Like orchids under glass bells
Laretta Dear, Our thermal comfort ranges change, whether we like it or not.
Laretta Dear,
Thank you for getting back to me about this webinar text. The input of another (human?) being on my much too theoretical bla bla is both useful and refreshing and your friend's questions about light structures and bioclimatics gave me food for thought. "Can a light structure be bioclimatic?" Yes! "Don't I need thermal mass?" No!
Bioclimatic design is about achieving maximum comfort with minimum energy.
So there isn’t one good answer or technique. Instead, you have to have an understanding of the climatic context and work with it not against it. That means your strategies will depend on where you build. For this friend of yours in Bretagne, heat might be less important than in Provence. But it's not to be ignored for all that.
She says she wants a lot of heat and so she wants to cut off those Western trees and bushes.
Where exactly does she want the heat of the Sun? On the terrace in front of her tiny house? Or inside the place with large window bays? And what is the status of her project? Is her house plan already done and she is ready to build? Or can she still change stuff around?
Everyone wants a lot of heat and Sunshine in their house. Except you :) You are one of those weirdoes who need coolness to sleep at night, who open their windows in the dead of winter to "freshen up".
You live in a tiny stone cottage in the middle of the forest, heating yourself up with sticks and twigs in an iron cook stove. Last year you where sitting with your t-shirt on while I was putting yet another layer and shivering.
But that was last year.
Since this autumn I have attacked my fear of cold, with measurable success. Do you remember how my poor little feet and fingers would get all white and how I couldn't feel them anymore?
Well, I have since done my best to increase the hormetic stress on these poor cold feet and cold they are no more. Nor am I nearly as afraid of opening windows in the dead of winter. My thermal comfort range has increased immensely.
And so does everyone's comfort range change with the passing of time.
As we get older, our bones need more heat than they did when young. Most children could survive naked living outside if you'd let them (don't try this at home). People living in houses with thermostats, it seems, get shortened comfort ranges because their environment is so still.
Like orchids under glass bells.
We used to have a thermostat in the mountain apartment, we kept cranking it up and in time had settled at around 23 degrees Celsius until visiting friends complained it was too hot.
Today is the first truly sunny day here. Still there are 16 degrees in the house, because we haven't bothered to light a fire. I am completely fine with that, which would've been unthinkable months ago.
Our thermal comfort ranges change, whether we like it or not.
Tiny houses and other light structures are notorious for indoor thermal fluctuations. The reason for that is the simple fact that they lack the thermal mass that would act as a buffer against these fluctuations that happen outside.
In a house with a lot of thermal mass, the inside, protected by a massive wall, gets only a muffled echo of what is happening outside. The rest of the fluctuation is solved with additional heating.
The issue is that it takes a really long time to heat up all of that mass. That's why mountain holiday cabins made of stone or masonry are notoriously cold the first few days, even though the heating is full on.
Light structures on the other hand will heat up in a matter of minutes. But they will not hold that heat well unless it's more or less continuous. In this case, heavy insulation is key to keeping that heat in.
In the summer time, the issue is more or less the same. Massive buildings will take a long time to heat up, meaning they will keep cool a lot longer. Whereas a light structure will heat up quickly and needs to be heavily insulated.
All in all, a light structure like your friend’s will have a lot more fluctuation of the inside temperature. She might consider the fact that priming her thermal flexibility might be the best thing to do if she wants to live tiny. Otherwise she'll spend her time heating up and cooling her place to reach thermostat levels.
On the other hand, if she insists on cutting those Western trees, she will have heat indeed. If the summer setting Sun is hot and hits her tiny little house straight, she will have some August afternoons full of misery.
She can make a nice compromise by playing with the Sun's position at sunset both in winter and summer. The Sun sets in the summer at a full NW direction, right? In the winter, it only ever gets to SW.
That’s almost a whole quadrant difference! We use that difference to build bio-climatic adaptations. Like this one:
She can cut the trees that keep her from having afternoon sun in the winter up until spring, and leave the ones that might protect her from the heat in the summer. Don't forget that the trees might also not be high enough to protect against the Sun when it's too high in the sky.
The simplest and quickest way would be to make a short 3D model of the place in SketchUp and make a Sun path analysis, but let's not get ahead of ourselves. It's also a lot of fun to just use the SunLocator app to see the Sun's path in real-time on the ground.
As always,
Jo
PS. Did you know there are 3D printed adobe houses now?
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