alex_m's blog

The very thick walls of straw-bale houses (also rammed earth, double-thickness adobe, etc.) need an equally wide foundation (18-24 inches or more) to support them. In mild climate with sandy soil this is not a big problem, as the concrete foundation can be modest in depth (1-2 feet). But where deep frost-heaving or expansile soils are present (much of the country) you may require foundation depth of 4 feet or more. Making a 2 ft wide and 4 ft deep foundation takes a hell of a lot of concrete and rebar.

I have 2 ideas to reduce the materials required in such conditions. One is to engineer your foundation in the shape of an I-beam instead of a solid rectangular block. The I-beam principle is widely used in steel, engineered wood, and reinforced concrete to maximize strength while minimizing weight and material (hence cost as well).

--see cross section drawing below -- At the bottom of the foundation you'd have a 1 ft high by 2 ft wide base, then a web 8-10" thick by 3 ft high, then another 1 ft by 2 ft section sitting on top of the web -- total height of your reinforced concrete I-beam ~5 ft.. You would undoubtedly need an engineer to certify this design, but it would be easy to build and save a lot of cement and iron.

The second scheme I've thought of could be substantially cheaper and even "greener" -- an old idea but seldom used, why I don't know -- the grade-beam foundation. I associate this idea with FL Wright, but he may not have invented it. You excavate a trench to required frost-stable depth, say 5 ft deep by 2 ft wide, fill the trench with rocks to approximately grade level. Then build your foundation form, say 14" deep by 24" wide, directly on top of the rock base. On the rock base, Wright even used heavy wood timbers fastened together, instead of concrete, for some of his foundations; and if you had a bunch of used railroad ties or creosoted bridge timbers you could easily concoct some mixed-media foundation, sandwiching the timbers and reinforced concrete, using the timbers on the outside as "form," reinforced concrete in the middle, all tied together with rebar and reinforcing mesh.

Heat from the sun: I added a solar collector to the south wall of my bilevel suburban Denver house in the fall of 2005. It's a little like a section of greenhouse stuck to the side of the house. Since there was an upstairs window practically right over a downstairs window, I didn't have to make any permanent modifications to the house to allow air circulation through the collector. On sunny winter days, I just open the upper and lower windows and set up a portable fan in one of them. Passive convection would circulate some air from the lower to upper level, but adding the fan greatly increases the heat output. collector in winter, fan running 8mm twin wall polycarbonate

Construction:

The structure is modular; a rectangular base of 2x6 redwood (tapered to conform to the irregular concrete/brick patio) sits on the concrete patio and is bolted to the house foundation. The side and front frames that sit on the base are made of ~2" x 2" weather-resistant wood -- redwood and cedar, most of which I scavenged from my scrap collection. A couple of the thin cross piece supports are cut from salvaged 1" oak flooring. All the wood panels screw together and could be disassembled in an hour or two. The translucent panels are 8 mm. twin-wall polycarbonate (Verolite brand), which is widely used in greenhouses, very strong, UV resistant, and heat transparent, though it's not cheap. The polycarbonate can be cut with a fine-toothed, plywood-type or thin carbide blade if you're careful. I mounted some lengths of sheet metal I had (salvaged baseboard radiator backs), on to the house wall, with stand-offs so air can circulate in front and back. These darkly painted steel pieces help the efficiency of transferring solar heat to the air circulating through the collector. All wood pieces were primed and painted with exterior latex paint to match the house exterior.

Winter use: Around mid-October, it becomes cold enough and the sun angle low enough to get significant supplemental heat from the collector. I monitor the air temperature in the collector with a remote sensing thermometer; around mid-morning, as the collector air gets above indoor room temperature, I open the two windows and turn on the fan, blowing air from upper into lower level. Since I'm almost always home, controlling it all manually works OK. If I weren't almost always here, I would have to install a thermostatic controller for a fan and some electrically operated vents in the windows, or figure out some other circulation system, because temperatures can vary a great deal as the cloud/sun conditions change. E.g. it can be cloudy and freezing cold at 09:30, and the collector temperature might be 28 F. degrees; if the sun comes out at 10:00 it can rise to over 110 degrees in 1/2 an hour. On the typical sunny winter day here, I'll heat my house up to 66 F. degrees (with the natural gas furnace hydronic system) when I wake up. Then, starting mid-morning, I will operate the collector about 5-6 hours, with the furnace turned off. Depending on outside temperature, I may or may not need to turn the furnace on again in the evening.

Summer setup: By early June, I don't need to heat the house, and slide out the large polycarbonate panels, and replace them with sections of redwood lattice held in by screws into the frame. I insert a custom-fit rectangular planter box in the base, and plant vines and flowers: morning glories and various beans, which over the summer, climb up the trellis and provide shade for the windows. (By mid-summer, the sun elevation is such that very little direct light would come in these windows anyway, but the trellis and vines are a nice decoration anyway.) The photo below shows the vines in mid-summer, halfway up the trellis. By late summer the vines totally cover the trellis.

Costs and savings: With all the custom fitting and angles, this was a complex carpentry project that took ~40 hours to build. I used a lot of surplus wood and hardware I had on hand, but bought a 10' cedar 4x4 that I ripped down to make the long pieces for top section and 3 4x8' polycarbonate pieces (about $2.25/sq. ft.). My total material cost was ~$300, but you'd spend about $60 more if you had to buy all the wood and hardware. How long did it take to recoup the cost in energy savings? Comparing my heating costs with the previous years', I'm estimating that I saved enough natural gas to pay for the project, more or less, in its first winter of use. Now beginning its third winter of use (2007-8) it's still working fine and I'd guess saving me a few hundred dollars a year in fuel costs.

mid-summer trellis setupcollector side detail, summer

Why: Heat rises, so near your ceiling the air is probably the warmest in your house (good reason for slow circulating fans in high ceiling houses, but that's another topic). If there's an attic above your ceiling it's probably a major conduit of heat loss in winter. Adding insulation to your attic is said to be one of the most cost-effective energy saving investments you can make. Typically the attic will also get very hot in summer, so insulating it will also greatly reduce cooling problems in summer.

 

My project: Soon after buying my 32 year old house in 1999, I realized the attic insulation was pathetically inadequate. This house has roof trusses and the original builders simply put a few inches of loose mineral (rock) wool in the spaces between the 2x4 rafters. 32 years of settling and blowing around left the remains of the rock wool in very scattered condition. Many spots were bare -- you could look right at the gypsum drywall of the ceiling below!

Extensive remodeling in this house involved new and replaced wiring, recessed ceiling lights, bathroom fans, etc. etc. that required much climbing around in the attic, over the rafters, displacing and replacing insulation. Obviously, I had to finish all those big projects before adding more inches of insulation in the attic. Therefore it was summer of 2002 before this job got done.

Choosing the method of adding insulation was easy. I wanted to leave the few inches of rock wool there -- it would be nasty to remove and why waste it? So, by far the quickest and cheapest method was to add more blown-in loose insulation. Recycled cellulose, made from old newsprint I think, with flame and bug retardent chemicals added, was the clear choice. You can actually rent machines to do this, buy the bags of material, and do it yourself. But it was cheap enough to hire a professional and I'm glad I did. They knew how to seal off the attic from living spaces below, had more powerful blowing machines than you can rent, and knew how to get even coverage. And it's a really dirty job.

The two fellows came one morning, did the whole attic and were gone by noon. I had about 1700 sq. feet of attic area, to which they added 6+ inches of blown cellulose for total cost of $668. The R-value of what they added is ~23, so my total ceiling R-value now is probably close to the recommended 30 for this area. I now have between 7-8 inches covering the entire attic.

cellulose blown insulation

Energy savings:I averaged my natural gas usage in therms for the 6 highest heating months (Oct - Mar) of 2000-2005 -- two winters before and three after attic was insulated. The average savings after insulating was 330 therms for the 6 heating months, approximately 1/3 of the total usage for those 6 months of the year (980 before, 650 after). Natural gas was pretty cheap in 2002-3, a little over $.50/therm, but has approximately doubled since then, though it spiked higher in 2005-06, it has come down a little since then. But at then current rates, my insulation project paid for itself in the beginning of third winter (fall '04-winter '05). At present gas price, the project would have paid for itself in the second winter.

depth approx 7-8"

Abstract: Compact fluorescent (CF) bulbs can be used advantageously in many home lighting applications -- offering much longer bulb life and considerable savings in the electric bill. However, they differ radically from tungsten filament bulbs (incandescent and halogen types), so you need to consider: when to turn them on and off, where not to use them, and their environmental hazards.

The conventional wisdom: Standard incandescent bulbs are very inefficient, putting out only 10-15% of the electricity they consume as light - the rest is dissipated as heat. But they are cheap and we are accustomed to the warm, broad spectrum light they provide. Halogen (also tungsten incandescent) bulbs are very slightly more efficient, last a bit longer, and have a pleasant, brilliant light quality; but they cost slightly more than conventional bulbs and achieve little if any energy or cost savings.

Compact fluorescent (CF) bulbs, only 2-5 times more expensive per bulb now than incandescents and halogens, are about 4 times more efficient in light output -- a 13-15 watt CF puts out the equivalent of a 60 watt incandescent or a 50 watt halogen. And they last 5-10 times as long as regular tungsten filament bulbs; so, between much longer life and much greater electrical efficiency, they are significantly less costly to operate, and their widespread use would save significant energy on a national and global scale, with all the benefits that would accrue from that.

There are excellent articles about bulb types and efficiency/cost issues at these sites:

Lowes.com light bulb guide:
http://www.lowes.com/lowes/lkn?action=howTo&p=BuyGuide/LightBulbBG.html

Wikipedia has excellent article on CF's & good discussion of environmental hazard:
http://en.wikipedia.org/wiki/Compact_fluorescent_lamp

General Electric site has cost calculator to compare annual, life-cycle, and per-lumen cost of various bulb types:
http://www.gelighting.com/na/business_lighting/education_resources/tools...

BUT the conventional promotion of CF's ignores several important issues, so here are --

A few contrarian considerations:

1. CF's and tube fluorescents are made to have various color spectral outputs, from warm, soft white, like incandescents, to natural, like sunlight, to cool-white. Try them out at the store to see what you like. Putting different spectral types in one room might show unpleasant color contrasts.

2. CF's will fit your standard (medium) sockets, but some profiles may not fit in your (table or desk) lamps if shade bow is too narrow. Socket extenders may or may not help.

3. CF's can be dangerous if used in the wrong places: outdoors if exposed to water -- be sure they are rated for exterior use; in enclosed fixtures, i.e. where glass shade/cover prevents air cooling, the elevated temperature can shorten life or cause fire; with dimmers, could overheat, cause fire -- dimmable CF's are sold, but are much more expensive.

4. Switching on and off -- with tungsten filament bulbs it is always beneficial to switch them off immediately when light is not needed, i.e. as you leave the room; but with fluorescents the question is much more complicated because each on-off cycle shortens bulb life. In fact, when I first tried switching to CF's about 10-12 years ago and put them in locations where I would normally switch them on and off several times a day, they burned out very quickly -- far sooner even than an incandescent in that location. I tried different makes and styles and all were disappointing. But, my anecdotal experience of years past may not be generalizable. I may have just had bad luck with several and manufacturing technology may have improved. My current way of using them, described below, using newer CF's has been more favorable. The US Dept of Energy gives different advice on their web site; they say that it is most cost-effective to switch off a CF if doing so will save 15 minutes of electricity use; but I think the question is still unresolved as to how much on-off cycling shortens bulb life --
http://www.eere.energy.gov/consumer/your_home/lighting_daylighting/index...

5. Waste heat is not wasted in winter. All conventional discussions of energy savings with CF's assume that an incandescent bulb's turning 90% of its wattage into heat is wasted. In winter, when you are heating your house with some energy source, that is not wasted energy. Admittedly, the cost per BTU of resistive heating like this is several times the cost of natural gas or heating oil. But the glowing bulb also gives some radiant heat if you are close to it, so may allow a lower room ambient temperature (see discussion elsewhere of radiant vs. convective heat sources). Example: my house has 2 heat zones (natural gas, hydronic system). I keep the lower level fairly cool in winter (60-62 deg F.); I have an office on that level that I use a few hours per day. When I'm in it, I'll typically have one or two incandescent bulbs and 1-2 CRT monitors on and they keep it a comfortable 67-68 degrees. I avoid heating the entire 1400 sq. ft. zone just to make this one room comfortable.

6. The opposite argument obviously prevails in summer -- heat from incandescents is usually unwelcome, and would add to cooling load if you're using some kind of active cooling (fans, A/C, etc.).

Considerations 4, 5 and 6 have led me to the following way of using CF's (subject to change if I learn more):

7. How I use CF's now (2004 to present): I keep a 13 w. spiral CF in an outside post light year-round -- it is switched by a photocell on the post -- on at dusk, off at dawn. I've read that some CF's won't work with photocell switches, but this one does fine. I'm using a regular interior bulb, but the housing protects the bulb sufficiently from water. There is sufficient air circulation to keep the bulb from overheating. Year-round, my garage-workshop has several overhead 4 ft tube-type fluorescent fixtures with a mix of cool-white and warmer bulbs. I only turn them on when needed, and then leave them on if there is a chance I will be in the workshop again within an hour or two -- i.e. I try to cycle on-off at most once daily, but sometimes more than this. Same pattern with some under-counter tube fluorescents in my den/bar area. In winter I use mostly incandescents in indoor lamps, but I am quite diligent to turn them off unless I'm in the room. In summer, to avoid incandescents heating the house, I change several bulbs over to CF's and try to cycle them on-off at most once daily. I do NOT put CF's in areas where I'm constantly turning lights on and off or switching them on very briefly -- bathrooms, closets, den track lights, laundry/utility, and obviously where there are dimmer controls (dining room, kitchen ceiling). CF's would certainly NOT be suitable in a motion-sensor switched fixture that is frequently cycling on and off.

8. CF's (indeed all fluorescents) contain mercury and must be recycled appropriately (NOT in your usual trash or recycling bin). Broken bulbs must be carefully cleaned up and recycled. Reportedly big retailers like Home Depot and Walmart will soon have provisions for safe CF recycling. I see very little written so far about the pollution from manufacturing CF's. It's all done overseas, so if they save us money, who cares if China and Hungary are contaminating their land, right? If you compare the very simple nontoxic ingredients in a standard bulb to the complex electronic circuitry, solder, plastics, mercury and rare earth elements in a CF you may think a little more about their global impact.

Recycling sites for your area: www.earth911.org

Article about CF mercury content:
http://www.popularmechanics.com/blogs/home_journal_news/4217864.html

More at: www.lamprecycle.org

Print reference:
http://www.amazon.com/o/ASIN/0916571068/ref=s9_asin_title_1-1966_p/002-1...
-- Real Goods Solar Living Sourcebook (new 30th Anniv. edition published fall 2007) has detailed article about various types of electric lighting -- and much more about all aspects of energy efficiency, off- and on-grid home power systems, etc. Combination of educational articles and product catalog.