The short, and most generalized answer to your question is most likely that if you were unlucky enough to be working in a work administration space before the popularization of AC, you were likely quite hot. However, because of the relatively concurrent development of both air conditioning and the office as a typological form, many fewer people would have been working within these unairconditioned spaces. And further, the spaces which did exist would have been configured differently than present-day offices to allow for closer proximity to opening windows and fresh air.

A more in-depth answer requires us to look at the development of the office itself. The office as we know and understand it today is a relatively recent phenomena, largely developing and becoming widespread at the turn of the twentieth century.

The office is generally linked with a post-railway expansion in the organization and operation of businesses. The limited scope of business pre-railways meant that the business being conducted was still relatively simple and generated relatively little paperwork. Limited generation of paperwork in turn meant a limited need for administration personnel, and thus limited need for what we now understand to be white-collar working spaces. As an example, in 1849 a total administrative staff of three assistant postmaster generals and a small handful of clerks made up the office staff of the United States Postal Service, which at the time was overseeing 16,749 post offices. Around the same time the Second Bank of the United States had only two administrative assistants on payroll!

In order to fully answer your question, we need to triangulate the relatively late development of the commercial office with the advent of air conditioning.

Frank Lloyd Wright’s Larkin Administration Building (1903), widely considered one of the first ‘modern’ office buildings, is praised in large part because of its sophisticated air conditioning and purification system. Wright demanded the development of such an advanced system both to mitigate the environmental impacts of the location of the office building (within a complex of manufacturing buildings in downtown Buffalo), and to facilitate the specific aesthetic design he envisioned. While air conditioning technology would go on to develop much further, the example of the Larkin highlights the relatively concurrent development of both the office as we know it today, and of air conditioning technology.

The literature is generally in agreement that during the period of office coalescence, at least in part, these spaces were kept from expanding beyond a certain size, shape, and configuration because of the technological limitations of heating and cooling the space. Essentially, as you’ve pinpointed, large spaces could not be kept within tolerable temperatures during regular seasonal fluctuations. This meant that the spaces which were constructed pre-popularization of contemporary AC like the Empire State Building (1930) and Rockefeller Plaza (1937) featured quite narrow floorplans, designed to facilitate the circulation of air, and allow each worker to be placed in close proximity to an openable window.

As AC became more effective and more affordable, office buildings began to be designed with deeper floorplans, pushing more workers away from openable windows and deeper into the building. This evolution is how we have reached the relatively standard deep open office configuration which we associate with office spaces today.