Greg Hickey

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since Dec 24, 2011
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Recent posts by Greg Hickey

To add to John's post. As he 'owns the trees' and you don't you have to reach agreement to use the land in anyway that effects his timber. So if you want to clear a pasture or plant a garden (clear trees to increase sunlight), you need his permission and have to compensate him for the timber. Also his interest will reduce resale of the land should you ever chose to sell. Who wants to buy your place if they don't own or have clear control to the property?

Also, rights vary from state to state, but expect that he will have some rights to come and go from the property to inspect the timber. As a woman 'moving on with her life' after a divorce, do you really want your ex to be coming and going from a small parcel of land? Could make you or a potential partner in the future uncomfortable. Compensate him for the future value of the timber and make a clean break. Co owning property with an ex spouse is never easy even in amicable splits.
8 years ago
You are in a great location for learning about cob. I am sure you are aware of the activities on Mayne Island. Take a short hop and see cob in action. That will tell you more than anything what cob will do in your weather/climate.

As far as my understanding of strawbale (admittedly my data is old. I gave up on the idea of strawbale about 8 years ago.) is that the very high compression of the straw keeps moisture in the form of vapor from migrating too deeply into the bale.

Realizing that my information was old I did some reading. It seems maximum breathability is the recommendation.

There are no historical precedents of bales being used with moisture barriers, and consequently there is no data on how the two perform together. Most historical data for unwrapped bale walls demonstrates the importance of walls of maximum breathability: a mansion in Huntsville, Alabama, has successfully endured Southern humidity since 1938; a 1978 building near Rockport, Washington, receives up to 75 inches of rain a year; and an unplastered building near Tonasket, Washington, with no foundation and unplastered walls shows no apparent deterioration of the bales since 1984. Recent bale structures in northern New York (humid winters) and Nova Scotia (cold humid winters) have been monitored and demonstrate good performance in these difficult climates.

To better clarify my point on moisture with cob:


Cob is a form of earthen building developed in the British Isles, a very wet area famous for beautiful mists and vicious storms. Yet the native cob buildings in these places have withstood centuries of harsh weather and still remain in use today. When I built a cob studio Pensacola, Florida in 2002 many people were skeptical that it would survive our 98% humidity and frequent hurricanes. However, the building has had no problems despite soaking rains throughout the building process and a hurricane that destroyed many of the surrounding wooden buildings. Even in humid climates cob does not rot, grow mold, get eaten by termites, or melt on the rain.

Cob is very porous and can absorb a tremendous amount of water without softening. In fact, unless it is completely submerged, cob will never just “melt”. It will however erode over time if it is exposed to direct rain. The solution to protecting cob from moisture is “a good hat and boots”. In other words, a cob house needs a good roof with wide eves and the bottom of a cob wall must sit on a non-absorbent stem wall so that it cannot wick moisture up from the ground or be splashed by water coming off of the roof. Cob walls are very thick, often two feet or more, so even the heaviest rain will never soak through more than the outer layers of plaster. Even if your walls get soaked with rain occasionally (like in a really big storm) they will be fine as long as they can dry back out. For this reason it is very import to never plaster a cob wall with a non-breathable coating like cement stucco.

As to your question on gradient, I am going to say that when the humidity is the highest on the Island, Winter, the structure will be heated from the inside creating a high or steep gradient (migrating outward.) The time of year when the gradient would be shallow would be the warmer months when humidity is at its low point. I am confused by your statement that "in the winter ... interior moisture content is high." From a relative humidity perspective, the air is less humid inside than outside presuming there is some heat differential to the outdoors. The warmer it is the lower the relative humidity. So the air inside the walls should be less humid by volume than the air outside. Am I wrong here? If so I apologize.

If in fact the inside is less humid than outdoors the air density gradient will be from low humidity to high humidity, even though it seems counter intuitive.

Humidity and air density

Most people who haven't studied physics or chemistry find it hard to believe that humid air is lighter, or less dense, than dry air. How can the air become lighter if we add water vapor to it?

Scientists have known this for a long time. The first was Isaac Newton, who stated that humid air is less dense than dry air in 1717 in his book, Optics. But, other scientists didn't generally understand this until later in that century.

To see why humid air is less dense than dry air, we need to turn to one of the laws of nature the Italian physicist Amadeo Avogadro discovered in the early 1800s. In simple terms, he found that a fixed volume of gas, say one cubic meter, at the same temperature and pressure, would always have the same number of molecules no matter what gas is in the container. Most beginning chemistry books explain how this works.

Imagine a cubic foot of perfectly dry air. It contains about 78% nitrogen molecules, which each have a molecular weight of 28 (2 atoms with atomic weight 14) . Another 21% of the air is oxygen, with each molecule having a molecular weight of 32 (2 stoms with atomic weight 16). The final one percent is a mixture of other gases, which we won't worry about.

Molecules are free to move in and out of our cubic foot of air. What Avogadro discovered leads us to conclude that if we added water vapor molecules to our cubic foot of air, some of the nitrogen and oxygen molecules would leave — remember, the total number of molecules in our cubic foot of air stays the same.

The water molecules, which replace nitrogen or oxygen, have a molecular weight of 18. (One oxygen atom with atomic weight of 16, and two hydrogen atoms each with atomic weight of 1). This is lighter than both nitrogen and oxygen. In other words, replacing nitrogen and oxygen with water vapor decreases the weight of the air in the cubic foot; that is, it's density decreases.

Wait a minute, you might say, "I know water's heavier than air." True, liquid water is heavier, or more dense, than air. But, the water that makes the air humid isn't liquid. It's water vapor, which is a gas that is lighter than nitrogen or oxygen. (Related: Understanding water in the atmosphere).

Since heat will convect from hot to cold and air density will flow from high (less humid) to low (humid) the gradient should be the highest when the temperature differential is highest in the wet winter months, even when their is high humidity outside as is the case in the Pacific Northwest.
8 years ago

I think there may be some misunderstanding on cob, here. Cob walls have (depending on thickness) around a R-30 value. That is NOT low insulative quality. Strawbale does have a greater R value due to the additional depth of the bale. However it is not load bearing and thus only an infill that needs a rigid frame structure in addition to the straw. Both are good choices for the northwest. Are you on the west or east side of the mountains?

As far a humidity, both breath. True. Both need to be protected from the rain/wind. Expanded eves usually does the job. Cob does not saturate with humidity due to the density of the dried earth. Strawbale does not absorb a lot of moisture due to the compressive pressure of the bale. Straw must be baled, by the farmer, at around a 1000psi. That is very very tight. But is keeps moisture from gaining access to the interior of the bale and molding.

Both do need a good exterior coating to combat the moisture in the NW. Most people use a plaster on either construction. You will find that even in high humidity winters the walls will allow some migration inward, but not much. The real danger is sealing the wall and not letting it breath outward when it can. Then you will get an unhealthy structure, mold, and eventually interior structural damage.
8 years ago
Fred, The sheet steel would be too thin I believe. Plate steel might work better. Longer to heat but even distribution. I would not bother with sanding either. Season it as one would with Cast Iron or use oil to keep from sticking. I think Lodge sells a cast iron grill sheet for pancakes, etc...
9 years ago

Propane freezers work just like a typical mechanical (compressor) model. The difference is they use heat from the burning fuel to create pressure in the tank rather than a compressor to build pressure. The upside is no moving parts to wear out. The down side is they are more expensive to purchase at present.

There are a lot of off grid cabins in WA that are run entirely off propane. From lights, to frig, to hot water heater. While most gas appliances are "RV sized" there are a few companies out there making full sized appliances, including up to 21 cu. ft freezers. If you do put it outside, know that it will surface rust/stain with the higher humidity outdoors. If it is covered it will take longer, but will eventually. Not a mechanical issue, just cosmetic. However, gas appliances are expensive to sit out and rust.

9 years ago
Interesting take on estimating firewood of standing trees per acre from the University of New Hampshire:

9 years ago

The studies were done for pulp production. I believe the gains come from the ability to harvest every year after the first three years for many years before a timber crop can be harvested. So you are looking at 7 to 17 years (depending on the tree variety) of culm production vs. 1 tree coupled with greater density per acre than trees. Bamboo is in the grass family and from sprout to full height in one year, after the root system is fully established (typically 3 years.)
9 years ago
I am glad there is so much discussion on Bamboo. I think it has been well covered here; but will add from forestry studies Bamboo produces 40 times more mass than timber significantly reducing the acreage needed. Rose, I would also ask you to consider this. What will the purchase price of the land plus taxes run you for the three acres? If you cost it out, you may find it is cheaper to buy your wood than to buy land for the purpose. Of course there is the intangible benefit of self sufficiency which has to be considered.

I have friends in Northern Maine whom heat exclusively with wood. They run 4-6 cords a year for about the same square footage, depending on the severity of the winter. They have a logging truck bring the trees to them in trunk form; and cut and split themselves. (funny how I always get an invite to visit in the last summer/early fall. ) If I recall they spend about $2000 a year on a load of wood. I believe at that price level there is parity with taxes. Factor in the cost of felling and hauling your logs up to the house, and you might find it cheaper to buy a smaller parcel or put the wood lot into more productive purposes.
9 years ago

Interesting idea. I have a question though. Although we don't get a lot of hard freezes where I am, I have been on early morning patrol breaking up water tanks with an axe for stock on the occasional hard freeze. Running water is harder to freeze than still water; but will drawing water off the bottom of the tank create enough current to break the surface tension of the top water? Streams can crust over even hard freeze while the stream underneath flows normally; but still requires the surface ice to be broken for the stock.

The kids must love the luge course the hose creates downhill of the tank! Open a round bale for a landing zone, grab some cardboard, and they could stay entertained all day.
9 years ago

I am glad you are pursuing this and hope you share the process and results here. Living on the Texas Gulf Coast, I have a similar climate and challenges. I have considered and Ammonia/heat based system as an alternative to a commercial compressive unit. But have not had the time to do the research and the math on ammonia as a medium. I would be interested in how you got to the number 210 degrees.

Yes the stove will get much hotter than 210 in the burn chamber, reburn chamber and some of the exhaust flue. It does not exit at this temperature because the stove is surrounded by a heat sink that absorbs and stores excess heat. In your case this would be the gas storage tank just before your expansion valve. Here is the down side as I see it. When it is hot outside (a/c needed) one would have to be standing over the RM Stove feeding wood into it. If it is inside, then you are heating the space you are trying to cool. If it is outside, you are in the heat constantly (over a hot stove) and not inside gaining the advantage of the cooled space. So yes, it could work and work well; but may be more trouble than one would like.

As a water heater it would work very well. The many of the old wood fire stoves had a hot water box on the back that absorbed waste heat and store it in water providing not only hot water for the household, but decreased fuel needed to keep stove at temp. A RMS would do just as well; and if your ammonia tank was submerged or jacket by hot water it would take very little energy to return it 210 before the expansion cycle.

While this is not the information you asked for, have you considered a passive solar collector to preheat the ammonia then use propane/methane/natural gas to finish the heat cycle? A solar still or solar composter uses a glass fronted box with reflective coating to collect, store, and heat the interior of the box with just sunlight. In the case of a solar still the temperature nears 210. In a composter temps reach a minimum of 160 degrees necessary for sterilization. With the gas at these temps it would not take much fuel to 'top it off' at 210-215. One can even make there own methane from harnessing the natural byproduct of composting waste or manure. The only real challenge is wiring your pilot light to activate from the thermostat signal.

9 years ago