The materials you use and if you have louvered windows that you can open (with screens on the insides) on the bottom can be a passive way to let more air in in warmer months. It still works better if they flow through or you have your windows on opposite sides and a vent on the top for the warm air to escape. When windows are on one side and the other side is a solid wall the air cannot be pulled through as efficiently.
Bugs still get in the hot house. Every once in a while you will have to do a thorough sanitizing of the shelves, floor and walls. Unfortunately once the bugs get in, they are safe from predators too unless you capture and release the predators in the green house.
the better fans are attached to the outside wall with louvers and they pull the hot air out or reverse and pull outside air in.
Fans inside the hothouse move air inside but cannot cool. Try looking at solar panels to operate the fan. One solar panel can usually operate one fan. That is how the fans are operated at my working place. We also have the double entry although people still don't get it that the purpose of the double entry is that the two doors should not be open at the same time or left open.
This is the type of fans that my boss recently installed on the new hydro houses and they are operated by solar panels. Actually the farm uses very little electricity in the daylight hours and has a lot of experiments with solar and wind power.
There is a windmill operated aerator. Pavillions with solar roofs operate the pumps for the aquaponic tanks pumping water from the fish holding tanks to the growing beds and from the hydro tanks to the rails in the hydro houses.
The pumps turn off at night but still actually keep running even on an overcast day. There is electrical backup for times when the garden has night activities. The hydro needs to switch to electrical power at night but the fans don't need to be running and grow beds can tolerant no flow at night and the main pumps circulating pumps and aerators in the fish tanks also have backup electrical power at night.
https://www.sunshineworks.com/solar-fans ... houses.htm
Workers who work for the power company get their electricity free as part of their benefit package. My grandfather was a retired electrician and that was the deal he got.
Happy gardening in Hawaii. Gardens are where people grow.