The calculation of regularly occupied space can be fine-tunedas decisions for “fixed” (attached to a wall) counters with overhead cabinets and equipment are integrated into the design. The square footage where the cabinets and equipment are located is not considered
Some spaces can be exempt from being considered “regularly occupied” due to the nature of their use. Previously published CIR’s offer some guidance. Provide a narrative explanation of why a given space should be exempt based on use of the space as views and daylight may negatively affect the use of the space, not the frequency or time that the space is actually used. For example, museum gallery spaces, high security and privacy areas, dark rooms for photo development, and others can all be exempt from the calculation.
If natural ventilation strategies are integrated into the design, ensure that key elements of the natural ventilation system, such as operable windows, window actuators, controls, operable atrium elements, and solar chimneys, are not compromised during value engineering. Educate decision-makers about the natural ventilation design and the importance of maintaining all the key components. If these elements are altered in a way that compromises natural ventilation rates, the mechanical system may no longer be sized appropriately.
The surface area of window openings must, for compliance with ASHRAE 62.1, be equal to or greater than 4% of the occupied floor area that the design considers naturally ventilated. Multiple windows in aggregate can provide the operable area needed to meet the requirements.
Too much glazing, particularly east- and west-facing glazing exposed to low-angle morning and afternoon sun, may cause glare and overheating. Use overhangs, energy-efficient glazing, and daylighting designs that control glare, such as interior shades or lightshelves.
