Hello ICFHybrid.  Yes, 100% always means 100% of the annual heating needs.  As described previously, to achieve 100% with PURE passive solar (i.e., using ONLY irradiance, a fixed roof overhang design, and a thermal mass design that is NOT augmented with any other electrical/mechanical system), you need to be in a location that receives irradiance on a dependable and frequent basis.  To achieve 100% you often have to get aggressive with solar fenestration area.  Yes, there are locations where this design objective is realizable, however, you typically then also have to address the potential of overheating the building in the fall and spring months.  A proper thermal mass design can certainly help mitigate this overheating issue, as well as give you some heat storage capacity to go perhaps a day or so without irradiance.  Nevertheless, you are still always at risk of having a week or more without any significant irradiance.  In the western portions of the PNW, you will routinely have multiple weeks without any significant irradiance.  As such and because building codes also require it, you will also need to have an additional heating system to backup the passive solar.  As described previously, if your backup system is a hydronic radiant floor heating system that has also been properly integrated with your passive solar design, you can utilize the hydronic radiant floor heating system controller and pumping elements to significantly extend your passive solar heating performance and to also address the potential overheating issue too.  Much of this is explained in our DIY calculator instructions on our website.  Heat storage is currently accomplished via insulated underground concrete water tanks although we have been field testing another technical approach.  Heat rejection (used in fall, summer and spring months) is normally accomplished via earth ground heat transfer, but we have also done this in conjunction with water work projects (with controller addressing floor climatic dew point issue).  Our company has only been in business since 2010 (currently based in Seattle area) and our initial efforts have largely been associated with the integrated system engineering design and controller design.  We are in the process of relocating our company headquarters to southern OR (which is a passive solar meca of sorts) where we intend to expand our residential and light commercial construction service efforts.  We have recently been considering adding a Gallery section to our website as well so please stay tuned...

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