It used to be a fair question. It is becoming less of one — and the answer depends heavily on which unit you are standing in.
Calgary's climate has historically meant that cooling was optional — summers are short and nights cool off. A great many older buildings were built with no cooling at all, and for decades that was perfectly comfortable.
Summers have become warmer and smoke seasons have become a factor, and the calculation has shifted. Not because Calgary needs cooling the way Toronto does, but because there are now stretches where an un-cooled unit is unpleasant, and because smoke means you cannot simply open the windows.
It is not uniform across a building. The units where it matters most:
A north or east-facing unit on a middle floor with openable windows is frequently fine without cooling.
Options depend entirely on the bylaws, and this is where you need to check rather than assume:
Ask two questions before you write an offer on an uncooled unit: does the building permit any form of air conditioning, and what did the previous owner do in July? The second question usually gets you a more honest answer than the first.
Cooling is increasingly something buyers ask about, and an uncooled top-floor west-facing unit is a harder sell in a warm summer than it was a decade ago. In a building that permits no cooling at all, that limitation belongs in your pricing expectations — both when you buy and when you eventually sell.