Heat would be lost in cold climates.
Do all houses have attics.
An attic framed with rafters will provide a fairly open space that can be used for storage or even converted to living space.
Attics need to be able to breathe and should remain the same temperature as the outside air.
Some very old homes have attic access only through a removable vent panel at a gable end wall of the roof.
It might be cooler in very hot climates with adequate vents high up.
Not all houses do.
If you live in a cold climate as we do in canada the roof on your house is likely sloped to allow rain and melting snow to run off.
In contrast a house built using roof trusses will have an attic space full of angled web framing that connects the top chords analogous to rafters to the bottom chord which frames the ceiling beneath the attic space.
An older home might have very little insulation if any at all so you should have some added.
Does your house have an attic.
Attics were common in all but the most arid climates in the united states.
Even the air space above a flat roof needs to be vented.
Although a minimum of one attic access opening is required by the building code for homes that meet that minimum requirement mentioned earlier one access may not be enough for large homes especially ones with a center cathedral ceiling that becomes an obstacle separating the two sides of the attic.
When a house has a sloped roof and horizontal ceilings there is going to be some dead space between the ceiling and the roof otherwise known as the attic.