It's great to see some of the folks joining this discussion.
Mark Chalom is one of my passive solar heroes, I am a long time student of Mark's.
He has an abundance of experience and knowledge!
I use the term passive solar because solar is the primary design criteria.
Yes, insulation & indoor air quality play a huge part of a quality design program but solar is front and center for a passive solar design.
Increasing insulation levels has been an inevitable evolution of the classic passive solar design as it is with a Passive or Ambient House.
I do believe there is a point of diminishing returns on levels of insulation, each designers needs to make that determination according to their specific goals and climate.
You mentioned reducing the area of south facing windows.
I am a big fan of large dramatic south facing glass (within reason).
Some of the designs I have built, fine-tune the incoming direct solar radiation by utilizing exterior architectural shading elements.
A well designed south roof projection can limit large south facing window's direct solar gain and can still supply an interior space with appropriate seasonal solar gain, fantastic natural light & inspiring views of gardens & western landscapes.
A Sketchup solar model can give a designer an accurate view of shading to achieve desired effects.
A properly designed and oriented passive solar home is generally self regulating.
That said, I am a huge proponent of operable interior window treatments to give precise control of incoming light intensity, insulate against night time winter heat loss and provide occupant privacy
A well designed passive solar structure is a dramatic, dynamic living space synchronized with the seasonal solar changes.
I agree increasing the building envelope's insulation and reducing window area will get you closer to the 100% heating and cooling needs but at what cost.....definitely additional material costs and potentially a less dramatic living space.
I love the idea that there is a wide palette of strategies to chose from in creating a highperforming home design.
Keep up the great work.
Stay curious....
Steve Kawell
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Steve Kawell
Owner
Durango Solar Homes
Durango CO
stevekawell@gmail.com------------------------------
Original Message:
Sent: 03-21-2022 11:42 AM
From: Mark Chalom
Subject: Ambient House: Heating and cooling with 100% ambient energy
Kieth, nice to meet you. I enjoyed your post. I support and follow your direction. I do use less insulation leaving some for others and subsidise with wood from beetle kill or Electric from our PV. I do not try to cover the extremes. Passive solar works so well. Just balance energy in with energy out. Using mass to flatten the curve. I live in Santa Fe and get to Pagosa to visit friends and for Medical needs. I would be pleased to find and meet you sometime and share. I have a few homes in Pagosa and we could have a fun and productive visit. Some goes for Santa Fe.
Mark Chalom
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Mark Chalom
Builder/Architect
Solar Design & Analysis
Santa Fe NM
chalomm@gmail.com
Original Message:
Sent: 03-18-2022 07:46 PM
From: M Keith Sharp
Subject: Ambient House: Heating and cooling with 100% ambient energy
Steve,
I am an old passive solar guy as well. Ambient House is a refinement of passive solar, in combination with Passive House (or super insulated houses if you want to go back to the 1980's). With the best features of passive solar and Passive House, along with some new features (principally, active control of passive gains and losses), it is possible to serve the entire heating and cooling load. No mini-split needed. We installed a post-heater downstream of the ERV, just in case, but it is not wired up yet and hasn't been needed.
Compared to classic passive solar homes, the main differences are more insulation and smaller solar aperture. Thermal mass is in the same ball park. If you would be interested, I could run the model on an example home to see what it would take to serve the rest of the load compared to what you typically build. If you get over to Pagosa, let me know. You are welcome to come see our house.
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M Keith Sharp
Emeritus Professor
Louisville KY
keith.sharp@louisville.edu
Original Message:
Sent: 03-18-2022 12:11 PM
From: Steve Kawell
Subject: Ambient House: Heating and cooling with 100% ambient energy
Hello Keith,
Just want to say thanks for spreading the virtues of passive solar home designs.
I have been designing and building passive solar homes for over 30 years and been living in a passive solar home for the past 25 years.
One of the benefits of these designs is that the occupants are synchronized with the seasonal changes of our natural world.
If the home is oriented & designed correctly it is self regulating, warm and sunny interior spaces in the winter, cool shaded spaces in the summer.
This greatly reduces the heating and cooling loads but does not really cover all heating and cooling conditions.
My experience has not been to design homes that achieve 100% of the heating and cooling needs with the passive solar features.
In my climate it is most cost effective and more comfortable to figure that 75-80% of heating and cooling needs come from the passive solar design.
We can have a week long winter storm front move through my area with clouds and cold temperatures greatly reducing the comfort of the home.
I have found that a simple backup heating system can supplement at these times keeping occupants very comfortable.
The same goes for the summer cooling season, a high pressure can setup in June or July and not allow for adequate cooling with night flushing alone.
A simply Mini-split system carries the home during these weather events.
The all electric heat pumps can be run off of a PV system with a grid tie or battery backup.
My experience has shown that this is the most comfortable and cost effective design.
Wishing you all the best,
Steve Kawell
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Steve Kawell
Owner
Durango Solar Homes
Durango CO
stevekawell@gmail.com
Original Message:
Sent: 03-15-2022 12:36 PM
From: M Keith Sharp
Subject: Ambient House: Heating and cooling with 100% ambient energy
Thought this might be a good forum to spread the word to those most likely to be interested.
There is wide-spread dogma that passive solar heating and passive cooling can only serve a fraction of the heating and cooling loads. Don't believe it! Some pioneers, such as Maria Telkes and Norm Saunders, knew better and designed homes in particular climates that needed no auxiliary energy for heating and cooling. The thing that was missing, though, was a formal method for achieving such performance in any climate.
The key is balancing enough insulation (low envelope loss) with just the right amounts of solar gains and passive cooling, along with enough thermal mass to bridge intervals of unavailability of the appropriate ambient energy source for the local climate (periods of cloudy weather during the winter so that solar heating is not possible, and warm nights during the summer so that ventilation cooling is not possible). (For the solar nerds, the mathematical model is described here: Sharp MK. Indoor comfort achieved exclusively from ambient sources across US climates. J Sol Energy Eng 143(6):061005, 2021. The model is really simple. It runs in Excel.)
The first Ambient House is being built in Pagosa Springs, CO. It has remained comfortable for more than a year with no auxiliary energy use. It was on last year's National Solar Tour here: https://vimeo.com/581885086 In this rather cold climate (zone 6), it has at least 16" of insulation in the walls, 32" in the ceiling and 12" under the floor. The basement walls and the floors on two levels are concrete for thermal mass. The windows for solar gain are small by passive solar standards, just large enough to get enough heating during the winter, but not so large as to produce unmanageable overheating during the summer. Cooling is by nighttime ventilation. Some rudimentary data collection is underway, with more extensive instrumentation to be installed this summer.
Given the large carbon emissions of most current buildings, it would be great to see more 100% ambient-energy-conditioned buildings constructed. Let me know if I can help you with a new home or a remodel.
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M Keith Sharp
Emeritus Professor
Louisville KY
keith.sharp@louisville.edu
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