Archive for the ‘heating’ Tag

Energy Vampires Beware! The Kill-A-Watt Meter Is Here!   Leave a comment

This week wraps up my personal energy audit and I have to say it has been eye opening. I’m in love with my Kill-a-Watt meter now (yes I am a nerd). I think I’ll probably keep using it to take some longer term measurements here and there, and I’ll make it available to any of my friends who want to borrow it as well. In a future post I’ll get into some of the surprising results that we got, but I’m still measuring my computer’s usage as I type this. What I have done is an analysis of what percentage of our home energy usage is heating, cooling, water heater, passive appliances, and active appliances. I did this through a combination of meter reading, bill analysis, and direct measurements. This is based on only one year, and I didn’t take into account heating degree days or cooling degree days, so the HVAC numbers have a rather high error rate.

I described in a previous post a simple method for estimating how much energy use use for heating and cooling. I forgot to mention that if you have both gas and electricity, you’ll need to convert therms into kWh. For the analysis at our old house I used the converter at For us: heating was 16% of the annual total and cooling was 20%.

The next task was a bit more challenging, and that was determining the passive electric load. The first step is really easy: read the meter. For a couple of weeks, every night right before I went to bed I grabbed a flashlight, pad, and pen and walked out to the electric meter to record the kWh display. And the next day my husband did the same as soon as he got home from work in the afternoon. During that time we had (almost) no active electricity use. I figure that the garage door, toaster, etc. are minor enough compared to 15 hours of passive usage that it didn’t significantly affect the readings. After dividing the difference between the two readings by the elapsed time, you get kWh/hr. Ours came to just over 5 kWh per day. That is our passive load, aka energy vampires, and includes things like the water heater, cable box, refrigerator, microwave and stove clocks, cell phone chargers, etc.

The second step was the step that I found so exciting this year, and that was measuring the contributions to the passive load from all of the applicable appliances with plugs. For several weeks I’ve been using my Kill-a-Watt meter to measure the daily electric usage for many of our appliances, including everything that is plugged in all the time. By subtracting out this measured total from the passive usage I calculated from the meter, I was able to estimate how much electricity the water heater uses and the non-water heater passive usage. For us: water heater uses 18% of the annual total and passive appliance use 13% (which means active appliance use is 33% of the total).

It is really nice to know that heating and cooling use less electricity than our appliances. Unfortunately it is probably easier to reduce energy used for heating and cooling (shade, insulation, sweaters, etc.) than appliances (turn of the TV and computer?). I did take a closer look at our passive load and I think we can reduce it by 15% by moving a few more things to power strips that get turned off at night. We found some surprising energy hogs that I’ll save for a later post.

Note that I didn’t bother using my electric rate to calculate $ spent on heating/cooling/water heating/passive/active appliances once I had the kWh, but for a lot of people that would be the desired end number.

Posted September 28, 2011 by mayakey in energy use, home

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Calculating Baseline Energy Use   1 comment

The easiest task in a personal home energy audit is to analyze electric and gas bills to observe patterns. If there’s a time of year, like spring or fall, when for an entire billing cycle neither cooling nor heating is needed than it’s pretty easy to determine an average typical non-HVAC daily and annual energy use. Then it is pretty easy to subtract and  determine how much cooling and heating increase energy demand during the appropriate season. It’s a rough calculation, since there may be seasonal fluctuations to the “typical” energy demand like more lights on during winter, but it’s a good start. I calculate that we typically use 10-11 kWh per day non-HVAC, which comes to 3,840 non-HVAC kWh over the course of a year (65% of total). Heating required approximately 990 kWh for the year (15% of total), and cooling required approximately 1,200 kWh for the year (20% of total).

The next task is to break down that “typical” energy use a bit, but this requires a bit more effort since you have to read the meters. Reading the meters isn’t challenging, especially now that digital smart meters are being rolled out. I hear that some utilities are already using the smart meters to provide customers with real-time tracking ability from their computers, but walking into the back yard and reading the meter really isn’t much work. There are a few different strategies for meter reading schedules. You can read it once per day to get a feel for your real “typical” energy use and the fluctuations, you can read it twice per day to differentiation baseline and active use, or you can read it many times per day to track specific appliances.  The latter is what I did last time I did a home energy audit, and it is a BIG PAIN! So this time I have a Kill-a-Watt to do the measuring for me, and we did twice per day readings. For a couple of weeks I read the meter immediately before going to bed, and Mike read the meter as soon as he got home. During that time there was very little active use of electricity: a toaster or blender for breakfast, a brief light on in the pre-dawn, and the garage door. I consider those to most likely be negligible over the 15 or so hours of baseline energy use. What I mean by baseline is the stuff that is always on: refrigerator, cable box, thermostat, etc. It’s the baseline because even if you eliminate all active energy demand the house will still draw this baseline amount. It’s relatively constant, with minor fluctuations like water heater working harder in winter and fridge in summer. So now I know that our baseline home energy use is approximately 4.8 kWh per day, which is almost half of our typical daily energy usage.

There’s very little that I can do to reduce that baseline energy usage. I’m not getting rid of the fridge or the alarm, and while I would love to turn off the cable box I can’t without breaking it. What I want to know is how much of that baseline goes to the water heater. By using the Kill-a-Watt I’m measuring as many of these baseline contributors as I can and then I’ll be able to calculate an estimate of how much hot water contributes to our energy usage. My guess is that it is most of the baseline.

Posted September 2, 2011 by mayakey in energy use, home

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Ecstatic at 64 Degrees   1 comment

This weekend has, in once sense especially, been an absolutely awesome weekend. The temperature of our house has not dropped below 63 degrees! I actually did little dances of joy a few times when I walked by the thermostat. Why is 63 degrees significant? Because our thermostat is set to 60 degrees (55 during the day on weekdays, it’s a programmable thermostat), so it never turned on all weekend long. That is despite outdoor temperatures in the 40’s and 50’s and lots of clouds. We haven’t even winterized the house yet! In our previous house the heater would have been on almost constantly during a weekend like this. The highs over the next couple of days are not forecast to reach 50 degrees and there is still a good chance of more rain, so we’ll have to see if we can keep the heater off with an ambient high below 50 degrees.

I realize most people got to “our thermostat is set to 60 degrees” and choked. But really, it’s not that bad. My husband and I have an agreement since we have opposite temperature ranges. He gets uncomfortably hot easily, and I get cold easily. So in the summer he controls the temperature and sets it as high as he can tolerate, and in the winter I control the temperature and set it as low as I can tolerate. In the old house I was stuck paying over a hundred dollars a month to heat a house to 65 degrees, so I refused to set the thermostat any higher than that. When I lived by myself I was literally non-functional below 65 degrees, and my finger joints always ached. Since my husband moved in with me several years ago I found that I could decrease the set temperature and still be comfortable. I’m not entirely sure why another person’s presence makes 60 degrees feel like 65 degrees alone, but it does for me.

My coping strategies for a cold house are 2-3 clothing layers including at least one sweater/sweatshirt, wool mules with a cork sole, a wool blanket on the sofa, 3-4 blankets on my side of the bed, and really hot showers at night before bed. At least in my opinion, none of those things inconvenience me. Since I love cuddling up under a blanket I would be doing some of them no matter what the set temperature. After a while you get used to the low temperature.

I would like to set a challenge to anyone to lower their thermostat setting by a couple of degrees this winter. Leave it lower for at least a month to give yourself a chance to get used to it. You might surprise yourself. I’m not saying that you’re going to like 60 degrees, or even 65 degrees, but find what your lowest comfortable temperature is. There is a certain magic to living seasonally, and by that I mean actually experiencing each season and not just watching it go by without experiencing it.

Posted November 22, 2010 by mayakey in energy use, home

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Winter Heating Review   3 comments

Spring is here in Sacramento, and now I can look back at the winter season and how we did on gas usage this winter. Compared to last year, we used a lot more gas in December and January, less gas in February, and a little more in March. Honestly, I’m surprised our gas usage wasn’t even higher. We knew we would use significantly more gas in December than last year because this year my mother came here for Christmas, whereas last year we left town for a week and turned the heater off. Compared to two years ago, when Christmas was also in Sacramento, our gas usage was on slightly higher this year. I think that the main reason for the higher gas usage was the fact that in previous years the interior wall separating the two halves of the duplex was heated on the other side, whereas this year the other side was vacant and unheated. Also, we want to move out so badly that we didn’t have the heart to update our weatherization.

Instead of updating the weatherization, we dropped the thermostat again. Previously, when I lived alone, I could not set the thermostat below 65 degrees F, or I was too cold to function. After my husband moved in, we found that we could easily drop the thermostat to 62 degrees F before I was non-functional. So this year I challenged myself and we set the thermostat to 60 degrees F. (We have an agreement that I control the temperature in the winter since I get cold easily, and my husband controls the temperature in the summer since he doesn’t handle hot weather well.) Amazingly enough, I did fine! We added a blanket to my side of the bed, for a total of four blankets, and that kept me warm at night. And I had my sweaters, blankets, and wool mules to keep me warm-ish during the day. It helped that my husband does the dishes usually now, so I am no longer immersing cold hands in colder water every evening. I cannot really explain how I seemed to do better this year with the thermostat at 60 degrees compared to last year with the thermostat at 62 degrees, though.

Another interesting side effect of dropping the thermostat to 60 degrees was actually decreasing hot water usage. Usually in the winter I am so cold that when I shower I use 100% hot water. I know it is not good for my skin, and numerous times I have tried to make myself use less hot water with no success. This year, though, I had to turn on the cold water during my showers. I guess that I acclimated so well to the decreased air temperature, that I just couldn’t take the pure hot water showers any more. Mind you, I still took really hot showers, they just weren’t as hot as in years past.

What will we plan on doing next year? Well hopefully next year we will be in a house that does not have single-pane aluminum-frame windows and sliding glass door, and that maybe has some insulation. We anticipate using SIGNIFICANTLY less gas in the new house because it can’t possibly be worse to heat than the dump where we live now. But what temperature will we set the thermostat to? Maybe 60 degrees again, because while it was tough at times, I did okay. If the new house does have better windows and insulation then it won’t feel as drafty, too.

Posted March 22, 2010 by mayakey in home, resource use

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