Building Green: Energy Efficiency and Aesthetics From The Same Materials (Part 13)
by Ted Owens, New Mexico, USA on 04.25.07
The small Japanese lamp (about 3 watts) is plugged into the same electrical outlet as the television and stereo system. This lets you know that there is power to the appliances. If you are not using the TV or stereo, the light reminds you to turn off the power, and thus the phantom loads.
In the last column, I discussed the advantages of generating electrical energy for your green home by using photovoltaic panels that convert sunlight into electricity. Even if your photovoltaic system won't be added until well after the home is completed, it's a good idea to start thinking about the process now. The installation will be greatly simplified if you add a run of empty conduit going up to the roof of the house. Then, when you are ready to "go solar", the electrician's work will be much easier as the wiring can be routed through this pre-exhisting conduit. Not only is it less expensive to install this conduit during the construction phase, it will save you the trouble of having to break through the attic and walls to do the wiring after the fact. The conduit will run to where your inverter will be installed, which is most likely near your circuit breaker panel, etc. This pre-existing set-up will allow you to install a grid-intertie system at some point down the road with minimal modifications to your home.
A grid-intertie system is somewhat different than the system I installed, which is off the grid and self-sufficient. With a grid-intertie, the excess power you generate is fed into the electrical grid during the day. At night, you use power from the grid, just as a typical home does. With a properly-sized system, you will generate more electricity than you use, thus potentially zeroing-out your electric bill. My home, like many photovoltaic- powered homes, uses a bank of batteries to store excess electricity. A grid-interite system is much more cost-effective than a stand-alone system (as long as utility power is available on your street) as it saves you the expense of batteries, which can account for one third of the cost of the entire system.
Almost all electrical appliances these days use some electrical power even when the appliance is not in use. The United States Department of Energy states that 75% of the electricity used to power home electronics is consumed while the devices are turned off. Seventy-five percent! This passive use of energy—known as "phantom loads"—can also be quite a drain on your electric bill. (If the appliance manufacturers had to pay our utility bills, perhaps they would make their products a bit more energy-efficient.)
The easiest way to reduce or even eliminate phantom loads (which should be standard procedure in any home, and is essential in a photovoltaic-powered home) is to install a switch for those electrical outlets that supply power to televisions, stereo systems, computers, etc. A small 2-3 watt lamp should be plugged into the same outlet. The lamp acts as reminder to turn the switch off after the tv or stereo has been turned off so these appliances are not drawing any power when they are not in use. The lamp itself only uses a small amount of electricity, while adding a nice ambient light to the room at night. Since a switch needs to be added to the circuit, this may require an additional conduit run to the point of the wall switch, which requires some planning up front. Talk about this with your electrician before the process of wiring the house begins. If your house is already built and you want to add a switch, a surge protector/power strip with an on/off mechanism will serve the same purpose. By the way, if your home is running on a stand-alone photovoltaic system (not tied to the grid), you do not need surge protection for its own sake, as your entire electrical system is running off a battery and therefore not at risk for power surges.
Make sure all of your appliances have an EnergyStar rating. This makes it easier to weed out the energy hogs from the those that are efficient with power. More in the next article.
See also: Part 1, part 2, part 3, part 4, part 5, part 6, part 7, part 8, part 9, part 10, part 11 and part 12.
[This has been a guest post by Ted Owens, a green designer and filmmaker. More details on green building design and construction can be found on his website and in the Building with Awareness DVD and Guidebook. -Ed.]
Something else to think about when planning/designing your home and its electrical system is inverters, even those higher end ones are not 100% efficient so there is always loss in them and large ones are quite costly. So many of our devices today operare from low voltages and have plenty of low voltage power supplies, for example your cell phone vehicle charger. I'm working toward a wiring system where I have 12v automotive type wiring throught the house and keeping a lot of my electronics running from that. Using standard off the shelf automotive components has kept the cost down very low and I can now easily take my electronics with me since everything is running from their vehicle adapters already. Its also allowed me to start building a smaller more modular solar system since I don't need to invest in a huge inverter from the start. I can simply buy batteries and charge controllers and power all the low voltage devices when once I'm ready can buy and inverter for some of the non 12v stuff but when that time comes I already have most of the other components in place and won't need as large of an inverter.