In most places in the U.S. a well designed house should need very little fossil-fuel or grid-electricity based help with heating or cooling, as long as one follows a few basic design principles such as outlined in the Solar Ark: 

  - the building is elongated on an east-west axis

  - the building is shortened on an north-south axis

  - the south side is higher than the north side

  - the south side is glazed [at the proper angle] to harvest heat in winter

  - movable insulation such as curtains or shutters cover windows at night

  - all other sides including roof are heavily insulated

  - large amounts of dense materials [thermal mass] are used on the inside

  - the living space of the house is surrounded by temperate climate zones

  - a solar chimney provides cooling air currents in summer

  - seasonal plants or roof overhang provide shade in summer 

[this set of rules was tailored to the Ark's location, a mountain desert at 7300 ft altitude; needless to say a house in Phoenix, Arizona would have a rather different one focused more on cooling than heating]

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The Solar Ark was built using rock; flagstone; recycled brick, tile, glass and lumber; straw bale; pallets; earth block [adobe] and pumice.

The combined south sides have more than 200 linear feet of glass, harvesting over 50.000 watts of solar energy on a clear winter day, to heat over 5000 sq.ft. of living space, shops and greenhouses . Lemons grow without supplemental heat while outside temperatures drop to minus 25 degrees F in january. And should there be a prolongued cloudy spell it is easy to maintain comfortable temperatures with the wood stoves [masonry stove shown on methane page].                              

 .                   GREENHOUSE DESIGN                       .     A 'mainstream' greenhouse is usually a separate building, packed with plants at  an unnatural density and due to all-around glazing too hot at day and freezing at night, needing lots of electricity and propane for fans and heaters to make plants grow; not to mention pesticides and fungizides, chemical fertilizers etc.

In the Solar Ark 'greenhouse' is an aspect of house, shop and garage, a green belt along the glazed south side. Fertilizers derive from compost and methane digester effluent;  beneficial insects and frogs, lizards and toads  keep pests in check and heating/cooling and venting are accomplished through passive solar design.

Instead of expensive double glazing we use the 'greenhouse within the greenhouse' method to grow plants all year long. Ponds serve as prewarming/water softening/nutrient enrichment facilities to improve the [brutally] hard well water for irrigation.