In Floor Radiant Heat

I live in an eco-house that is being heated by a heat pump that gets it s energy from the ground. The Sun heats the ground in summer and I use the energy stored in winter. The heat pump itself uses some electricity. To make it as energy efficient as possible, one should let it work only at night. But the problem is to know what the weather will be next day. Because I use floor heating and the concrete in the floor conserves a lot of energy, you will only know next day if your decision last …