You should keep tropical birds in a dry, draught free, good ventilated birdhouse.
Some bird keepers call themselves “cold breeders”. If you like it to keep birds “cold”, take then birds out the neighbourhood. Don’t keep birds out of warmer area’s as you are not able to hold them warm. In my opinion is 20°C the limit.
There is much discussion about how big a bird cage should be at least.
Most cages you can buy are 60x40x40 cm or something like that.
If you consider that birds has wings to fly, then should you give them enough space to use them. They should be able to fly from perch to perch and not spring.
My standard is: A cage should be at least 100x60x60 cm. Put not more then 6 birds (max. 10 cm) in such a cage.