Iain McClatchie wrote:

Nick With enough insulation, it wouldn't need any water, nor windows.

Windows are bad. They are expensive, and installing them is expensive,
and the framing leaks heat, and they can leak heat and air and water and
sometimes bugs and burglars. Let's replace windows with outdoor cameras
and computer projectors or flat screen TVs, with fluorescent lights and
doors or push-out panels for fire escapes.

The windows make this house. The interior was deliberately opened
up so that most rooms could see the incredible views.

For drama, you might put windows or a single layer of polycarbonate glazing
on an isolated low-mass sunspace with an enclosed solar staircase roof and
a dark mesh curtain near the windows.

A house in a 4000 degree-day environment can get through cold sunny
days just fine with solar heating alone so long as it can store the heat.
If the heat will be stored in the habitable envelope, the water will
only swing about 10 F before things get uncomfortable.

A thin layer of 120 F water goes in a lay-flat poly film duct above
a low-e ceiling surface in the living space heated by hot air from
a sunspace during the day. At night, the sunspace gets cold and
the airflow stops and a slow ceiling fan with a room temp thermostat
and an occupancy sensor warms room air as needed.

Nick