Don't mind me just mowing my roof.

Green roofs have a huge list of benefits.

They keep the place better insulated, both warmer in the winter and cooler in the summer.
They help reduce local air temperature, particularly in cities, by reducing reflected sunlight / radiation.
You can farm animals on them(see https://oldcountrymarket.com/ )
You can have a rooftop garden and bee colonies. See the western half of Vancouver BCs Convention Center. Where they maintain a wildflower garden and beehives on the roof of the building and the chefs inside the building harvest honey from the beehives. ( https://www.greenroofs.com/2022/08/18/featured-project-vancouver-convention-centre-west-expansion-project/ )

Only fault of the realtor is they didnt get the place landscaped prior to the photo.

They've got drawbacks, too, especially since most examples of them in residential construction are the efforts of, shall we say, enthusiastic amateurs.
Because soil holds moisture for an extended period of time, they tend to get saturated, and then excess moisture migrates down to the waterproofing system, which will inevitably leak over time. Most amateur-built earth sheltered homes are not using particularly sophisticated waterproofing materials, and rarely take a defense-in-depth approach to them that could mitigate a failure in one layer of the system.
Maintenance is expensive: once any part of the waterproofing fails you are going to have to dig it up to repair it.
Soil - especially wet soil - is heavy and the prescriptive structural parts of residential building code aren't really intended to address this kind of construction. You need an engineer to ensure the house is properly structured for the loads involved, and if you're building new that extra structure is going to cost money and limit design options.
Building into a slope to allow roof access for planting, mowing, etc., limits daylighting options, and particularly in the US where bedrooms are required to have an egress window it can be nearly impossible to design a floorplan with the expected gradient of public to private space.
Don't get me wrong, I love the concept, and I've even drawn up plans for one I'd like to build on the lot next door to me once the nigh-derelict rental house currently occupying the space gets condemned... But this is one case where I absolutely do not want to be buying somebody else's project. I don't trust the other people who build them to do it right.
- Green roof designs are frequently lava rock with alpine vegetation and good drainage. Even then you have to be very careful about weight. This looks like a storage building on a farm they are trying to sell as a house.
Camouflage your bunker from airstrikes and air reconnaissance.
The only fault? Dude shoulda made it look like a hobbit hole, it wouldn’t have stayed up a day on the market.

The whole point of these types of places is to save on heat/cooling.

I don't know. I looked at the photos, and I'm pretty sure this place is built for drugs.
I can see the value in that, basically nature's insulation - though I'm not an architect nor an engineer, but that looks like a flat roof - so would overgrown grass or sodden soil put some crazy weight and pressure on the structure?
- It has to be designed for it, yes. A friend of mine built a house with a living roof. They even host parties in the second floor yard.
The point of this place looks more like it's for building bombs without having the government find you.
And enjoy some nice surprise moisture I'll bet

Very unusual unfinished, unpermitted concrete bermed home with unpermitted septic system and no power on 4.97 secluded, wooded acres. Individual well. 4-1,000 in ground propane tanks, 500 gal water storage tank. Used to be powered by a solar system & a generator, both of which were stolen (and other equipment) but electric nearby. Owner was working on a self-sufficient home but passed during construction having spent over $400K on the project.

They were building a bunker.

but passed during construction having spent over $400K on the project.
A boomer building a bunker.

You can usually delete the tracking stuff after the question mark in the link

Thank you I will ensure to do so
- Oh interesting thank you for the info, I was dealing with that today while trying to share an article it had a short id number I deleted but then it broke the link. Also it seems like tiktok generates a custom tracking link each time that shows the person who shared it with you and I haven't found a way to edit the link to get rid of that

Depending on how it's built and insulated, it might be much cheaper to heat and cool, though.

replace that roof with native plants and you have solarpunk

It was definitely a boomers bunker. A capitalist stronghold being usurped by the Solarpunks is short-story worthy.

Deja vu! I legitimately looked at this listing (not in person). I think it's neat but we don't have the time or money for all of the problems of an unofficial unpermitted unfinished prepper pad of unknown quality.

Zero percent chance any of it, at the very least the septic, could be permitted after the fact. It is nice Bo is at least disclosing it has an unpermitted on-site septic system, but a bootleg OSS is more expensive than no OSS at all.
Source: used to work for the county where this site is located.
It's a house for elves. Don't you think?
- A home for Hobbits

Getting permitted may be about impossible, but there's a lot going on here. On a creek, near a lake, not too far outside a major city, I dig it. And 5 acres is nothing to sneeze at. I've got half that in Florida Swamp and still haven't explored it all after 4 years.

5 acres for 245K between Seattle and Portland is nothing to sneeze at
- Rainier is decently off the I-5 corridor, but it actually has some of the best potential in the region if the county-state-country ever got back into rail transit.

This is the kind of place I want. Mostly underground. Like a Hobbit hole.

My sister just bought a house like this!

Fun fact: it can be difficult to get an appraisal for one of these, especially if in a location where not many others have been built or sold. They almost had to back out of the purchase because the underwriter couldn't sign off without an appraisal, but luckily, they were able to find one.

Does she have to mow the roof though?
- She sure does

My dream home

You do you BB but it makes me itchy to look at.

Would be better in the midwest where we have multiple tornadoes a year. I bet their electricity bill is nice though.

A bit of a fixer upper but I'd totally live there, especially for that price (I live near San Francisco).

Seller could have doubled the price for the cost of installing a round door.

I kinda get "new-age cult" vibes from some of the interior pictures

Also, while I bet the house is quite heat efficient, the underground design means that rooms in the back will get no natural light, which would be pretty miserable.

This isn't that far from the Ramtha School of Enlightenment cult and when we were trying (and failing) to buy a home in the area we toured two similar places with bomb shelters. They have mild doomsday lizard people teachings.
the underground design means that rooms in the back will get no natural light, which would be pretty miserable.
Much like a basement in a regular house.

I want it

The building itself looks quite claustrophobic and possibly haunted, but the outside looks so serene.

Zelda has ruined my mind, my first thought was definitely that I could get a few rupees by smashing all those pots before I even noticed it was an unusual building.

And they say videogames don't cause violence, smh

That much underground would be awful for mold allergies. And IDK how much time and money is needed to deal with nothing ever getting permits

Very unusual unfinished, unpermitted concrete bermed home with unpermitted septic system and no power on 4.97 secluded, wooded acres. Individual well. 4-1,000 in ground propane tanks, 500 gal water storage tank. Used to be powered by a solar system & a generator, both of which were stolen (and other equipment) but electric nearby. Owner was working on a self-sufficient home but passed during construction having spent over $400K on the project. Current best use may be to bring in power, do engineering calculations & permit this structure as a shop/ag building & build another home/manufactured home. Owners have some construction photos. Great buy at the list price. There is still a lot of value there. Located in the country East of Olympia.

How bad it would be for air quality and exchange would come down to the HVAC almost entirely as long as the build quality is there. A modern energy efficient house is sealed so tight that the sum of all air leaks to the outside is smaller than a baseball.
The build quality would of course be the biggest concern, if they didn't do the weatherproofing and water management right there would be water seepage and a high likelihood of a roof leak that would be horrendous to address.