In order to achieve energy independence in our homes, we need to create a net-zero energy home. In short, this is where we produce as much energy as we consume using any number of renewable forms of energy. To do this, though, we need to use renewable energy conservatively and efficiently. This is the second in a three-part series.
The most critical factor in energy efficiency is the quality of the building envelope, or the shell of your home or office. Whatever you can do to minimize heat transfer – or allowing heat to escape in the winter or intrude in the summer – will minimize your biggest source of energy consumption: the heating and air-conditioning (HVAC) systems. A tight building envelope includes insulation in the outer walls, floors and ceiling, and a tight seal with caulk or weatherstripping around doors, windows, ductwork and pipes. If you’re building a new home, the best options include insulating concrete forms (ICFs), structural insulated panels (SIPs), or spray foam insulation like Icynene. Each of these alternatives will minimize heat transfer, and the corresponding load on your HVAC system. The spray foam can also be used to provide superior insulation on an existing home, though it is more costly than in new construction.
If your HVAC system doesn’t have to work hard, that’s great. But what’s even better is if it works smart. A geothermal heating and cooling system will enable you to leverage the natural heat stored in the earth to heat your home in the winter, and conversely exhaust your heat into the earth in the summer. Geothermal systems are actually ground-source heat pumps, and are much more efficient than the air-source heat pumps that were popularized years ago.
Your refrigerator(s) and other major appliances are next on the list. If you have an old refrigerator (manufactured before 2000) you can probably cost-justify a new refrigerator and pay for it with the energy savings in a few years. New ENERGY STAR refrigerators typically use 40 percent less power than traditional models, and can often pay for themselves within ten years. If you’re looking for a new appliance, including dehumidifiers, dishwashers, washers & dryers, televisions and computers, be sure to look for the ENERGY STAR label. You may pay a little more for it, but the additional cost will almost always be offset with energy savings within a few years.
The last area with the most low-lying fruit is lighting. Lighting typically accounts for 20-30 percent of your total electric bill, so it’s a great place to start. Many people have begun switching over from traditional incandescent bulbs to compact florescent bulbs, or CFLs. CFLs use 25% of the energy of a comparable incandescent bulb, and typically last 5-6 times longer. One primary concern about CFLs is that they contain mercury, so it is very important to recycle them rather than simply throwing them away. Many home stores, like Home Depot, have a recycling program so that the bulbs can be properly de-manufactured.
An increasingly attractive alternative is LED lighting. Light-Emitting Diodes are by far the most efficient lighting technology, and they are quickly becoming an affordable option. While CFLs use one-fourth of the energy of an equivalent incandescent, LEDs use only one-tenth of the power of a comparable incandescent. And while CFLs typically last 10,000 hours, LEDs are designed to last 60,000 hours – 40 times that of a traditional incandescent! Here’s the fascinating point: 90 percent of the energy used by an incandescent bulb is heat, and only 10 percent is converted to light. LEDs, on the other hand, use 90 percent of the energy for light, so only 10 percent is wasted as heat. In the summer, this will also reduce your cooling bill!
One shortcoming that is often overlooked is dimmers. Indeed, dimming an incandescent does reduce the amount of power consumed, although some of that energy is still wasted as heat. Some CFLs are dimmable, but tend to be 4-5 times more expensive than their non-dimmable counterparts. The lighting variance on CFL the dimmer is also not nearly as wide. LEDs are also available with a dimmable option, but are also very expensive ($30-90 per bulb).
An energy audit will often identify a number of home improvements, and can often reduce your energy use by as much as 50 percent. Once you’ve stopped wasting electricity, it’s time to start producing your own using clean, renewable energy from the sun. Look for more on this in the final part of this three-part series.
This was published in the Going Green section of the January 2010 issue of Spirit Seeker magazine.