Poolish problem : vimarsana.com

Hi,I have been experimenting with Poolish for a couple of weeks now, and love the results, except I am having a problem with my dough fermentations not doubling in size ? I got my recipe online by a guy apparently well known, but I cannot remember his name. My poolish always works great, it has 16 hrs fermentation because our house is not that warm, but it is always vigorous