The Shades are Now Up

We planned this house to utilize the sun's power for heating, passive solar heating.  The downside is that it can get very hot in the summer, so we put up blinds to keep the sun from overheating the house. 

Yesterday, it was suddenly cold, and my father felt it.  Since it was Shabbat, when turning on/off electric appliances is forbidden, I needed a natural, non-electric way to quickly heat the house.  I went to all the windows in the livingroom/diningroom and raised the blinds.  I even gave the Israeli flag we use as a curtain a quick twist, so the sun would stream in.  It worked. The house temperature went up just enough.