Page 317 - The Engineering Guide to LEED-New Construction Sustainable Construction for Engineers

LEED Indoor Envir onmental Quality 279

LEED 2009 also notes that the free-opening of the window must be at least 4 percent of
the net floor area, which for the maximum setbacks in IEQc6.2 is a 20 ft by 20 ft net floor
area.) As in IEQc6.1, for commercial or institutional uses, typical workstations can be
seen as individual offices, desks, or tables in cubicles, booths, and other usual locations
where an employee performs most of his or her work. To determine the occupancy for
these nonresidential uses, it would be most appropriate to again start with the full-time
employee equivalents as defined in the Sustainable Sites category in Eqs. (2.4.1) through
(2.4.3), as were used in IEQ credit 6.1.
For occupancies where shift employees share the same workstations as other shift
employees at their different work times, and for uses where there is really only one
main shift, providing individual controls at locations equal to 50 percent of FTE should
adequately meet the intent of the requirement. If there are alternative regular uses,
where many occupants in different shifts work in alternative locations, then the
definition of the required number of individual thermal controls will need to be analyzed
and validated differently. However, for most commercial and institutional uses, the
minimum number of individual comfort control locations (ICCLs) can be calculated as

ICCL ≥ 0.5 × FTE (6.6.2)

Group Control The second part of this credit is to make sure that there are thermal
comfort controls in group spaces, such as conference rooms and classrooms, so that
the groups gathered in these areas have greater control as appropriate for their
group needs.

Special Circumstances and Exemplary Performance Thermal comfort control as described
in ASHRAE Standard 55-2004 should be balanced with the minimum indoor air quality
requirements, as required per ASHRAE Standard 62.1-2007. Also, since many of the
features for thermal comfort relate to windows and the HVAC systems, this credit has
been labeled with an EB from the USGBC. It is more difficult to change in an existing
building. There is no exemplary performance point for this credit.

6.7 IEQ Credit Subcategory 7: Thermal Comfort

IEQ Credit 7.1: Thermal Comfort—Design
As stated in IEQc6.2, thermal comfort is based on many environmental and personal
factors, including air temperature, radiant temperature, humidity, airspeed, clothing,
and activity levels. Thermal comfort is also addressed in IEQc6.2 and IEQc7.2. This
credit, IEQc7.1, deals with designing the HVAC and other energy-related systems with
added emphasis on thermal comfort. Figure 6.7.1 depicts a dessicant wheel used in
HVAC systems to help reduce outside humidity levels prior to the cooling coils.
Humidity is frequently the factor used for thermal comfort control. IEQc7.1 is worth
one point in both LEED 2.2 and LEED 2009.

USGBC Rating System
LEED-NC 2.2 lists the Intent, Requirements, and Potential Technologies and Strategies
for IEQc7.1 as follows, with updates to reflect LEED 2009: