The INTENT is to provide a high level of thermal, ventilation and lighting system control by individual occupants or specific groups in multi-occupant spaces (i.e. classrooms or conference areas) to promote the productivity, comfort and well-being of building occupants. The requirement in the credit language states "Provide controls for each individual for airflow temperature and lighting for at least 50% of the occupants in non-perimeter, regularly occupied areas." LEED NC Version 2.1 Reference Guide expanded on how compliance with EQc6.2 could be accomplished for "Group Multi-Occupant Spaces" and established lighting, temperature, and airflow requirements for multi-occupant spaces. The reference guide states "For each space less than or equal to 10,000 square feet in floor area, provide at least three separate lighting controls, one airflow control and one temperature control each for every 2,500 square feet; AND For each space greater than 10,000 square feet in floor area, provide at least three separate lighting controls, one airflow control and one temperature control each for every 10,000 square feet." This expanded reference language seems to have referenced ASHRAE 90.1-1999 language in Section 9.2.1.2 (a) that each control device shall control a maximum of 2500 ft2 for a space 10,000 ft2 or less and a maximum of 10,000 ft2 areas for a space greater than 10,000 ft2. Note that the control device refers to lighting control rather than HVAC control. For larger spaces such as cafeterias, auditoriums, and gymnasiums which are normally less or more than 10,000 ft2 each, the requirement for one temperature and airflow control each for every 2,500 square feet (10,000 ft2) can result in these HVAC controls fighting each other compromising occupant comfort, the credit intent, and energy efficiency. Cafeterias, auditoriums, and gymnasiums spaces serve as a single, special group-functionality and usually house transient occupants for a short period of time. As such, it is more rational and sustainable in HVAC control design to treat such a special group-functional space as one single HVAC zone. In terms of HVAC control, ASHRAE 90.1 requires "each zone shall be individually controlled by thermostatic controls responding to temperature within the zone." The reference guide\'s defining HVAC controls in the same way as lighting controls is inconsistent with ASHRAE standards and in our opinion lack of rationale and inconsistent with the intent of the credit for a large interior zone with special group functions, such as a cafeteria or a gymnasium. For such functional space, the intent of this credit is still met with one temperature, one airflow control and adequate lighting controls. We, therefore, request clarification on zone size for multi-occupant spaces with special group function, such as gymnasiums, cafeteria and auditoriums, relative to the number of temperature and airflow controls required in a single zone.
The ruling committee disagrees that it is "more rational and sustainable" to always treat multi-occupant spaces as a single zone. These spaces are often used for a variety of purposes, and may well benefit from multiple zones responding to different occupancy and program function patterns. It is this flexibility and adaptability that generates the recommended zone sizes. This is clearly relevant to lighting as the writer acknowledges. For this to be appropriate for temperature and airflow requires careful design, as the writer acknowledges that otherwise the controls can be inefficient and compromise comfort. However this argument is not limited to special group multi-occupant spaces, as open offices often face similar design challenges. Multi-occupant spaces with special group functions such as gymnasiums and cafeterias are considered to be regularly occupied spaces as noted in CIR ruling 10/5/04 and 11/9/01. As such their zone size is defined in the LEED NC 2.1 Reference Guide pgs 289 - 290. Exemptions for the number of airflow temperature or lighting controls for these spaces will not meet the credit intent of providing a high level of occupant control, and therefore are not acceptable in this instance. Applicable internationally.