Jan 2016 Resolution thoughts

January 6, 2016

Using the analytic categories from last year about reducing my carbon footprint, here are things I’ve explored and directions for 2016.

Substitution. In December 2014 we bought a 2010 Prius to replace Krista’s 1994 Subaru Legacy. The change in mpg was from mid-20s to high-30s (most of her driving is in Moscow, it does better on longer runs on the highway using cruise control so it can do more of the thinking).

Our milage data shows her car drove about 7300 miles in each 2014 and 2015, the latter with a 50% improvement in fuel efficiency.

Replacement. On the other hand, my work has me driving around Moscow. I find that I need to get between places faster, or take things larger, than bicycling facilitates. That is, I can’t achieve the driving reduction behavior I want, so I’m thinking about replacing my ’89 Toyota wagon with a used Nissan Leaf and moving to a carbon free automobile. I drive almost exclusively in Moscow and occasionally to Pullman and rarely to Lewiston. It seems the Leaf will meet my needs.

 Year 2012 2013 2014 2015
Krista’s car (red) 7927 6313 7370
My car (white) 5241 2336 4472 4107
My pickup (blue) 1059 2078 1576  966
Krista’s Prius (silver) 7318
totals  14227  10727  13418 12391

In 2014 I gave away our 15 year old riding lawnmower/snowblower. For two years now I’ve contemplated replacing the remaining gas lawn mower (self-propelled walk behind) with a reel mower and/or an electric (corded or cordless) mower. I think a purchase needs to happen in 2016, even if I keep the gas mower as backup.  Key issue is storage, I need a way to put either of those devices away out of the weather.

More Substitution. Karina and I used a Kill-A-Watt to measure the energy used by our refrigerator (part of a campaign to get a new fridge). Over a 3-day period (73.75 hrs) it used 9.06 KWH for an annual rate of 1076 KWH/yr. Karina has found replacement refrigerators with Energy Star ratings and energy usage ratings as low as 466KWH/yr and multiple options below 650KWH/yr. Now, realizing that the rating is like an EPA milage number (your milage may vary), it’s still hard to imagine we can’t get a better performing fridge.

We pulled out the fridge, it was made in Aug 1998 (17+ years ago). Googling how long a fridge lasts we found 3 sources: 80% last between 9-15 years; 10-15 years; and average 13 years.

SO, owning a refrigerator for its lifetime has 2 energy costs: operational cost and construction cost. One is paid daily, one is paid every 10-15 years.

As an aside, I wondered if there were a fridge that would pay for itself in energy savings (compared to keeping our current fridge (if it would last another 15 years)). I looked up the Avista power rate and multiplied by the KWH savings/year of our current vs potential new fridge = $45/year.

Karina was reluctant to search for a refrigerator that was 18+ cubic feet, 450KWH/year and priced under $700, but she found one (I think). Her reluctance stems from a desire to buy the features in the more expensive fridges she has found– which maybe should be a new category for this analysis: Too much vs Enough.

However, the analysis raised another question. When talking about payback period, are we talking the best sale price we can find, or the suggested retail price? That is, what does price measure: cost of inputs or other intangibles in the merchandising process?

Generation. I regularly observe that the solar air heater is in operation in the Cookhouse. I have resolved to get its water heater running. I intend that project to be the pilot one, with the home water heating to follow. The Barn is partly ready for solar hot water and solar air heating conversions, but it will be the third project to tackle. The house uses gas for hot water, the Barn uses gas for both water and space heating, so I have several opportunities to reduce direct carbon use through generation.

Cold Pizza for Breakfast

January 25, 2015

Richard Heinberg just posed a long essay Our Renewable Future (Or, What I’ve Learned in 12 Years Writing about Energy) which is a worthwhile read and something to return to later.

Near the end of section 7 he writes:

[there is only] one meaningful indication of success in all these [renewable energy] efforts, and that would be a decline in society’s overall energy use… What we need is not just to trim energy use here and there so as to save money, but to reconfigure entire systems to dramatically slash consumption while making much of the remaining energy consumption amenable to intermittent inputs. (emphasis mine)

‘Intermittent inputs’ is a reference to the idea that the wind does not always blow nor the sun always shine. He’s suggesting we need to organize ourselves to both make hay when the sun shines and be prepared to do something else when it doesn’t.

I already live with some intermittent energy supply. We heat the house with a woodstove. My evening ritual involves making sure there is enough fuel and kindling on the porch that I don’t need to make a morning trip to the wood pile in my bathrobe. The morning starts with lighting a fire. It gets stoked or relit periodically during the day/evening, depending on the day’s needs.

Energy storage is a way around intermittent supply, but it comes at a cost. Today I was thinking about what it would mean to my morning routine if I used only intermittent energy to start my day. After the fire, step two is making coffee. I use an electric kettle to boil the water. Since the winter sun is not up, I’d need a battery to power the kettle, or wait for the stove to heat the water. Step three is often making some toast.

Then comes the shower. My explorations at energy reduction have included making the hot water supply intermittent. Right now that involves putting my conventional hot water tank on a timer, its off when we typically don’t use hot water (eg, while we are sleeping or at work). Heinberg has me thinking about what it would mean to have the hot water heater “on” when the sun is shining.  I’d want to time my hot water use for late afternoon, and with an insulated tank, into the early evening. Morning would be the time of tepid water, and maybe not for wake-up showers.

Summer vs. winter is another way to think about periodic inputs. Perhaps I need to think differently about winter hot water, when I can’t count so much on the sun. Do I need two heating systems, the woodstove and a solar collector? Or do I need much more storage for hot water to “make more hay” when the sun does shine?

Perhaps I should I learn to like cold pizza for breakfast.

2015 Resolution – Reflect on Conservation

January 3, 2015

Progress on reducing my direct carbon footprint

Following on my conceptualization for the solution to reducing my direct carbon footprint (this analysis), here is the year in review:

Reduction. I think my theme for 2015 needs to be reflection on conservation, and its nuances.

In previous New Years posts I have tracked our car milage and was pleased to see our progress reducing miles driven. Alas, the reduction was lost in 2014. The lesson: bike/walking to reduce miles in town is easily overwhelmed by driving out of town, which should be obvious, it takes quite a few avoided short trips in town to equal the milage of one trip out of town.

2012 miles 2013 miles 2014 miles
Krista’s car (red) 7927 6313 7370
My car (white) 5241 2336 4472
My pickup (blue) 1059 2078 1576
Prius (silver) new 12/4/14
totals  14227  10727  13418

My friend Stephen has a longer dataset and can demonstrate real progress reducing his driving, so it is possible.

spaeth carbon wedge car

In our cars, reduced use requires constant vigilance. In contrast, the area of lawn I mow is being reduced steadily by orchards, gardens and landscaping at the Cookhouse. I haven’t used the 15-year old riding lawn mower/snowblower in 12 months. Since, I’ve proven its possible to manage what is left without the rider, it needs to go away this spring.

Another notable experiment in reduction was to put a timer on our hot water heater. Now we make hot water for morning showers and again for evening dishes. While the savings from not maintaining hot water is small, we have proven in the past 6 months that we don’t lack for hot water when we want it. This experiment needs more study. For example, can we time the water heater so we use up much of the hot water and only store tepid water (rather than having the water heater reheat the water we just used and then storing that hot water)?

Substitution. Another of the strategies to reduce my direct carbon footprint is to substitute technologies.

The Cookhouse was built with all LED lighting and I thought I was done converting the Barn, but the other day I found one more CFL — a small one in a reading lamp. The house is partly converted, the Kitchen, family room and bathrooms are done.

My efforts at substituting LED lighting for CFLs are producing limited results; my home electric bill is not going down much (if at all), because the refrigerator, freezer, dishwasher and electric dryer are such a large fraction of the use that they overwhelm the savings in the lighting.

The used Prius that Krista will drive in place of the “red” car appears to give her 40+mpg vs the previous 25+mpg in “red car,” so if we can hold the miles driven steady, it should be a decrease in fuel used.

Replacement. The oven in our gas stove died last spring and (sigh) there are no parts to repair a 10 year old stove. The process of deciding has been slow, but we are headed toward an induction stove, all electric. The decision process was explored in this column. Replacing this appliance will produce a permanent decrease in our direct use of carbon, but a small one compared to the gas water heater. I’m having the electrician get me ready to do the water heater, but can’t afford that change yet.

While the 15 year old gas lawn mower is still running, I’m considering replacing it with an electric one. Since I’m not sure how that will work in when the grass grows fast in the spring, I’ll keep the gas one around for another season.

Generation. I have some more data on the impact of the solar air heater in the Cookhouse. My previous report was from a short duration observation. Now I have a year’s worth of data which appears to show April, May & June readings with less consumption than heating degree days would predict. Since the structure is still unoccupied the only energy use is for heating. Goals for 2015 are getting hot water preheating going in the Cookhouse and in our house. This data are also encouraging me to develop solar air heating to supplement in the barn.

849 electric usage

Electric heating in the Cookhouse for 2014

Local Food Dinner in February

February 23, 2014

Last year my wife and I sold seats for a local food dinner as part of a fund raiser. I picked February for the event, intentionally to make it challenging — and to see what I would learn. The guest list required that the meal be vegetarian, but not vegan.

Lessons & Compromises. The biggest lesson was about storage and volume of our local producers. Ingredients that we know are are grown locally were not available commercially in February. I checked with a couple local farmers, they had already emptied their storehouses. Some ingredients we had stored in our cold cellar (apples, carrots, garlic), others (beets) not. Milk came from Spokane, WA (80 miles); I could not find butter or cream locally. The cow milk feta cheese could have been local, but I could only find Brush Creek’s marinated feta and wanted their fresh. Probably an issue of storage and low sales volume.  Oils — I used olive oil and butter  (as oil) and neither has a local source or a local work-alike.

It took some time and advance planning. The pumpkin puree in the rolls was made the week before– emptying out the last of our stored pie pumpkins. Hydrating and cooking the garbanzo beans took the whole morning the day of the dinner. The rolls are slow rising and they were started about 8am and were rising by the wood stove before 10am. I ended up using commercial vegetable broth for the soup– making broth ahead didn’t happen.

Best Discovery. Mushrooms from Rosalia.


Appetizer: Chili-Lime Roasted Chickpeas  Fresh lime was a compromise, but I understand that citrus historically was shipped long distances and kept well (eg British Navy use of limes to prevent scurvy) so it may be possible to consider a limited amount of citrus if some amount of low-carbon transport is available.

Soup: Roasted Garlic & Potato with Homemade Croutons  I got day old bread from a local bakery. (It did not contain the most local of our whole wheat supplies, but was organic and regional.) Garlic was from our yard. Potatoes and beets could have been very local, but were only in-state. Carrots and onions were local commercial, but I had stored them.

Roll: Pumpkin Dinner Roll No local buttermilk, I made it up from powder. Commercial dry yeast. Same flours as the pie crust. I made the pumpkin puree. Butter was not local, because we lack the dairy processing.

Main Dish: Vegetable Frittata with Corn Bread Crust  The pleasant surprise was grey oyster mushrooms from Rosalia WA. I also used mixed varieties of baby potatoes, carrots, golden beets and previously blanched/frozen local asparagus. I had dried the tomatoes and made the garlic scape & olive oil. (No olives are not local)

Salad: Apple, Beet, Carrot

Dessert: Cherry – Rhubarb Pie with whole wheat crust. Half whole wheat flour from our most local mill, half durham flour from the USDA Wheat Lab at WSU (actual origin and milling unknown). 100% whole wheat makes a crust that my family does not appreciate. Filling from our freezer.

Passion for trees

February 14, 2014

Appearing in Moscow Pullman Daily News, editorial page, Feb 14, 2014

HIS VIEW: Pitching in as a volunteer urban forester

byline: Nils Peterson is a member of the Moscow Tree Commission, who celebrates his passion for trees by building timber frames such as the Berman Creekside Park picnic shelter.

I am passionate about trees. When I was in 4th or 5th grade my parents took us to see the wooden naval ships in Baltimore Harbor. That is my first memory of being impressed by big wood. Since then I’ve been awestruck by both individual redwoods and old growth forests.

My passion for trees increased when I discovered the Timber Framers Guild and their efforts at recovering a lost building art. I find that working with hand tools allows me to attend to idiosyncrasies of timbers, which helps me appreciate trees as individuals.

Working with wood gives me a deep appreciation for Eric Sloane’s great little book “Reverence for Wood,” and inspired a talk I gave a few years ago at the Unitarian Universalist church in Moscow. The beginning of the presentation invited the audience to engage in one of my favorite activities in the church — staring at the floor. The floor is red fir, installed 100 years ago. Its knot free straight grain suggest to me that it grew in an old growth forest and was maybe 100 years old when it was harvested — saplings at the time of Lewis and Clark. That wood connects me to ecosystems and to time.

The birch tree that stood in former Moscow resident Lynn Unger’s front yard now spans the center of my barn.  It unwittingly turned me into an urban hardwood lumberjack. I discovered the diverse beauty of the trees growing in our city. Ash, box elder, chestnut, cherry, elm, linden, locust, maple, Russian olive and walnut all found places in the barn before I finished. I made friends with some of the area arborists and became something of an ambulance chaser after local hardwood.

Harvesting urban hardwoods also connected me to some of the area’s wood turners. They often took pieces too small or knotty for me and turned them into art. You can often see examples of their art at Farmer’s Market.

Now I have a small orchard, mostly plum and apple. Pruning the young trees each spring is a meditation, a chance to see how each tree responded to last year’s cuts and to choose my next step training the tree. And then in the fall I learn if my efforts are bearing fruit. The orchard is teaching me patience in a collaboration with the life of the trees.

But perhaps the greatest lesson I’ve learned from my passion for trees is about community. Barn raising requires community. For me, almost two decades after raising my first timber frame, the whole activity is less about building and more about engaging, sharing, connecting. The process, and the trees, have become my teachers, helping me to be more in tune, more connected, more reverent.

Cultivating Moscow’s urban forest is also a community activity. Inevitably, I suppose, my passion for trees and they lessons they taught, brought me to the Moscow Tree Commission. Recently the DNews reported on a new project of the Commission, “Adopt-a-Tree.” (Feb. 1&2)

The idea of Adopt-a-Tree is like Adopt-a-Highway, to provide a mechanism for individuals and community service organizations to volunteer assistance to Moscow’s urban forest by providing specific services to select trees that are on City property and Rights-of-Way. The goal of the program is to extend the resources of the Parks Department staff, promote civic pride, and enhance the urban forest.

I hope this program creates a channel for community members to direct some of their own passion into enhancing our community trees.  Learn more on the City website, or come see the Commission when we have a booth at Farmers Market. And follow your passion for trees.

New Years Resolution Jan. 2014

January 7, 2014

Analysis of 2013 Resolution and Results

As with 2013 it took me awhile to formulate a resolution. I learned from the last one to be more concise and more specific to help the subsequent assessment.

What is not clear in my previous goal is if a main goal can be met by meeting one of the subgoals (eg. examples) or if the goal required meeting all the subgoals. [Previous resolution is here]

Perhaps my biggest gain was not in meeting my specific goals but sharpening my conceptualization of the problem in this analysis of how I can eliminate my direct carbon footprint.

Review of 2013 goals
Substitution. I did make headway on substituting technologies. I started Avista Buck-a-Block on the house and Barn to use offset renewables in place of fossils for my electricity generation. I’ve been exploring LED lighting and buying sample bulbs from TMart and on eBay. The CREE 60W (equiv) is the best of all of them but at twice the price. I think I have replaced half of the most commonly used bulbs in our house, started on the Barn and committed to making the Cookhouse LED from the start. The biggest wattage gain was finding this 5W LED spotlight to replace some 50W halogens.  I also researched with an electrician swapping out the gas water heater and gas dryer in the Barn for electric ones. Wiring is not in place but the breaker panel has enough capacity and the distances are short. Major de-cluttering of the barn’s basement is required to make the task feasible. I’m not sure I understand what I really intended by the local food substitution goal. I’ve certainly fiddled with that, but it needs to be re-phrased.


Progress — we reduced our total driving by 25% (measured as miles driven) compared to 2012.

2012 miles 2013 miles
Krista’s car (red) 7927 6313
My car (white) 5241 2336
My pickup (blue) 1059 2078
totals  14227  10727

Green Production. I have built a solar air heater in the Cookhouse and its reducing some heating demand. The solar water preheater is still under construction, but its part of the plan. And the Cookhouse itself is all electric with Buck-a-Block in place, so it has carbon offsets for all its utilities. My cooking experiments have been sporadic, but I’m better at using the Crockpot, with several soup recipes that I make as a batch and re-heat for my lunch. The next leap here will come with an installed and easy to use solar cooker to replace the crockpot. That has to wait finishing my current building project. Similarly, the mud oven needs a permanent home and roof to become more than a novelty.

Path to a Steady-state Economy. This was a rosy goal, but I don’t know what it means. Perhaps it was really an overarching goal to the others.

Upgrade my Bike Trailer. I’ve been riding my bike and even using it for some shopping, but my only progress on the trailer was finding a place to buy a better tow bar/hitch.

Resolution for 2014

What I should have named in 2013 was that the Cookhouse would take much of my energy for projects. The goal for 2014 is to: (1) finish the Cookhouse (which means getting a Certificate of Occupancy for at least the lower floor and at least one commercial cooking use); (2) implement the solar water pre-heater, and (3) instrument the building so that I can begin documenting its performance.

Time and energy allowing, another goal is to get the solar water pre-heater on our house finished and a solar air heating system implemented in the Barn. Each of these is partially started and each has run into various hurdles that work on the Cookhouse is informing.

More data on solar air heater

December 12, 2013

The recent cold snap let me collect some interesting new data. Previously I had reported on temperatures in the building with the solar heat on and off, but that didn’t tell how much energy was being captured by the collector. At the end of that post I speculated on a way to approximate measuring the energy.

Each day during the cold snap I read the power meter at 10:30pm. The Weather Depot website gave me the Heating Degree Days for each day. (Heating Degree Day is the indoor temperature minus average outdoor temperature; a measure of how much heating is needed. Colder days have more HDDs.)

This gave me a table, and I could calculate a ratio HDD/KWH which should be a constant

HDD (55F indoor) KWH/day Ratio
52 62.44 0.839
42 51.32 0.824
33 39.75 0.825

The ratio lets me predict, knowing the HDDs, how much energy the building would use.

I turned the solar on Wed, and collected data. It was a fairly clear day, high haze but strong shadows. If the solar is effective it should save me energy, ie, reduce the KWH that would be expected to be used for a given number of HDD

It Worked!  The Solar heater came on for 4-5 hours. While I never saw the temperature inside rise above the 55F thermostat setting, I used 6 KWH fewer than the HDD on Wednesday would predict.

6 KWH is 22% savings – about 1/4 of the energy, which roughly agrees with the collector operating for 1/4 of the day. The building has no thermal storage, its like a greenhouse that warms up in the sun and cools again when the sun sets.

The water heater portion of the system is the way I will store energy. I hope to do a final system leak test on that system this Saturday.

UI job portfolio

December 1, 2013

I’ve applied for a job as an Instructional Designer at the UI and they have asked for a portfolio:

Please send examples highlighting three projects in your portfolio that you are most proud of… Be sure to include why you selected each of the three projects to highlight… these examples can be submitted as various forms of media, including URLs, screen shots, electronic files, etc.

This is my reply, which occasioned an interesting reflection that seemed worth capturing here. In my cover letter I had already provided a sample of my pedagogic philosophy, the 3P’s article written at the founding of the BioQUEST Consortium in the late 80’s. “3Ps” refers to three elements of learning science we believed were critical to understanding science as a scientist in a community of practice: Problem-posing, Problem-solving and Persuasion.

The items I’ve included in this portfolio expand on aspects of the 3Ps with my more modern understanding of Internet as a tool for learning: my work at WSU on portfolios and assessment. The third item is two short courses I designed for elementary students.

1. Portfolios. This entry turned into a reflection on how I understand electronic portfolios of and for learning, and their relationship to a resume and the credentialing of learning.  For this piece I set out to share some of my blogging, which was done following my philosophic stance on portfolios, “work in public,” which I learned from George Hotz. Hotz was the teenager who was the first to “jail break” the iPhone. He quit a team working in secret to hack the iPhone and instead chose to work in public. At CTLT we followed his trials and requests for help in his blog.

Hotz served as an encouragement to create the WSUCTLT blog on WordPress. We (my CTLT colleagues and I) sought a place to do our work in public that did not involve the traditional academic publishing cycle. When I went looking for our experiments and reflections on portfolios, I found that the blog was missing.  I had since moved our collaborative blogging away from the WSU brand where this post which summarizes much of that work, Not your father’s Portfolio, can be found.

An electronic portfolio is both more durable and more tenuous than its paper predecessor. Its also more powerful. Its not a thing or a place, its a practice.

It was a prescient insight. Parts of my portfolio from the middle 2000’s have vanished, but my practice of portfolio building has not. Since leaving WSU in 2011 I have not added to the corpus of work related to learning and its assessment appearing in our blog, CommunityLearning, but I have continued the practices we espoused. In 2010 I reflected on my CV and its utility for the new directions I sought:

I need a way to create a CV that converts my experiences into credentials that a new community values.

My work for the last three years has been an exploration of how to help Moscow become more resilient in the face of climate change. The lesson we learned from Margo Tamez (see father’s portfolio link) was to work in the media and places appropriate to your community. Consequently, I have blogged less here, and focused my work in Facebook (login required) and ItCouldBeLocal, a catalog of my exploration of recipes for local eating in Moscow, Idaho. There are three threads to the work: food security, understanding climate change, and urban planning. I seek to learn from, and provide insight to, my community of “friends.”

2. Assessment. This work began with CTLT’s efforts to assist WSU in developing more robust systems of assessment because “[a]ccreditors repeatedly remind classroom faculty that accountability expectations are changing, and that grades, if they ever were, are not now sufficient for meeting accountability requirements. It is a caution that is in part recognition that the isolated perceptions of any single group—even a group of expert educators—will not satisfy the many stakeholders invested in higher education.” This video summarizes our 2009 NUTN award winning article “Engaging Employers in Assessment.” The work is based on our ideas about online portfolios and students “working in public,” and adds the idea of attaching a rubric to gather feedback from an audience. We called this concept the “Harvesting Gradebook;”  most of the details of the Harvesting Gradebook’s development have been lost with the demise of our WSUCTLT blog/portfolio. CTLT, after its reorganization into OAI, used the “harvesting” ideas to gather evidence of the success of WSU’s undergraduate programs as part of the WSU’s 2009 NWCCU re-accreditation. This Prezi  supports a webinar on rolling up student level assessment in support of university accreditation.

3. Course Design. The work in items 1 & 2 above was done over multiple years in collaboration with CTLT colleagues. During the 2000’s my University-level course design work was done as consultant to WSU Course Designers and faculty. One interesting example Meriem Chida’s course, subject of the video above. My personal course design work was in WSU’s College of Education during the 90’s and none of that has survives from my pre-online portfolio days. However, in 2010 and 2011 I created and led two short courses at Palouse Prairie School in a program they called Community-Led Learning. Children signed up to participate in an 8 week course led by a community member each Wednesday afternoon for 90 minutes. The first course I created explored Wikipedia and the collaborative creation of knowledge. It was an experiment to test with students some of the ideas I was exploring regarding Web 2.0 learning. The second CLL course was on making bread, the beginning of my post-WSU foray into sustainability.

What I think is important in these portfolio items is the trajectory they illustrate, from the 1980’s pre-Internet pedagogic focus on solving problems as a path to learning thru the 2000’s explorations of student portfolios and methods to assess those portfolios, which culminated in applying the methods to assessing undergraduate student learning across WSU, and then a return to the very intimate scale of exploring how grade school children can learn by working hands-on to solve small problems.

My own current problem-solving involves the homebrew of solar space and water heating in a new building I am constructing. My practice depends on finding and learning from the portfolios (blogs and websites) of other DIY solar enthusiasts and passing on my explorations, such as the first data from my solar air heater.

First data from solar air heater

November 30, 2013

I have been making (slow) steady progress on the “Cookhouse” project. The utilities got installed over the summer by some great contractors: Nolan Heating, Jeff’s Electric, Don’s Plumbing, Jamin at Energylock for the spray foam insulation and Tom at Avista for the new transformer. I spent Sept-Nov working outside on the siding which caused me to need to get the solar air and water heaters finished up enough to put the glazing on.

collectors on the south wall. Air heater is the set of tubes at the top, water heater is below

collectors on the south wall. Air heater is the set of tubes at the top (above the scaffold deck), water heater is below (click to enlarge)

I built two things into one collector. The lower 12 feet is hot water (pre-)heating. But having watched the sun angles I realized that there were 5 feet above that which get winter but not summer sun. I made an air heater in that area. I suspect the air heating gets some heat rising from the water heater — I didn’t seal them off from one another.

The hot water system is inspired by this design and will be the subject of another post.

For the air heating, I did a variation on the “solar can heater”  I used pre-made ducts rather than messing with a bunch of cans. I have a fan that draws air from the upstairs ceiling, thru the collector, and blows near the floor downstairs (opposite flow from the illustration).

To control the hot air system, I installed two conventional thermostats. One is typical house heating thermostat (on when cold) and the other is an attic fan controller (on when hot). The combination (hot in the collector, cold in the house) turns the fan on.

When the electric and heating was turned on I hooked up the solar air heater. In late October I measured 172F in the collector, 60F air going in upstairs and 122F air coming out downstairs.

indoor and outdoor temps for experimental and control days

indoor and outdoor temps for experimental and control days (click to enlarge)

Last week I was able to do some more systematic data collection on two sunny days with similar outdoor conditions. Nov 21 was the experimental day, Nov 22 the control. What I found was that the heater can warm the downstairs by 10+ degrees F over the warming I get without the heater (just the sun in the windows and warming the south wall).

I need to get some better instrumentation to take more data, but that will have to wait for another post.


Footnote. I have been mulling over how to get a better measure than these temperature data, what I want is units of energy. Since the only energy use in the building now is heating, I can read the meter for KWH in a 24 hour period. I just found this site where you can get heating degree days (1 degree-day = 1 degree difference in temperature for 24 hours). Even better, you can control the indoor reference temperature.

SO, if I turn the solar off and pick a cloudy day, I have a measure of KWH/day and a measure of delta-T/day which will let me estimate the building overall R-value/day. I think I can use that estimate of R-value along with the KWH & degree-day for a sunny day to estimate the energy gathered by the solar system.

UPDATE 12/29

I made 2 of these manifolds to fit 9 3" duct. Duct material is 5 foot. Backing is 1.5" of TuffR rigid insulation painted black. Once installed the pipes were sealed in with spray foam.

I made 2 of these manifolds to fit 9 3″ duct. Duct material is 5 foot. Backing is 1.5″ of TuffR rigid insulation painted black. Once installed the pipes were sealed in with spray foam.


Inside view upstairs. Hole at top is air going out to collector. Light comes in because collector not installed. 4" duct below goes downstairs where fan draws air down.

Inside view upstairs. Hole at top is air going out to collector. Light comes in because collector not installed. 4″ duct below goes downstairs where fan draws air down.

This is a conventional attic fan thermostat (on when hot) set at 90F. This (plus indoor temp) decide when fan comes on to draw air thru heater.

This is a conventional attic fan thermostat (on when hot) set at 90F. This (plus indoor temp) decide when fan comes on to draw air thru heater.

New Year’s Resolution Jan. 2013

January 5, 2013

My goal is to reduce my carbon footprint with one example of each of the following methods. This article outlines why acting now is so important.

1. Substitution

  • one fuel for another (e.g., replace a fossil fuel use)
  • one technology for an other (e.g. florescent light bulb for incandescent )
  • one local product (e.g., a local food to replace a non-local one)

2. Economization

  • by reduction of use (drive fewer miles [in 2012 we drove: Update on our driving in 2012:
    • Krista’s car (red) 7927 miles
    • My car (white) 5241 miles
    • pickup (blue) 1059 miles)
  • by substitution (e.g., drive a more efficient vehicle, example green cars here)

3. Green production

4. Identify a path to a steady-state economy in one aspect of my life

5. Upgrade my bike trailer and use it in 6 months of the year