The Solarhome Project was established by Australian building designer/entrepreneur David Macfarlane with the aim of creating a stylish self-sufficient house – with all the mod cons and comfort expected of a luxurious modern home – that is not only fire-proof and cyclone-proof, but additionally, so energy-efficient that it can be 100% electrically powered (including heating, cooking, and hot water) entirely by an off-grid solar-charged battery without the need of gas, oil, a wood fire, a fossil-fuel-powered generator, or grid backup.  In other words, a genuinely zero-emission house, not just 'net-zero'.  As far as we are aware, this has never been attempted before, particularly in a cold climate.  Tamar Solarhome is the prototype of this design, which was built in Tasmania (during 2016) to test its performance in a challenging climate.

The house essentially consists of a 150mm-thick concrete outer shell (including the roof), with an unbroken internal layer of 250mm-thick polystyrene insulation in the walls, ceiling, and floor, triple-glazing, airtight construction, heat-pump-generated hot water and internal air heating, 25 high-performance solar panels, and a massive battery which stores enough electricity to power an occupied house for 5 days, during winter, with no solar input at all.  As you can probably imagine, it turned out to be a very expensive build, but did actually operate successfully as an up-market holiday rental without a hitch for almost five years.  However, a backup generator eventually had to be installed after some guests plugged in an electric vehicle overnight and drained the battery, followed by a winter week without sunshine.  So we finally discovered the problem with, and limits of, emission-free living and renewable energy – it can't supply electricity on demand.  The next prototype, the Solarcabin, to be built in the Hunter Valley north west of Sydney before the end of 2022, is considerably less ambitious; a very affordable 27m² cabin; easily buildable on any site, thermally comfortable in any climate, and designed to be totally self-sufficient for power, waste, and water.