Free shower

How to have a

NZ Lifestyle Block - - The Good Life -

OUR OUT­DOOR BATH­HOUSE is just a for­mal version of a camp shower. A shal­low tray of wa­ter sits up above you, lined in black (bu­tynol), in­su­lated and glass-cov­ered.

It’s a pretty sim­ple sys­tem: the sun pours into the wa­ter through the glass; when it’s hot enough you can shower be­low, con­science-free.

In prac­tice, it has one big down-side: as soon as the sun goes down or the clouds come over, the wa­ter loses heat, and af­ter three or four sun­less hours, it’s lost too much heat for com­fort­able show­er­ing.

An in­su­lated lid would im­prove the sit­u­a­tion and put a lid on it, as it were. That would cope with the need for an ‘end of a long sunny day’ shower sce­nario, but what if you had a partly-cloudy day? Un­less you’re up there open­ing and clos­ing the in­su­lated lid, the wa­ter is go­ing to get pro­gres­sively chill­ier.

In the spirit of de­com­plex­i­fi­ca­tion, I opted to avoid au­to­matic open­ing/ clos­ing mech­a­nisms when de­sign­ing our lid. That left the cloudy-day pos­si­bil­ity of get­ting ex­tra sun­light into the wa­ter dur­ing the sunny phases, a bit like pump­ing faster to beat the slow leak of a bike-tube.

The sun doesn’t trans­mit heat to us, just light. It’s the in­fra-red light we’re af­ter, and the heat is the re­sult of it speed­ing up elec­trons in what­ever it hits, eg your skin if you’re sun­bathing, or wa­ter in this case.

Catching sun­light is a mat­ter of area and of con­cen­tra­tion. I re­mem­ber well the acrid smell of scorched school-shoe rub­ber un­der a fo­cussed mag­ni­fy­ing­glass, and the sub­se­quent can­ings and de­ten­tions.

More catch­ment area is easy to or­gan­ise – all you need is a mir­ror re­flect­ing into the wa­ter. Even bet­ter, if the mir­ror is the un­der­side of an in­su­lated lid, you’ve just killed two birds with one stone as you get twice the sun­light into the wa­ter and have a lid to trap it there.

This idea took me off to the trea­sure-trove pile un­der the trees on our block, and I came back with an old shower-door, some Dex­ion an­gled steel used for shelv­ing frames (it looks like over-sized Mec­cano) and as­sorted pieces of the pos­si­bly-use­ful kind.

Rather than a glass mir­ror – heavy and vul­ner­a­ble – I opted for sec­ond-hand stain­less-steel, marginally less ef­fi­cient but much more likely to last.

The lid needed to hinge from the down-sun side of the wa­ter tray, so it needed a pul­ley up in space some­where above. It also needed to tilt past the ver­ti­cal to be use­ful in mid-sum­mer, al­though the best out­come would be an ad­just­ment for track­ing the sea­sonal sun an­gle.

The Dex­ion steel made all of this easy. I used it to build a struc­ture like a black­board easel so we can ad­just the length of the back up­right to con­trol the tilt. So far, so easy.

Power to the peo­ple

Some US $2.2 tril­lion of this will go on rooftop and other lo­cal PV sys­tems, hand­ing con­sumers and busi­nesses the abil­ity to gen­er­ate their own elec­tric­ity, to store it us­ing bat­ter­ies and – in parts of the de­vel­op­ing world – to ac­cess power for the first time.


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