Operable Windows & Mechanical Ventilation

Hi Charalampos,

I recently got this credit in a mechanically ventilated building with operable windows.

Yes, it is acceptable.

Hello Charalampos,
because of technical reasons and limited project budget, we have room temperature control units in some rooms, but not in every shared multi-occupant space. However, a louver push button is available in every room (multi-occupant spaces and individual occupant spaces). The occupants are able to adjust the louvers which are mounted on the façade individually.
Can we get this credit point with the current design?

Hi Charalampos,
I have got an answer from GBCI today:

"As stated on page 527 of the 2009 LEED Reference Guide for Green Building Design & Construction, June 2010 edition the requirements are to:

"Provide individual comfort controls for 50% (minimum) of the building occupants to enable adjustments (for workspaces only in Schools projects) to meet individual needs and preferences. Operable windows may be used in lieu of controls for occupants located 20 feet inside and 10 feet to either side of the operable part of a window. The areas of operable window must meet the requirements of ASHRAE Standard 62.1-2007 paragraph 5.1 Natural Ventilation (with errata but without addenda2).

Provide comfort system controls for all shared multi-occupant spaces to enable adjustments that meet group needs and preferences.

Conditions for thermal comfort are described in ASHRAE Standard 55-2004 (with errata but without addenda2) and include the primary factors of air temperature, radiant temperature, air speed and humidity."

The louvers you mention may allow the project to reach the minimum 50% of the building occupants if the occupants are located 20 feet inside and 10 feet to either side of the operable part of a window. Page 529 states the following:
"Individual Thermal Comfort
To satisfy this portion of the requirement, start by identifying workstation locations that are intended for individual use, including private offices, open plan workstations, reception stations, ticket booths, etc. Confirm that 50% or more of individuals occupying these locations have at least 1 means of individual control over thermal comfort.

Operable windows may be used in lieu of individual controls for those occupants located within 20 feet of the exterior wall and within 10 feet of either side of the operable part of the window. The operable portion of the window will need to comply with the free-opening size criteria of ANSI/ASHRAE 62.1–2007 section 5.1. The minimum area of the window opening may be 4% of the net occupiable area for ventilation purposes; however, larger opening areas may be required for thermal comfort under a wide range of outside conditions. For example, in an area 20 feet by 20 feet, the opening size per window would need to be 16 square feet to meet the limits used in this credit.

Multioccupant Spaces
Start by identifying areas where groups occasionally congregate, such as conference rooms, break rooms, and lecture halls. Specific types or numbers of controls are not listed in the credit requirements to allow for flexibility in designing to the unique uses of each project. Confirm that there is at least 1 accessible means of control over thermal comfort in the space (operable windows or louvers could satisfy this requirement). Meeting spaces that can be subdivided, as with a movable wall in a convention hall, must be designed so that occupants in each area have control of their individual area."

This answer sounds positive, but I'm still not very sure.