Configure the mechanical system so that when windows are open, cooling is turned off to avoid wasting energy. You can accomplish this by hooking operable windows up to wireless sensors that communicate with the cooling system. 

Update the count of total individual workstations and those with controls. If the controls do not add to be 50% of total workstations then investigate the potential to add more controls or change the layout to make them more accessible to windows. 

If using a mechanical system, confirm that the project design is progressing with a system that allows for multiple controls.

A mechanical system with more individual controls may cost more than a conventional system. This cost can be offset, though, by lower operating costs, a more flexible layout, and improved occupant productivity. 

Operable windows are generally higher in cost than fixed windows.

Operable windows, although offering some energy and comfort benefits, have some drawbacks. They allow in outside air, which may not be of the highest quality, and also allow in outside noise. The unconditioned air they allow in can affect the operation of mechanical systems. 

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.  

Underfloor air or ceiling-air plenum are common systems for allowing occupant comfort control. In addition, they can: 

allow for flexibility in layout and design, and ease of electrical wiring, installation of work stations, and arrangement of work spaces; 
realize first-cost savings in reduced duct work, lower floor height and possible an additional floor with more leasable space;
and enhance daylighting by creating higher floor-to-ceiling heights.

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.