Final answer:
The provided information does not specify the number of residence halls without A/C. It discusses the history of air conditioning and its impact on cities, but does not provide the data needed to determine the number of halls without air conditioning.
Step-by-step explanation:
The number of residence halls without A/C is not specified in the provided information. To know how many residence halls do not have A/C, the specific data regarding the total number of residence halls and the number equipped with air conditioning units would be needed. None of the provided excerpts directly answer this question. However, the impact of A/C on living arrangements and energy efficiency is highlighted.
The provided details about the emergence of air conditioning highlight its role in changing living and work environments, particularly by making Sunbelt cities more habitable. Additionally, the concept of energy efficiency is discussed in relation to refrigeration systems and the performance coefficient (COP) which is affected by the temperature difference between Th (hot reservoir) and Tc (cold reservoir).