers. Don't leave them plugged in when you're not using them, and don't use them if your device doesn't really need to be charged. Unplug them as soon as they finish charging.
- Turn your computer off if you’ll be away for more than an hour. I recommend you set your preferences to automatically turn the monitor off and sleep the computer when it’s been inactive for 15 minutes, and hibernate/standby after 30. What's the difference between sleep and hibernate? In laptops, sleep still uses a little electricity to keep whatever you were doing in memory, but hibernate stores it instead and shuts off completely, using no electricity (unless it's charging, i.e. plugged in). In desktops, they're pretty much the same thing; they're still using some electricity.
If you're going to be away for more than a hour, shut the computer down completely and flip off the power strip. Contrary to rumor, it does not take significantly more energy to boot up a computer than to let it run for even relatively short periods of time.2 It is also not true that turning your computer off every night (and/or day while you’re away) is bad for it. It will not damage the hard drive.3 In fact, it’ll save some life and prevent possible overheating. Plus, as we all know, restarting a computer can solve a myriad of silly software problems. It’s good for it.
If you have peripherals you rarely use, plug them into a separate power strip from your computer that you can then leave off until you need one of your peripherals.
If you need help activating your computer's power-saving settings, see your OS's help program or check EnergyStar's tutorial. And if you're a Mac user, Apple has a cool energy use calculator for its computers.
By the way, screensavers don't save any energy at all; they're completely pointless for flat screens. Some of them even keep your computer from automatically sleeping.
- Heating water is the next expensive energy suck after home heating. Be conscious of the time you spend in the shower—it will cost you. If you take short showers, fine. But if your showers last more than ten minutes, consider taking a bath instead. It'll use less water. The absolute best thing, of course, is to take short showers and install a low-flow shower head (you can get one for around $10 if you shop around).
Also, if your hot water heater is electric, get in the habit of turning it off before you go to bed at night or when you’ll be on vacation or otherwise away from the house. I have to say, though, if you shower in the morning and aren’t going to want to trudge down to the basement when you wake up and then wait half an hour for the water to heat up, turning it off every night is probably not the best option. However, there’s no reason not to do it while you’re away or if you shower at night. It can save you a surprising amount on your electric bill.
Whether your water heater is electric or gas, make sure you insulate the pipes. Insulating hot water pipes prevents heat-seep and insulating cold water pipes keeps them from freezing and breaking if the temperature drops very low. For specific directions on insulating water pipes (and even water heaters), see Eartheasy’s page on energy-efficient heating.
Laundry: Most of us were taught to use hot water for whites and tough stains, warm water for permanent press, and cold water for delicates—but that really doesn’t hold anymore. Most laundry detergents now are powerful enough to clean laundry just fine with only cold water. There are even detergents that are specially formulated for cold water, although buying these may not be necessary. If you’re unsure, do a test load in cold water with your regular detergent and see if you can tell the difference. The same goes for dishes. There’s no need to use scalding hot water; room temperature water will usually do just fine. Also, turn off the "heat dry" option on your dishwasher; instead, when it's done just crack open the door an inch or two to facilitate air drying.
Adhering to the “fill not run” rule will almost always save a significant amount of water (and money). This rule refers to the value of filling a basin with water rather than leaving the water running while you perform a task (bathing, shaving, washing/rinsing dishes, etc.). And please, leaving the water run while you brush your teeth is just plain careless.
- Cooking: My mother always said that the oven loses a fifth of its heat every time you open the door, but I guess I thought it was just an old wives' tale. Well, it's not. So don't keep opening the door every five minutes to check on the food. Another quick hack: turn the oven off ten minutes before the food is done. As long as you don't open the door, the remaining heat will be sufficient for the last ten minutes of cooking time. The same goes for electric stovetops.
Ever wonder why one of the coils on your electric range is smaller than the others? It's so you don't waste energy when cooking with a smaller pot or pan. Remember, size matters.
If you don't need a huge fridge, don't get one. Seriously, if there are two or three people sharing a refrigerator, a regular sized one is plenty big enough. The bigger the icebox, the more space needs to be kept cold and the more energy is used to do so. Also, make sure it's not set too cold. Good fridge temps are between 35 and 38 degrees, 0 for freezers.4
 Green Houston, the mayor's Office of Environmental Programming website.
 "User Guide to Power Management for PCs and Monitors," Bruce Nordman, et al. Lawrence Berkeley National Laboratory. January 1997.
 "Refrigerators & Freezers for Consumers," Energy Star.