This project was a first for vbA - a 100% "off the grid" home. Starting with the first principles of "Passive Solar" Design, this 1,600 sq. ft. home is not connected to the power grid in any way. The walls are made of SIPs (structural insulated panels) which have an R-38 within 6 1/2". The active solar systems include solar hot water and photo voltaic panels on a semi detached garage oriented exactly due south. The solar hot water panels circulate glycol into a massive heat sink made of a sand water mixture which is located underneath the slab of the home. The systems are all computerized and when heating is required, over and above the direct transfer of the glycol coming off the rooftop panels, the heat sink transfers its heat into the piping, which in turn transfers it into the in slab radiant system.