The negawatt is what energy efficiency and conservation is all about.
The idea becomes very important when we start to talk about energy production. To illustrate the idea, I’ll use photovoltaic power as an example. Let’s say that you are interested in PV panels, and you are thinking about installing a PV array at your home or business. The first step is to evaluate the cost of saving energy VERSUS the cost of producing that same amount of energy.
Let’s use your entertainment center as an example. You have a TV (Energy
Star® rated), a DVD player, audio amplifier, and maybe even an old VHS player.
Each and every one of these devices is drawing power, even when they are turned OFF (they are designed like that for a variety of reasons). In geek speak, this is known as a phantom load.
Using a watt meter, we find that together, these devices are drawing (18) continuous watts. It is energy that is being consumed, but not really put to any good use. How much energy does the entertainment center consume per day?
18 watts x 24 hours / day = 432 watt hours / day
This system uses 432 watt hours / day. Over the course of a full year, it will consume almost 158 kilowatt hours. At the going rate of electricity, that will only cost about $16 per year. No big deal, right?
To produce an equivalent amount of power with a PV system, we would need to figure out the solar insolation value for the area. The solar insolation value is how much sunlight hits an unshaded part of the earth on the average day---at maximum power. We call this “peak sun hours.” We can find the value here, on the NREL (National Renewable Energy Laboratory) website. For our area, it is approximately 5 peak sun hours / day. Here’s the math for figuring this out:
432 watt hours per day / 5 hours per day of sunshine = 86.4 watts
Of course, no system is 100% efficient. Most PV systems are “derated” by 15% -20%. Let’s avoid getting too detailed here. We’ll just call it a 100 watts.
PV systems are currently being installed for $3 - $5 / watt. That means we’ll need to spend $300 - $500 in order to generate the same amount of electricity that is being consumed by the entertainment center.
That energy is not so cheap anymore . . .
What is the cost of saving that same amount of energy? Well, if the entertainment center is plugged into a switched outlet, it wouldn’t cost anything; you would simply have to turn OFF the system at the wall switch, just like you turn OFF a light.
If it’s not on a switched outlet, you could install a power strip and turn it OFF there. Power strips are pretty cheap, usually < $10 each. Most people would find that too cumbersome; they would probably want to install a “smart” power strip like this one. It automatically turns OFF these devices when you power down the TV, eliminating most of that phantom load. These sell for ~ $30.
So . . . you can see that the negawatt is the cheapest solution. In this example, it ranges in cost from $0 - $30, compared to $16 for the annual cost of electricity, or the $300 - $500 cost of producing the same amount of energy using a renewable energy (PV) system.
How many negawatts have you produced lately?!