Thriving On Low Carbon

Useful aspects of the eMonitor

Tom DeMarco wrote, "you can't control what you don't measure" (widely misattributed to Peter Drucker BTW). Well hell, there's lots you can't control no mater what. A less ambitious implementation of measuring is to aid in understanding how a system operates. The eM is good for this.

One useful feature is the setting of Alerts. The eM software offers a lot of Alert choices. It can tell you when your electric cost for the month passes a certain level. I like the ones such as:

- Notify me when a particular circuit is drawing little or no power for an extended period

- Notify me if it looks like my refrigerator or freezer door was left open

- Notify me when a particular circuit or appliance seems to have been on for an extended period

- Notify me when a piece of cooling or refrigeration equipment is short-cycling, a condition that is likely to require a repair.

- Notify me when one of the selected piece(s) of equipment uses at least % more energy than it did before

On one of our SMC projects, we got an alert that the water heater was using more energy than typical, and we traced it to a hot water leak. One aspect of Alerts is that you need to be prepared for false alarms. My eM tells me almost daily

"It looks like your 'Refrigerator' door may be open; you might want to check it.If the door is closed, check the seals. This alert is triggered by a compressor that is staying on longer than usual, so if it is not a door or seal problem it could indicate another problem with the unit."

It doesn't seem to be used to modern refrigerators, which draw less power but run for longer when they are on. Also, I get an Alert that tells me

"Your SiteSage service has detected that your Minisplit heat pump circuit is not drawing any power or the expected level of power."

That's because I have a superinsulated house with good solar gains on sunny days, so the heat pump turns off most days by mid-morning, and doesn't come back on until the evening some time.

Using the eM I can see where our energy goes. I can tell if we left the basement lights on all day. I can see how much energy the preheater uses in the HRV to defrost the core. It's been most useful in diagnosing an issue with the Fujitsu heat pump.

At House 5, the outdoor compressor unit was right outside the living/dining room, about five feet from where we sat for reading or eating. We virtually never heard it run. In the new place, the compressor would periodically whine so loud we could hear it all over the house. Using the eM, this is what a day's worth of energy usage looked like:

Here I selected a day where there were minimal solar gains, so the unit ran all day. The outdoor temperature was around freezing. The pattern showed that roughly once an hour the heat pump would ramp up over seven minutes to absolute full output, in fact, the input power measured of about 2,400W was about 1/3 higher than the unit is rated for. I verified that the eM was measuring correctly by putting a ammeter on the line - it measured just under 10A, correlating nicely with the power the eM measured.

The nifty aspect of inverter-driven minisplit heat pumps is that they modulate their output depending on the building load. And running at a reduced output, using the same heat exchangers, is more efficient. And running the indoor and outdoor fans, and the compressor, at reduced speeds is much more efficient. So my unit was heating the house fine, but using more power than necessary and making a racket. How that got fixed is a whole separate story, but it was the power traces from the eM that convinced Fujitsu tech support that there was something worth looking at here. Here's what the energy use looks like in the unit running properly:

Yesterday also had little solar gain, and was about 45F outdoors. The heat pump's peak power draw here is 400W, and it averaged about 200W over the twenty-four hours. It is likely running at a COP of about five! And it is quiet, too.

After we got these control settings fixed, the heat pump used less than two-thirds of the energy per heating degree day than it did when it was cycling to full output then off. The eM helped us in the process of understanding this and ultimately solving it.

Another useful application of the eM is to be able to see how much power appliances draw when they are nominally off. I deliberately try to avoid appliances with electronics and clocks, because they draw parasitic power all the time. We own a microwave, toaster oven, refrigerator, chest freezer, dishwasher, clothes washer, clothes dryer, and heat pump water heater that all have no displays or clocks. According to the eM, none of them draw any power when off. In contrast to that, here's the March 2014 power trace for our induction range:

On thirteen of the days we didn't use the range, and because it draws about 6W continuously, on these days it uses 0.13-0.14 kWh. So the monthly baseload is about 4 kWh. This month, that will be 28% of the usage. If the eight appliances I listed above all drew 6W continuously, then we'd consume about 450 kWh/year in parasitic power (or what some people call phantom loads, or vampire loads). That would approach ten percent of the total anticipated annual energy usage here. I'm told some cable boxes draw 40W continuously!

 

The eMonitor

I have a new toy. It's a totally geeky toy - almost everyone else would rather have a large plasma screen TV. It's called eMonitor and it is made by Powerhouse Dynamics. You can buy one from folks at Powerwise Systems or Energy Circle. It's a device that measures energy usage in your house circuit by circuit, and uploads that info to a web site where it can be viewed in a number of ways. Any circuit being measured has a current transformer (CT) (or sometimes two, for some 240V loads), and you can get versions with 14 CTs, or ultimately as many as you want. I chose one that does 24 CTs. That doesn't get every circuit - I have some left over in what is called Unmonitored Power, maybe 3% of the usage. If I'm really curious I can always move some CTs from one circuit to another.

It's a costly doodad.  Mine lists for $695. Plus, you pay for access to the web site to see the data. In my case, I paid $240 for two years of monitoring access, plus an additional $108 to include my solar electric system (PV) in the mix. I installed the system myself, but they (or their lawyers) recommend that it be installed by a licensed electrician. It took a couple of hours to put it in and then enter the circuits on the web site, so it's clear what each circuit being monitored is feeding. If your electric panel has been poorly or inaccurately labeled (the norm in my experience) count on a couple of hours, preferably with another person, to track down what is on each circuit breaker.

When you're done with the installation, the panel is pretty darn full of wires. The eMonitor has a component that stays inside the panel, that the CTs connect to, and it communicates wirelessly to the unit outside of the panel that connects to the modem and thereby the outside world.

When I go to the Sitesage web site (recent, very unfortunate name change :-), this is what I see:

The top of the page shows how much power the house is using, how much is being produced by the PVs, and what the net power draw or export is. It also shows the largest power users. In the snapshot above, you can see that the heat pump water heater (HPWH) is running, the Fujitsu minisplit heat pump is on at a very low level (outdoor temperature of 48F is shown - they must get that from another web site, there aren't temperature sensors connected to the eMonitor, although Powerwise can fix you up with all kinds of sensors too), the unmonitored power is 65W (my Macbook Pro, actually, as I write), and the heat recovery ventilator (HRV). There are other tabs for more information, or to set alerts, etc.

Next on the page is a donut chart showing energy usage over the past 30 days. It's been wintry, so the minisplit has been the dominant user. I'm not sure what the horizontal bar graph in the upper right corner is measuring.

Here I can see total usage vs. production for various periods - either by month for a year, or by day for a month. Average outdoor temperature, and heating and cooling degree days are shown as well. On the right, the actual energy usage pattern can be viewed for various durations.

The button entitled Export Data allows you to to export data by minute, day, or month into an Excel spreadsheet - very nifty.

There's a lot more to say, about looking circuit by circuit, setting alerts, and how this is useful. More in another post.

 

 

 

Design matters

Once we bought the new house in the fall of 2012, we began to work on the new design. We were starting with a one bedroom house of 1,142 sf, on one level with a full basement.

There were some framing oddities that were revealed as the gutting process proceeded. The house, though very leaky, had 2x6 walls and 2x10 rafters. It had a low wall plate height of about 7'6" but most of the house had ceilings that followed the roof line. Its south side faced about 11 degrees east of true south. We had good solar access, which was improved with some selective tree cutting. There was a separate outdoor entrance to the basement, but it cut off east light to the house.

Given that we both might end up working at home in years to come, we wanted three bedrooms. Although it’s a bit of a luxury, we had developed an appreciation for having two bathrooms for when guests visit (and for eventual resale of the house). After the sun-drenched quality of Nerdwood we never got used to the paucity of natural light in the main public space of House 5, especially in the winter when it was shaded by the house to the south, so a well-glazed south façade was a key program element. And we wanted a good entry space with a generous closet and space for a bench.

I worked on several schemes, including variations that added a small addition to the existing one floor house, and variations that added a partial second floor. I had some solutions that would be good but added too much new space, which drives up the cost. I drew my SMC architect colleagues Ryan Bushey and Matt Coffey into the process, and both were instrumental in improving the design. Finally Matt bore done on the design one evening and with a few deft strokes drew a scheme that vastly improved anything I had done while keeping the new addition to 12’x16’. I’ve made a few tweaks to his design, but what we’re building is fundamentally true to his concept and as the spaces took shape we are so grateful for his intervention. The final design has a generous entry space and closet, two small bedrooms and a modest master bedroom, two baths, and a thirty foot long great room space on the south. Below is Matt's design sketch.

Looking southwest (and southwestern!) in the Great Room:

Looking back to the kitchen:

Given that it is a one story house, my design had a few small skylights to bring in top light. I had passed the design around to other friends in the design biz, and Jamie Wolf of Wolfworks had some of his usual insightful questions, and the one that really hit home was, why so many skylights? That prodded me to look at each one carefully, and we’ve ended up with only one, above the kitchen island. Having a one story house with cathedral ceilings enabled us to use awning windows high in the gable ends to bring light high into the bedrooms without putting a hole in the roof. Thanks Jamie! In the photo below you can see we've pushed the windows hard against the wall so as to use the wall most effectively as a reflector to bounce light across the room.

Matt’s design solved one of our conundrums, which was how to get easily from the house to the basement. We wrung our hands about giving up an exterior access to the basement, but justified it because of having so much storage/shop space in our outbuildings. My architect brother-in-law Paul Hajian of Hajian Architects looked the plans over, and said, your basement stair has a landing 2/3 of the way down that is on the outside wall, you could cut the foundation there and access that landing from outdoors too. Great idea! So we cut a notch and built an exterior stair. Once inside, the stairs down are to the right, which might make it challenging to get something long into the basement, so we hinged the main run of stairs at the top, so they can be hoisted up out of the way if we want to get a kayak or suchlike down there.

We’ve been so fortunate to have so many talented designers looking over our shoulder and making this little house sing. Thanks all!

 

Some reflections on the project

Before I get all geeky about this Deep Energy Retrofit journey we've been on I have some overall reflections on the past year. I've built two houses for myself over the years, but I always stopped working, and focused completely on the construction process. I was on site whenever anything was happening. This project was different. Both Jill and I continued working at our respective jobs. In the other hours we worked on the house project, even though we had a builder and subcontractors (I should say, that given how full our construction schedule was at South Mountain, it was clear that we were going to have to look elsewhere for our builder). I don't think I've ever worked as hard as I did from May last year through January 2014. Jill took charge of the work we did on the grounds. My job was to stay ahead of the workers in terms of providing details and answering questions as they came up, ordering materials, and also to do some of the actual work. In the end, I built the new bulkhead, insulated the basement, installed the HVAC system, and did numerous other small tasks.

Our principal pressure was time. After we sold House 5 we lived in a one room unheated building and we knew cold weather would determine when we needed to be in the house. We got off to a very slow start (the principal task of the owner/general contractor is to get people to show up. Pete D'Angelo tells a story of a woman at a party who couldn't get an electrician to come. Pete told her, if he says he's coming tomorrow, that means next week. If he says he's coming next week, that means sometime in the next month. What did he tell you? She replied, he said he's coming as soon as he can. Oh, said Pete, that means he has no intention of coming at all, at which she burst into tears.) Ultimately the project took about two months longer than my initial schedule. Some of this was due to the amount of work that actually needed to be done to the structure, and some was the showing-up issue. I would have made fewer errors and compromises if I had more time. Perhaps we should have bit the bullet and found a rental house for a year and taken more time to do the project.

In the end (not the real end - we're not done but we're in) we have a beautiful place that's bright and cozy and works well. Yet I could have done better on materials choices, and sending less waste to the refuse district. I'd say we'll do better next time, but I've already told Jill that if I ever suggest we do a gut renovation again she should just shoot me immediately :-)

Ideology trumps economics

One of the interesting twists in the sale of House 5 is that I priced the solar electric system as an option, since it was an income generator, making $1,250/year of electricity. Ultimately the house was purchased by our friend and next door neighbor in the cohousing. He is a staunch Tea Party Republican, and quite knowledgeable about investments and money, but solar isn't part of what the drill baby drill party wants to hear about. So he wasn’t willing to pay the $5,000 bargain price we offered on the PVs (a four year tax-free payback here!) So we had them removed ($500 cost) and had a new layer of shingles installed on that roof. So we kept our 4.76 kW PV system for about $2,000 and it’s re-installed now on the new place.

Back

It’s been a long time since the last post here and much has occurred! Jill and I got hitched on June 2^nd 2013 on the beach at the Gay Head Cliffs, then spent the next 7-1/2 days packing up our household at House 5 in Island Cohousing in preparation to moving to our new place. We closed on House 5 on the 10^th. Not a recommended honeymoon.

By then the work on the new place on Great Plains Rd was in full swing. It was gutted to the studs and rafters, revealing that even though it is a relatively recent building it was paint and inertia that had kept it standing (and lack of real snow loads on MV.)

 The house has an interesting history. I think it was built in 1996 or 1997, in Edgartown, as a guest house. The property changed hands and the new owner offered the house to the previous owner here, if he would move it. He put in a new foundation. I am guessing that he did that ahead of vetting that the entire house could be moved, and that the mover told him that he could move the 16’x32’ portion but not the wider half. So he got the part that had a kitchen, bedroom and bathroom, and then built the rest new here in West Tisbury. This is fortunate for us, because the part that was moved was built quite poorly.

The whole place had low cost finishes – stinky carpet, vinyl flooring, and some low end wood laminate. It also smelled. There was evidence of mouse activity, the foundation was uninsulated so very moist, and there was a 14’x10’ section where the floor slab was left out and the void filled instead with crushed stone. This is not uncommon – the water heater and well pressure tank are located here, and the thinking is that leaks and condensation just goes down harmlessly. Unfortunately, stinky soil gases, and ones that have no odor such as radon, come up. It’s a bad idea to have 140 sf of soil contact in your house.

The floor plan also wasn’t optimal. It was still a one bedroom house, with poorly differentiated space. It also didn’t take advantage of the building’s south orientation. These factors, combined with the leaky shell (over 3,000 CFM50) and vague thermal boundary, all led to the main decision, which was to gut the interior and implement the thermal improvements from inside. Normally we prefer doing Deep Energy Retrofits from the exterior, but that presumes that the interior is basically satisfactory. The house also had exterior shingles, roofing, and trim that were only ten years old. As it turned out, changing the window and door openings so radically meant that almost all of the shingles have been stripped, so no savings there. In a way, we paid about $100K more than we might have for an undeveloped lot, and for that we got a four bedroom code compliant septic system, an excellent well, 200 amp underground electrical service (and an additional 100 amp one to the outbuildings), an excellent foundation, a roof and some mediocre framing! We also got two funky outbuildings, which began their lives as far as I can tell as box truck bodies, eight feet wide and 16 feet long and 23 feet long. Both received insulated gambrel roofs. Before the house was there, the small one was where the previous owner lived, and the large one was his shop.

Purchasing an existing house also freed us from what is increasingly painful to me, which is developing a new house site and all the destruction that occurs. And taking an existing house and making it better appeals to me more than starting from scratch, despite the fact that from this vantage point it’s debatable whether we have saved money doing so, and working with an existing shell and massing always generates compromises.