Ovens - Before buying an oven, first you have to ask yourself whether you need a gas oven or electric oven. This decision is based on your cooking preferences. Also, consider the type of cleaning process it uses. Standard ovens will have to be cleaned manually, but there are now self-cleaning ovens with programmable settings, which use high temperatures to clean off any residue. Continuous cleaning ovens have special finishes that absorb or burn off splatters from the oven.

Refrigerators - As a rule of thumb, plan on purchasing 8-10 cubic feet of space for a family of two, then add an additional cubic foot of space for each family member. Refrigerators with freezers on the top are more energy efficient than models with side freezers.

Dishwashers - Always find out the amount of water a dishwasher uses for every different cycle. Look for features that reduce water use. Newer, more expensive stainless steel models enhance efficiency during drying cycles and can tolerate higher water temperatures.

Ventilation Hoods - The fan will be the most important factor here. Axial fans are inexpensive but not as powerful as centrifugal fans. Try to find hoods that have a tempered glass light lens. These are more durable than the plastic lens, which yellow and crack, and they last longer. You should also consider buying one with a low sone number. Sones measure the noise level created by air-moving appliances, and the lower the sone number, the quieter it is.

Garbage Disposal Systems - There are a few things to consider when you want to buy a garbage disposal. Think of how many meals per week are prepared in your kitchen, how often you entertain, and the importance of quiet operation and long product life. You also must know if you are hooked up to a septic system or regular water system.

Air Conditioners - When looking for a powerful air conditioner, check out the yellow energy tag (represented as Energy Efficiency Ratio or EER) and consider its efficiency. The EER numbers range from a minimum of eight to a maximum of 12. You'll want to look for high EER numbers. After this, you also need to consider the space of the room you'll be putting the air conditioner in, as well as your budget. Do you need to cool the whole room? Does the weather change a lot where I'm located? The answers will help you find a suitable model that will fit your needs. Try to match the unit's cooling capacity with the size of the room. According to the Department of Energy, air conditioner size should be determined by multiplying the room's square feet by 20.

Water Heaters - Look for hot water heaters that are energy efficient. There is an EnergyGuide%u2122 label you can read to determine the estimated energy consumption of a particular unit and its estimated annual operating costs. Using these information, you can compare models and see which ones are better at energy saving. As for tank size, it refers to the number of gallons of water that the water heater can hold. The more gallons you need per hour, the larger the tank must be. Of course there are also tank-less systems which heat water as you need it. Tankless water systems are powered by either electricity or gas and turn off when not in use. However, they have trouble supplying large amounts of hot water at any one time.