ASHRAE Journal - October 2010 - 82

iaq applications
30% higher than those required by Standard 62.1. All of the programs allow natural ventilation as an alternative to mechanical, with requirements based on vent opening sizes and access requirements that are based largely on existing building codes. LEED gives extra points if the design is based on an engineering approach rather than these rules of thumb. The other key point under ventilation is outdoor airflow rate monitoring, which is a requirement or a source for extra points in several programs. Several allow the use of CO2 monitoring to meet this monitoring requirement, despite limitations in the relationship between indoor CO2 concentrations and ventilation rates.19 In terms of particle filtration, Standard 62.1 requires MERV 6 filters upstream of cooling coils and other wetted surfaces to limit the likelihood for microbial growth and MERV 6 or MERV 11 filters in outdoor air intakes when the outdoor air is not compliant for PM10 or PM2.5 respectively. Standard 189.1 increases both of these limits for outdoor air filtration, while other programs give extra credits for increased filtration. The manner in which these programs deal with ventilation and filtration highlights their tendency towards an incremental approach to IAQ that uses or marginally increases the stringency relative to Standard 62.1. tion rates as the sole link between these critical goals. One challenge is the use of ventilation for IAQ control under conditions of poor outdoor air quality. While increased ventilation can help reduce occupant symptoms,15 that relationship assumes that the outdoor air is clean. Ventilating with polluted outdoor air will degrade IAQ, at least in terms of contaminants that are not generated indoors. A strong case exists for a more comprehensive and demanding approach to IAQ in green and sustainable building programs and standards. The reliance on Standard 62.1, even with incremental increases in the requirements, neglects the fact that this standard is intentionally comprised of minimum requirements on which consensus could be reached. Therefore, it leaves out many important factors and valuable guidance to support good IAQ. One area that a comprehensive, high performance IAQ standard or guideline needs to address more seriously than is done currently is that of moisture control. While Standard 62.1 and other documents contain requirements or credits for moisture management, moisture problems are such a serious IAQ issue that they merit more than the minimalist approach in Standard 62.1 and building codes. Code requirements for vapor retarders and other measures have existed for decades, but moisture problems continue to occur, which points to the need for a more demanding set of requirements and recommendations. More comprehensive IAQ standards also need to address material emissions in a manner that moves beyond current approaches.

Discussion and conclusions
In addressing the relationship between building energy efficiency and IAQ, one needs to consider more than just outdoor air ventila-

FLOWHOOD ELECTRONIC FLOWHOOD
DIRECT DIGITAL READOUT 25-2500 CFM

AUTOMATICALLY CORRECTS FOR AIR DENSITY & BACKPRESSURE CHOICE OF METERS - AIR FLOW ONLY, OR AIR FLOW, VELOCITY, PRESSURE & TEMPERATURE OPTIONS INCLUDE: MEMORY, AVERAGE & SUM TO 2000 READINGS, SEQUENTIAL RECALL, AUTO-READ REPAIR POLICY - TWO WEEK TURNAROUND OR LESS CUSTOM TOPS MADE TO ORDER

Shortridge Instruments, Inc.
7855 East Redfield Road • Scottsdale, Arizona 85260 (480) 991-6744 FAX (480) 443-1267

www.info.hotims.com/30920-53

www.info.hotims.com/30920-58

ASHRAE Journal

October 2010

ASHRAE Journal - October 2010

Table of Contents for the Digital Edition of ASHRAE Journal - October 2010