In the absence of operable windows, it is difficult to meet the 50% credit requirement unless the mechanical system is designed with zones to provide multiple comfort controls.
Chilled beams and radiant ceiling panels can provide individual temperature controllability. Given the appropriate climate, internal loads and envelope design chilled beams can be a good fit for this credit, especially if other options like operable windows are limited—for example in laboratory buildings.
Additional controls imply higher construction costs, with additional wiring, and maintenance for uninterrupted operations. There are low-cost options, such as baseboard heating radiators and heat pumps that are easy to operate and provide good local comfort. Compare the upfront costs of better controls to the long-term benefits of higher productivity, better test scores or hotel occupancy, plus savings in energy usage.
Facilities managers may have reservations about providing controls to users. The range of control can be limited to a certain range, however, and should be programmed to be reset at least at the end of the day with the building’s typical temperature setback. Be sure that occupants will be educated on how to use controls.
For example, a school has 10 classrooms with 20 students each, five private offices and one hallway reception desk. The individually occupied spaces are the offices and administration desks with total occupancy of 5 + 1 = 6 people. At least three of those occupants should have access to controls to meet the credit. The multi-occupant spaces are the classrooms, and each classroom needs at least one independent control.
For example, an open plan office has 100 desks and 10 private offices, for a total of 110 individually occupied spaces. At least 55 of the people occupying those spaces must have access to comfort controls. The same office also has two conference rooms. Both conference rooms need their own controls.
Note the credit requirement is based on number of occupants for individually occupied and number of spaces for multi-occupants. Only half of the total building occupants must have controls in individually occupied spaces. However, each of the multi-occupant spaces must have independent controls.
Providing comfort controls that allow an occupant to turn a system on only when using the space, and turn it off at other times, supports energy efficiency goals. Whether or not it can contributes to demonstrable energy reductions for EAc1: Optimize Energy Performance is another question. Except for operable windows, this would be difficult to demonstrate.