wrong, western philosophy is often based on dichotomies - something is either this or that, but it is more of an analytical tool (I am not nature despite that I am a part of nature). Eastern philosophies are often mystic, though there is western mysticism - that some aspects of existence are incomprehensible on a rational basis and therefore dichotomies are illusory. But such a perspective does not inherently make people better stewards of the environment - in fact they might conclude that their every action is “natural” by definition.

Swimming pools are normally constructed empty. They were withstanding surrounding soil before they were filled, and concrete strength increases with age (for about 90 days, typically). On the other hand, a sunken structure like a pool that is roofed over, becomes a “confined space”. Unlike a typical structure, heavier-than-air gases cannot escape from the pool. Such gases could originate from the drain system or flow from leakage outside the pool area. For examples, leaking propane or various gases from sewer lines in the vicinity. A sunken greenhouse would almost certainly be a building code violation for that reason. If you build it, ventilate it by means both active and passive and do not enter if you can’t verify that ventilation is working.

“the necessity always to have been” could mean that for something to BE permanent, it is always necessary that it has existed previously. Whether any thing in this universe can be said to be permanent under such a criterion (within the perspective of spacetime) is doubtful. But if time is a feature of this universe, then there could be perspectives beyond it where all of this universe is permanent, I suppose.

when I was young, I read a bunch of “Eastern” philosophy and thought mysticism was really cool. I guess I still do, but it also feel like a little bit of a copout to say the Tao which can be explained is not the true Tao. I mean, come on! We are verbal creatures and we ought to be able to verbalize our understandings of things. We ought to be able to identify our motivations and desires and act on our principles.

In my later years, I have come to be a “hard determinist” based on my understanding of modern physics. The past and the future exist deterministically - they are immutable. And yet, we are agents of causality - the eternal immutable future that exists does so because of what we choose to do in each moment. So that is kind of a return to some eastern mystical shit I think. Sort of a Zen koan for the 21st century if you like: how can the future already exist when we are causing it by our choices in the present? Some say it is because we are only imagining we have free will and our actions are not really free; but we all know that we FEEL free to choose - so let’s take it as axiomatic that we are free; then can hard determinism be the case? It is like the sound of one hand clapping . . .

I am not “a philosopher”, but really we all are. If you never wonder about the nature of your own existence, are you even fully conscious? If you start asking about existence, then you will also have at least passing interest in what some wise predecessors may have considered. If your philosophical musings pertain to more practical and mundane matters like ethics and sociology, the same applies. As a member of society, I am inevitable oriented to be aware of “normative” perspectives - what is right-and-wrong, how to behave, etc. - but these norms have a lot of breadth; what path is “right for me”? Maybe the paths available inform your philosophy, but I think we all at least imagine that our philosophy should and sometimes DOES govern the paths we choose. If you have not thought about your philosophy, choosing paths is nothing but random motion.

could be Phenomenology; we only know what we sense - but we cannot know if what we sense is accurate or complete; in fact it is neither. We have no way to truly “know” the nature of reality or if it is independent of our own existence. By “we” I of course mean ME, because I only sense your presence tangentially - only MY existence is certain (to me).

I am not sure if that is the same; the assembly on the solar panel was larger diameter than the rest of the piping system perhaps around the size of a two-inch PVC ball valve, where the rest of system was (if I recall right) about 1-inch or maybe 1.5? But I guess there could have been a component like this inside. I am familiar with these for automotive thermostats in cooling systems, but I never pictured that they might have meant this. Otoh, why not? It would do the job and maybe work for OP’s project; especially if they are made for a range of different temperature conditions.

I used to have a solar water heater for my swimming pool, and it had a wax-actuated valve (!) When the water in the panels was hot enough to melt the wax, a paddle could start turning, and water could flow in the panels. If the water cooled, the wax would congeal and the paddle would “freeze” - blocking water flow - the pool circulating pump had a pressure regulating valve and relief valve, so when the panels on the roof were not accepting water, the pump would bypass them and deliver water straight to the pool without heating. I thought it was quite clever (the wax and paddle assembly were inside a sealed device - I never actually saw how it functioned, only recall the vendor explanation). I have not seen a comparable invention in several internet searches over the years.