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Must View: The Critical Issues with Conventional Chinese Style Passive Solar Greenhouses Revealed – How to Solve with an Easy Retrofit Plan

In the following video, we compare the performance results between the traditional Chinese style passive solar greenhouse and the SolaRoof greenhouse. Critical issues have surfaced this way. After digging out the problems, we show a way to retrofit using the existing framework. A wonderful DIY project for you to start fresh or convert your existing greenhouse, to fully utilizing the wonderful properties of soap liquid bubbles.

Want to watch the version without comparison studies? See below…

The folloiwng infrared imaging profiles of the Chinese style passive solar greenhouse (click for source) indicate why it is not much of use in making the North wall opague and pack-filling it with dirt, a practice that most people have been taught to do so without understanding the issue clearly:

For those who would like to study Mr Jianyi Dong’s greenhouse that I mentioned above in the video, please click here.

Now you know everything about the difference!

By Aubrey Zhang

Since obtaining PhD in Electrochemistry in 1994, I have been through many things, such as post-doctoral research work using STM to study atomic level electrodeposition of Cd on Ag(111) surface at UIUC (Urbana-Champaign at University of Illinois), lifetime free-lance preaching, CEO of TheoLogos Publications and PyraPOD Global Inc, former salesman of diamond tools for Superprem Industries, former CEO of DiaSolid Kitchen & Bath, finishing carpenter, working for CRE Green, a solar company in Kelowna, BC. Now I have started this new business designing and manufacturing PyraPODs. After all these experiences, my life motto is this: sharp mind must combine with skilful hands. With my wife Margaret we have three kids - Riley, Grace and Anita.

4 replies on “Must View: The Critical Issues with Conventional Chinese Style Passive Solar Greenhouses Revealed – How to Solve with an Easy Retrofit Plan”

Aubrey –

Thanks for sharing Richard\’s bubble insulation SolaRoof design. I found your site when searching for more information on Dong Jianyi\’s greenhouse after seeing the webinar video you reference.

For more persistent bubbles (longer interval between bubble generating cycles) you might consider adding J-Lube, a veterinary obstetric lubricant. On his YouTube channel, the \”Honey Do Carpenter\” discusses adding this to shampoo based foam to make a more persistent foam for mixing foamed concrete.

Also, the thermal modelling results you show for the Chinese greenhouse seems to use a relatively low mass north wall compared to some I have seen in pictures (meters thick earthen wall). Especially at high latitudes, I suspect that a (nearly) vertical absorber (whether active or passive) is beneficial in mid-winter, and if it is an active absorber, it could better control temperature spikes at mid-day. I don\’t think the north wall needs to be an either/or proposition, though. It can be both a good absorber and be well insulated. I am at 47 degrees north latitude, but that is still well south of Jianyi, but much farther north than most of China and a good bit of Mongolia, if I am not mistaken. We also average in excess of 200\” of snow per winter, and have had as much as 360\” in a season, so snow load design is an important consideration for me.

An active absorber system can also be fabricated quite inexpensively, for example, here:
It might be possible to use the same pump system as for the foam nozzles to circulate through the absorber panels, though the requisite pressures and flow rates might not be a good match between the two systems. However, both systems should be able to share the same water mix, I think. Circulating warm water through the soil on cool night could also be beneficial for the plants.

Thanks again. You\’ve given me much food for thought.


Kevin, thank you for your comment and concern!

In our case, persistence of bubbles is not the major issue, as long as you have bubble foam insulating the double layer cavity in winter and liquid film inside the cavity for cooling, you are roughly on the right track. The north wall issue, take a look at this IR imaging first, then you will know it is not that critical either – finding the critical and determinating factors is critical:

IR imaging of Chinese passive solar greenhouse

That is why in our design of my backyard build of PyraPOD, we came up a simpler approach to the geo thermal gain: we create a underground poopl filled with gravels and water. As simple as that!


Thank you for all the information. I first enountered Solaroof about 10 years ago, and I studied all the material I could find.

I have become interested in Chinese style solar greenhouses this past year, and I am considering building one here on my farm in Northern Vermont, near the Canadian border.

I don’t see many working examples of larger (3,000 s.f. +) greenhouses using this technology. Are there any working commercial models that you can refer me to?

Scott, thank you for the asking.

The short answer is, no, as I am the first one who have joined and started to commercialize the technology. There may be a few DIY projects in North America but I do not see anyone sharing about. I tried to contact Ross and Kat Elliot in Ontario and left message twice, they have never called back.

The next of our large design (new version of CityPOD) is roughly 50,000 SQF. I am in the process of buying a 108 acre farm land to set it up there. Will let you know when that happens.

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