Do you realise that when you release chicks into the brooder they make a lot of noise showing discomfort? They are trying to sing that song mostly when the temperatures are very low!
In the early life of chicks, their  bodies are unable to contribute on temperature regulation so they are always dependent on the environmental temperature in the brooder!
A cold room results into a cold body for the chicks, a very hot room results into very high temperatures in the chick’s body!
If temperatures are not properly regulated, it results into poor growth, increased susceptibility to disease and poor feed conversion. 
If the temperature is so high, the chicks will have to use and lose a lot of energy to cool down the heat in their body through panting…….the lost energy would have been used for growth and development 🤷🏼‍♂
If the temperatures are very low, the chicks may have to use and lose a lot energy by increasing metabolic processes in order to generate heat in the body…..this may weaken the immune system too!
Exposing chicks to cold temperature  damages the development of the immune system and digestive system! Meaning, the chicks exposed to cold temperature have a poor growth rate and are highly affected by disease….and such chicks will always eat alot to keep their bodies warm leading to feed wastage without growth !
Your major role in the brooder is to keep the chicks  confortable!  
For maximum growth, create a condition where they should not use energy to gain or lose heat in order to maintain body temperature!
It therefore means that environmental temperature can play a role in determining the growth and performance of your flock and the cost of either raising a broiler or a layer. If a lot of energy is lost, it will mean you need a lot of feed to compensate! Energy is lost in either high or low temperatures !
The most useful equipment that you need to use regarding temperature regulation in brooder are:
1.Temperature chart
2. Thermometers
3.heat sources
4. Curtains.
* thermometers are installed at the chicks level. Always check the thermometers every after 1 hour. You can as well set an alarm for the thermometers to notify you if the temperature go below or high!
* curtains are installed in a way that you can open for atleast 1 or 2 hours to balance the temperatures and allow air flow.
* heat sources to use include gas brooders which are self controlling or brooder pots with holes.
We can as well rely on the behavior of chicks to understand if the temperature is balancing.
🐥Remove your shoes and enter into the poultry house.  Let the birds step on you! If their feet are cold, means the temperature is very low. 
🐥chicks sitting in feeders or feeder trays? Temperature  is low!
🐥 birds pilling up or huddling together in groups in corners or around the heat source means temperature is low.
🐥birds panting means temperature is very high an unbearable 
🐥birds running away from heat source?
🐥chicks stretching themselves on the litter Temperature is very high! 
🐥birds failing to pass out their excreta? High temperature. 
Adequate temperature allow chicks to distribute themselves evenly in the poultry house, with each bird eating and drinking and running around!
*Advantages of pre-heating the brooder before arrival of chicks*.
Chicks are supposed to find a warm brooder with warm litter. The temperature of the litter should just balance up with the temperature of the chick’s body.
If the brooder is cold, the chicks will start losing heat into the litter or ground leaving the chicks cold and chilling.