Determining the amount of thermal energy that must be either added to or removed from a space to maintain a desired temperature is a critical aspect of building design and HVAC system selection. This process involves quantifying all sources of heat gain and loss within the defined area. An example includes accounting for solar radiation through windows, heat generated by occupants and equipment, and thermal transfer through walls, roofs, and floors. The result is expressed in units such as British Thermal Units per hour (BTU/hr) or Watts.
Accurate estimation of this thermal requirement is essential for energy efficiency, occupant comfort, and cost-effectiveness. Underestimating the requirement can lead to inadequate heating or cooling, resulting in uncomfortable conditions. Overestimating it leads to oversized equipment, higher initial costs, increased energy consumption, and potentially short cycling, which can reduce equipment lifespan. Historically, simplified rules of thumb were used, but advancements in building science and computational tools now enable more precise and reliable assessments.
