We’re Saving About $135/yr

As I’ve been researching ways to reduce power consumption, I’ve been measuring the annual power use of each appliance in my house (see my post on the Kill-A-Watt for details). When I measured my refrigerator, I found that it used 2.17 Kwh in just 13:22. That means that at our average Kwh cost of $.1007, my fridge costs me $$.3896/day, $11.85/month, and $143.20/year. That might not sound significant, but what if it could be less? A LOT less?!

I’d recently seen some info about using a chest freezer in place of a fridge. I thought the idea sounded whacky at first. It’s being done by many power-miserly people – particularly those who use solar power. You see, refrigerators are inherently inefficient in their design. When you open your fridge door, in goes all sorts of room-temperature air that must now be cooled and the cool air you’ve been paying to cool comes out. This is where a chest freezer has quite an advantage. Aside from being better-insulated than refrigerators, chest freezers don’t lose much cold air when you open them because cold air sinks and hot air rises. You ever notice the open coolers in the grocery store with no lids, yet the contain frozen items? This is because the cold air stays down in the freezer.

So how does this work as a fridge, I mean freezers freeze stuff, and I just want my stuff cool, right? It’s simple:

You take a chest freezer, turn the thermostat to as cold as possible (so that when it’s on, it’s running at full-steam), then purchase a separate thermostat such as this Refrigerator or Freezer Thermostat (Temperature Controller). These have long been used by people who brew their own beer to keep their beverages at given temperature range for long periods of time.

This device (or others like it) plug into the wall, and your freezer plugs into it. It consists of a temperature probe which is placed inside the freezer (no tools required) hooked to a relay that turns the power (at the plug) on and off. This is totally safe and already how your freezer works, so no wear and tear. This just way easier than modifying the freezer’s internal thermostat and voiding warranties, etc.

Once plugged in, your set the external thermostat to your desired temp (mid to high 30’s) When the temperature inside the freezer moves above your set temp, it powers on the outlet, turning on the freezer until it reaches the desired temperature. Once reached, it cuts power to the freezer. Many people who use this arrangement report their freezer compressor running 2-5 minutes per hour!

So just how much does this save? Most people report an electricity use doing this between .10 Kwh to .4 Kwh per day. Our current average Kwh price is $.1007 (just a hair over ten cents). That means that doing the above will cost you between $.01 and $.04 cents per day. That’s between $3.67 and $14.70 per year! You will not find a fridge that approaches even half this energy use. Because I bought a new energy star freezer, I am projecting somewhere in the middle – $.20 Kwh/day. This is twice the cost that many people are experiencing, but I don’t like to get my hopes up. If I am anywhere close, my cost will be just $7.35 to run my freezer fridge for one year. That’s a 95% cost reduction. It could be even better, it could be even worse. Even if it were $.40 Kwh/day, the cost will still be less than $15 for the year, an 89% improvement!

Have a hard time believing that? A brand-new Energy Star freezer will use about $38 per year as a freezer – it’s right on the tag. When it’s used in the energy-sipping capacity like this, it uses a fraction of that energy.

Of course, you have to 1) have or obtain a decent chest freezer 2) have a place to effectively use a chest freezer as a fridge 3) and purchase or make an external thermostat capable of powering the unit on/off frequently. In our case, we had the willingness, the room, but not the freezer or thermostat. We decided on purchasing a new Energy Star 14.8 cu.ft. freezer for $398. We purchased the above thermostat as well. This unit should be going strong for 5-10 years, long after we’ve recovered our purchase price.

If this is something you want to consider, I recommend the following:

1. Use a Kill-A-Watt to measure your power use and determine your real kwh cost per day
2. Multiply this cost by 365. If you live in PA, remember that once we experience deregulation this winter, power cost will likely rise at least 30%.
3. Consider if you can purchase or locate a decent freezer
4. Consider if you can purchase or construct a thermostat relay (I could not build one for the cost of the one above)
5. Consider if you could live with a chest freezer rather than a traditional fridge.
6. If so, Consider the cost savings over 3-5 years after your cost to purchase the freezer (if need be) and a thermostat.
7. If the cost is justifiable, go for it!

Regarding the last item, my wife was suprisingly willing to do this after going and looking at freezers. There’s some nice benefits of this approach:

1. It can be hard to see items in the freezer, harder to reach them, etc. The top-down effect of using a chest freezer offers a bird’s eye view of the contents.
2. The chest freezer doubles as quite a bit of effective work area
3. The former refrigerator area can be re-factored into a pantry, more counter space, etc.
4. The right chest freezer can be nicely organized. Ours came with four nice sliding baskets that make it easy to organize.
5. Should you decide to implement an alternative source of power (solar or wind), the less power you need, the better.

This might not be for everyone, but we’re excited to give it a shot!

I’ll post an update in a few months with my power usage.