ASHRAE Indoor Air Quality Guide

Transcription

1 ASHRAE Indoor Air Quality Guide Presented For: Chicago ASHRAE By: James Livingston, Regional Sales Manager, Ruskin Company 1

2 Purpose of Presentation Comment on ASHRAE IAQ Guide topics as related to air control devices Provide information on the function and benefits of these devices Provide advice on their application 2

3 IAQ Guide Basics Objectives Presentation Agenda 1 Design & Construction 2 Control Moisture 4 Moisture in HVAC 6 Capture/Exhaust Contaminants 7 Reduce Contaminants 8 Advanced Ventilation Approaches 3

4 Purpose of IAQ Guide Provide advice on how provide good IAQ via means that are: Cost effective Practical Currently available Technologically sound Sustainable Goal: Increased usage & IAQ! 4

5 8 Objectives Guide Approach Objectives address components of building IAQ Each Objective contains individual Strategies to help achieve the Objective Benefits designers, constructors, owners and facility managers 5

6 Scope of IAQ Guide Buildings covered: Commercial & institutional Office Retail Educational Lodging Public assembly 6

7 Scope of IAQ Guide Buildings not covered: Kitchens Medical procedure rooms Natatoriums Cold buildings Laboratory Industrial Residential Chemical storage 7

8 Why IAQ? Health & well being of occupants Financial success & sustainability of building 8

9 Common Sources of Poor IAQ Two Basic Categories Gaseous Radon, C02, chemical vapors, etc. Biological (with 2 subcategories) Microbial Bacteria, molds, mildews, viruses, dust mites, animal dander, etc. Particulate Dust, pollen, building material fibers, process byproduct (such as saw dust), etc. THE SOLUTION TO POLLUTION IS DILUTION W. K.

10 Health Issues Increased allergy & asthma symptoms Colds & infections Carbon monoxide poisoning Legionnaires disease Lung cancer from Radon exposure 10

11 Financial Impact Repairs or modifications to correct issues Potential temporary building closure Difficulty in renting spaces Legal action due to sick building or other issues 11

12 A Different Way Of Thinking Traditional high priority features include cost, space, aesthetics, etc. Make IAQ a priority in the beginning! Early discussions & strategies by all parties Improving IAQ after the fact is difficult and sometimes impossible 12

13 Objective 1 Manage the Design & Construction Process to Achieve Good IAQ Strategy 1.1 Traditional Design 13

14 Objective 1 Strategy 1.1 Integrated Design 14

15 Objective 1 Strategy 1.2 Commissioning Not just post-construction Employ a Commissioning Authority (CxA) for pre-design and during construction Ensure the design meets owners requirements and is being constructed correctly 15

16 Objective 1 Strategy 1.3 Selecting HVAC Systems Use environmentally-friendly & energy efficient systems when possible Displacement ventilation If conventional means are used (CV, VAV, etc.), be sure good IAQ practices are used (62.1 ventilation for example). 16

17 Objective 1 Strategy 1.5 Effective Operation & Maintenance O&M can be just as important as design & construction Expected level of owner s O&M efforts? Consider O&M during design & construction Provide documentation & training 17

18 Objective 2 Control Moisture in Building Assemblies Moisture is a common cause of IAQ problems and responsible for the most costly litigation and remediation Thermal bridging enables interior frost build-up & condensation Condensation liquid can travel through capillary action to inaccessible locations 18

19 Objective 2 Strategy 2.2 Limit Condensation of Water Vapor within the Building Envelope and on Interior Surfaces Use Thermally Efficient (Insulated) Control Dampers at outside air intakes 19

20 Strategy 2.2 Why use Thermally Efficient Dampers? Reduce condensation to prevent bacteria, mold, mildew Thermally broken to prevent frost build-up Lessen leakage into or out of space Generally Class 1 leakage 4 cfm/ft² at 1 w.g.

21 AMCA 500-D Section 6.9 Thermal Efficiency Test Test setup Figure 5.10 Damper tested in both airflow directions ±2 F Steady State Temperature for a period of 10 minutes Applied torque

22 AMCA 500-D V-groove reference damper 9 cfm per square foot at 1 w.c. How much more efficient is the test damper when compared to the reference damper?

23 Thermally Efficient Damper Features Insulated & thermally broken blades Blade & jamb seals for low leakage Thermally broken frames Non-metallic bearings

24 Thermally Efficient Damper Performance AMCA Standard 500-D AMCA certified leakage AMCA certified performance AMCA certified Thermal Efficiency

25 Objective 2 Strategy 2.3 Maintain Proper Building Pressurization Building pressure affects moisture infiltration and exfiltration Negative pressure in hot, humid conditions promotes moisture infiltration into spaces Positive pressure in humid spaces increases condensation buildup within envelope 25

26 Strategy 2.3 Pressurization often is not consistent throughout building due to: Stack effect Wind speed & direction Temperature HVAC supply & exhaust rates 26

27 Strategy 2.3 Airflow measuring stations can assist with pressurization 27

28 Pick the Product for the Application Use Electronic Air Flow Measurement for very low velocities and large openings Use Velocity Pressure Measurement for high velocities or small openings.

29 Electronic Airflow Measuring Thermistors, heated mass flow sensors, hot film anemometers, etc. Measures energy to heat element Low velocities as little as 0 fpm 29

30 Velocity Pressure Airflow Measuring Differential Pressure Minimum 300 fpm Total Pressure Chamber Pt Ps Static Pressure Chamber Pv = Pt - Ps

31 Locations For Airflow Measuring Stations

32 Suggestions for Measuring Outside Air VAV & CV Systems Air measuring station w/ control damper built-in Damper control is manual or by BAS DCV Systems Air measuring station with built-in control damper and control system Control system maintains CFM set point as fans scroll up and down Any system, limited space Air measuring combined with outside air louver Can be as little as 4 total depth 32

33 Suggestions for Measuring Supply Air Fan inlet Highest velocity point in the system Total system supply airflow Retrofit single floor or pressure area Probes or stations Can install as close as 4 in front of existing dampers New construction single floor or pressure area Air measuring station w/ control damper built-in Damper control is manual or by BAS 33

34 Suggestions for Measuring Return Air Retrofit single floor or pressure area Probes or stations Can install as close as 4 in front of existing dampers New construction single floor or pressure area Air measuring station w/ control damper built-in Damper control is manual or by BAS 34

35 Suggestions for Measuring Exhaust Air Use velocity pressure probes or stations Works well with high velocity exhaust airflow Much less expensive than electronic airflow stations 35

36 Objective 4 Control Moisture & Contaminants Related to Mechanical Systems Strategy 4.1 Control Moisture and Dirt in Air- Handling Systems Fungi & bacteria are normally present on building interior surfaces, including HVAC components Microorganism growth in HVAC system results in malodors, nasal & throat irritation and buildingrelated illnesses 36

37 Strategy 4.1 Outside air louvers can prevent rain penetration Louvers 37

38 Louvers With Plenum Behind 38

39 Water Penetration 39

40 Sloped Plenum Detail 40

41 Strategy 4.1 Traditional louvers provide protection from non-storm rain Wind Driven Rain Resistant louver provide storm condition protection Let s look at the differences 41

42 Traditional Louvers: Strategy 4.1 Horizontal blades Drain Gutters Wide Spacing High Free Area Low Cost Stops some rain Not effective in storms 42

43 Strategy 4.1 Traditional louver sizing AMCA Water Penetration test Beginning Point of Water Penetration free area velocity (FAV) Determine design FAV considering AMCA test data CFM/FAV = Total Free Area required Reference louver Free Area Guide to determine appropriate louver size 43

44 Standard 500-L Louvers 5.6 Water Penetration Air Exhaust Waterdrop Manifold Wetted Wall Manifold Test Unit Water Droplets Air Entrained into chamber through louver Still Air Condition! Exhaust Fan Air Flow Measurement Collection Zone

45 Test Conditions Standard 500-L Louvers 48 x 48 size 15 minute intervals Manifold (raindrops) -4 per hour (3.15 gal/15 min) Wetted wall -.25 gpm (3.75 gallons/15 min) Ventilation airflow only no wind 1250 fpm max free area velocity

46 AMCA Still Air Water Test

47 .01 oz./ft² of free area Water Penetration Graph Beginning Point Of Water Penetration:.01 oz/ft² at 1,023 fpm Free Area Velocity

48 Still Air Test with Non-drainable Louver

49 Where to use: Traditional Louvers Properly drained applications Sloped plenums & ductwork Floor drains Protected areas (overhangs, barriers, interior, non-prevailing wind elevations) Screen applications (vision barriers) Sizing Use Safety Factor (15% to 20% min) Does NOT stop storm rain

50 Traditional Drainable Louver 29 mph wind, 3 /hr rain, 1,000 fpm intake velocity

51 New Louver Technology Wind Driven Rain Louvers Horizontal or Vertical blades Drain Gutters on horizontal Hooks on vertical Close spacing Lower Free Area Higher Velocity Effective in storms 51

52 Std 500-L Wind Driven Rain Test 5.11 Water Rejection Wind Driven Rain Air Exhaust Test Louver Wind Driven Rain plus Air Entrained Into Chamber Through Louver Rain Water Discharge Nozzles Wind/Rain Machine Exhaust Fan Collection Zone 52

53 Std 500-L Wind Driven Rain Test Rejection Effectiveness Classes A 99% to 100% B 95% to 98.9% C 94.9% to 80% D below 80% (std. louvers) 3 rain/29 mph wind 8 rain/50 mph wind 53

54 Wind Driven Rain Louver 29 mph wind, 3 /hr rain, 2,000 fpm intake velocity

55 Rear view, 29 mph wind, 3 /hr rain, 2,000 fpm intake velocity

56 How Much Water Is Applied? 3 Per Hour Rain On 1m X 1m 21 Gallons Applied Over 1 Hr. Class A (99% or better) allows 27 fl. oz penetration Class D (80% or worse) allows over 4 gallons Std Louvers (60% or lower) -over 7 gallons

57 Wind Driven Rain Louver Benefits Prevent rain infiltration Lessens interior water damage & mold growth Helps keep walls & floors dry Helps keep filters dry Excellent for Penthouses Allow higher intake velocities Use smaller louvers! Reduce future problems & liability

58 Wind Driven Rain Louvers Horizontal blade models Vertical blade models 40% - 50% free area 2 to 8 deep Class 800 to 1200 fpm Moderate p Traditional appearance 40% - 45% free area 3 to 7 deep Class 1500 to 2100 fpm Low p Best performance 58

59 Sizing Example 48 x 48 & 7,000 cfm 6 Traditional 710 fpm.07 p 60% Wind Driven Rain Effectiveness (29 mph) Cost Horizontal WDR 1,002 fpm.16 p 99.8% Wind Driven Rain Effectiveness (29 mph) Cost Vertical WDR 1,030 fpm.09 p 99.8% Wind Driven Rain Effectiveness (50 mph) Cost x 36 (25% smaller) 1,488 fpm.18 p 99.8% Wind Driven Rain Effectiveness (50 mph) Cost 2.3

60 Rooftop Intakes Traditional style, allows rain penetration Wind Driven Rain Design, prevents rain penetration

61 What About Snow? 61

62 Suggestion for Stopping Snow Penetration Heated screen behind louver Prevents snow blowing into ductwork Reasonable pressure drop Relatively slow airflow -350 FPM Face area velocity.

63 Objective 7 Reduce Contaminant Concentrations through Ventilation, Filtration and Air Cleaning First goal is to reducing contaminant sources, then capturing & exhausting Remaining contaminants should be Diluted with ventilation air, or Reduced by filtration and gas-phased air cleaning (FAC) 63

64 Strategy 7.2 Continuously Monitor and Control Outdoor Air Delivery Fixed minimum outdoor air dampers may not provide optimum control of intake CFM, particularly in VAV systems Over-ventilation is common now estimated 30% annual savings in U.S. building energy costs if ventilation per standards is maintained 64

65 Suggestion for Maintaining Proper Outdoor Air Intake Levels Use air measuring station with built-in control damper and control system to maintain CFM set point 65

66 Air Measuring & Control Stations Advantages System automatically modulates damper to maintain CFM Can be used as minimum outside air damper only (overridden when economizer damper opens), or Can be used as entire outside air damper 66

67 Pressure Signal Chart text Air Measuring & Control Damper Documentation I/O Chart Provided w/ unit Calibration Certificate 0-10 VDC Input -CFM Setpoint 0 10 VDC Output -Measured CFM Alarm when CFM falls below setpoint

68 Strategy 7.2 Continuously Monitor and Control Outdoor Air Delivery Proper placement of airflow stations is critical Installing too close to an elbow or other disrupting feature can affect performance 68

69 Air Measurement Station Placements for Acceptable Installations

70 Air Measurement Station Placements for Acceptable Installations Air Measurement should be in the Mechanical Spec!

71 Air Measurement Station Placements for Acceptable Installations 5D 1D 90 DEGREE UNVANED ELBOW

72 Strategy 7.2 Continuously Monitor and Control Outdoor Air Delivery Consider using airflow measuring sensors between fixed louver blades Higher velocity, better accuracy

73 Accuracy Considerations: Outside Air Measurement Advantage Outside Air 20,000 CFM supply air measured ±1,000 5% accuracy (S.A.) 16,000 CFM return air measured ±800 5% accuracy (R.A.) Air Flow Sensing Stations THE DIFFERENCE Could be off by ±1,800 CFM Versus measurement at the intake 4,000 5% accuracy (O.A.) ±200 5% accuracy (O.A.)

74 Objective 8 Apply More Advanced Ventilation Approaches Strategy 8.2 Use Energy Recovery Ventilation Where Appropriate Required by ASHRAE & 2010 in some cases 74

75 Code Driven Requirements ASHRAE Energy Standard Energy recovery is required on individual fan systems that are: 5000 cfm or greater, and Outside air accounts for 70% or more of the design supply air quantity Energy recovery system shall have 50% effectiveness: Change in enthalpy equal to 50% of the difference between outdoor air and return air at design conditions

76 Status of Code Adoption: Commercial As of February 2013 Most States are Expected to Adopt by End of 2013!

77 DOE Climate Zone Map for 90.1 Helena MT Duluth, MN Boise, ID Chicago, IL Burlington, VT Salem, OR Baltimore MD San Francisco CA Phoenix, AZ El Paso, TX Memphis TN Miami FL Figure B-1 Albuquerque, NM Houston, TX

78 How do Climate Zones affect ERV? ASHRAE states: Exhaust Air Energy Recovery. Each fan system shall have an energy recovery system when the system s supply air flow rate exceeds the value listed in table based on the climate zone and percentage of outdoor air flow rate at design conditions.

79 ASHRAE Standard Stretch standard for energy efficiency Glimpse of the future of 90.1 Currently being specified for some government buildings Requires even more energy recovery As low as 10% outside air requires energy recovery in some cases The energy recovery effectiveness shall be 60%

80 Energy Recovery ERV Latent Recovery Energy Recovery Wheels Fixed Plate w/ Latent Transfer HRV Sensible Only (no latent) Fixed Plate Heat Pipe Runaround Loops 80

81 Wheel ERV s How They Work Wheel Rotates between the Return Air and the Outdoor Air Airstreams Return Air Temperature and Humidity is absorbed onto the Desiccant Wheel Outdoor Air is tempered (Heated/Cooled) as it flows across the Wheel Outdoor Air Humidity Decreases or Increases as air flows across the Wheel

82 Exhaust Air Transfer Ratio EATR is the % of air being exhausted from the occupied space that leaks around the ERV wheel and re-enters occupied space. Importance: Per ASHRAE 62.1

83 Dedicated Duct System

84 Ducted to Rooftop Unit

85 Common ERV Configurations Stand Alone Unitized Typically 300 to 12,000 CFM

86 Small ERV s 150 to 1000 CFM Only 18 to 22 tall!

87 Example of small ERV application

88 Small ERV Installation

89 Questions? 89

90 Thank You! 90