Page 293 - The Engineering Guide to LEED-New Construction Sustainable Construction for Engineers

256 Cha pte r S i x

Effective as per the
Design CIBSE Applications
Manual 10:2005, Fig. 2.8

Natural Ventilation
CIBSE Applications
Requirements
Manual 10: 2005 or
Manual 13: 2000 as applicable
Calculations Room-by-Room Airspace
(Do Either) Model for > 90% of
Occupied Spaces per
ASHRAE 62.1-2007, with
errata but without addenda,
Chapter 6

FIGURE 6.2.1 Requirements for increased ventilation in naturally ventilated spaces LEED 2009.

Mixed Mode Ventilation LEED 2009 requires for IEQp1 that mixed mode ventilation
meet the minimum ventilation rates in ASHRAE 62.1-2007 Section 6, regardless of the
ventilation mode based on any acceptable engineering calculation method, although
not specifically restated in IEQc2. LEED 2009 also has the addenda requiring that mixed
mode ventilation follow the CIBSE Applications Manual 13:2000, Mixed Mode
Ventilation as listed under the natural ventilation requirements.

Special Circumstances and Exemplary Performance (LEED 2009)
At this time, improved indoor air quality is primarily sought by exchanging
indoor air with air of better quality from the outside. However, this may not be
the best solution in all cases. There are two main concerns that frequently occur.
The first is the possibility of poor ambient air quality in some areas during different
seasons, and the second is the increased energy use required to condition the
additional outside airflow. Therefore, there are also other methods for improved
indoor air quality that are being researched and recommended. Many are specific
to a certain class of indoor air pollutants such as particulate matter or VOCs and
may be important for some applications. These might serve as a special circumstance
or an innovative design credit at this time, although future versions of the LEED
rating system might add options for special cases. One of the most commonly
used indoor air quality mechanisms is filtration, which decreases particulate
matter, a pollutant that may carry other contaminants such as microbes or
allergens. Improved filtration is partially addressed in the IEQ credit subcategories
3 and 5. Some other methods are mentioned in the Discussion and Overview
section of this chapter.
There is no EP point associated with IEQ credit 2 in either the 2.2 or the 2009 version
of LEED.