Plant trees around your house. Shadow and natural cooling because they tend to evaporate water. Use white outer surfaces to reflect sunlight for additional benefit.

that shouldn’t have any better effect than any other form of blocking the sun, which can be accomplished with trees, or very inexpensive shade cloth. NightHawkinLight developed some sort of super heat reflecting paint that you can make at home, you’ll want to check his channel for updates because he’s been improving it

As @FuglyDuck@lemmy.world said, you’re building a greenhouse. Nearly all sunlight that gets through the glass will contribute to heating up what’s inside, and none of the heat will be able to get out. The major reason for the greenhouse effect is that there’s no way for hot air to escape.

Under an open sky, the sun heats up the ground, the ground heats up the air, and the hot air gets blown away by wind and rises through convection, being replaced by colder air from surrounding areas. An equilibrium is reached when the air takes away the same amount of heat per second as the sunlight brings in. But in a greenhouse: the sun heats up the ground, the ground heats up the air, and the air is trapped. It has nowhere to go, so everything continues to get hotter and hotter. The air heats up the glass walls and roof of the greenhouse (the sun helps with that too), until the walls are hot enough to expel all the heat that’s brought in by the sun, in the same way as the non-greenhouse ground would. The end result is that the inside of the greenhouse is way hotter than the outside.

Note that this has very little to do with what chemicals the air is made up of. Even if the gas inside the greenhouse has a “sun blocking effect”, it would still have to absorb all that energy from the sun, and that heat would still be inside the greenhouse.

See other answers for better alternatives :)

From your description, this sounds a lot like how double/triple pane windows work, or like a Trombe wall. Although a Trombe wall is meant to heat a home, vents could be used to take advantage of convection currents that shed the heat away from the house.

That said, this wouldn’t necessarily be cooling per-se, but would be avoiding heat gain. And at that point, any material that’s loosely coupled to then house would be equally effective, like a wall with studs 24" (60 cm) apart rather than the USA standard of 16" (40 cm).

In fact, this is how some homes with massively overhanging roofs manage to passively keep themselves manageable in the summer, since the overhang blocks direct sunlight from reaching the walls and windows at summer’s high noon, but lets light in when the sun is lower in winter. Soffit vents let convection currents flow up the inside of the roof, exiting at a ridge vent. So the idea is sound and already deployed in relevant climates.

Laws of thermodynamics. You can’t totally trap heat. All you can do is encourage it to spread a bit faster in one spot compared to all the other places it’s spreading.

My grandma used to water the garden around the house and spray water over the roof on hot days. Try that first.

so… you’re building a miniature greenhouse.

The problem is insolation. technically, that’s just light that hits the earths surface… but in this context, it’s light that passes through your glass chamber. it then hits whatever is inside and turns into heat, causing things to heat up.

Like a car in full sun. This would likely increase your thermal gains and not decrease them. (because for the gas mix or whatever inside the layer to have any effect… light already needs to be entering the system.)

Alternatively several things can be done to reduce solar heating. The first is painting your building a white (or very light color- sky blue, sandy tan, etc. titanium white is best… but… really who wants a stark white house like that?) Another is planting things. Trees in the yard will transpire- they release water into the atmosphere as part of photosynthesis which is why tree-shade feels cooler than blocked-sunlight-shade.

Then there’s the living-roof set up. Basically you have some type of water barrier, then you have a large grow box (think of it like having a raised-bed garden tall enough and large enough to live under,) In which you plant… stuff. I recomend talking with whatever DNR-type you have (most state DNR’s in the US, at least, have ‘native seed mixes’ you can buy by. my state has a wildflower mix that’s… not entirely “weeds”…heh.)

Along that line of living roofs; you might be inclined to find some type of leafy climbing vine- Stay away from kudzu, it’s horribly invasive, and I’d suggest staying away from non-native ivies as well. (though, those may be less offensive.) These plants will also transpire, and have the added benefit of absorbing and using the light as something other than heat.

If you don’t like the idea of your house covered in vines… you could also go with a living wall There’s lots of options there… some of them easier and more maintenance free than others. (you can also grow vegetables or whatever here, if you should like.)(you can do them indoors, too, for a natural air-purifier… anything leafy works.)

I mean, anything that reduces incoming heat is going to keep the interior cooler; the question is by how much? You’d still have to have a door of some kind, so it would never be perfect.

But there’s houses that are built all or partially underground, or have roofs that either reflect sunlight or otherwise reduce/eliminate its ability to heat the interior of the house. So the idea is not that far off from the same principle.

Hell, just using a roof that does something with the heat reduces interior temps a good bit. I’ve seen a house with solar water heating on the roof stay a few degrees cooler, and that’s only the roof that’s insulating anything. I suppose you could do that on every surface and get a bit better results.

But direct sun is only part of what makes an interior hotter. You can have a house surrounded by trees that gets a bare minimum of sun and it’ll still be within maybe five degrees of the outside air. Our house is mostly shaded, and we do stay a little cooler than neighbors that don’t have big ol’ trees playing bouncer for sunlight. If it weren’t for humidity, we’d use the AC a lot less. A few days ago it was 90 outside, and “only” 85 inside, after a nice rain where we had shut the AC off and opened the windows to enjoy it. It wasn’t truly comfortable, but it wasn’t so bad as to be unlivable for short spans either.

Wouldn’t try that on most days though.

Isn’t this just another type of insulation? Not saying it’s bad, just that it’s incremental, not revolutionary.

I wouldn’t call this geoengineering.