1	School Ventilation & the Impact on Indoor Air Quality Sheila Batka U.S. EPA Region 5, Chicago
2	School Ventilation – A New Issue?
3	Ventilation and Indoor Air Quality (IAQ) Topics Historical References Background Basic Functions of a Building & its Heating, Ventilation & Air Conditioning (HVAC) System Troubleshooting & Identifying HVAC System problems that Impact IAQ
4	History, Health & Science of Ventilation Ancient Egyptians observed that stone carvers working indoors had a higher incidence of respiratory distress than those outdoors King Charles I in 1600 decreed building codes intended to reduce disease transmission in crowded rooms In 1777 Lavoisier began his study of oxygen and CO2 in crowded rooms
5	History, Health & Science of Ventilation In 1836 a Cornish mining engineer (Tredgold) established 30 CFM per person Lead to dichotomy in purpose of ventilation – physiological or comfort? From civil war observations, physicians wanted 60 CFM per person In 1895 ASHVE approved 30 CFM per person in response to a physician’s (Billings) work on spread of TB
6	History, Health & Science of Ventilation
7	HVAC Basics HVAC is for Heating HVAC is for Ventilation HVAC is for Air Conditioning AC > Cooling – its dehumidification too!
8	IAQ Basics "Good" Indoor Air Quality (IAQ): Managing these parameters includes ventilation systems - Control of Air Pollutants and Sources Includes moisture control Fresh Air Ventilation Introduction & distribution of adequate outdoor air Thermal Comfort Control Maintenance of acceptable temperature & relative humidity
9	Producing an IAQ Problem: People introducer or susceptible occupant Pollutant or source Pathway for pollutant to travel Pressure difference moving air NOTE: Possible for ventilation influences
10	IAQ Pollutant Risk Reduction Principles Source Control Eliminate Substitute Ventilation Local exhaust from source General ventilation Air Cleaning/Filtration Captures targeted pollutants Exposure Control (Least Desirable)
11	Local Exhaust Exhausts air at source of contaminant directly to outside Immediate area is under negative pressure relative to surrounding areas Examples: Restrooms, Kitchens, Science Laboratories, Housekeeping Storage Rooms, Printing & Duplicating Rooms, Industrial Arts Areas, Home Economics Classrooms
12	General Ventilation Diluting Indoor Air with clean Outdoor Air to reduce concentrations of unavoidable pollutants i.e., carbon dioxide (CO2) & body odors May be helpful in reducing other pollutant levels Although best to control sources
13	Basic Function of Buildings & Ventilation The Indoor Environment Designed to provide comfortable climate for occupants Air is conditioned for our comfort Ventilation/Distribution through mechanical and natural (i.e., double hung windows) systems Heated and cooled by mechanical systems and outside influences Consideration for Limits Limited air exchange/energy flowing around/through walls, doors, roof, windows, etc. Occupants & Maintenance can impact conditioned air
14	HVAC system can be a pathway a driving force a source
15	HVAC Systems – Variety! In-room: Window, stand-alone, ceiling Central units serving multiple rooms Chilled water or refrigerant (DX) Constant Volume or Variable Volume CV – constant fan, temp varies VAV - constant Temp, fan varies
16	Ventilation: Vital Functions for Bodies & Buildings Ventilation with outdoor air is important Complex interactions Most schools lack adequate outdoor air Continuous path is critical Designed to allow adequate airflow
17	Ventilation Checklist
18	Ventilation Checklist
19	Ventilation Checklist
20	Continuous Path - Many Choke Points
21	Common Ventilation Problems in Schools Inadequate ventilation with outdoor air Negative building pressure Building materials, books, and paper records deteriorate twice as fast at humidity levels above 60% Excessive building exhaust
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23	Blocked Intake Screen Hard to see Purpose is to prevent bird, rodent, and big debris entry Often clogged with small debris
24	Air Intake located by dumpster & bus…
25	Blocked Intake Grille Common practice after oil embargo in 1972 Easy to identify Removal could make big difference in IAQ
26	Clogged Filters Extended-area filters are better Preventive maintenance schedule is important
27	Clogged Mixing Chamber Lunch bags, wall decorations, and last year’s test papers
28	Potential Dangers High voltage Motors, belts, and pulleys Microbiologicals growing in ducts and equipment Falls
29	Closed damper In addition to a chunk of 2x4 jammed against the damper, there are several others reasons that the damper may be closed
30	Disconnected Linkages Due to breakage or corrosion, or in an attempt to save energy ($)
31	Mis-Set Time Clocks 24 hour and weekly styles Power-outages, daylight savings time, and others can cause OA to be OFF when needed, and ON when not
32	Minimum Settings Dictates minimum outdoor air damper position % OA doesn’t mean much
33	Other Problems Defective Freeze-Stats Defective operation & inappropriate use of manual-reset freeze-stats No Air Pressure Compressed air sent through-out building to control OA supply Popular in pre-1980s buildings
34	Clogged Blowers Especially in unit ventilators, trash can clog the air blowers
35	Broken Fan or Belt Preventive maintenance is important for belts
36	Fans Turned Off Check the breaker panel inside the building, and the disconnect next to the fan
37	Burned-Out Fan Motor Motor may be burned-out, or could be wired backwards causing the blower to run in reverse
38	Clogged Heating & Cooling Coils Primarily results from use of cheap air filters, improper installation of air filters, and improper cleaning or replacement of air filters
39	Blocked Exhaust Intakes & Ducts Note the disconnected exhaust duct
40	Blocked Exhaust Outlets Who knows why someone did this?
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42	Difficult Access for HVAC Units HVAC located in attic of school Caged Ventilation Unit of Portable Classroom
43	Important Tool – Ask Questions about Your System! Remember, HVAC system can be both source & pathway for the distribution of pollutants Any Modifications? Controls Functioning Properly? Filter Clean? Return Air is Ducted or Open Plenum?
44	Areas of Design Concern for HVAC Systems Exterior/Interior Roof Top Units w/ Mechanical Rooms Open to weather Not easily accessed or maintained (Filtration, settings) Roof problems causing ponding – Potentially near supply Classroom Unit Vent Problems Large # of units to maintain Outdoor Air intakes close to ground level Prone to drafts Indoor/Outdoor Access often needed to service dampers Tendency of staff to use units as shelves or plant stands
45	Finally??? We completed the path from Outdoors-to-Outdoors, So, the outdoor air supply is now adequate… Right?
46	Educate Others Example: Path is complete, but occupants turn unit off due to noise or discomfort You’ve educated occupants, so OA is now adequate, right?
47	Blocked Supply Grille Tops of unit ventilators often used as storage space Sometimes purposely blocked due to discomfort or noise
48	Blocked Return
49	Many Types of Vents A well designed vent or grill may alleviate complaints about “Too much air” blowing on the occupants
50	Sources of Moisture Liquid Rainwater Groundwater Plumbing, occupant use
51	HVAC Moisture Control Highlights What’s Relative Humidity (RH)? Amount of moisture contained in a volume of air, relative to the amount of moisture it could hold at a specific temperature As temperature falls for the same air, RH goes up Space RH Dew points & condensation potential Space loads & duct design Ventilation & education HVAC System Design System Ensure proper condensate drainage System control per design Design - size Coil design (fin spacing) Condensate drain design Maintenance Clean coils, filters, & drain pans
52	Outdoor Airflow Measurement You can’t look and guess at the amount --- IT HAS TO BE MEASURED ! Don’t expect 15 CFM per person
53	Identifying HVAC Concerns
54	Identifying HVAC Concerns
55	For further information…. U.S. EPA’s Indoor Air Quality “Tools for Schools” Program http://www.epa.gov/iaq/schools/ Sheila Batka, U.S. EPA Region 5 312-886-6053 Batka.sheila@epa.gov