"My BH is very hot if i do on the humidifier and it will be like the sauna in the afternoon. Also if the day is not windy the temperature can be up to 31 deg celcius . If i do on the humdifier the temperature will be like 32 or 33 ( in the afternoon) as the air inside the house is heavier becoz of the moist . The damp air inside the house can not get out as it is much heavier. So the heat get trapped. I also don't really know why this happen but many people can use humdifier to reduce temperature and it is a big headache for me for the start ."
Sound like the BH now more like a steam cooker to me. All the heat trap inside the BH and according to him, during the windy day, the temperature is ok. But the problem is bird prefer still air in the BH to feel secure. If you let the air move inside the BH, the temp will drop, the humidity will drop and I think the birds population will drop too. Correct me if I am wrong...
I ask him to check the temperature of the water that supply the humidifier under hot weather. It could be hot too. I remember when I when back to Malaysia, the water for the tank is hot like water coming out from the water heater. So, naturally the mist created my the humidifier will also hot.
How to ensure the water is cool? I remember sometimes when the weather is hot, I prefer to sit on the marble floor instead of sofa. It is cooler. So, if the water can pass through the "cooling" substance, then we can cool down the water. The humidifier will help to reduce the heat a bit.