Cool Down with a Solar Attic Fan

solar_fan_roofOur prize for winning the 4th quarter of the Energy Showdown last year was a very cool solar attic fan.  It took us awhile to get around to installing it but we found plenty of motivation and dry weather in July.  I convinced my dad to come help, despite his preference to stay at ground level.  I took the fun job of cutting a hole in the roof (gotta love those sawzall projects) and then he helped me install the fan itself.

We were both a little surprised when the fan started spinning as he handed it up to me.  But it was sunny and the air temperature was above 80 and that’s all it takes for the fan to get to work.  The brand we got is called “the SunRise” from SRS (SunRise Solar, Inc) and it was made in Jordan, Indiana.  I’m happy to know we have some solar manufacturing in the state and so far I’m definitely impressed with the fan.

It’s a very simple one-piece unit that was pretty easy to install.  (For detailed instructions, check out this article from Home Power Magazine.)  My first step was to climb into the HOT attic and pick a location near the roofline and near the center of the attic.  I drilled a hole halfway between two rafters and left the drill bit in place. Then I climbed up on the roof, found my drill bit, stuck on the circular cardboard template that came with the fan, and used the sawzall to cut out a circular hole.  (I did nick the rafters on both sides but only a tiny bit.)

solar_fan_caulkAfter that, we pried the neighboring shingles loose so we could position the fan unit into place.  A few screws, a huge tube of caulk, and we were done!  We probably could have done the whole thing in under an hour but of course we had to take two trips to the hardware store – one for screws and a second one for a star-shaped drill bit that fit the star-shaped screws we had picked out.  Good times.

It’s hard to tell for sure how much of an impact the fan is having but it has definitely been running a lot.  The mechanics are pretty simple – there’s a photovoltaic panel attached to the motor but with a thermostat so that the fan will only run if the air temperature is above 80, which it has been for most of the last six weeks.  The goal is to pump hot air out of the attic, keeping it a little cooler and slowing down the amount of heat that seeps into our house.  I think it does reduce the burden on our air conditioner.  Yes, we have been running the air conditioner (set at a modest 81 or 82) although it’s mainly to keep the humidity down since we’re in Indiana swamp season (90% humidity nearly every day).  We also use fans, which make a huge difference.  Right now we only have a ceiling fan in the living room so we have a couple of box fans.  The trick is to minimize power use by only turning the fans on when you’re in that particular room since they don’t actually cool the air temperature; they just make you feel cooler by blowing away the layer of hot air around your body.  (Check out this post about staying cool from Mr. Electricity for a nice graphical explanation and some other non-AC cooling tips.)

Eventually we hope to add more ceiling fans but that will require an electrician.  For now, I’m planning to stick just with projects that involve cutting and gluing, which I think I mastered in kindergarten.

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One Step Closer to Solar Electric Panels

Solar Pathfinder Reading of Our RoofThe good folks at SIREN gave a stirring presentation last month about how now is the time to switch to solar electricity.  Panel prices have fallen significantly due to the recession, electricity prices look poised to raise (at least here in Indiana where Duke Energy is spending several billion dollars to construct a coal gasification plant in Edwardsport and pass costs on to customers), and there’s a brisk market for renewable energy credits.  We had already caught the fever a bit and the talk just convinced us it was time to get an actual site assessment and cost estimate.

We’re working with Alex Jarvis of Solar Systems of Indiana, a quirky guy who knows a heck of a lot about solar.  He came out to discuss some different options and to do a site reading of a few potential spots using his handy dandy Solar Pathfinder.  It’s a very simple little device that maps shade to determine if a particular spot has a good solar window.  The image above is from the middle of our roof, which has a very good solar window of about 85% between the key sunshine hours of 9:00AM and 3:00PM – solar time.  (See rant on Daylight Savings Time below.)

pole-mounted-solarHe also measured a few other spots in our yard so we could think about doing a pole-mounted solar panel.  You could argue that the pole-mounted systems are a little on the ugly side but they are very practical in terms of maintenance – no climbing on the roof, no trying to patch the roof under the solar panels – and they are great for houses that have a shaded roof but sunny yard.  We are leaning in that direction simply because our roof is 20 years old and will need to be replaced well before the solar panels.  Alex actually has his panel (shown at right) configured so he can move it around during the day to maximize its exposure to direct sunlight and therefore maximize electrical generation.  He is the first to admit that is way too hardcore for most people but he is a tinkerer and enjoys fiddling.  Most people just retilt their panels twice a year at each solstice.  At the spring solstice, the panel is tilted closer to horizontal since the sun is higher in the sky during the summer.  At the fall solstice, the panel is tilted more vertical since the sun is low in the sky during the winter.

After that is the decision of what kind of solar panels and inverters to get, which I must confess is mostly Greek to me but Will is drooling a bit at the thought of enphase microinverters that broadcast all kinds of exciting data for him to analyze with a fine-toothed comb.  We’re looking at getting six modules that are each rated somewhere around 240 watts, giving us a system that is around 1.44 kilowatts.  Here in southern Indiana, we average about 4.7 hours of direct sunlight per day once you factor in cloudy days and the fact that our days are significantly longer in the summer but shorter in the winter.  In a perfect world, our solar panels would produce 6.8 kw-hr per day (1.44 kw x 4.7 hours) or 2,470 kw-hr per year.  However, there are some losses that we have to take into account with our lovely fudge factor friend, the derate factor.   The derate factor has several components:

  • Shade on our system.  Our solar window is about 85% open, 15% shade.
  • Losses from the inverter, connections, and wiring
  • Losses from dirty solar panels (we’re going to assume we can keep ours clean – with a hose if needed)
  • Losses from improper angling (again, we’re in good shape with a pole-mounted system that can be tilted at least twice a year)

In the end, we figure our derate factor is about 0.8 (meaning we lose about 20% of the ideal production level), which reduces our expected output to about 5.4 kw-hr per day or 1,970 kw-hr/year.  That should still just about cover our needs and in our area it’s not worth overproducing since the electric company will just keep rolling over our credits until we move.  If you’d like to try this game at home, check out the PV Watts calculator developed by the National Renewable Energy Lab.  Soon we should have some prices to go along with our power estimates but for now we’re excited about the possibilities and also trying to brainstorm how we might landscape our yard to make the solar panels blend in a bit.  Any and all suggestions are welcome!

Daylight Savings Time Rant:  Indiana only recently adopted Daylight Savings Time while staying in the Eastern Time Zone, and I am not a fan.  Today the sunrise was at 6:30AM and sunset at 9:15PM, which means our solar noon is really about 1:50PM and our key sunshine hours are 10:50 to 4:50.  It also means that the fireflies don’t come out until 10:00 and it’s awfully hard to schedule fireworks, bonfires, or drive-in movies that children (or I) can stay awake for.  I liked it better when we were in straight-up Eastern Standard Time and never had to worry about changing our clocks.

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Solar Furnace Verdict: We Like It A Lot But Our Savings Are Minimal Because We Live in the Cold

solar_furnace_2Winter has passed, giving us time to sit and review how our solar furnace worked.  It’s a bit tricky to evaluate exactly how effective it was since we made several other changes to the house last fall (sealing up gaps around windows, turning our thermostat down to 59) but we feel it made a huge difference.  Here are our thoughts and I’ll dig into the numbers down below.

The Good

  • Mmmmm, warm.  We enjoyed the sunny days when the solar furnace raised our indoor temperature to 72 while our gas furnace thermostat stayed set at 59.
  • Warm air did circulate fairly well through our house (although it did stay warmest in our living room, which is where Will has his home office and where the dog likes to spend her time).
  • The solar furnace reduced our output of carbon dioxide by 1,792 pounds between the electricity and natural gas conserved.
  • Since this was a demonstration project cost-shared by SIREN, it was a low-cost way for us to enjoy solar technology.

The Bad

  • Solar furnaces do absolutely nothing when it’s cloudy and can not fully replace a regular furnace.  (Having one made me much more conscious of when we have sunny days.)
  • Our dollar savings were pretty minimal, about $52 for the season.
  • Payback time would be 58 years (40 if you get the tax rebate) but “normal” people would see higher savings (see note below)

The Ugly

  • Someone who keeps their thermostat at 70 during the day would see much, much greater savings because they would be replacing a lot more gas/electric furnace time.
  • Someone who relies on electricity for heat would see much greater savings because it’s more expensive than a gas furnace (even counting both the gas and electricity needed to run a gas furnace).
  • Someone who lives in a place with more expensive electricity would also see higher dollar savings – our electricity is nominally 9.7 cents per kWhr, which is really about 12.5 cents with the fees added in.
  • It’s likely our solar furnace would be even more effective if we increased the thermal mass in our home to absorb that heat on sunny days and keep it longer into the night.  We could also use more insulation in our attic and crawlspace.
  • All these numbers should be taken with a grain of salt as we changed a lot of variables at once, which is a common challenge as people green their homes – who wants to make just one change and wait a whole year to document how effective it was?!

Now some numbers.  Last winter (November 2009-April 2010) we used about 352 CCF of natural gas (one CCF = 100 cubic feet of gas) while this past winter with the solar furnace (November 2010-April 2011) we used about 236 CCF.  That’s a reduction of about 33%.  Will took a look at the outdoor temperatures and overall they’re pretty comparable from winter to winter.

Part of the savings we saw is due to lowering the thermostat on our gas furnace.  We turned our thermostat down about six degrees during the day, from 65 to 59, and about 3 degrees at night, from 62 to 59.  Past studies have shown that homeowners reduce their energy usage about 1% for every 8-hour period per degree.  However, we’re guessing those studies were looking at people turning their thermostat down from 72 degrees and we’d expect energy savings to be smaller as you get lower.  (This is because it takes more energy to heat when there’s a larger differential between the outside air temperature and the inside air temperature.  Somewhere I saw a very pretty exponential curve showing this but I of course can’t find it right now.)

Let’s say down in our temperature range the savings is more like 0.6% for every 8-hour period per degree.  So during the day (roughly 16 hours) we would save 0.6% x 6 degrees x 2 time periods = 8%.  At night (roughly 8 hours) we would save 0.6% x 3 degrees x 1 time period = 2%.  That gives us 10% total.

We also caulked around all our windows and insulated our electrical outlets and attic doors.  Past studies say that can reduce energy usage 10-15% but our house really seemed pretty tight beforehand so let’s say it was just 8%.

The solar furnace is the rest, (so 33% – 10% – 8% =) 15% savings.  Not enormous but we enjoyed a much more comfortable home since the solar furnace would routinely heat our house up to 68 or 70 while we left our gas furnace thermostat at 59.  Dollarwise, our energy is cheap and therefore our savings were modest.  We pay about 55 cents per therm/CCF.  So our overall gas savings for the winter was a modest $64 ($0.55 x 116 CCF).  Out of that, only about $27 can be attributed to the solar furnace (45% of the total savings).

However, our gas furnace also uses quite a bit of electricity to run the fans.  Again, I had to back calculate to estimate how much since we can’t put a kilowatt on our furnace.  Our total electricity usage for the 2009-10 winter was  about 1943 kW-hrs over 6 months.  For the 2010-11 winter, it was 1,156.  That’s a difference of 787 kW-hrs but a big chunk of that can be attributed to our new refrigerator, which we found uses 1.9 kW-hrs less per day, or about 342 for the winter.  That leaves us with an overall reduction of 445 kW-hrs (a 22% savings over last year), which at 12.5 cents each would be a savings of $55.  Out of that, about $25 can be attributed to the solar furnace (about 45% of the savings) while the rest is due to the lower thermostat and weatherizing.

So our total solar furnace savings = $27 from gas + $25 from electricity = $52. That means our payback time on a $3,000 solar furnace system (installed price) would be about 58 years.  Not super.  However, there is a big tax rebate available that will refund 30% of the system cost, bringing the price down to $2,100 and the payback time to 40 years.  Still pretty slow but we are very sure the savings would be much better for someone who normally keeps their thermostat around 68 or 70.

In terms of carbon dioxide, we saved both on natural gas and electricity.  Natural gas generates about 12 pounds of CO2 per CCF of natural gas (according to the Carbon Fund).  So 116 CCF x 12 pounds = 1,392 pounds of carbon dioxide saved.  Electricity generated from coal generates about 2 pounds of CO2 per kW-hr (according to Kilowatt Coal).  So 200 fewer kW-hrs would mean 400 fewer pounds of carbon dioxide generated.  (As a side note, natural gas actually produces less carbon dioxide than coal if you convert everything to kW-hrs for a side-by-side comparison but in this case we’re sticking with CCF since that’s what appears on the gas bill.)

Total carbon dioxide savings?  1,792 pounds from the solar furnace, or about 9/10ths of a ton.  Whew!

So, our bottom line conclusions are:

  • Qualitatively, we really like our solar furnace.  It really cranks out the heat and we enjoy waiting to see when it will magically kick on and give us hot air from the sun.  On sunny days it will run from about 11:00 to 4:00 and can easily heat the house up 10+ degrees.  The fan isn’t too loud and with our open floor plan, the warm air circulates fairly well.  We have considered putting in a fan or two towards the far end of the house to improve circulation even more but have decided we like having our main living area be the warmest and our bedrooms be the coolest.   We would like to experiment with adding a little more thermal mass to the house (to soak up the heat and radiate it back into the house at night) and of course more insulation.
  • Quantitatively, we’re a little disappointed in the payback time but we think that’s mostly because of our radically low furnace thermostat setting.  The solar furnace performs the best during the spring and fall “edge” seasons when there tends to be more sun and a lower differential between indoor and outdoor temperatures.  If you’re determined to keep your indoor air temperature at 68 or 70, your furnace will run a lot during those periods and the solar furnace can make a huge offset.  However, we were often opening our windows during those periods to let the “warm” 60 degree air into our house.  And even during the coldest and darkest parts of winter, the gas furnace never really had to run very much to keep the house at 59 so there wasn’t a lot of usage to offset.

I’m going to try to get some data from two other friends who have solar furnaces who I believe keep their gas furnace thermostats at a higher setting, to see what they have observed.  I would also love to figure out how the solar furnace compares to installing insulation, in terms of return on investment.  What kind of savings would you see from $3,000 worth of insulation?  Maybe that will be our next experiment…

**UPDATE**  Our friend Woodie Bessler ran through some calculations to see how a $5,000 investment in a solar furnace from RREAL compares to buying $5,000 in photovoltaic panels at $5/watt and using them to run an electric heater.  His conclusion?  The solar furnace produces more heat in BTUs.  This made us feel good about our system.  However,

  1. The output is comparable if the cost of PV panels drops to about $3.85/watt.
  2. Excess electricity from the PV panels can be used to power other things, whereas excess heat from the solar furnace will do nothing (and may even be undesirable).
  3. An even better option may be to use PV panels to power a geothermal heat pump, which would produce three times the heat, meaning an equivalent amount of heat could be produced for about half the cost.

You can see a pdf of his calculations here.

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Solar Chargers

A Soleo solar charger left of a smaller and cheaper off-brandEven with our reduced electrical usage, installing enough solar panels to meet our average needs just isn’t cost-effective for us yet. Photovoltaic (PV) prices have dropped a lot in recent years so even though we can’t afford a big system, there are a couple of cheaper options for trying out solar energy on a small scale.

Before our first big train trip last year, I bought a small (and cheap!) solar charger for my cell phone. It’s about the size of a box of cards and has two suction cups so that it can be placed directly onto a window. Despite costing less than $30, the solar panel has a battery behind it so that you can charge the battery first and then hook up your phone later. That turns out to be a really good thing because it takes over a week to charge fully!

Something that I didn’t realize before getting this solar charger is that most solar panels require direct sunlight. When I put the charger on a south-facing window, it didn’t charge at all, despite getting indirect sunlight for most of the day. I had to place it on our east-facing window, where it got 1-2 hours of direct morning sunlight, for it to charge.

More recently, we won a much nicer (and more expensive–$90 or so) Soleo charger as part of the SIREN Energy Challenge. This solar charger has a built-in battery with three panels attached, each a bit larger than the first charger I got. When it’s open, the charger looks a bit like a tilted flower, with solar panels for petals (you put a pencil, included, through the center to keep it upright). The advantage of this charger is that you can rotate it so that it gets direct sunlight throughout the day. The drawback is that you do have to rotate it. This one only takes 2-3 sunny days to charge (or a little less than a week if you don’t rotate it) plus it has a larger battery (more capacity).

Both chargers have a bunch of adapters for changing a variety of cell phones. The Soleo also includes a USB adapter so that it can charge or run a USB-powered device. It can also be charged by USB if need be.

We have three different devices that we’ve tried with the charges: a normal cell phone, an iPhone, and an e-reader. Neither charger has a very accurate charge indicator, so it’s hard to know exactly how well they work, but the cheap charger would charge the cell phone fully and have some juice left over or charge the iPhone by half to three-quarters. It couldn’t charge the e-reader because it doesn’t have a USB adapter. The Soleo can charge the phone about five times from full or the iPhone once or twice. It can charge the e-reader about as well as it can charge the iPhone.

Are we saving any money? Not really. Cell phones, even power-hungry ones like the iPhone, and e-readers just don’t draw that much power. Over the course of a year, each phone probably uses less than a kWH each, so even if we charged all of them by solar, we’d be saving well less than a dollar a year. And, unfortunately, we can’t charge them by solar all of the time because they run out of power faster than the solar cells charge their batteries (especially during those cloudy winter days we’ve been having).

On the other hand, the chargers provide a lot of convenience under certain circumstances. On our latest trip, Maggie forgot her phone’s power cord but was able to charge it using the solar panel. I can also leave one of the solar chargers in my bag in case I need to use my phone more than normal. The cheaper one especially could be left in a car window to charge and you’d have it handy if you needed to quickly recharge a small electronic device.

The real issue is that most of the things we use draw a LOT of power compared to the amount of electricity a small solar panel can provide, even on a sunny day. If we were willing to keep our phones off more often or to use only small LEDs for lights, a small solar charger like these two would be enough to make a significant dent in our use. When compared to the amount of electricity a television or computer uses, the difference amounts to a rounding error.

I’d recommend getting a small solar panel to most people so that they can play with it, figure out the benefits and drawbacks of solar without a huge investment, and get a better sense of how much power a kilowatt-hour actually is!

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Bring on the Spring!

south side of houseI am so ready for spring.  I can’t stop garden planning and I’m ready to run out and start DOING things if only it would be warm & dry for two days in a row (don’t want to overly compact the soil).  I also need to spend a little time creating a [sigh] budget.  I wish I were either fabulously wealthy or super skilled at transforming society’s garbage into useful structures like trellises and fences and grape arbors and outdoor showers.  But as I am neither, I have to prioritize and I’m having trouble.

So right now I’m focusing on one of my ideas that doesn’t need to be implemented just yet: planting some vines to help shade our south-facing window.  It has been lovely to have this winter (although I might try to beef up our curtains next year with some thicker insulating fabric for night time protection) but in a couple of months we’ll shift gears to keeping heat OUT of our house and this year I’d like to do it with plants.  We already have some trumpet creeper vine that grows all over the front porch railing so I think with a few well-placed structures we can coax it into a window-shading growth pattern.  Hmmm, that sounds a bit like some sort of nasty disease but I mean my goal is to have the vines grow up and over the porch to keep out the sun but I also want to maintain a view from the window to the garden plus it would be nice to have sun on part of the porch for my solar cooker.

There’s also the design challenge that our porch already has a roof overhang that is relatively low (like the ceilings in our house, about 7.5 feet).  There isn’t a good place to hang brackets to suspend wires, as suggested in the Carbon-Free Home, and I’m afraid if I put any sort of pergola on the porch it would feel really low (especially if the plants sagged at all).

front_of_house_trellis_sketch_croppedSo here’s what I’ve come up with (as translated with my crude drawing skills).  On the left is a trellis that would run east-west, creating a truly shady spot in front of our front door.  On the right is a trellis that would run north-south (perpendicular to the house), nestled in the corner next to the stairs.  I would connect them with 4 or 5 wires running parallel to the roof overhang, where vines could grow and help shade out the noontime sun but leave the southeast corner of the porch uncovered so I could set up my solar cooker.

Next step: Life-size mockups with giant pieces of cardboard lurking in my garage and some leftover bits of kite string.  I think there’s a good chance this set up might be a little too low for comfort, although we might not know for sure until we grow some vines and see how dangly they are…  But you know we’re game for experiments!

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Powering Down

A couple months ago, Maggie talked me into giving a presentation at the Simply Living Fair about our 3-kWh Challenge (which has more details, if the presentation is too high-level for you). The presentation went very well and has some more information (and hard numbers) about our electrical use since January. In my challenge post, I clocked us in at just under 80 kWh, but the official number from Duke Energy was just 71 kWh! The difference is just because we started and stopped measuring at different times, but it still sounds good.

My presentation slides are embedded below, but I’ll add some explanation underneath to replace some of the bits where I talked.

On the graph of our electrical usage, I included one line for each year plus a bar graph series at the bottom that represents our kWh usage per day based on my readings. There’s a LOT of variation, mostly due to hot water heating, the furnace, or A/C. When we stopped using all of those things in June, everything calmed down a lot.

In the end, we used 28% of the electricity we used last year, which is a tiny 14% of the electricity used by the average house our size!

We ended up using 115 kWh in September and are on track to stay under 120 kWh in October, so we’ve been able to maintain usage at 50% of last year’s numbers.

Just looking at electricity, we’ve saved about $175 so far this year and reduced our CO2 emissions by almost 2.5 tons (coal is not a very clean source of electricity)!

We’re incredibly happy with what we’ve done so far and plan to continue trimming as we head into the heating season! We knocked out some insulation projects today that will hopefully help and we’ll certainly keep you updated about the solar furnace!

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Rainy Solar Tour

Rainy Solar TourToday is the ASES National Solar Tour and we are one of the houses featured on the Bloomington Solar Tour but wouldn’t you know it, after an unbelievably dry summer and fall, today it is raining.  (The last time it rained was during the girl scout campout I organized.  I seem to have a gift.)  Our solar furnace is not very impressive on cloudy days and I think people are staying indoors for fear they might melt but maybe it’s just was well we have a quiet weekend after a busy week.

The Simply Living Fair went well and people seemed to enjoy Will’s talk about our efforts to get down to a 90 kilowatt-hour month (we managed it in June but are thinking 120 kilowatt-hours is a more reasonable target in the fall).  The green living tour to our house and two other green buildings was fun despite having a small crowd of about eight.  In general, everyone who came was happy; I just wish more people had come.  Maybe next year.

Will tests his IR thermometer on the dogOn Monday, Will got a new toy in the mail.  It’s an infrared thermometer and it looks a lot like a price scanner or a space age neuron gun.  You point it at an object, pull the trigger, and it tells you what temperature it is.  Will has had hours of fun testing the temperature of various surfaces around our home.  I’m not quite as entertained but I do appreciate that it will help us identify heat leaks in our ductwork, walls, windows, and attic access panels (Will measured a 20 degree difference between the ceiling in the main room and the access panel to the attic – pretty alarming).

Moving the ShedYesterday we sold our little playhouse shed, which meant we got to watch a guy come and load it on a special kind of tow truck to take it away.  I still feel slightly guilty for not figuring out a way to put it to use but it had been sitting empty for two years so it was time to let go.  The dog is still a little confused as to what happened but we figure she’ll lose interest now that there are no longer mice and skunks and other critters hiding out underneath.  (We thought she had excavated some major tunnels under the shed and were expecting a sort of underground labyrinth to be revealed but apparently she only dug out the minimum needed to squeeze her body under the boards.)

Next week we leave on the train to New Mexico for a week, which will hopefully be a nice fall break.  It will be good to see family, even if the occasion for gathering is a memorial service for Will’s grandmother.  We are looking forward to exploring a new train route and getting a change of scenery for a little while, although I hope the leaves don’t all turn colors and fall off before we get back!

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Solar Furnace is Here!

solar_furnace_1Okay, our solar furnace is actually installed!  Now if only it were cool enough to want to use it…  Still, that will come in time and for now we’re excited to show it off.  Here are some basic pictures of the final product; we’ll post pictures of the actual construction further down the road when we have caught up with ourselves (ha!).

It’s a lot flatter than I expected, about a handsbreadth deep.  I think it looks pretty good on the side of our house and Michael B. did an excellent job with the flashing around the edges.  So what you can’t see is that there are two holes in the back of the panel that continue through the wall of the house and into the living room.  One hole has a fan attached (that unfortunately sticks further into the room than we had envisioned) for pulling air from our house through the panel.  The fan is controlled by two thermostats.

solar_furnace_4One thermostat is mounted on the wall and lets us decide how hot we want our house to be (it cranks up to 90!).  The other is located inside the panel and makes sure the panel is hot enough to heat up air as it passes through.  We had it on for an afternoon right after it was installed and it gets amazingly hot.  We could totally set up a sauna in our living room if we wanted.

So here is my very crude graphic rendition of air flow through the panel heating our house.  We were a little surprised that the panel has no channels or grooves on the inside to direct air flow; it’s just one big black box.  The advantage is that you can cut the openings wherever you need them so if your house happens to have a phone jack or an electrical outlet right where you were going to install the fan, you can move it over a few inches and just put the hole in a different place in the panel.

We’ll keep you posted on results as the weather cools down.

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Coming Soon: A Solar Furnace!

Solar Air Heater on Boggess Home (slightly different model)Guess what?!?  We were chosen to have a solar air heater installed on our house as a demonstration project sponsored by the Southern Indiana Renewable Energy Network (SIREN)!  Solar air heaters (also known as solar furnaces) are essentially big black boxes that heat up in the sun.  They are filled with air channels so that air flows through the panel, heats up from the sunlight, and then the hot air goes into the house (generally with the help of a small solar fan).  Solar air heating is a form of solar energy that’s actually more efficient than solar electricity (photovoltaic panels) but doesn’t get as much publicity.  SIREN is excited to promote the technology and also hoping to launch a pilot project installing these systems on low-income houses.

Our solar furnace will come from the Rural Renewable Energy Alliance (RREAL), a company in Minnesota that makes them and also does a lot of work making renewable energy more accessible through training, education, installations, and a unique assistance program.  They partner with agencies that serve the low-income community to install these systems for minimal cost as a way to make low-income families more self-reliant.  Pretty cool stuff!  SIREN hopes to bring a similar program down to our neck of the woods and is looking for an agency to partner with, hopefully the South Central Community Action Program (SCCAP), which is a local group working on weatherization and energy assistance for low-income families (among many other great assistance programs).  Will and I are going through the application process so we can work together to try out the system, show it off to anyone interested, and further weatherize our home.

Want to see the system?  We’ll be posting lots of pictures on our blog when the installation happens and we’ll also be opening our home up for a few tours.  One will be as part of the Simply Living Fair coming up September 25-26.  We’re giving a talk on home energy reduction as part of the Saturday workshops and then our house will be featured as part of the Solar Energy Tour on Sunday.  It should be lots of fun!  (Disclaimer: I am chairing the organizing committee for the fair so OF COURSE I think it will be lots of fun.)

Hopefully we’ll get accepted into the SCCAP program and they will help us do some insulating and caulking later this fall to further increase the energy efficiency of our home.  I’m also still contemplating putting a greenhouse on our front porch to help improve heat gain through our south-facing bay windows but I’m  not ready to make any promises.  Regardless, we are looking forward to lowering our carbon footprint this winter while enjoying free hot air from the sun!

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Showering With the Sun

Maggie using the solar showerWill and I spent a pleasant hour in the hammock a few weeks ago talking about project ideas for the house.  He’s been especially focused on energy savings and was very excited about the idea of building a solar shower.  I have many fond memories of outdoor solar showers but the ones I have used in the past involve solar water panels, plumbing, welding, privacy screens, and several other features that would challenge my handywoman skills.  Ever practical, Will suggested that rather than plunging into a new construction project, we should pick up a simple camp shower and try it out so we could go ahead and turn off our hot water heater.

We picked up a solar shower kit at a local box store for $25 that consists of a curtain with a zipper, a solar water bag with a shower nozzle, and a support structure to hang it all from.  We hung the support structure and curtain from one of the big sugar maples in our backyard, filled up the water bag, and I took the first shower.  It was not a great experience.  The shower bag came with a long tube leading to a shower nozzle, which in theory gives you the flexibility to spray in many different directions.  In actuality, you have to keep the tube stretched out and sloping down to get decent water flow, which means crouching down and risking mooning the neighbors.  We had also neglected to stake down the curtain, so it was blowing around a bit and decreasing my feeling of privacy even further.

Solar Shower BagAfter that first shower, I cut the tube into a short piece so now I can stand under it comfortably (Will has to duck a little).  We put a piece of indoor/outdoor carpet under the shower so it doesn’t get too muddy.  It’s still a bit of a pain to fill, heat, and hang the bag but it’s doable.  Actually, the biggest challenge is keeping the water comfortable instead of scalding hot.  The solar shower heats up too well some days and we have to add cold water.

We’re going to try it out a little longer but I think it’s been successful enough that we will try building Solar Shower 2.0, perhaps using the directions from the Carbon-Free Home book.  They suggest building a platform of some sort and putting a small (10-gallon) black barrel up on it with a shower spigot sticking out.  Ideally, it should be designed so you can fill it from the ground using a garden hose (or rain barrel) so you don’t have to haul it up and down.  Sounds good to me!  Maybe we can build some actual walls around it too….

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