Violet was our first doe to deliver yesterday. Please welcome our three new baby boys to Up Hill House / Tumblewood Farm! One more doe to go.
As you can see in the photo above, we have 2 new eGauges. Each monitors up to 12 circuits, for a total of 24. When you count 2 lines in, solar and several circuits that have double breakers pulling unbalanced loads, that ends up covering 20 individual things we can now monitor. We were previously monitoring only 7 circuits plus solar and power from the utility.
We’re now monitoring the kitchen refrigerator, basement freezer, ventilator, ventilator pre-heat, barn, the backup electric resistance units in the bedrooms and living room, and a bunch of other circuits including the one we charge our plug-in hybrid.
We chose the EG3000 model without the HomePlug AV. Our router is very near the electric panel in the basement so it was easy to wire it directly using ethernet cables. The ethernet model requires a separate enclosure. You can’t put it in the panel box. This is fine because there is isn’t much room in the panel box, especially after you install 24 CTs and a load of twisted spaghetti wire (see above). My electrician installed this small box next to the panel with all the wires running through conduits. I’m going to cut a piece of clear plexi to fit over the box so you can still see everything inside, but keep the dust out.
The eGauge install was fairly similar to the eMonitor. You need to power the monitor devices directly from the breakers in the panel box, and you need to keep track of which lines you are monitoring. My electrician figured it quite easily, although he installed all the current transformers (CTs) in the opposite direction. Thankfully this doesn’t really matter as long as you are consistent in the direction you install them.
The 2 eGauge units plus the CTs and shipping worked out to $1,282. Our electrician charged us about $400 for the physical install. I did the configuration and spent several hours messing with the settings to get everything working correctly. The documentation is not great, but I figured most of it out. Having some prior experience with an energy monitor (we’re now on our third) definitely helped.
I don’t remember how much we paid for the eMonitor 2 years ago. I seem to recall in the $600 range for the 12 circuit wifi model, plus another $400 for install. It looks like you can now get a 24 circuit ethernet connected model for $700 plus the 2 year subscription fee, which for us was about $180.
So why did we switch?
1. No yearly licensing cost
I absolutely enjoyed the data that came out of our eMonitor (see our post 2 years ago), but I deplored their architecture and business model which required me to pay a subscription fee every two years to have access to my data on their servers.
eGauge has no licensing fees and stores its data right on the box, at 1 minutes resolution for the first year and 15 minute resolution after that up to 30 years.
2. Data quality
I’ve been tinkering with some new analysis techniques that required minute resolution data. So I downloaded 2 years worth of minute data from my eMonitor. This was not a pleasant experience since they only allow you to download 2 weeks of data at a time, the data files are large. Then I proceeded to look at the data and try to recreate the hourly data from the minute data. This should be an easy exercise, but I found that there were lots of little gaps in the data. I was not able to fully recreate the hourly data I had originally downloaded. After numerous emails with their service desk, they stopped responding. I don’t think they could explain the gaps. I don’t know if the problem was hardware, or data was lost in translation, but it didn’t give me a lot of confidence in the device or service.
I spoke about this issue with a few people at the Better Building by Design conference in Burlington, VT back in February. The Efficiency Vermont booth was demonstrating some energy monitoring case studies and had good things to say about the eGauge. I have a huge amount of respect for the Efficiency Vermont organization. Lots of smart folks there.
I enjoy building stuff and tinkering with different ways of analyzing and visualizing our energy usage.
With the eMonitor, I downloaded our data from their servers once a month. It wasn’t easy enough to do in any shorter increments and I wasn’t going to apply for a developer license to access their databases directly.
Since the eGauge data is on the box in my basement*, I can access realtime data through the built in web interface or through a simple API. This is awesome for makers. I’m looking forward to building a new realtime interface to view our energy data.
*Since the data is on the box in my basement, I’m setting up an automatic backup.
the eMonitor may be different now, but when I bought it 2 years ago, it came as a kit to monitor several different sized loads. We ended up not using one of the monitoring slots because we didn’t have a circuit I wanted to measure that matched the monitor amperage.
eGauge lets you mix and match components. I picked the number and size of the CTs and the type of monitor configuration to match my setup.
That’s it, go out there and measure stuff.
We won! Thanks to the Northeast Sustainable Energy Association (NESEA) for awarding us the 2014 Zero Energy Building Award at the Building Energy Conference (BE14) in Boston this week. Gina McCarthy of the EPA gave a rousing keynote, and shortly after Jill and I were called onstage to receive the award.
At the afternoon lunch panel discussion we gave a short presentation about the house along with a few other contestants including Carter Scott. It was a great crowd with good questions.
But the best part was getting to meet a few of my energy heroes.
Marc Rosenbaum is EnergySmiths and keeps a great blog at Thriving on Low Carbon. His name always pops up on interesting projects around New England and he knows his data, particularly when it comes to heat pumps. I’ve followed his writings and work for several years now. It was a pleasure to meet him in person.
I was also fortunate to meet Carter Scott of Transformations. I was still considering large masonry stoves, radiant floors and solar hot water in late 2009 when Jill and I were kicking around plans and researching different heating strategies. Then I found an article in Solar Today (2008) about a house Carter Scott was building for the Zero Energy Home Challenge in Massachusetts. This is also how I found Mike Duclos and our energy consultants, DEAP Energy Group. These houses featured double stud walls packed with cellulose, an air-source heat pump and solar PV. I was sold on the idea.
And speaking of heroes, I also want to thank our contractor Warren Coolidge. He took time out of his busy schedule and made the long drive to Boston to join us at the conference. Warren listened to all my crazy energy ideas and found ways to help us build the house, and keep it on budget (most of the time). He is a true craftsman and I very much enjoyed working with him. I don’t sell anything on this site, but if you want to build a net zero house in Washington County, New York, hire this man. You won’t be sorry.
We’ll be opening up the house again for NESEA’s Green Building Open House tour in October. See the house, the goats, chickens and turkeys. I’m sure Jill will also have some home-made cheese available. Mark your calendars and come visit us!
Less to type, more to love (no more ads).
Living in a super-insulated house, I get very excited when extreme cold weather arrives. It is the only way to see how well the house performs in low temperatures. This January was the coldest month that we’ve lived in the house.
We recorded 1380 HDD for January, 16% colder than January 2013. Our coldest day was January 3rd, with 69.7 HDD. Temperatures on this day ranged from a high of 2.8°F to a low of -8.5°F. Indoor temps ranged from 60°F at night to 70.5°F during the day.
I was particularly interested in how our air-source heat pump (ASHP) would perform in these long stretches of cold weather. Our unit (Mitsubishi MSZ/MUZ-FE18NA) is rated to keep producing heat down to -15°F. According to the specifications, the unit can produce 10,300 btu/hr at 5°F.
In order to determine how well the house performed thru the month I decided to keep the backup heat (electric resistance) off. This meant we relied only on our ASHP and the sun to heat the house for the month.
Looking at the data for January, it looks like our heat pump starts to fall behind demand when temperatures slip below zero. This appears to happen mainly at night. During the day, a small amount of sunlight can raise indoor temps even in the extreme cold. January 1-3 offer a good example.
I normally turn the heat down at night or off. I did this the night of January 1st. Night temps were not particularly cold, but continued to drop throughout the next day. By 7am Jan 2nd, the inside temp got down to 60°F and the outside temp had reached zero. By the time I turned on the heat again in the morning, the ASHP was not able to make up the difference for most of the day. A little sun helped get the inside temp up to a high of 64°F. On Jan 3rd, I considered turning on the backup heat, but I held out because the forecast said clear skies. By the afternoon inside temps were back up to 70 while outside temps hovered around 2°F. By Jan 4th, outdoor temps were well over the zero mark.
The January 2nd experience and a fortuitous conversation with Mike Duclos that day, convinced me to leave the thermostat set to 68°F when temperatures are forecast to be in single to negative digits overnight. This makes it easier for the ASHP to keep up with the demand and lowers the temperature differential it has to make up.
In total, our ASHP used 529 kWh in January. If we paid for electricity, our heat would have cost us just under $80.
Check out the interactive version of these charts on my other site, Netplusdesign.
Q4 2013 summary: 10% cooler, 22% more usage and 10% more sun as compared to Q4 2012.
Now that we are starting to collect our second year of performance data, I’ll be comparing our new data to the same period last year. Year-over-year comparisons should be more illustrative than comparing to previous months. I’m also switching to a quarterly reporting period to look for larger trends, but I will continue to post data monthly at netplusdesign.com
In Q4 last year our total usage was 1,599 kWh. This year is was 1,957 kWh, a 22% increase. Despite snow covering the collectors for a few days and cloudy weather, we still produced 10% more energy in Q4.
Overall, here’s how this quarter and the year compare to 2012.
|2013||Usage||Solar PV||Net usage
|2012||Usage||Solar PV||Net usage
We used 22% more energy (358 kWh) this quarter as compared to 2012. That’s about 3.8 kWh extra per day, or 158 watt hours per day more than last year. The last two quarters we’re been running 4 to 5 kWh higher per day. Last quarter I predicted this quarter usage would also likely be up 4-5 kWh/day from Q4 2012. It looks like we stuck to the lower bound, same as last quarter.
One noticeable difference this quarter was our heat usage. Q4 2012 our air-source heat pump used 205 kWh. This quarter we used 438 kWh, a 114% increase. It was about 10% cooler than Q4 2012, but we also had 10% more sun. It’s not really clear to me at the moment what is causing the increased usage. I’ll have to do a bit more detective work. Overall for the year we would have paid $180 to heat and cool our house, if we paid for electricity.
Water-wise our usage is down 5%, and our hot water usage is down 13% from Q4 2012.
Year over year comparison
Looking back over 2012 and 2013, most circuits we track stay about the same over time, excluding heat. The one set of circuits that have changed a lot over the last two years are in the category of ‘all other circuits’, meaning the circuits we do not measure individually. This category counted for 43% of our overall usage in 2013. This includes plug loads, lighting and ventilation. (Ventilation is only used from late fall through mid spring.) Plug loads include the home office, the TV, stereo, refrigerator, freezer, coffee maker, incubators and heat lamps for chickens in the spring, the Prius plugin, barn lights, electric fence, water bucket warmers, etc.
You can see that this category has steadily grown from 100 kWh/month to peaking in April at 330 kWh/month. I’m hoping we’ve leveled off, averaging around 250 kWh/mo. We will still have a peak in the hatching season, until the chickens take over this work for us.
You can see heat maps and detailed charts of temperature and electrical usage at netplusdesign.com. View hourly, daily and monthly values for solar, usage, net usage, temperatures and HDD.
We’re net positive for 2013! We used 7,206 kWh and generated 8,575 kWh for a net surplus of 1,368 kWh. We used an average of 19.7 kWh per day. We used 29% more energy and generated 3% less than last year. 2013 was 16% cooler than 2012. The coldest day of 2013 was Jan 3 at -7 degrees F, and the coldest day overall was Jan 24 at 60.8 HHD.
We’re 21% over our projected energy use of 5,950 kWh for the year. We used about 85% of the estimated 2,440 kWh for hot water energy. We used 26% of our heat energy estimate for the year.
Our BTU/SF/HDD is 0.425. BTU/SF/HDD is a common measure to compare the efficiency of houses of different sizes and climates. We recorded 6,810 HDD (base 65F) for 2013. The ASHP used 1195.782 kWh for heating in that period. Converting kWh to BTUs, 1195.782 kWh * 3,412.14163 (kWh to BTU conversion factor) then divide by 1408 SF and divide again by 6,810 HDD = 0.425.
We used an average of 66 gallons of water per day. 33% of our total water usage was hot water. It takes about 264 watts to heat each gallon of hot water and 2.644 watts to pump it from the well.
That’s it for 2013. Happy 2014 everyone!