The place we stayed in Finland was a superb example of how to generate heat in sustainable ways and then make maximum use of every bit of it! For example, to heat the water circulating in pipes around his home Micke uses heat given out from three sources: his own sauna, a wood-burning stove in the lounge, and home-made solar collectors on the roof!
Micke’s solar collectors were built after a couple of family members (both ladies, hurrah!) attended a how-to workshop, then went home and got straight to work applying what they’d learned. Unlike photovoltaic solar panels, collectors don’t convert heat energy to electricity; they just use the heat energy to heat other things, which means they’re simple to construct and easily within reach for anyone who fancies making one!
Micke’s consists of a black-painted metal sheet, with copper pipes on top, and glass on top of that. Essentially, super-heat-absorbent metal in a greenhouse! Water circulates in the copper pipes, and there’s anti-freeze in the water to prevent problems arising in winter. The copper pipes carry water – heated by the sun to around 60°C – in an insulated spiral down from the roof all the way to the boiler. There the copper reaches a larger tank of water where it is immersed and releases its heat, and from there the domestic hot tap is just a short pipe away :)
The wood-burning stove is super-economical once you get the knack of when and how much to start closing the air flow from the chimney. When the initial load of firewood has burned down and the outer stone layer is hot, that’s probably about right; the fire should then keep burning and releasing heat all day, which is preferable to loading in new wood every hour or so! The stove heats the room thanks to its stone exterior (too hot to touch), but also via a wide metal flue running up through the ceiling, which gives off extra heat not only in the lounge/kitchen, where the stove is, but also upstairs.
Something very clever goes on at Micke’s in that not only are the solar collectors hooked up to the boiler, but the wood-burning stove is too... as is the sauna!
Yes, Micke (like many Finns) is a year-round-sauna kind of guy. So if you have a small wooden room heated to 70°C or thereabouts by a(nother) wood-burning stove, that’s just more heat energy to harness!
Somehow the heat from both wood-burning stoves also contributes to warming the water and the house, and after all that there’s even some warmth left over for underfloor heating! Frankly I can’t explain exactly how – a glance at this photo of the boiler tells you it’s more than a little complicated! A more super-duper eco machine I don’t believe I’ve ever seen :)