The purpose of which is to limit heat loss or gain.
In domestic and general buildings, during winter months, to limit heat loss through the ceiling and walls where the manner of construction consists of a thin membrane material such as plasterboard as a lining.
Its corresponding performance during the summer months comes with a plus minus effect, in that the greater the amount of insulation, the greater the storage potential, therefore the longer the building will take to purge itself of the heat load during the evening cycle.
The house is less resistant to ambient change
Various entities including govt. based organisations will attempt to suggest that insulation will provide all the necessary comfort levels desirable but disappear into the wilderness when asked to show their rationale, or attempt to change the narrative.
The reality is that there is no advantage without a corresponding disadvantage and anyone advising differently should be questioned as to rationale.
Bigger is not always Better!
In most conditions, the use of an insulative medium above r3.0 is not warranted and even then should be used in a manner so saturation is avoided, and in the roof space appropriate venting should be employed with any high heat load absorbed being dissipated quickly and efficiently.
A decision should never be made until full awareness has been acquired.
Unfortunately there are those that think that when a word ends in ‘ion’, one is a substitute for the other.
A dangerous presumption!
Insulation, Ventilation, Air conditioning have totally separate areas of function and one does not replace, and or, is a substitute for, the other. Just as do the tyres, steering wheel and brakes in a car.
In simple terms:
Insulation – is like putting an on overcoat, to prevent heat loss or gain
Ventilation – is like breathing
Air Conditioning -cooling -a cost based climate system controlling living conditions reliant on consumption of electrical energy with or without water.
Putting on an overcoat is not going to make you breathe any better,
and the air conditioner is not going to improve the quality of air.
Conversely, breathing well is not going to make you any warmer, but it will contribute to your remaining cooler, and is guaranteed to keeping you healthier.
Use the right product for the right reasons and avoid trying to demean the validity of the product, or approach, on the basis of financial outlay because in the end you are the one that is ultimately going to wear the outcome
As with anything, a solution based on comprehensive understanding always produces the best outcomes.