1. Chapter 3B: INDOOR AIR QUALITY
Agami Reddy (July 2016)
Importance of IAQ
Indoor air contaminants
Air quality standards
Types of control- general methods
Ventilation standard- ASHRAE Standard 62
One zone and two-zone fully-mixed models
Sick Building Syndrome
HCB-3 Chap 3B: IAQ

2. Importance of IAQ Poor IAQ has large associated costs
- Productivity loss due to decreased comfort
- Health costs
- Litigation
Article by Fisk, ASHRAE Journal May 2002
US national health and productivity benefits from improved IEQ (air, thermal, lighting)
Health: $17 – 48 billion per year (respiratory diseases. Allergies, asthma,…)
Productivity loss: $20 – 160 billion/yr (US GDP in 2003 was $10.4 trillion)
HCB-3 Chap 3B: IAQ

3. Indoor Air Contaminants
Building material emissions
Equipment emissions
Dust
Human, animal and insect by-products
Toxins and allergens from microbial growth
Airborne pathogens
Chemicals, household, industrial
Outdoor contaminants drawn into building
HCB-3 Chap 3B: IAQ

4. http://www.kaycee.net/mold/index.html http://www.epa.gov/iaq/molds/
moldresources.html
HCB-3 Chap 3B: IAQ

5. Outdoor Air Quality Standards
EPA: National Ambient Air Quality Standards
NIOSH and OSHA
HCB-3 Chap 3B: IAQ

6. Indoor Quality Standards
HCB-3 Chap 3B: IAQ

7. Types of Ventilation Methods (dilution)
HCB-3 Chap 3B: IAQ

8. Slide from
William Bahnfleth
HCB-3 Chap 3B: IAQ

9. Removing Contaminants from Air-Stream
Gaseous elements:
- Absorption
- Physical adsorption (activated charcoal)
-----
Particulate: Filtering
Particulates or suspended particles come in a wide range of sizes, shapes and concentration. Different types of filters used.
Three operating characteristics of filters:
- Efficiency- ability to remove particles
- Air flow resistance- affects fan power and energy consumption
- Dust holding capacity- determines how often a filter should be cleaned or replaced
HCB-3 Chap 3B: IAQ

10. Figure 3.17 Efficiency of removing particles versus particle size, for several filter types. These curves are approximations based on manufacturers' data. They do not correspond to results of tests recognized by ASHRAE and should not be used for HVAC design. (Courtesy of ASHRAE, Standard :
HCB-3 Chap 3B: IAQ

11. ASHRAE Standard 62.1-2013 (dilution ventilation)
The purpose of this standard is to specify minimum ventilation rates and indoor air quality that will be acceptable to human occupants and minimize the potential for adverse heath effects
This standard is intended for regulatory application (new, existing buildings)
This standard is intended to be used to guide the improvement of indoor air quality in existing buildings
HCB-3 Chap 3B: IAQ

12. ASHRAE Standard 62 Two methods for compliance
- Ventilation rate procedure (prescriptive)
OA intake rates determined based on space/application, occupancy level and floor area
for typical contaminant sources and strengths
- IAQ procedure (performance)
requires monitoring certain contaminants,
ventilation modulated accordingly for control
(additional costs: sensor, control accuracy)
Potential for saving energy (demand ventilation based on CO2)
HCB-3 Chap 3B: IAQ

13. ASHRAE Standard 62
HCB-3 Chap 3B: IAQ

14. 0.3
HCB-3 Chap 3B: IAQ

15. 637 L/s
HCB-3 Chap 3B: IAQ

16. Two Zone Model Expressions derived for cases:
(i) one space which is non-uniform
(ii) multiple spaces which are uniformly mixed
- For (i), the space is divided horizontally in two spaces.
Certain fraction S of the supply air stream bypasses the occupied zone (this factor is also called the “occupied zone by-pass factor” or the “stratification factor”)
Because of stratification some of the outdoor air is exhausted without performing any useful reduction in the contaminants of the occupied zone
Ventilation effectiveness is the fraction of supply air which is utilized
HCB-3 Chap 3B: IAQ

17. Building with two zones served by a single VAV HVAC system
Another correction to the minimum ventilation air amount is suggested by ASHRAE standard for VAV systems
Multiple spaces may have different ventilation requirements.
Further, the thermal loads in these spaces would vary over the year and often by different amounts.
Since the single duct supply systems carries the entire supply air amount (ventilation plus recycle), supply air to the individual zones may not contain the required ventilation air amount
One would have to increase the amount of outdoor air so as to meet the needs of the most critical zone,
Large large energy penalty due to over-ventilation of the other zones.
HCB-3 Chap 3B: IAQ

18. Slides from
William Bahnfleth
HCB-3 Chap 3B: IAQ

19. HCB-3 Chap 3B: IAQ

20. Slides from
William Bahnfleth
HCB-3 Chap 3B: IAQ

21. Slides from
William Bahnfleth
HCB-3 Chap 3B: IAQ

22. Slides from
William Bahnfleth
HCB-3 Chap 3B: IAQ

23. HCB-3 Chap 4: Solar Radiation
Outcomes
Understanding importance of indoor air quality
Familiarity with possible sources and effects of indoor air contaminants
Familiarity with outdoor and indoor air quality standards
Knowledge of different types of ventilation methods, both local and general, and how they dilute and limit contaminants
Knowledge of the different types of air filters
Be able to calculate ventilation requirements based on ASHRAE 62 standard
Understanding of analysis methods involving one-zone and two-zone models of indoor spaces
Understand concept of ventilation effectiveness
Familiarity with sick building syndrome and responsibilities of different stakeholders
HCB-3 Chap 4: Solar Radiation