Leaves going white and crispy on Bean Plants

Peas certainly do NOT want to be in a greenhouse. They need to be in the cooler outside temperatures.

Sounds like you've cooked the poor things. What sort of beans are they?

French can go direct into the ground at the earliest mid-april but dependant on where you are leave it till may. They are very susceptible to frost, so please dont put yours out to early and dont forget to harden them off before they brave the wild new world  .  I love french beans nearly as much as peas, (I said nearly DD  )

Sorry to be blunt, but you're way too early. I won't start my beans until mid April. No way can you put them out until frosts have past, we have a good one at the end of May last year, so it's another 2 months before you dare put these outside.

It could be sun-scorching, especially if the glass is wet (basically water drops can act like lenses, so you get focussed pinpricks of light from rained-on or fogged glass).  If that's so, try shielding the plants with a bit of fleece (or slap some whitewash on the greenhouse panes).  You can grow summer beans entirely undercover, for early crops, so you should be able to keep the greenhouse to suit them. 

Are you ventilating the house during the day?  My mother's has been getting well up into the thirties (she's not got anything in one of them, and is deliberately letting it heat up to
warm the soil) with the windows closed, which is too hot for most things.

Also, they're quite greedy for water, so you need to keep their feet wet, especially if they're on the staging with the soil in the sun.