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Prof M Keith Sharp ScD PE

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RE: Read our innovation-showcase issue of Solar Today

Posted By M Keith Sharp 07-26-2024 07:26 PM
Found In Egroup: Everything Solar Forum \ view thread
Right, there are a number of reasons why a solar hot water system might not work as well as it should. Poor insulation is one. All the piping, heat exchangers, etc., need to be insulated well. Missing check valves is another issue, which can cause a loss of heat during the night almost as large as the ...

RE: Read our innovation-showcase issue of Solar Today

Posted By M Keith Sharp 07-26-2024 06:57 PM
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Joe, Are you also ducting supply air for the HPWH from outside? If not, then it's not balanced. It's pulling cold air into the house through cracks around windows, doors, etc. in order to have air to blow out through the sill plate. You need extra energy to heat that cold air. ------------------------------ ...

RE: Read our innovation-showcase issue of Solar Today

Posted By M Keith Sharp 07-25-2024 01:24 PM
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In response to a question: Solar water heaters produce around 50 times more heat than the electricity used to power pumps and controllers. A heat pump water heater (HPWH) produces 2-3 times more heat than the electricity used to power its compressor, but about half of that heat is taken from the air ...

RE: Read our innovation-showcase issue of Solar Today

Posted By M Keith Sharp 07-20-2024 08:36 AM
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Interested to hear how it works. To passively pull heavy cool air up to the second floor, you need a tall stack of light hot air. It is a nice fluid statics problem! A good feature of earth tubes is that they can cool air in the summer and preheat it in the winter. Condensation can be an issue in the ...

RE: Read our innovation-showcase issue of Solar Today

Posted By M Keith Sharp 07-18-2024 09:07 PM
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Agreed. With a heat pump water heater drawing heat from the house, the heat pump space heater would have to be used more. Solar thermal water heaters are better from an energy perspective than heat pump water heaters for all but a few of the hottest, southern locations, where the cooling in beneficial. ...

RE: Read our innovation-showcase issue of Solar Today

Posted By M Keith Sharp 07-18-2024 01:32 PM
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If you are thinking about building a house, or doing a remodel, the article by Jim Riggins is a must read. I am still amazed at the performance of the house and the quality of the design. It is nearly 100% heated and cooled by ambient energy. A heat pump was installed, but has rarely been used. Hot water ...

RE: Solar Today Article: Demand and Opportunity Today for Residential Energy Storage

Posted By M Keith Sharp 06-25-2024 09:42 PM
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Adobe is prettier than batteries, too! Even concrete, the black sheep of the thermal storage family, has lower environmental impacts per unit of stored energy than batteries. ------------------------------ M Keith Sharp Emeritus Professor Louisville KY ------------------------------

RE: What policy topics do you think Solar Today should cover this fall?

Posted By M Keith Sharp 06-03-2024 08:16 AM
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Jay, Good question. To serve all loads with electricity by our climate change deadline of 2050, we probably need even more new lines and need to replace many existing lines for higher capacity. That is why I think we should consider offsetting some of these loads with ambient energy. Heating and cooling ...

RE: What policy topics do you think Solar Today should cover this fall?

Posted By M Keith Sharp 06-03-2024 07:51 AM
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Bob, I like the max heating/cooling load limit. The original Passive House limit of 10 W/m^2 is a nice round number, and allows ~100% ambient conditioning in many climates with south glass of 5-10% of the floor area and a reasonable amount of thermal mass. The thermos bottle just needs a few south ...

RE: What policy topics do you think Solar Today should cover this fall?

Posted By M Keith Sharp 06-02-2024 01:23 PM
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Bob, I agree with most of what you say. The main issue is "cheap batteries." Batteries are not the whole picture. The latest estimates for a 100% renewable grid are $8 - $21 trillion, which includes the other important pieces, namely renewable generation, transmission lines and utility-scale storage. ...

RE: What policy topics do you think Solar Today should cover this fall?

Posted By M Keith Sharp 05-28-2024 08:28 AM
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Hopefully, I have made my point that, even though it can be challenging for some existing buildings, ambient conditioning isn't just for new construction. My family have been builders for four generations that we know of. Maybe longer if we dug into ancestry. So I know a bit about remodeling. Thumbs ...

RE: What policy topics do you think Solar Today should cover this fall?

Posted By M Keith Sharp 05-27-2024 11:33 AM
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Yes, electricity can be used for lots of things. It has high exergy. On the other hand, heating and cooling doesn't require high exergy. Why use a high exergy source to do a low exergy job? Maybe it could be justified if heating and cooling were a small load, but it isn't. It's around half of all building ...

RE: What policy topics do you think Solar Today should cover this fall?

Posted By M Keith Sharp 05-27-2024 11:04 AM
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Sorry for the delay in responding. Other commitments got in the way, including the ASES conference. "it can only be implemented on new construction." Simply not true. Sure, there are some existing buildings for which using ambient conditioning would be challenging or essentially impossible. Lack of ...

RE: What policy topics do you think Solar Today should cover this fall?

Posted By M Keith Sharp 04-03-2024 10:33 AM
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Debbie, Great idea. I copied below the Key Messages from our workshop white paper. By infographic, do you mean something with fewer words and more pictures? Good plan to involve Solar Building Division members. Feedback welcomed from this forum, as well. Key Messages 1. Ambient energy (from ...

RE: What policy topics do you think Solar Today should cover this fall?

Posted By M Keith Sharp 04-03-2024 07:18 AM
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Sure, thanks for asking. A large part of the policy impact comes down to federal research priorities, particularly at DOE. There was a comprehensive program of research, development, demonstration and outreach on passive solar and solar thermal systems that was cut by Reagan. Those were tough times ...

RE: What policy topics do you think Solar Today should cover this fall?

Posted By M Keith Sharp 04-02-2024 06:48 AM
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Kat, Buildings account for nearly half of US energy use and a large fraction of greenhouse gas emissions. There are tremendous opportunities for reducing the impact of buildings by adopting policies that promote the use of ambient energy for a wide range of applications, including heating, cooling, ...

RE: Solar Thermal Cooking: New Interviews

Posted By M Keith Sharp 03-21-2024 11:58 AM
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Luther, Thanks so much for all you do! Keep up the good work. Keith ------------------------------ M Keith Sharp Emeritus Professor Louisville KY ------------------------------

Happy birthday to ASES!

Posted By M Keith Sharp 03-20-2024 02:18 PM
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ASES is 70 years old this year! Thanks to Carly for the email announcement. 1954 was the year that Bell Labs patented a PV cell, but it was also the year that Farrington Daniels took his first UNESCO-funded trip around the world to discuss and demonstrate solar thermal devices, which were better known ...

RE: 🌱Neighborhood Solar Potential Assessment Tools for Citizens and Professionals

Posted By M Keith Sharp 01-08-2024 02:10 PM
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Elias, You probably know about PVWatts, also. I wouldn't be surprised if the tools you listed incorporate PVWatts for their calculations. The thing I like about PVWatts is that it is so simple - just pick a location and enter a few inputs. Best, Keith ------------------------------ M Keith ...

RE: New Article. Its been awhile though...

Posted By M Keith Sharp 01-08-2024 02:02 PM
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Thanks for the article. Pessimistic, but that is reality. We have a lot of work to do. ------------------------------ M Keith Sharp Emeritus Professor Louisville KY ------------------------------