Page 316 - The Engineering Guide to LEED-New Construction Sustainable Construction for Engineers

278 Cha pte r S i x

Intent
Provide a high level of thermal comfort system control by individual occupants or by
specific groups in multi-occupant spaces (i.e., classrooms or conference areas) to promote
the productivity, comfort and well-being of building occupants.
Requirements
Provide individual comfort controls for 50% (minimum) of the building occupants to enable
adjustments to suit individual task needs and preferences. Operable windows can be used
in lieu of comfort controls for occupants of areas that are 20 feet inside of and 10 feet to
either side of the operable part of the window. The areas of operable window must meet the
requirements of ASHRAE 62.1-2007, with errata but without addenda (was the 2004 version
for LEED 2.2) paragraph 5.1 Natural Ventilation.
AND
Provide comfort system controls for all shared multi-occupant spaces to enable adjustments
to suit group needs and preferences. Conditions for thermal comfort are described in
ASHRAE Standard 55-2004, with errata but without addenda, to include the primary
factors of air temperature, radiant temperature, air speed and humidity. Comfort system
control for the purposes of this credit is defined as the provision of control over at least one
of these primary factors in the occupant’s local environment. Project teams can choose to
use the addenda to either ASHRAE 62.1-2007 or ASHRAE 55-2004, but only if applied
consistently over all the credits applied for the LEED 2009.
Potential Technologies and Strategies
Design the building and systems with comfort controls to allow adjustments to suit
individual needs or those of groups in shared spaces. ASHRAE Standard 55-2004 identifies
the factors of thermal comfort and a process for developing comfort criteria for building
spaces that suit the needs of the occupants involved in their daily activities. Control strategies
can be developed to expand on the comfort criteria to allow adjustments to suit individual
needs and preferences. These may involve system designs incorporating operable windows,
hybrid systems integrating operable windows and mechanical systems, or mechanical
systems alone. Individual adjustments may involve individual thermostat controls, local
diffusers at floor, desk or overhead levels, or control of individual radiant panels, or other
means integrated into the overall building, thermal comfort systems, and energy systems
design. In addition, designers should evaluate the closely tied interactions between thermal
comfort (as required by ASHRAE Standard 55-2004) and acceptable indoor air quality (as
required by ASHRAE Standard 62.1-2007, whether natural or mechanical ventilation).

Calculations and Considerations
Just as in IEQc6.1, this requirement has two parts that must both be met. The first is for
the regular occupants of the building at their typical workstations, and the second is for
shared spaces that may be used periodically by regular occupants and also by transient
occupants. The definitions from the LEED-NC 2.2 Reference Guide for individual occupant
spaces, nonoccupied spaces, nonregularly occupied spaces, and shared (group) multioccupant
spaces can be found in App. B and are consistent with the LEED 2009 definitions.
Individual Control The first requirement is that 50 percent of the occupants have control
over their thermal comfort at their typical workstation or living space. Thermal comfort
controls usually refer to some form of conditioning and are usually for both heating and
cooling. This conditioning can be active (mechanical HVAC systems) or passive (natural
ventilation). A typical type of control may be individual diffusers, or access to an
operable window. (The occupant location should be no more than 10 ft sideways from
the edge of an operable window and no more than 20 ft away in front of the window.