Matt Coston

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since Nov 07, 2017
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Recent posts by Matt Coston

josh ober wrote:I guess what I’m having trouble with is understanding how cob would stay cool in the heat, considering the fact that it seems it would be absorbing heat from the sun.


It does indeed absorb heat, but different materials can absorb more energy before they actually start to feel warm.

I appreciate that could be a bit hard to wrap your head around. The fundamental reason for this property is highly technical and beyond my understanding, but is explained on Wikipedia:

https://en.wikipedia.org/wiki/Heat_capacity
https://en.wikipedia.org/wiki/Thermal_mass

An example given on Wikipeida (see this table) is that water requires about 4.5x more energy (measured in Joules) to raise its temperature by 1°C compared to an equivalent mass of concrete. So in layman's terms, concrete starts to feel warm four to five times faster than water does. This means water is the better material to use as thermal mass. Of course, water has a habit of leaking out of containers and destroying stuff. On the other hand, water can also be pumped through heat exchangers which allow you to push the heat around much faster. So there are a number of factors to consider.

Here's another useful table showing heat capacity. Sandy clay requires about 1.6x more energy than concrete to raise the temperature.

An interesting (and counter-intuitive) detail to note is that air has a higher heat capacity than concrete. But of course, 1 tonne of air occupies a much larger volume than 1 tonne of concrete.

Finally I just want to point out that I am not a scientist or engineer, so I would love somebody who is to confirm what I have written above.
4 days ago
cob
Hi Jay,

Jay Angler wrote:...if the goldenrod was grown in dirt with fertilizer, it might well show some of the changes for reasons other than the presence of higher levels of CO2.



There were two separate trials conducted (link to study at bottom)
    1) Comparing present-day goldenrod to historic goldenrod (which does not directly address your above concern)
    2) Conducting an isolated trial where the goldenrod was grown in polytunnels where atmospheric CO2 was the only variable (which does directly address your concern)

The report explains that the confidence in their conclusions from both tests is high: "...the current data do indicate a clear and unequivocal link, both historically and experimentally, between rising [atmospheric carbon dioxide] and a qualitative decline in pollen protein".

Jay Angler wrote:Who was that guy anyway?



He is a professional science communicator. He has a degree in physics engineering and a PhD in science education research.

Finally, I do also dislike how quickly he dismisses (in the video) the idea that soil health does not contribute. However I am comfortable believing the results of the study.

The study - http://rspb.royalsocietypublishing.org/content/283/1828/20160414
2 weeks ago
Apparently planning permission for offgrid homes using low-impact & sustainable techniques is easier to obtain in Wales, but I've never looked into that in detail.

You may want to look at woodlands.co.uk for finding land.

I've also heard you can put a caravan on a woodland and live there for up to 6 months of the year without any legal issues (I am not a lawyer, so do your own research).
2 months ago

paul wheaton wrote:Once you have access you will be able to upgrade to "tiny download" or "HD download"


Will that incur extra cost?
2 months ago
At the $150 reward level, we receive the 100hrs of PDC and 77 hours of ATC.

I can't find any info on whether this is streaming or download, SD or HD.

Can you please clarify that detail?

Many thanks.
2 months ago
Hi Chris.

To me, the important questions are:

1) How much smoke does it produce?
2) What it its long-term tolerance to heat? Will it still be working in 2 years time and hundreds of firings, or will it have been slowly but surely destroyed by the heat?

Obviously the second question can't be answered right now.

Looking forward to seeing your next videos though.
2 months ago

John C Daley wrote:Civil engineer who welds and sells earth block machines and plays with hot rods



Sounds like you may find the people at Open Source Ecology to be of interest to you (they designed an open-source rammed earth block machine and are working on many other machines). They are based near Kansas city, however their site is not open to the general public or to casual visitation. They do hold invitation-only events from time to time, including a new "immersion program."

I'm not affiliated with them in any way, but I think what they are doing is really cool.
2 months ago
The phys.org article has a perfectly mundane explanation:

"The simplest interpretation is that life is always evolving," said Stoeckle.

"It is more likely that—at all times in evolution—the animals alive at that point arose relatively recently."

In this view, a species only lasts a certain amount of time before it either evolves into something new or goes extinct.

3 months ago
My understanding is that it is a matter of UV intensity. UV sterilisation using sunlight is not possible outside equatorial regions, and even there you need to put the water into small bottles where the UV can penetrate through the entire container.

EDIT: I should add that I have never tried this myself.
3 months ago