Even in temperate North Carolina we have to turn on the furnace when winter comes around. A lot of folks here have heat pumps since they both heat and cool – and we need both. Electricity powers them, made plentiful by the many coal fired plants in the area. Since I now have my nifty power monitor in place I was curious to see how it impacted the home’s consumption.
It only reached the high 50’s today, and I set the thermostat at 67’ just to keep the edge off. The atrium collects some heat when its sunny and it was a little today. But the heat was definitely kicking on occasionally. Around 4pm in the afternoon I was getting cold so I turned the thermostat up to 72’. This evening I took a look at the monitor to see what had been happening.
Wow! Absent heating/cooling the house bounces between .5 and 1.5kWh depending on what happens to be on at any given time. Knowing that nothing else big was running at the time it was easy to pick out the times the heater was drawing power. It’s sucking up about 4X what the entire rest of the house was using! From the graph is easy to see that the power to keep the house at 67’ during the day is considerably less than the higher temp (5′ more, and against cooler outside temperatures too). There are three distinct large bands of usage that looks to be the effort to get the house warmed up, which tapers off a little once it stabilizes and then continues to cycle in order to maintain 72′.
Obviously I am somewhat guessing that this is what is going on since my measuring/monitoring capabilities are so primitive, but given I was around the house all day and KNOW that other major appliances were not running at the time it seems pretty reasonable. It would be impossible to for me regularly track what the HVAC is doing on an ongoing basis unfortunately.
But what does this mean in terms of cost? I exported the data and looked at the 12 hour period from 9am to 9pm. By looking at 5-10 minute average before the spikes I estimated the incremental consumption of the heater, and added both up. Heating and cooling is generally thought to be about 30-40% for most people. The power to just run the house during this period was about 9.6kWh. The incremental heating was nearly twice as much at 18.7kWh, or two thirds!
Now we can’t extrapolate 12 hours into the entire season, but this is certainly interesting. My HVAC has been serviced several times in the past couple years, but is it running efficiently? Is the amount of cycling and the energy consumed reasonable given the weather outside? Have I done everything I can to make sure I am using the resulting heat efficiently? My electric bill was pretty cheap last month as I was paying a lot of attention to power usage and not running the HVAC. I’m not too optimistic for this month!
The latest issue of Backyard Chicken (yes, there is such a thing) had an article decrying the availability of toys for pet cats and dogs while nothing has emerged for the burgeoning pet chicken population. While in my mind our girls are less pets than egg producing livestock, Mel and I thought we might give a couple of their suggestions a try.
One idea was a mirror. It so happened that Mel had a cracked one left over from a project that was sitting by our trash waiting to be transported to the dump (Our rural trash service requires everything to be bagged – this was too big). It’s an oval shape about 5′ high by 1.5′ wide. I installed stakes in the ground to hold it upright and stood it on its side in view of our living room. The chickens seemed interested while I was putting it in. But after one look, the novelty wore off. Apparently they were then satisfied in their own appearance or simply decided that the “other chicken” wasn’t worth any more of their time.
The other idea was a vegetable ball. This was a wire metal sphere stuffed with lettuce/treats that hung from above at a level the chickens could easily get at. When we saw a similar hamster sized ball at the pet store we were inspired to give it a shot, but then couldn’t find something large enough to be of serious recreational attention to our chickens. Necessity being the mother of invention, I managed to fashion a means to easily hang a head of cabbage purchased that same day using a corkscrew and some twine. Ta-Da! Instant cabbage-toy. They completely ignored it.
The next day I went out to demonstrate to them how my great new invention was. Part of the issue was likely that we bought purple cabbage, which the chickens had never seen. Part may have been that the head was so tight that they couldn’t see a place to start. So I unpeeled a couple of the outer leaves and tore off some pieces to give them a taste. That seemed to do the trick. This morning they are joyfully (just judging by the gleam in their eyes!) pecking away at it, working on their timing so the swinging doesn’t catch them right on the comb.
But as chicken toys go I think we are 0 for 2. As chicken owner toys go we seem to be batting 1000! At least we know these are toys to be enjoyed even if they just think its food.
The concept is great and when it works (and you have a lot of time on your hands) as it gives unprecedented insights into your home’s electric behavior. However the limitations become obvious right away and the name “Energy Detective” is right on – you have to be a detective to figure out what is driving the spikes in usage you see. My home is constantly having different things cycling on and off and isolating one is REALLY difficult. If it isn’t a major consumer of power and doing something to display a regular pattern, forget it. Also, you pretty much have to be looking at everything (the monitor and any devices or appliances) at the time to figure out what is going on. There are graphing and data export abilities incorporated, but since you don’t know what the home devices might have been doing at the time at best you can get indication that something interesting might have been happening.
I have found two things that I thought were really interesting. First is that your house is always using a good bit of power, even when you are asleep and most of everything is seemingly turned off. We often think about lighting as being an area that uses a lot of power (thus the push to switch to CFL bulbs and my constant habit of walking around the house turning off lights), but it really doesn’t. Things like the water heater, clothes drying, oven, and especially the heating and air conditioning dwarf the power used by lighting. We just have more control over lighting. Second is just how much power those larger appliances really use. I’ll see the monitor bouncing along at 800 watts (for the whole house) and then suddenly see it jump to over 4000 – just from ONE thing being turned on! It does make you very cognizant of using those devices (or maybe turning the heat down or finally programming that programmable thermostat), but it’s impossible to tell if they are working normally or not. I was also fortunate that I started using TED when the weather was moderate and the HVAC was turned off, which allowed better visibility to everything else in the house. Once the heating started kicking on, it became impossible to see what else was going on!I did make one noteworthy discovery though. I bought my house a couple years ago and was very happy that the crawlspace was very dry. One reason for that was because the prior owner had put a portable dehumidifier down there and routed a drain line to the outside. I did turn it down so it wasn’t running constantly, but otherwise left it alone. When I first installed TED I saw a regular pattern of something coming on about 30 minutes every hour and finally tracked it down to that dehumidifier. The dry crawlspace was great, but keeping it that way was costing me probably $150/year!
But I’ve had a number of problems. The main one is that the reporting regularly becomes “locked” so for some number of hours (between 2 and 10 that I’ve seen) the graph will show the exact same usage level. The pegging of consumption reporting is obvious once you see it as otherwise the readings change constantly.According to tech support this doesn’t affect the monthly reporting, but I’m not sure I believe that. It doesn’t happen too often (a couple times a week), but it’s pretty annoying. Viewing the TED software also regularly locks up Internet Explorer. It would be nice to leave it on to regularly check for interesting occurrences (it takes a couple minutes to initially bring it up and get the graph to display). The history that is kept is limited to about 3600 entries which isn’t much. Looking at the minute view is the most useful (seconds too granular; hours not granular enough) and that gives you about 2 days of activity. You can accumulate your own data if you remember to do an export every couple days; otherwise older information is lost. I have some other issues that I haven’t resolved yet as well, primarily that the first electric bill I’ve received since installing TED was about 40% higher than what TED told me I should expect. I’ve made some installation changes since then which will hopefully resolve that.
Because I’m willing to play detective and figure out where some of my electrons are going in the house, TED is a very worthwhile gadget and will likely pay for itself in just a year or two. But the holy grail of home energy monitoring really needs to included more information about exactly where power is being used. This is important for two reasons I think. One is that in order to modify a homeowner’s behavior towards better energy conservation you need have specific recommendations. The other is that there may be improvements that could be made (replace an old appliance that is not working properly, better insulate or seal the house, etc.) which would provide worthwhile energy savings but without more detail it’s difficult to say just what is worth spending money on. Hopefully these will be future enhancements.
In this age of tract home development, homes of a given type built in the same period have a lot in common. Building practices and technologies change very slowly and in a lot of ways aren’t much different now than 50 years ago. That said, every house is different and perhaps more importantly different people and families use their homes in different ways. So while some things about reducing energy usage at home will be universally applicable, and others won’t be. So part of what I want to capture in this series of blogs is the process; how I do it, what I look for, and the tools I use to get there.
My house is a little different than most. It was architect designed and built in 1978 and somewhat contemporary in style. It is essentially a big square with a little square in the middle.The little square is an atrium with translucent panels for a roof, slopped to the south. It might have been open initially, but now functions as semi-finished space, sort of like an enclosed porch/deck. Six sliding glass doors provide access from all points inside the house. The one story structure sits on a slightly sloped lot with a cinder block foundation. The foundation is made of cinder blocks and has enough space (between 4’ and 7’ high) for a lot of storage.
Most of the interior ceilings slope up towards the center of the house. In the three bedrooms and kitchen there is a little attic space with a lot of heavy insulation blown in. Having done a bit of renovation work I have learned that all the walls (and I think the ceiling joists) are insulated with a foam product that has since been discontinued (urea-formaldehyde I think). It seems to work pretty well, but has shrunk a bit over the past 30 years and turns to powder if it is touched.
Most of the floor plan is pretty open, but there are not a lot of exterior windows so it can be dark. The lot is heavily wooded as well which shades quite a bit. The atrium acts sort of like a car in a parking lot in the summer and can get really hot. There is a fan to push air around and clerestory windows to let hot air out. Both the Atrium and the kitchen have brick floors which can act as a heat sink, though I’m not sure how effectively that actually works.
Living in North Carolina means both cooling in the summer (often with very high humidity) as well as some heating in the winter. Overall the weather is great here; plants start coming up in February, a stark contrast to what I’d grown used to in Chicago (May, sometimes later!), so there are a number of months each year when I don’t have to run the heat or A/C. I have a heat pump that does both and seems to be original to the house.
Otherwise, there is a 2-car detached garage; a 70’s era solar hot water heating system (not sure how well that works either); propane that is used in the living room fireplace, cooktop, and outdoor gas grill; roof eaves that overhang about two feet, wood siding, and an asphalt roof that is just about at the end of its life.
Overall it’s a great house (in part just because it’s different, and I like different!), but the atrium panels have presented some heating/cooling problems. But I expect that most of the aspects I’ll address won’t be impacted by the unusual aspects of the building.
With the economy in the toilet and the expansion of interest in all things “green” I guess it was inevitable that my attention would turn to my electric bill. According to Duke Energy, who sells all the electrons in my neighborhood, I am about 10% above “average”. This means my 2400 square foot house in North Carolina uses about 1900kWh a month costing me $2300 last year. Since it seems like I am constantly walking around turning off lights (which are primarily compact fluorescent bulbs anyway), keep the house cool in the winter and warm in the summer, and think I am relatively conscious about electricity usage this doesn’t seem right.
So I’ve decided to get a better handle on my energy usage and costs. I have a degree in engineering and have a reasonable knowledge building practices and thermodynamics, so this should be pretty straightforward, right? Somehow I don’t think so.
It’s now easy to find references to the “low hanging fruit” of home energy conservation. Replace all your light bulbs with CFL’s, get a programmable thermostat to keep from heating/cooling when you aren’t around, and unplug the things you don’t use. I’ve already done those things and have undoubtedly benefited, but if I’m still above average there is obviously something else going on. So I’m going to look at the following areas that I think I can largely address myself:
- How good is my house at staying comfortable, knowing that heating/cooling is the largest consumer of energy?
- Where might I be wasting electricity that I don’t really need?
- Are there reasonable behaviors I can change to reduce energy usage?
What I am currently lacking is good data to guide my decisions. I have my electric bills for the past year, and that’s about it. I’d rather not just guess about what I could or should do without knowing if my efforts will be worthwhile. I’m willing to spend some money if I have some assurance of savings on my electric bill, but am not interested in just throwing out cash so I can call myself a “custodian of the planet”. So much for that giant solar electric panel on the roof.
But on that front, measuring payback is likely to be difficult because there are so many things going on in a house that impact energy use. Have you taken conservation efforts at home and know you have seen results in your bills?