Phalaenopsis leaf damage...cold? sun?

[Raqsharqi]

Our weather took an unseasonable dip, and our heater took an unappreciated delay. With the help of Christmas lights and enough candles to light a small church, we were able to keep the temperature in our new green house to no lower than 49 degrees. This morning, however, I noticed almost all the phalaenopsis have yellow spots, and a couple of them have what looks to be rotted leaf areas. I don't know if it is sun damage or cold damage or some other dam-age. I sprayed Physan 20 on all the spotted leaves just in case, but don't know what to do now. Thankfully, the heater is supposed to arrive today and night temperatures will be slightly warmer.