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Prof M Keith Sharp ScD PE

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Posted By M Keith Sharp 03-28-2023 10:59 AM
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David, I would like to point out a couple of things that are missing in your calculations. First is that built floor area is expected to double by 2060. A 50% energy efficiency reduction would be required just to keep consumption the same. Energy efficiency has fundamentally limited capacity to ...
Posted By M Keith Sharp 03-27-2023 06:21 PM
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Thomas, Thanks for contributing. I think an article with opinions from the consumer and utility sides would be informative, if only to "stir the pot." It appears that you are using "sustainability" here to refer to profits. However, the more important definition for this problem is environmental ...
Posted By M Keith Sharp 03-18-2023 09:12 PM
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I don't know, "survivalism" for me brings images of Mad Max apocalypse, articles by Bear Grylls, and "AR-15 vs. trench shotgun: Which is best for protecting your home?" I don't think that is your intention, but "do it yourself," "self reliance," "off grid," and "resilience" might be better descriptors ...
Posted By M Keith Sharp 03-17-2023 09:02 AM
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Bill, Thanks for taking the time to explain your project. Yes, warm floors make a big difference. A tight and well-insulated envelope also pretty much eliminates cold spots. 2x12 framing sounds expensive, especially if fully supported by a 12" thick foundation. If you are doing the work yourself, ...
Posted By M Keith Sharp 03-16-2023 06:37 PM
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Bill, Do you have an overall UA value? I have found that a peak loss of 10 W/m^2 (the Passivhaus standard) before considering internal heat gains is a pretty good place to start. This ends up being a bit better than Passivhaus after internal heat gains are added. I had to use higher R-values in my ...
Posted By M Keith Sharp 03-16-2023 05:54 PM
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Elias, So true and well said. The way your hometown buildings used to operate is something to which we can all aspire. Electric lights instead of daylighting is one of my pet peeves. ------------------------------ M Keith Sharp Emeritus Professor Louisville KY ------------------------------
Posted By M Keith Sharp 03-15-2023 12:35 PM
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Bill, High R-value and sunroom sounds good. How much thermal mass are you including? A slab-on-grade floor insulated underneath can provide a good part of it. Low envelope losses, just the right amount of solar gain and sufficient thermal mass are the keys to reaching 100% ambient conditioning. You ...
Posted By M Keith Sharp 03-15-2023 12:18 PM
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Right, the good news about heat pumps is that they save 2/3 of the energy. The bad news is that they only save 2/3 of the energy, and you have to buy them. With ambient energy, you can save 100% and you don't need a heat pump. ------------------------------ M Keith Sharp Emeritus Professor Louisville ...
Posted By M Keith Sharp 03-08-2023 10:07 AM
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Bill, This is a great discussion, and thanks for asking questions that I am sure others have as well. Internal heat generation is a small, but significant, contributor to serving the heating load in the winter. Paradoxically, energy efficiency is counterproductive in the winter, since any reduction ...
Posted By M Keith Sharp 03-07-2023 01:45 PM
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I have even heard a code developer call houses built to code "the worst houses you can legally build." How can codes be changed to promote ambient energy systems and performance beyond the code limits? I have some ideas, but want to hear yours as well. ------------------------------ M Keith Sharp Emeritus ...
Posted By M Keith Sharp 03-07-2023 01:32 PM
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The PV math is different for Ambient House. Our house is about 3500 sqft. In 2022, we used no auxiliary energy of any kind for heating or cooling, other than a few fires in the fireplace. The house is otherwise all-electric and we used about 4000 kWh for the year. PVWatts says a ~ 2 kW system would get ...
Posted By M Keith Sharp 03-07-2023 01:01 PM
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Haven't read the book, but sounds like utility mismanagement is yet another reason to add to the list of reasons (unusual weather, vandalism and policy changes) favoring local ambient energy systems. The recent storms in California, Kentucky and Tennessee have caused power outages for many people. Some ...
Posted By M Keith Sharp 03-03-2023 09:19 AM
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Solar buildings! Why? Buildings have the most potential of all sectors for dramatic reductions in energy use and carbon emissions. They consume 71% of US electricity, as well as 25% of natural gas [EIA 2022]. Building operations, building materials and construction are responsible for 47% of total US ...
Posted By M Keith Sharp 02-16-2023 01:12 PM
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Ella, This is exciting and has lots of potential. The short articles could be quite useful if they had citations and links of more in-depth work. A bit of constructive criticism, if I may. You have three themes for PV, but none for passive solar. Solarpedia has three main categories: Passive Solar ...
Posted By M Keith Sharp 02-14-2023 10:35 AM
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Things get lost during a move. I was delighted to recently find my copy of "The Solar Cat Book" by Jim Augustyn. From the back cover: "A cat sunning himself in the doorway of a barn knows about solar energy. Why can't man learn?" (E. B. White) That is wisdom distilled! ------------------------------ ...
Posted By M Keith Sharp 02-13-2023 01:17 PM
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A back-of-the-envelope calculation says that about 2000 square feet per person would be enough in the US. That sounds a bit large compared to residential floor area, but when commercial and industrial buildings are considered, we could get all the power we need from roof top PV. No need to disturb more ...
Posted By M Keith Sharp 02-12-2023 02:30 PM
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Utility hijinks regarding excess power from your own PV is another reason to consider passive solar space heating and other solar thermal technologies. With these systems, the excess energy is stored at home (IN your home for passive solar, in a tank of water for solar water heating). The utility never ...
Posted By M Keith Sharp 02-12-2023 02:03 PM
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Yes, basically everywhere. I like this map showing PV necessary to power the world: http://landartgenerator.org/pdf/PosterSolar.pdf. The little rectangles are all that are needed. A map of solar potential shows that northern Africa has widespread potential. ------------------------------ M Keith Sharp ...
Posted By M Keith Sharp 01-13-2023 01:04 PM
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Sure, there are a number of differences, but one thing is not different. The human population cannot be larger than the capacity of the Earth to produce enough food, just like other species in their limited environment. Money, fossil fuels and everything else is secondary to that immutable principle. ...
Posted By M Keith Sharp 01-12-2023 01:03 PM
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From a population dynamics standpoint, homo sapiens is not much different than any other species. The Isle Royale deer and moose do not use currency, nor do bluegills in a farm pond or trout in an alpine lake. Yet all are subject to the limits of their environments. The human overpopulation problem is ...