I work at a childcare centre and am seeking clarification on the best sleeping environment for babies. In our cot room we have air conditioning and fans, all our families at the moment bring sleeping bags most being a 1 TOG, and want their children to sleep in them as this is how they sleep at home. As we are going into summer and there are days when the weather is greater than 30 degrees Celsius. I was wondering should the children be dressed to their environment which could sometimes require children to be only in a nappy or singlet, or should the environment be adjusted to how the children are dressed? And if the latter how much should the environment be changed, should it be as minimal as possible, or as much as required for the children to feel comfortable in their sleeping bag, swaddle, etc.?

Do you use the air-conditioning &/or fans in the cot room all year round?
If so, then the clothing for sleep would be the same all round, providing you maintain the same temperature.
Babies & children should always be dressed according to the environment - this is referring the the environment (or temperature) in the room in which they are sleeping.

It can be difficult to work out in advance what may be the most appropriate clothing/bedding for baby when sleeping.
While Red Nose recommends dressing baby according to the room temperature, rather than trying to modify the room temperature with heating or cooling, if you are using air-conditioning &/or fan, then you would still dress baby according to the room temperature. The same principle would apply during colder season.

If the clothing that parents send for their baby to sleep in when in day care, is appropriate for the room temperature, then that should be used.
Ensure no hats (or other head covering) are worn during sleep.

Red Nose has the following information.
https://rednose.org.au/article/bedding-amount-recommended-for-safe-sleep
https://rednose.org.au/article/how-to-dress-baby-for-sleep

There is no recommended temperature range for sleeping babies/children in Child Care, nor does Red Nose recommend that heating/cooling should be used (or not used) to maintain a specific room temperature.
https://rednose.org.au/article/what-is-a-safe-roo