Benefit of Open fermentationFermenting out in the open can be beneficial during the early stages of fermentation for a couple of reasons. First, you get some oxygen exposure which helps the yeast build a strong population.Second, there’s nothing keeping the heat generated by fermentation from escaping. Lids can help trap heat and, depending on your ambient temperature outside the fermenter, your wine could get too hot with a lid in place.Most commercial wineries will ferment red wines in open containers to allow heat to escape and to have better access to the cap. When you ferment on the skins they will float to the top and for the cap. This cap protects the wine from outside elements but it must also be punched back down into the wine from time to time to help extract more flavor and aroma compounds from the skins.