Thriving On Low Carbon

Out with the old, in with the new

The Island Coho houses were designed to have heat and domestic hot water (DHW) supplied by an oil-fired boiler (pedantic distinction - a furnace heats air and blows it around a house, and a boiler heats water which is pumped around the house). They chose a pretty good boiler - a German Buderus G115, and the two bedroom houses got two heating zones worth of fintube baseboard heat, one per floor level, and the three and four bedroom houses have a third, for the first floor ell. When this boiler was specified, it used the smallest oil burner nozzle available, which was 0.5 gallon/hour, and therefore its heating output was about 70,000 BTU/hour (for geeks - this is higher than you'd think, because the nozzle is rated for an oil pressure of 100 psi, and the burner on this boiler is running at 150 psi, which means it bumps the nozzle flow up to about 0.6 gallon/hour.) I've previously noted that these aren't superinsulated houses, but they're relatively small houses - 1,166 ft2 to 1,800 ft2 - in a mild climate. So the design load of our house is about 22,000 BTU/hour (NB: this is primarily an IP blog, sad to say). So on the coldest night of the year, the boiler only needs to run about 1/3 of the time. On an average winter day, it may run about half of that, and in the shoulder seasons, even less.

When the boiler is not firing, it loses heat up the chimney vent and off the boiler itself as it cools down. Our boilers here are sidewall vented (don't do this with oil, it's a black mess on your exterior wall around the vent) and so may not be losing as much as if they might if vented vertically up a chimney, but here I speculate. The boiler, DHW tank, and the uninsulated heating piping all reside in the basement. On Martha's Vineyard it is common to put fiberglass batts in the basement ceiling (the first floor framing) and leave the basement walls themselves uninsulated. A basement like this can take all the heat loss you can throw at it. Heat goes into the ground and into the outdoors above grade. An eight inch thick concrete wall with an air film on the inside has a thermal resistance (R value) of about 1.5, which is halfway between a single glazed and a double glazed window.

Right around Christmas, the basement was 59F, which feels fairly temperate. Just before Christmas, we installed a Fujitsu 12RLS single zone minisplit heat pump in our living area. More on that in a bit. On the morning of December 26th, we turned the thermostats controlling the oil boiler down to the minimum setting so the heat pump could do all the heating work, and then the boiler only fired to make DHW. I put a Hobo state datalogger on the oil burner. This nifty instrument shows when the burner is on and when it is off - it logs its "state". When the boiler was operating to make heat and DHW, I saw it run between 3 and 6+ hours daily. When the boiler operated only to make DHW, its operating time dropped to about one hour per day. In what I recall to be little over a week, the basement temperature dropped about 10F, to below 50F. The difference was all the heat not being lost from the boiler and the heat distribution piping. Brrrr.

We operated the boiler without using the second floor heating zone and relied on the heat from the first floor rising by natural convection up the stairs to the bedrooms and bathroom upstairs. These rooms ran 2-4F cooler than the main level. For a week in early February I turned the heat pump off and used the oil boiler again, so I could get some good data on burner run time and oil usage. During this week it averaged about freezing outdoors, and from my burner run time I figured we used just over 2.5 gallons/day of fuel oil. Some of this was for DHW, but less than would be indicated by the roughly 0.6 gallon/day we measured when the boiler only ran for DHW. The reason is that when making only DHW, the boiler would run for about 20+ minutes every 8-9 hours, because it had cooled off in the interval and first had to heat its own water storage and cast iron mass up to temperature before it could effectively heat the DHW. Once the DHW tank thermostat was satisfied, the oil burner turned off, stranding all that heat in the boiler, there to cool off to the flue and the basement. When the boiler was making heat also, it never cooled off for very long, so it didn't use as much energy to make the DHW.

The image below is a snapshot of the burner state from 6:00 am one morning to 6:00 am the next morning. The boiler fires pretty often, on for a couple of minutes then off for six or seven. At about 3:00 pm and again about 10 hours later there is a long cycle, about thirteen minutes, for DHW. A little after 11:00 am, the boiler stops firing for heat - most likely a sunny day. It picks up again around 6:00 pm, then it's off a bit after 8:00 PM - looks like we turned the thermostat down, because the boiler doesn't fire again for heat until the wee hours.

During this week, we used somewhat over 2 gallons of oil daily for heat. That is perhaps 290,000 BTU per day input energy (NB: disclaimer - I'm really fond of Marc's Sloppy Math (tm) - I don't care much about 2% accuracy - most useful conclusions and design directions can be made with 10% accuracy. I am good about getting the decimal point in the correct location, which comes from using a sliderule back in the Stone Age.) Now let's compare with the energy used by minisplit heat pump.

I'll say more about the technology in another post, but the short story is that the Fujitsu is an air source heat pump, which uses electrical energy to operate a compressor to extract heat from the outdoor air and deliver it to the inside of the house. It takes no special genius to get heat to go from hot to cold, but the other way around is harder. Your refrigerator is a heat pump, using electricity to take heat from inside the cold refrigerator compartment and dumping it into your warmer house. The heat pump delivers warm air from a unit high on the the living wall. Here's the outdoor unit:

Here's the indoor unit, over the stunning Nicky Corrao watercolor painting:

The hunky looking white pipe contains the refrigerant lines and wire that connect the indoor and outdoor units. Normally this would be outside but the gutter interfered...

We've heated the house (with the exception of the ell, which we keep closed off from the house, and which seems to run at basement-like temperatures without direct heating) for a bit over three months now with the heat pump. When the heat pump was installed I had the electrician wire an old fashioned electromechanical electric meter in line with the heat pump so I could see how much energy it was using. I've been reading the meter at least once daily. On the coldest day, we used almost 21 kWh. On mild days more recently, we use as little as 3 or 4 kWh. During similar temperatures as occurred during the week we ran the oil boiler, the minisplit has used 12-13 kWh/day. Converting that to BTU gives a daily input of around 43,000 BTU. The oil boiler was using 290,000 BTU, remember? How can the heat pump be over 6-1/2 times better?

Well, for one thing, the reason we use heat pumps is that they use one unit of electrical energy to move more than one unit of "free" energy in the outdoor air. This ratio is the Coefficient of Performance (COP) and higher is better. The Fujitsu is probably operating at a COP of 3 or more. So the energy input into the house might be 130,000 BTU or even more per day. Plus, the heat pump is not heating the basement or losing energy up a flue.

So we've gone from a cost of over $8 per day for heat, to $2.25 per day. And we're heating to slightly higher temperatures, for reasons that need to be left to another post!

 

 

 

 

Lineage and community

In Buddhism, lineage is the line of teachers who have passed the Dharma from teacher to student in a recurring and unbroken cycle - the student becomes the teacher of the next student. On my third post to this new blog, I was tickled to see one of the comments was from Canadian building scientist Harold Orr. Orr was one of the team who designed the Saskatchewan Conservation House in 1977, one of the first superinsulated homes. Orr was one of the first to use a fan to create elevated pressures across a building enclosure to measure and locate air leaks, the technique for which we now use the instrument known as the blower door.

I think of myself as being in Harold's lineage. This student never met the teacher until a couple of years ago at the North American Passive House Conference, but he learned a lot from what Harold did and wrote. I shook Harold's hand with considerable gratitude.

Lineage is vertical and successional. In contrast, community is lateral and evolving. To continue with the Buddhist analogy, the word is sangha. Sangha is a mutually supportive community composed of members with a shared vision and set of values. The environmental/solar/energy efficient building community has been my sangha for over thirty years. I've made a number of my closest friends from this community, and I've learned almost all I know about the work I do from it. Working as we did beginning in the late 1970s, we were learning a lot that no one could teach us, and we shared both successes and failures. A bunch of us learned and aged together over the past decades, and the journey has been a lot easier and way more fun than if we were on our own.

For some of us on this path, the most exciting thing happening now is the influx of young, smart, fire-in-the-belly folks who are the next generation of this community. They're heaps smarter than we are, and they learn what took us decades in weeks. In turn we have experience to share. If we're really blessed, the next student in the lineage appears. I can tell you, they're on their way!

Where's your carbon?

A few years ago, probably after reading Jim Merkel's book Radical Simplicity, I worked through one of the carbon calculators. My carbon footprint was different than most Americans, because I lived in a house that I designed to run primarily off of renewable energy. It was eye-opening to see that four domestic airplane flights annually, three of them in the eastern US, and one to the west coast, were half my carbon footprint (note - my preferred airline carbon calculator is this one, which includes an RFI toggle). Forty percent of the total was driving a car - 18-20,000 miles a year, even though it was a 40 mpg car. Over two thirds of this was work-related, so I rationalized it, but I actually don't like driving and therefore had a double motivation to reduce auto miles.

Now living on MV, I drive much less - well under 10,000 miles annually is what it looks like, and almost all off island. Plane travel is reduced (but I'm about to go off to two trainings in Pittsburgh to ramp up the number of people in the US able to train Passive House Consultants - these are real handwringers for me) but the house as we received it has a much heavier carbon footprint than the one we left. But, we fix.

It's midnight, do you know where your carbon is?

Payback

Part of the intent of this blog is to lay out the process we are muddling through to take this house off of fossil fuels and towards low carbon energy sources. At some point in every workshop or seminar I teach, whether it's on Zero Net Energy Homes, or Deep Energy Retrofits, or Passive House principles, someone stands up and makes an impassioned speech about how all this is well and good but what's the payback?

I'd like to get this one out of the way up front. In the make-over of this house, I, who have never been known as one loose with a buck, am spending what is mostly my own money (with the exception of various incentives and tax credits, and let's do discuss them, but not right now). So I don't expect to spend it foolishly or without due consideration. However, here are my responses to the payback question, in order of how much I think they matter in the whole cosmic scheme of things:

1 - The quickest response I have is, if you predict the future price of energy over the lifespan of these improvements, I'll tell you the payback. My habit when pushed to actually do some financial analysis is to present it in the form of scenario planning - I'll often select three rates of energy inflation and do the calcs showing the Net Present Value of the investment in each inflation scenario. The longer you project it out, the more dramatic are the differences. The usual result of this exercise is that those who are the decision makers begin to act from a position of risk avoidance, because the highest inflation rates in fuel costs get scary.

2 - The second response is to poll the building and design professionals assembled to see how many in the past year or two had a (residential) project in which they installed a 10 kW automatic generator, or they did a kitchen that cost over $100,000. Usually most of the hands in the room slowly go up. How rigorous was the payback analysis on each of those purchases? My observation is that people spend money on what makes them feel good, and just because what makes me feels good (and fortunately, many of my clients through the years) is seeing my ecological footprint shrink. Why does that expenditure draw so much more scrutiny than the money spent on the magazine kitchen or the BMW?

3 - The serious response is that the situation with the climate is likely already past dire and to have a tolerable planet (hat tip to Hank Thoreau here) we need to cut carbon emissions by a factor of 5 to 10, so payback is irrelevant, but least cost strategies are very important. However, least cost strategies are best implemented at larger scales (let's fix the worst houses that the most people live in first, maybe) but these need political agreement, and that's hard to come by in the country blessed with the best government money can buy. Each of us can choose (without convening the US Senate) to make changes in our own house and behavior (well, now I live in cohousing, it's not quite that simple, as you'll learn) so that's where we act.

Besides - if you're not selling drugs (as the former chief probation officer of the state of MA apparently was) how great is the return on your investments otherwise? I'd rather have my dollars on the roof making kWh than playing the slots in the Goldman Sachs-supercomputer rigged casino called the stock market.

 

Are we done with payback and can we move on to more interesting things?

 

Bought the farm

This expression means that the person has died. Although there are various explanations, none verified, of the meaning of this military slang, a less macabre interpretation could be that once you've bought a piece of property, it's all downhill from there.

At the end of 2010, after selling our house in Meriden, we bought our particular farm here in Island Cohousing. As most new homeowners know, every direction you look, you can imagine a way to spend money. Living as we now do in a maritime location, I can tell you that at least a house is not as bad as a boat, which I learned is an acronym for Bust Out Another Thousand$.

 

What's a renter to do? Air sealing can be low cost and effective

After over thirty years of home ownership, I found myself a renter on MV. This made good sense to us - we didn't want to buy a house while we owned our NH home, and we got to try out the cohousing life without making a more permanent commitment. For the first time since I was a kid, I was living with an oil boiler for my heat and domestic hot water (DHW).

If you arrived at this blog, you don't need to be convinced that it's a worthy goal to burn less fossil fuels. That's not the only reason to want the oil system gone, though. Have you ever been in a house where there has been a spill of fuel oil? It soaks into the ground below. You can smell it for decades. The cost of clean up can exceed the value of the house.

For the meantime, though, we were going to be heating our water and the house with oil. We'd started with the 330 gallon oil tank 3/4 full at the beginning of June, and I didn't want to buy any more oil through the winter. We had data from the last renter who'd been there and they'd used an average of 435 gallons of oil annually over a two year period. We had some work to do, then, to meet our no more oil goal.

Heat in houses is lost by conduction through the foundation (yes, heat flows down - it flows from hot to cold), walls, and roof; by conduction through the windows and doors; and by air leaking into and out of the house. It would be an unusual situation in which a renter would add insulation or change windows in a house (although they might convince the landlord to implement upgrades that they agree to pay more rent for). But the air leakage can easily be 30% of your heating bill, and it's the easiest, and least expensive, to address.

The way building performance professionals measure air leakage is with an instrument called a blower door. The most popular product is made by the Energy Conservatory, it's called the Minneapolis Blower Door. An expandable frame fits into an exterior door opening, and it is covered with a nylon shroud, into which a large calibrated fan is installed. A digital manometer measures the pressure drop across the fan and the pressure drop from indoors to outdoors. The idea is to use the blower door to depressurize the house to a fixed pressure below outdoors (typically 50 pascals in homes) and measure how much air it takes to sustain this pressure difference. The tighter the house, the less air the blower moves to reach 50 pascals. A MN blower door will move over 6,000 cubic feet of air per minute (CFM) (that's quite a gale). Some houses are so leaky that you need more than one blower door to bring them to a 50 pascals pressure difference. Others, like houses built to the Passive House standard, might require under 100 CFM. (Disclosure - I am a Certified Passive House Consultant, and probably certifiable in other ways as well, so I'm a True Believer in very tight houses, and a mechanical ventilation system.)

Being a building geek, I own a blower door, so it was a simple matter to test the house. Besides using the blower door to get a CFM at 50 pascals measurement (called CFM50 in the trade), we can use them to find leaks, and to assess which part of the house is leaking the most. When I look for leaks, I use a theatrical fog machine, which I'll describe in a future post. The results of my testing showed me that the house was 919 CFM50. This is better than the typical new house but leakier than I expected. I then used a technique developed by Michael Blasnik called Zonal Pressure Diagnostics. This told me that the leakage between the house and the outdoors through the basement were four times higher than the leakage through the attic. This helps focus attention on the places where the largest improvements may be made.

Some of the leakage locations were obvious. There were big gaps below the exterior doors. The attic hatch had a cover that was too small, and was un-weather-stripped, and had no insulation to boot. As is not uncommon, this last was despite the construction drawings showing a weather-stripped and insulated hatch cover. In the basement, there were holes I could see outdoors through around the door at the base of the bulkhead stairs (though, at least this house had a door at the base of the bulkhead -  a common omission) and around the triple awning window at the south end of the basement. In about two hours of work, and maybe $30-50 of materials, I dropped the leakage from 900 to 650 CFM50. This is work that probably has a one year payback. I installed a door sweep on the exterior door; weatherstripped the hatch and made a 4 inch foam insulation plug to go on top of it; and used foam sealant in a Pageris foam gun (this link is to the professional tool, but there are less costly homeowner versions) and some caulk for the small gaps (less than 1/4 inch) to seal at the basement window and door.

It's not beautiful, but it works.

The House

When we moved to MV in June, we rented a house in Island Cohousing in West Tisbury. This is a group of sixteen homes and a Common House, developed, designed, and built by South Mountain Company (where I consulted for 20 years before coming to work here last June) in the late 1990s. For the previous twenty-five years, I'd lived in a house I designed and built in Meriden, NH called Nerdwood. It was a dose of reality to leave a house that got most of its heat and hot water from renewable energy (sun and wood), was drenched in sunlight, and was able to coast with no heat input for a considerable amount of time, to inhabit a house with, well, let's just say less attention to these attributes.

I had been a consultant on this project, and I built an energy model to help make choices in the building design. I'd urged a strategy that traded mechanical system cost for building enclosure cost, advocating a single point source heater (back then, a sealed combustion gas heater, such as a Rinnai, today perhaps a pellet stove or a single zone minisplit heat pump) instead of a multi-zone oil-fired forced hot water system. The cost difference buys the enclosure upgrades. Unfortunately, fuel oil was $0.85/gallon in 1998 even on MV (it's inflated at about 14% annually since then) so extra insulation and triple glazing were ruled out. Two energy upgrades remained over standard construction - the insulation used was blown-in cellulose installed by one of the best insulators anywhere, Matt Viaggio, and the windows were Canadian Thermotechs, which use hollow fiberglass frames and sash filled with foam insulation to increase the insulating value of the window over a wood window. These windows were specified with a glazing product called Energy Advantage  , which lets more solar heat in than most other glazings.

The Island Coho houses got a lot of other stuff right, as you might imagine. The group had identified protection of the Island's sole source aquifer as their primary environmental focus, so each building here has a Clivus Multrum composting toilet. Designing a house around the straight drop toilet chutes adds a serious constraint, and the houses, which came in 2, 3 and 4 bedroom models, all have the same basic layout to accommodate the composter.

As with all South Mountain homes, the materials used on both the interior and exterior are beatutiful, durable, and have a story. The trim is river recovered cypress, the floors are sustainably harvested birch or ash, the porches use native milled timber, and bathroom tiles are from recycled auto windshields. Compared to what houses designed to be affordable usually are, these are beautiful - no carpet, vinyl, particle board, etc.

They are also very well designed, with light on at least two sides in most spaces, and quite space efficient. The base 2 bedroom homes are 1,166 ft2. Our house, which is a three bedroom that also has three of the optional bays, has a gross area of 1,589 ft2. It's larger than we'd like, but there y'ar, as they say in Minnesota (Jill is from MN so I have learned to at least understand the language if it's not spoken too quickly, and who ever heard a Minnesotan speak quickly?)

All of the houses have full basements for a foundation, and that's yet another story.

 

What's this thriving on low carbon about, anyway?

 
I moved to Martha's Vineyard on June 1st, 2010, with my sweetie Jill and a dog. I'm passionate personally and professionally about living well with less throughput of materials and resources (OK, bicycles excepted here...) The focus here will be how I'm thinking about our house, transportation, food, waste, etc. Opinions expressed may be well thought out or not - no warranty express or implied. Please let me know what you think, and feel free to take issue.

Girl and dog