Planning of a DIY LiFePO4 battery - air conditioned

Thanks for your comments. My first idea for heating was also to use heat pads. But for active cooling (beside just a fan), I don't have many options beside a peltier. The idea is, even if the peltier (in fact a heat pump) has a relatively bad efficiency, it will be more efficient as a heat pad for heating. Because I need the peltier anyway for cooling, I've decided to use it also for heating and so I don't need additional heat pads.