foundation vents....open or closed?
First, I apologize for not knowing the correct terminology but....our house has vents all around the house at ground level. We have a crawlspace so I assume this is what is vented. They are in multiples of 2 with screens and little plastic flaps which open and close. Should these vents always be open for say, the summer and then closed in the winter? Right now, I am noticing some are open and some are closed :(