I did just that to my house in France. Everybody here (south east of France) does that. Seen the savings and that it both cools in the summer and warms in the summer, it's a complete no-brainer. In addition to that I switched my open fireplace to an enclosed one: the efficiency when burning wood is greatly increased. And I stockpiled on wood. So should there be electricity shortage preventing me from using HVAC to warm the house, at least nobody is going to prevent me from putting wood in the fireplace.