I have been building an extra-dimensional space which I can connect to with portals. With these portals, I can cut down on the shipping rates and times. So I have made a global trading company of "zombies" that move every good imaginable all over the globe. Now that my trade company is set up and running,I find myself with some free time. But I fear that my extra-dimensional space may be taken over by someone else if I leave. So I want to make a temperate rain-forest inside my extra-dimensional space to dwell in. For this, I have made 8 teardrop shaped halls. They are connected to each other at the points and each to its neighbour forming kind of a wheel. There is normal earth gravity in the halls pointing perpendicular to the wheel. since it is extra-dimensional space that means that there is no outside.

Each hall is 5km from tip to bulb. The bulb is 1.2km high and 3.6km wide. And has a volume of 6km3. The lower half i have filled with fertile sediment and channels/ponds of water. I have placed lighting in the roof providing 9GW of power/light for 12 hours a day(24h). The ceiling is highly textured and a perfectly diffuse reflector. It has a set surface temperature of 1°C that dous not change in temperature.

Will these settings allow for a temperate rain-forest biome?

If they don't, then what do I need to change?

Will most "rain" come from clouds or condensation upon the ceiling falling down?

Alaback's definition of a temperate rain-forest. Annual precipitation over 140 cm (55 in) (KJ) Mean annual temperature is between 4 and 12 °C (39 and 54 °F).

  • $\begingroup$ Let me be the first to say, welcome to worldbuilding Postllim. $\endgroup$ Commented Sep 12, 2021 at 13:14
  • $\begingroup$ I was thinking it would gradually heat up but I see you have magic. Judicious application of extra magic can fix other problems as they arise! $\endgroup$
    – Willk
    Commented Sep 12, 2021 at 15:37
  • $\begingroup$ i have thought of a bunch of fixes for different problems. but i have no idea which problems would arrise $\endgroup$ Commented Sep 12, 2021 at 15:41
  • $\begingroup$ Wow 9GW lights.. can't you put sunlight in extra-dimensional space ? or is this a stupid question.. I think "extra-dimensional" should be in the question title.. when I opened this topic I thought of greenhouses on planets immediately. This "extra-dimensional" complicates things. $\endgroup$
    – Goodies
    Commented Sep 14, 2021 at 22:02
  • $\begingroup$ @Goodies i think that it is a fair bit less than sunlight. to get that figure i doubled the wattage of growing lamps and multiplied by the area to be illuminated. $\endgroup$ Commented Sep 14, 2021 at 22:07

1 Answer 1


Rainforests are 3d

This bothered me in the comments, because this "extradimensional space" is a bit of an open end, if you don't specify how it works. Let's assume your extradimensional space means you have 4 (or 5, 6) dimensions. Your rainforest will be 3d and could exist in an isolated 3d intersection (a hall) of several 4-dimensional extradimensional spaces. Your 8 halls have the shape of bubbles, or teardrops.. and there is a normal downward gravity where you want to build this rainforest installation. It will be nowhere near as easy as Biospere 2, because your realm will be completely isolated.


There is no sun, this world has only an inside, no outside. You'll have to put everything inside. To do a viable rain forest, you'll need to maintain several balances, CO2 versus O2 is one of these. In an earth rainforest, there is an atmosphere residing above the forest, providing circulation or air. Your hall allows for only 1.2 km of atmosphere, which will require proper ventilation !

"Greenhouse ventilation design is key to ensuring optimal environmental temperatures for crops. The two types of greenhouse ventilation are natural and mechanical ventilation. These systems both work on the principle of thermal buoyancy, using cold, dense air to push warmer air up and out of the greenhouse."


How to realize circulation.. pump around air. Take some space for air transport channels and reservoirs of certain gases (like N2) in your construct. You could use artificial intelligence to manage the pumps.

Temperature control

You use a large lamp (9GW) to warm the inside of the hall (bubble) that contains the rain forest. With a ceiling of 1.2 km, I would advise to use more than one lamp, spread the heat. Don't overdo it.. the heat won't go anywhere in your closed bubble and you'll have a lot of greenhouse gases inside (CO2) and except for evaporating water there will be no way to go.. energy will mainly stay inside, you'll need some for the pumps and lights.


A rainforest has flora and fauna. Many flora in a rain forest depends on fauna, to carry seeds, eat fruit and spread seeds in excrements, or provide transport of pollen, like bees and other insects do. To prevent instability in your ecosystem, you'll need some predators too.

Fertilizer should be temporary. Not all plant species in rain forests like fertilizers. You can't grow a forest on fertilizer forever, and you'll need cycles of growth and decay. To facilitate biodiversity, leave dying trees in the forest, allowing for fungi and insects to thrive.


If you want to fill your hall with a familiar (earthly) rainforest, there should be abundance of water, because plants and animals will need that. Circulate large amounts of water vapor. If possible, arrange a rain season, include a stream, or a small lake. You may need to upscale a bit, to facilitate things. Open water will make your rainforest a lot more credible!

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    $\begingroup$ thank you, i forgot about ventilation. i shall have the lighting be distributed across the ceiling. you got the extra-dimensional thing right. as in there being no outside. i didn't include fauna in my question to keep it focused. i know i would need way more space to be able to keep a breading population of predictors. ill have about 50 of these wheels in my actual space. but they are all self similar. $\endgroup$ Commented Sep 14, 2021 at 23:30
  • $\begingroup$ I'm just a hobby farmer knowing a bit about greenhouses. I think the isolation is the most difficult problem, your rainforest is completely sealed off from the outside. Anyway if you like my answer, you can upvote, or acknowledge the answer.. I wish you success with your worldbuilding project ! $\endgroup$
    – Goodies
    Commented Sep 14, 2021 at 23:37

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