OH BOY!! I did not know that so vents it is. Did not like the idea of a closed non breathing room so I am glad I asked about it. Those swivel pvc vents will work good and an 8" pipe will work out in the block layout without the need to cut any block.

More on venting - I believe ripening fruits give off methane gas which is combustible. Granted, there may not be a lot but in an enclosed area it could be nasty.

I think you should have at least one inlet vent and one outlet vent about four inches in diameter depending on how big the room ends up being. One at the lowest place in the room for inlet and one at the highest place for outlet that should give you a passive airflow. On the outside end of the pipe you may want to use 90-degree elbows this will keep water out and if you don’t glue them on you can turn them toward or away from the wind to regulate the temperature. I would also make some type of adjustable end cap so you can regulate the temperature in the winter when it freezes and the summer if it gets to hot, maybe use a four-inch PVC water valve you can put it on the outside or the inside which ever is more convenient. Don’t forget to screen the ends for critter control.

I want to build a combination root cellar/generator room into the hillside behind my house. It will be a double chamber design with the generator on one side and the root cellar on the other with a block wall dividing the two rooms. This will be cheaper than building two seperate rooms. There is not enough room to get a backhoe in to dig the hole so it must be dug by hand and this will take some time and much energy. The ground is drying out and digging has become more difficult so I may have to soak the ground in the evening and dig early in the morning to get her done. I plan on using 8" concrete block with rebar and filling the walls with cement and then pouring a 6" thick concrete roof and burying it. Placing the room behind the house will allow for a short run of copper wire into the house for connecting the refrigerator and one other wall outlet for lights. My generator is big enough to run a refrigerator and is quiet when it is running and being inside a buried room will will deaden the noise even more. The root cellar side will have shelves for holding our canned goods and bushels of potato's and fruits. One question I have is, do I need to install some kind of ventilation system in the root cellar? If I don't, will there be condensation inside the room during the winter? If so this could rot my stored goods and defeat the purpose of having a root cellar.