It's crazy to use corrogated pipe buried in the earth for air you breathe. In time, it will become the same life threatening mold and bacteria disaster as all early solar hot air/rock storage homes. A fellow engineer at an AF research lab did it for his home in the low desert, and had to shut it down after a year...his wife and kids were getting sick. I think it's much safer and more energy efficient to run a ground source pex loop, in bores or deep trench, with the water to air heat exchanger. Much less energy to move the heat/cool.
If you must use pipe for air, it would need to be smooth, with carefully sloped with drains, and a way to clean it out.
You will also see a lot of greenhouses using corrogated pipe under the floor, as they think it will be a seasonal energy store. Baloney, look at the data for large installations and you will see it's a failure; the downward and outward conduction losses to the earth are so bad that I am not convinced that it is worthwhile. If foamboard is used along with massive excavation, then yes, you can use earth. An insulated water storage tank, however, can provide substantial storage, and I think at a much better price to build. A retired engineer build a small greenhouse with insulated water heat storage, collected data that showed impressive performance. He collected excess heat at the peak of the greenhouse during the day ajnd heated at night via small water to air heat exchanger.
I'm very interested in hydroponic greenhouse growing for my climate, but the real stinker is summer, as it really needs cooling via evap coolers besides reduced sun (shade/diffusers).
Hydroponics as bugs and diseases are brutal here, within 3 years you are in a state of constant warfare, as your garden soil is loaded with diseases and bugs. I quit growing outside after 3 years of being totally hailed out just before harvest. I was doing nothing but picking bugs, spraying oil and soap sprays, and copper soap sprays for pests and diseases. The first year you think you are a genius, then aphids destroy your late cold weather crops, powdery mildew and a variety of bugs get progressively worse each year. With hydro, you can sterilize the growing buckets/gutters/trays and/or media after each crop is harvested, so it's first year every year.