Proper insulation and ventilation is the first and most important energy saving measure. It can reduce heating needs to one-third (about 50 kWh heat/m2/y) or even one tenth (less than 15 kWh heat/m2/y) of what an average house would need. Remarkably, a properly insulated house, which only needs a third of the heat to keep you warm, will not be more expensive to build. The extra investments in insulation, ventilation and high-efficiency glazing, can be offset by a smaller and cheaper heating system. An efficient house will also be healthier and more comfortable to live in - it avoids 'cold radiation' (as from windows), the differences of temperature between heated and non-heated rooms is less, and it can be more efficiently ventilated.
In hot regions, energy use for active cooling (air conditioning) can be minimized or even avoided if the construction is well-thought out. In a moderated climate, active cooling can always be avoided.
Electricity consumption differs dramatically in households around the world. In fact, the average household in Europe consumes 4,667 kWh, in Japan 5,945 kWh per year, whereas the typical American household consumes 11,209 kWh. American households use three times more electricity for lighting, and twice as much in refrigerators than in the EU. This doesn't necessarily reflect a difference in comfort. As we'll explain, there are high efficiency appliances that consume 2 to 10 times less electricity for the same functionality, and that are usually of higher quality too.
Using only highly efficient and money saving appliances can reduce the electricity consumption of an average household to as low as 1,300 kWh/y, without any loss of comfort. This is almost 10 times less than the U.S. average.
Using electric hot water heaters or space heating is extremely inefficient. At the power plant, some 60 percent of the energy is lost as waste heat. Another 10 percent is lost in electricity lines and transformers before the electricity even reaches your home.
Use efficient lighting
Replace incandescent bulbs with compact fluorescents (CFLs). Compact fluorescents use four times less energy, and last eight times longer (8,000h instead of 1,000h) than incandescent light bulbs. For example, a typical 75W incandescent bulb will be replaced by an 18W compact fluorescent. The compact fluorescent will be more expensive to buy, but you will need to replace it 8 times less often and it will use less electricity, which often makes it the biggest electricity saver in your house. At a minimum, we recommend replacing the bulbs in all lamps that are used for 30 minutes a day or more.
Fluorescent tubes are even more efficient than compact fluorescent lamps, and last even longer (10,000-20,000h). Only use tubes with a modern ballast starter that avoids flickering and lights immediately - good ones add another 20 percent efficiency. Another option is a CFL with a dedicated fixture. The electronic ballast which is part of the fixture lasts 40,000 hours and bulbs can be replaced separately at lower cost. Both CFLs and fluorescent tubes are also available in dimmable fixtures. This can increase comfort, save even more energy and extend the lifetime of the bulb.
Avoid halogen floor lamps, which typically have a power of 300W or more, produce lots of heat and are actually so hot that they can cause serious burns and start fires. Besides, on hot summer days they are very uncomfortable to be around. A CFL floor lamp only uses 50-80W at 104° Fahrenheit. They can save loads of energy and even your life.
Also pay attention to the light fixtures. Clever use of reflectors, and directional lamps to get the light where you need it can save you another 50 percent energy cost and improve your comfort! Well thought out use of efficient lights can reduce electricity needs up to 8 times.
CFLs at the end of their operating life should be disposed of properly so the mercury inside can be recycled. To be clear, even if not recycled, CFLs are still the better choice, since the inefficiency of incandescent and halogen lights causes far greater environmental damage - including mercury emissions from coal fired power plants. (But please do recycle the CFLs.)
Also, conversion to efficient lighting often leads to an increase in the use of light. To some degree, this can be a positive effect, as it can increase comfort and your well-being. But it can also lead to wasting light, such as leaving lamps on when there is no need to (e.g. when you leave the room). This is reinforced by the misconception that turning CLFs on and off is expensive. As a general rule, always turn off the lights when you leave the room or the house.