The drawing above from Matts Myhrman’s and S.O. McDonald’s free strawbale building book Build it With Bales is very clear. It shows how angled window openings let in more light than squared window openings. You’ll also get better views and have more space in doorways this way. Angled and curved openings are both effective. Curved openings seem more aesthetically pleasing and natural looking. That’s how we did the window openings on our earthbag roundhouse.