Vertical glass vs. sloped glass earthship design

I was wondering why you chose to have vertical windows on the front face rather than angled - building code difficulty or construction problem? Does the greenhouse area get cold at night in the winter?

We chose vertical glass because of the heat. Sloped glass ships (SG) get significantly more sun, year round, than vertical glass (VG) ships. And the sun is HOT, my friend. Very very hot. In fact, the sun is so hot here at our latitude that if I had it to do over, I would have gone for a westerly facing angle instead of due south. In southern Virginia, cold is not the challenge; heat is the challenge. Summer night lows can be as high as 80 in our neck of the woods, so the concept of convection cooling at night just does not apply. Ships located in the western desert can rely on convection cooling since the nighttime lows (even in summer) can hover closer to 60.

The other thing we've done to deal with the heat is separate the greenhouse from the living space with exterior grade sliding glass doors. The greenhouse gets as hot as the outside in summer (90+ sometimes), but only as cold as 55 or 60 in the winter. We open and close the greenhouse doors as needed to adjust the temperature. This is especially useful in the winter, when the greenhouse will heat up to a balmy 85. We open the doors and the house is flooded with warm air. The greenhouse, even though we have lots of below freezing nights, does not go below 55 in the winter. We grow tropical plants like lime and lemon grass in our greenhouse. In the summer, we keep the doors closed so the heat stays in the greenhouse and out of the house. We also have a commercial grade greenhouse ventilation fan. Without the fan, the greenhouse is upwards of 100 on a sunny day, even in winter!