20101018
Hello Marc,
Thanks for telling us about your project. Welcome to you and other recent members at the Yahoo Forum.
The Sola Roof must support two layers of glazing that are separated widely apart - this is to provide the Cavity Space that will fill with Liquid Bubble Insulation in a dynamic process. You need to generate the bubbles as needed to use the stored cooling or heating energy of the Liquid Thermal Mass. The Sola Roof process allows the bubbles to be substantially destroyed at any time and the key to such performance is the Bubble Flow Path, which is a flow circuit within the Cavity Space.
For DIY projects we can get good results by using tunnel structures and dividing the Cavity Space at the ridge of the tunnel. In cold climates, an outer tunnel frame makes a lot of practical sense, since the snow can cave in an air-supported outer film. But air-supported Sola Roof projects have been operated successfully. My very first experiment in 1974 was a double air supported layers with no frame at all. Ross has used an outer air-supported film for nearly a decade. So, it is possible.
When we use a frame for the outer film the advantage is that there is not such a critical situation in the case of loss of the blower. If the blower fails or you loose power to the blower then in some cases there could be a more critical situation. You can use a static pressure blower without having any effect on the bubble system. Bubbles are generated because of the pressure across the bubble screen - this is produced by a fan or blower-wheel that is the key component of the Bubble Generators.
A double support for the separate film layers is not a big deal - because the inner framing can be very light and cheap since it only supports the inner film, which takes no snow or wind load. This inner frame can have a dual purpose of support for hanging crops and lamps or creating a shelving system for multiple crops. This is an area where we must share our experience to learn best ways and low cost solutions that are effective.
In all of the huge commercial greenhouse markets we see that framed structures are most common and that growers are not using air-supported covers - so, I assume that thousands of farmers are not wrong - there are good and practical reasons that structural framing is preferred. It will be interesting to see what other members think about this good question.
--- In solaroof@yahoogroups.com, "Pezeril" <pezeril.marc@...> wrote: > > Hello everybody ! > > Happy to meet this great forum, i am very excited since days after learning this bubble technology and i am now very concerned by its developpement : > > i've got the project to build 2 domes and a tunnel greenhouse connected together to develop a permaculture nursery, bioponics and aquaponic for production and demonstration purpose. i am a good DI Yer? and i would like to incorporate a solaroof on the greenhouses... blowers, water storage, bubbles... seem not impossible to me, BUT, i have a question : > > - the bubble cavity is supported by 2 greenhouses... i just think in my (little) mind "that's one too much"... > Okay, now you will know my question : Why it isn't possible to adapt standart method of pressurised double poly greenhouses to bubble greenhouse ? > > Of course i have read that wind pressure on bubble will break them.. and that air blower will break the foam too... and i think peoples will say pressurised films need a constant 24/24 blower (not very energy efficient)..BUT, i persist : > > By insulation the interior of the greenhouse that's precious area not employed to culture... so, isn't it possible to maintain a static pressure between the two poly and fill the cavity with bubbles or air constantly ? > > imagine i've got a 10KWatts output on my hydrogenerator and it's not a problem for me to use 1KW to run pump and blowers... what will you say to this idea ? > > Thanks !! > > Happy to meet you ! > > Marc >