MAD-AIR 2016 Mechanical Air Distribution and Interacting Relationships. John Tooley Advanced Energy (919)

Transcription

1 MAD-AIR 2016 Mechanical Air Distribution and Interacting Relationships John Tooley Advanced Energy (919) Tuesday, April 05, 2016

2 MAD-AIR When? 31 years ago 30 years ago 28 years ago Bought a blower door Began to test homes Wrote MAD-AIR

3 1988 Original Paper Google search: Mechanical Air Distribution and Interacting Relationships le/1969.1/6566/esl-hh pdf?sequence=3 MAD AIR

4 MAD-AIR Agenda A few air flow fundamentals 26 house study of pressure differences Soil depressurization study % of house air originating from the garage % of house air originating from the crawl space Code changes that effect MAD-AIR Real world effects

5 3 Driving forces that cause pressure differences in homes 1. Wind 2. Heat (stack pressure) 3. Fans Duct leakage Interior door closure Exhaust and supply fans Imbalanced flow in zones

6 Air Is A Carrier

7 Duct leakage 3. Fans Duct leakage Interior door closure Exhaust and supply fans Imbalanced flow in zones

8 One portion of SUPPLY air to the outside = One portion of unconditioned air in Supply Leakage To Outdoors Supply Air

9 Supply Leakage To Outside Can Cause A Negative Pressure In The House -

10 Return Leakage From Outdoors One portion of RETURN air in = One portion of conditioned air out Return Air

11 Return Leakage Can Cause Positive Pressure In The House +

12 Air change rate 236 Houses Infiltration rates AHU on and off Tracer Gas FL, NC, TN and WA 71% 26%

13 22 Two Story Colonials With Basement Duct leakage to the indoors we hope! Duct leakage to outside Duct leakage to inside 473 CFM 183 CFM Source: NAHB Research and EPA

14 Supply Leaks to Inside + +

15 Return Leaks to Inside

16 MAD-AIR house study to show interactions House age 1-5 years We looked at: Duct leakage Interior door closure Exhaust devices Combination

17 MAD-AIR is a function of 1. Tightness of the home or rooms 2. Flow to rooms and house 3. Existence of free flow of air back to the return 4. Exhausted air from the house 5. Supply air to the house 6. Occupant behavior

18 2015 IECC Climate Map & House Tightness 3 ACH 50 3 through 8 5 ACH 50 1 and 2

19 MAD AIR Facts The tighter the house envelope, the greater the pressure between inside and out Pa. WRT Out 200 CFM -5.0 Pa. WRT Out 200 CFM Leaky House 2,200 CFM50 7 ACH 50 Tighter House 800 CFM50 4 ACH 50 Assumes 1500 square feet with average ceiling height of 8

20 Square Inches All houses leakier than 2015 IECC Leakage Area in Square Inches of 26 New Houses Number of Houses

21 Duct Leakage Effects Duct leakage Interior door closure Exhaust devices Metal Flex

22 Pascals Duct Leakage To Outside Effects Duct Leak Pressure Difference (House With Reference to Outdoors) No pressure indicates 1. no leakage 2. equal supply and return leakage or 3. the house was too leaky to pressurize House WRT Outside Number of Houses

23 Pascals Duct Leakage To Outside Effects Duct Leak Pressure Difference (House With Reference to Outdoors) Number of Houses

24 Interior Door Closure Effects Duct leakage Interior door closure Exhaust devices

25 Interior Door Closure Pressure Effect - + FP Bedroom Bath Bedroom Master Suite R

26 Bedroom WRT Outside Pascals 1.6 Pascals Closed Bedroom WRT Outside Pressure Difference in Closed Rooms (With Reference to Outside) Number of Houses

27 Door Closure Pressure Effect Test No more than 3 pascals of pressure difference between the inside and outside with all bedroom doors closed and the heating or cooling system on high speed.

28 Pascals House Main Body WRT Outdoors All Interior Doors Closed (House With Reference to Outdoors) Main-body WRT Outdoors Number of Houses

29 Infiltration Rates In 5 Houses With Interior Doors Open and Closed (Tracer gas) Interior doors open (Ave. 0.31) Interior doors closed (Ave. 0.91) Number of Houses Source: Infiltration Rates and Pressure Differences in Florida Homes Caused by Closed Interior Doors When The Central Air Handler is On FSEC James B. Cummings, John J. Tooley and Neil Moyer

30 Air Change Rate Natural Infiltration Rate Vs. Interior Door Closure Air Change Rate (Tracer Gas) Mean Number of houses Natural ACH Interior Door ACH

31 Measured Infiltration Rates In One Home With Various Interior Door Positions (Tracer Gas) Blower On Blower Off N-ACH Duct Leakage ACH

32 Depressurization (Pa) of the Main Body Caused by Interior Doors Closed and AHU Operation Vs. Estimated Time Occupants Close Doors Door Closure (%) 100% 80% 69 Homes 60% 40% 20% Pressure Difference ( Main Body WRT Outside

33 Pressure Balance Defined All rivers that are dammed, release water in order to manage water levels behind the dam Allowing adequate water to the river below, neither too much nor too little All air dammed behind a closed interior door must be released to manage levels of comfort, energy use, moisture condensation and mold Allowing proper air flow from the closed room to the main portion of the house, neither too much nor too little Hall Ceiling Bedroom Ceiling

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35 2015 IMC and ACCA Manual D 2015 IMC Return Air Openings The amount of return air taken from any room or space shall not be greater than the flow rate of the supply air delivered to such room or space. ACCA Manual D Returns: A lowresistance return path is required for each zone. If a room is isolated from one of the returns, transfer grills can be used to establish a circulation path between the isolated room and the return

36 Pressure Relief??

37 ACCA Manual T

38

39 Fan Effects Duct leakage Interior door closure Exhaust devices

40 More Flow Out of Tighter Houses?

41 Pascals Interior Doors Closed and Exhaust Fans On (House With Reference to Outside) House WRT Outdoors Number of Houses

42 Pressures can cause Soil gas entry Garage vapor entry Combustion problems Spillage Back-drafting Flame roll-out Moisture damage and mold

43 Soil Gas Sources and Pathways Into The House Showering and Bathing Herbicides Fertilizers Soil: Radon, Pesticides/insecticides Sewer pipe leaks Septic drain fields

44 Soil Depressurization Study pa 1.75 pa 2.5 pa Patio Basement Pa. House WRT Outside 6.75 pa 9.25 pa 7.5 pa 3.5 pa 4.5 pa 3.5 pa 3.0 pa 2.5 pa 4.25 pa 1.8 pa 2. Garage 1. 3 ft. Lawrence Berkeley Laboratory

45 Pest Control

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47 Spray Fertilizer

48 Septic Drain Field

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51 Air Transported This house is depressurized

52 Air Transported This house is depressurized

53 Air Transported

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55 45% 40% 35% 30% 25% 20% 15% 10% 5% 0% Comparison of Median Infiltration Rates Proportion of House Air Originating from Garage 36.7% Forced Air Furnace in Garage N = 15 Stephen S. Morris, P.E. Municipality of Anchorage Department of Health and Human Services 17.0% Forced Air Furnace in House N = 5 31 Houses 18.4% Hydronic N=11

56 69 House Study (Alaska) Benzene Class A carcinogen US Govt. Minimal Risk Level (MRL = 4 ppb) One of the Top Ten Most Hazardous Air Pollutants Gasoline 3-5% benzene 60% of homes with attached garages had benzene levels that exceeded the US Govt. Minimal Risk Level (MRL = 4 ppb) Source: Phil Kaluza, ABSN, Alaska

57 What s in the garage can end up in the house

58 Proportion of House Air Originating from Crawl Space Source: Advanced Energy

59 Negative Pressure -

60 Backdrafting Back drafting is a hazardous situation!

61 Pressure Induced Flame Roll-Out Pressure induced flame roll-out is a hazardous situation! Flame Roll-out

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63 Kitchen sinks

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66 Flame Roll-out

67 Pressure Induced Flame Rollout

68 What normally happens

69 CO Detectors Solution: Sealed combustion or power vented inside living space or all electric.

70 3 Questions 1. Is Energy Efficiency more important than health, safety and durability? 2. Should we cure one problem without creating another? 3. Can we continue to treat buildings as incremental parts, improving one part without considering the whole?

71 QUESTIONS?