Hot tub spas have become popular in luxury gardens, far removed from sustainable design principles though they be. Cedar- and redwood-clad hot tubs are available for outdoor installation. Whirlpool effects are provided as an aid to relaxation. They come in 'personal' and 'party' sizes. Spa chemicals are used to keep the water safe. A dip in a hot spa tends to be invigorating if of short duration but enervating if prolonged.
The plumbing arrangements for a hot tup spa are similar to those for an indoor hot bath: there needs to be a hot supply, a cold supply and drainage. Electrical fittings for whirlpool pumps and jets require particular care for outdoor use (where the risk of physical damage to the wiring is greater) - this type of pump was invented by the Jacuzzi company which gave its name to hot tub spas.
The links at the top of this page take you to information on the history of outdoor and indoor hot water baths. We believe there is much to be learned about the design of garden hot tub spas from the ways in which our predecessors have enjoyed outdoor bathing in hot water. It is a curious fact that a hot water bath in a hot climate can cool you down, while a hot bath in a cool climate will warm you up. Why heat warms is obvious. The explanation for a hot water tub cooling you down is that it removes surface salts and oils and opens the pores. Getting out of the water also produces the sensation of moving to a cooler place. Try it.
A sustainable approach to garden hot tub spas would involve:
Using sun or wind generated electricity to heat water involves relatively sophisticated equipment. Water can also be heated by placing black-painted water panels (eg radiators) behind glass sheets.
Beachcomber hot tub in garden
Whirpool spa in garden
A whirling pool
Hot tub spa