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2019 IAQA Annual Meeting
Elliott Horner, PhD
UL Environment
M: 678-249-8856
Jim Dennison, CIH, PhD
Century Environmental Hygiene
O: 970-266-8000
“ASHRAE’s
Indoor Air Quality Procedure
in Ventilation Design”
2019 IAQA Annual Meeting
ASHRAE
• Content
• American Society of Heating, Refrigerating and Air-
Conditioning Engineers
• Publish a wide variety of standards
• 55-- Thermal Environmental Conditions for Human
Occupancy
• 110-- Methods of Testing Performance of Laboratory
Fume Hoods
• 62.2 -- Ventilation and Acceptable Indoor Air Quality in
Residential Buildings
• 188-- Legionellosis: Risk Management for Building Water
Systems
• 189.1-- Design of High Performance Buildings
2019 IAQA Annual Meeting
Standard 62.1
Ventilation for Acceptable Indoor
Air Quality• Content
• Design standard
• Last complete update 2016
• Continuous maintenance with triennial updates
• ANSI Standard
2019 IAQA Annual Meeting
Mechanical Code
• In the U.S., cities and states generally adopt
the International Mechanical Code, with
local modifications
• IMC is based mostly on ASHRAE 62.1
403.2 Outdoor Air Required The minimum outdoor airflow rate shall be determined in accordance with Section 403.3. Exception: Where the registered design professional demonstrates that an engineered ventilation system design will prevent the maximum concentration of contaminants from exceeding that obtainable by the rate of outdoor air ventilation determined in accordance with Section 403.3, the minimum required rate of outdoor air shall be reduced in accordance with such engineered system design. [IMC commentary states “An engineered ventilation system is more of a direct method of controlling air quality and would be classified as an “Indoor Air Quality Procedure” in ASHRAE 62.1. ASHRAE 62.1, as a whole, is not a referenced standard in the code… but, the exception to this section could certainly be viewed as allowing the indoor air quality (IAQ) method of that standard as one of the possible means of complying with the exception.”
2019 IAQA Annual Meeting
ASHRAE 62.1:
Minimum OA requirements
• Content• Compliance methods
• Ventilation Rate Procedure
• L/s per person + L/s per area
• IAQ procedure
• Dilution needed for acceptable IAQ
• Natural Ventilation
2019 IAQA Annual Meeting
ASHRAE 62.1:
Minimum OA requirements• Ventilation Rate Procedure
• L/s per person + L/s per area
Count people, Measure the area and Add
May waste energy, but defensible
2019 IAQA Annual Meeting
ASHRAE 62.1:
Minimum OA requirements
• IAQ procedure
• Dilution needed for acceptable IAQ
Identify Design Compounds, Find Emission Rate, Determine Limit
Compute Mass Balance
May save energy, but values needed may be absent
Add in air cleaner: What is the removal efficiency? (add factor to mass balance)
Cleaning conditioned air saves energy
Manufacturers want to know the compound(s) for efficiency measurement
2019 IAQA Annual Meeting
ASHRAE 62.1:
Minimum OA requirements
• IAQ procedure
• Dilution needed for acceptable IAQ
What is the removal efficiency? (add factor to mass balance)
Manufacturers want to know the compound(s) for efficiency measurement
• Removal efficiency measurement is expensive• Chemical classes probably behave similarly – within limits (pentane / heptane)• Similar compounds: very dangerous (benzene), others not (toluene)• Short list (8 – 10) of representative compounds for efficiency testing is needed
2019 IAQA Annual Meeting
LEED Green Building program
• Content• Does not currently permit using IAQP
2019 IAQA Annual Meeting
Selection of Design
Compounds
• Content• Look at prevalence in IA
• As compared to possible Design
Targets (limits to design to)
• Selected Compounds from
different classes
2019 IAQA Annual Meeting
Carbon Dioxide
• Content• Controversial Compound
• Data on “direct cognitive effects of CO2” exists
but not confirmed
• CO2 is used as a surrogate for bioeffluents from
people
• Several studies reported that
perceived acceptable AQ correlated with ~1100
ppm CO2 or ventilation rates that are in the
range giving 1100 ppm
2019 IAQA Annual Meeting
Mixtures
• ContentMust have a way to address
Consider the VOCs: toluene 300
ug/m3. Add just 3 more VOCs at this
level and IAQ is probably
unacceptable
2019 IAQA Annual Meeting
Mixtures
• Content
𝐸𝑚 =𝐶1𝐷𝑇1
+𝐶2𝐷𝑇2
+⋯𝐶𝑖𝐷𝑇𝑖
• Pre-Defined Mixtures in draft
2019 IAQA Annual Meeting
TVOC: backstop or red herring?
• Criticisms
• Not health based
• Was it ever? Misrepresented
• Different definitions
• Selected list vs sum? Should be sum!• (that is what total means – see Webster)
• Sum of C5-C17 or C6-C16?
• Does that difference exceed TAB % error?
wear on HVAC parts?
2019 IAQA Annual Meeting
TVOC: backstop or red herring?
• Benefits
• Aggregate limit
• Overall chemical hygiene
• more clean vs less clean
• Precautionary Principal
• Formaldehyde in 1980 vs today
• Flame retardants, bisphenol A
• 2000 new compounds / year into commerce
https://www.pbs.org/newshour/science/it-could-take-centuries-for-epa-to-test-all-the-unregulated-chemicals-under-a-new-landmark-bill
2019 IAQA Annual Meeting
Conclusions
• IAQP is a logical way to design HVAC
if you get the right compounds and limits, and
can accurately estimate sources
• Consensus must be developed over the method,
compounds and limits
• Difficult to select compounds and limits based
on current knowledge base, but with enough
effort, may be reasonable
• Involved discussion with groups like AIHA and
USGBC needs to occur
2019 IAQA Annual Meeting
Bibliography
• ANSI/ASHRAE Standard 62.1, Ventilation for Acceptable Indoor Air Quality. 2016