Are there any bakers in the thread? I've been struggling to get a successful sourdough boule out this winter. I live in a very drafty apartment and we're probably 60 degrees inside on a normal day. The last couple loaves I've made haven't risen, resulting in a flat, stodgy boule that stays golden yellow and shiny, rather than deep brown and crackling.
I use the Tartine method, basically fixing a levain the night before -> mixing the dough -> 40 min rest -> add water and salt -> bulk fermentation for 4-5 hours, doing a turn (gently folding the dough on itself) every 30 minutes -> bench rest -> shaping loaves -> rise and second fermentation for ~5-6 hours.
I can't tell if I need to give these steps more time or if I'm drawing them out too much; I've been baking like this for about two years but my success only comes in summer when the ambient temperature is helping me out. I've tried using warmer water in my dough and keeping it in the oven with the light on, which keeps it at about 70 degrees.