air sealing and ventilation improvements for multifamily buildings

Air sealing and ventilation

improvements for multifamily

buildings

February 2, 2012

Jim Fitzgerald Dave Bohac

Center for Energy and Environment

Better Buildings: Better Business Conference

Better air quality through sealing leaks between units and ventilation improvements

What causes problems?

Air leakage & air flow rate measurements

• 6 building CEE study

Air sealing and ventilation case studies

Maybe save energy too

What causes problems?

Sometimes people smoke (and cook and ??)

Convert to smoke-free building

Association of Nonsmokers - Minnesota

http://www.mnsmokefreehousing.org/

500+ smoke-free apartment buildings listed in Minnesota

http://www.mnsmokefreehousing.org/

Owners – cooking odors are worst problem

W hat type of odor or contam inant is the m ost com m on source of

objectionable air in buildings you m anage?

0% 5% 10% 15% 20% 25% 30% 35% 40% 45% 50%

cooking odors

tobacco odors

other

none

don't know

How big are air flows between units?

Pacific Northwest:

• Building average – 13 to 26% air from other units

• Individual units – as high as 35%

NJ mid-rise: 4th floor – 22% from other units

West Coast: 4% air from adjoining units

Francisco & Palmiter (1994)

Harrje et al (1988)

Feustal & Diamond (1988)

Multi-zone Tracer Gas Studies

How big are air leaks between units?

Minnesota: Modera et al. (1986)

• 52% air leaks between units

• 1900’s low-rise masonry

Chicago: Diamond et al. (1986)

• Similar results to Minnesota

• 1900’s low-rise

Sweden: Levin (1988)

• 12 to 36% air leaks between units

• 3 Swedish apartment buildings

What are the driving forces to

move air into and though

buildings?

What are the driving forces?

Winter

Stack Effect

Taller Building => Bigger Effect

In at the bottom and out the top


Wind Effect

In on windward side and out on leeward side

Taller Building => Bigger Effect

Mechanical ventilation is required by code:

bathrooms, corridors & some kitchens

Exhaust ventilation => draws air into an apartment

Flow imbalances can also cause air to move from

one apartment to another


Mechanical System Effect

Does it help for a smoker in a lower floor unit to open a window?

Not upstairs neighbor

Pressure in smoker’s unit

will be about the same as

outside, which increases

pressure to upstairs and

increases flow from

smoker’s unit to upstairs


Anyway it can!

Gaps in walls, floors, mechanical chases

Some are accessible and others too diffuse or

inaccessible for sealing

How does the air travel between units?

Gaps around sink plumbing

Most openings are small and diffuse

Baseboards and sprinkler heads

Chemical smoke moves out of baseboard leak

Clear acrylic caulk required plus moving bookcases, etc

Gaps along baseboard under carpet

Gaps behind baseboard heaters

Gaps around bath fan

Bathroom exhaust fans

Leaky (2.5 si)

Tight (0.1 si)

Recessed Light Fixtures

Hidden high rise chases = large uncontrolled flows

Can practical air sealing and

ventilation treatments reduce

secondhand smoke (SHS) transfer?

6 dissimilar buildings common to local multifamily

building types

This research project was funded in part by ClearWay Minnesota, … funded by proceeds from the Minnesota tobacco settlement. These findings are solely the responsibility of the authors and do not necessarily represent the official views of ClearWay Minnesota.

General approach to reduce odor transport between apartments and improve air quality

Ventilate the source • Capture source before transported

Reduce transport between apartments • Seal building leaks

• Reduce driving force - pressure difference

Ventilate receiver’s apartment


Ventilate

Seal

Ventilate

Duplex 8-Plex

12-Plex

1930s

1970

1964

Minnesota SHS transfer study

New 4 story

138 unit

11 story

1982

2001

1999

Minnesota SHS transfer study

Quantify – Building tests

+ Before and after fan pressurization tests

+ Total “effective leakage area” of apartment

+ Fraction of leakage area to outside and to other

units

Guarded Zone Multiple Fan Air Leakage Test

Up to 6 tests per unit

Test 1 Test 2

U nit A U nit B U nit C U nit A U nit B U nit C

Q B 1 Q A 2 Q B 2

C om m on A rea C om m on A rea

Q50

B to tal = Q B1 Q50

B to A = Q B1 - Q B2

Test 3 Test 4


Q B 3 Q C 3 Q B 4

Q C om m 4


Q50

B to C = Q B1 - Q B3 Q50

B exterio r = Q B4

Fan Fan Fan

Fan Fan Fan

Fan

Test 1 Test 2


Q B 1 Q A 2 Q B 2


Q50

B to tal = Q B1 Q50


Test 3 Test 4


Q B 3 Q C 3 Q B 4

Q C om m 4


Q50

B to C = Q B1 - Q B3 Q50

B exterio r = Q B4

Fan Fan Fan

Fan Fan Fan

Fan

Test 1 Test 2


Q B 1 Q A 2 Q B 2


Q50

B to tal = Q B1 Q50


Test 3 Test 4


Q B 3 Q C 3 Q B 4

Q C om m 4


Q50

B to C = Q B1 - Q B3 Q50

B exterio r = Q B4

Fan Fan Fan

Fan Fan Fan

Fan

Test 1 Test 2


Q B 1 Q A 2 Q B 2


Q50

B to tal = Q B1 Q50


Test 3 Test 4


Q B 3 Q C 3 Q B 4

Q C om m 4


Q50

B to C = Q B1 - Q B3 Q50

B exterio r = Q B4

Fan Fan Fan

Fan Fan Fan

Fan

1: Total Leakage

2: 1 – 2= Leak to Right

3: 1 – 3= Leak to Left

4: 1 – 4= Leak to Out

Quantify – Building tests

+ Before and after fan pressurization tests

+ Total “effective leakage area” of apartment

+ Fraction of leakage area to outside and to other units

+ Before and after tracer gas tests

+ Week long average tests

+ Passive perfluorocarbon tracers

+ Nicotine

+ Particles

+ Measure exhaust ventilation flow

+ Measure before/after treatments

+ Up to 7 units per building

Tracer gas tests show considerable air movement between apartments

Fraction of Air Coming From Adjoining

Units Compared to Total Inflow

Building Min Median Max Min Median Max Min Median Max Min Median Max

Duplex 6% 35% 65% 19% 27% 34% -30% -9% 13%

8-Plex 1% 3% 24% 3% 8% 42% -1% 5% 18%

12-Plex 1% 12% 26% 9% 12% 17% -9% 1% 8%

138 Unit 1% 11% 25% 1% 7% 22% 1% 1% 13% -12% -4% 0%

11 Story 2% 5% 12% 1% 2% 9% 0% 1% 4% -11% -3% -1%

4 Story 1% 2% 10% 0% 2% 7% -3% -1% 1%

All Units 1% 5% 65% 0% 3% 22% 0% 8% 42% -30% -1% 18%

ChangePre-Treatment (%) After Sealing (%) After Ventilation (%)

26% 16%

26%

One-week tracer gas measurements

Range Median

Top-floor units: 2 to 26% 16%

Mid-floor units: 1 to 20% 5%

Lowest-floor units: 1 to 4% 2%

How Does the Fraction Vary by Floor?

Fraction of Air Coming From Adjoining Units

Compared to Total Inflow


Total air leakage of individual units

Building Min Median Max Min Median Max Min Median Max < 1.25

Duplex 2,101 2,368 2,636 115 130 145 3.16 3.56 3.97 0%

8 Plex 837 1,008 1,031 46 55 57 1.93 2.04 2.46 0%

12 Plex 731 917 1,318 40 50 72 1.61 2.02 2.90 0%

138 Unit 390 665 754 21 37 41 0.86 1.01 2.06 88%

11 Story 376 454 958 21 25 53 0.57 0.76 2.14 86%

4 Story 921 1,156 1,559 51 63 86 1.05 1.85 2.30 14%

All Buildings 376 861 2,636 21 47 145 0.57 1.66 3.97 22%

NELA (si/100 sf)Ref. Flow Rate(cfm50) ELA (si)

Building Min Median Max Min Median Max Min Median Max < 1.25

Duplex 2,101 2,368 2,636 115 130 145 3.16 3.56 3.97 0%

8 Plex 837 1,008 1,031 46 55 57 1.93 2.04 2.46 0%

12 Plex 731 917 1,318 40 50 72 1.61 2.02 2.90 0%

138 Unit 390 665 754 21 37 41 0.86 1.01 2.06 88%

11 Story 376 454 958 21 25 53 0.57 0.76 2.14 86%

4 Story 921 1,156 1,559 51 63 86 1.05 1.85 2.30 14%

All Buildings 376 861 2,636 21 47 145 0.57 1.66 3.97 22%

NELA (si/100 sf)Ref. Flow Rate(cfm50) ELA (si)

LEED Green Building Rating system for MF SHS control requires ELA

divided by wall & floor & ceiling area to be less than 1.25 si/100 sf

ELA – equivalent leakage area, reference 4Pa & coef. = 1

(1999)

(1982)

(2001)

Blower door air leakage tests

Fraction of air leakage to adjacent units

Total

Building ELA (si) ELA (si) (%)

Duplex 130 26 20%

8 Plex1 55 28 59%

12 Plex1 50 28 57%

138 Unit 37 5 16%

11 Story 25 8 26%

4 Story 64

All Buildings 47 9 27%

1 - leakage to adjacent units includes leakage to common area

To Adjacent Units


Leakage Area of Individual Units

712

34

1.8

612

28

1.1

514 512 510

28 1.3 24 0.5 33

2.5 1.1 4.4

414 412 410

34 2.4 22 0.1 53

1.0 2.3 4.2

314 312 310

21 3.0 25 1.3 33

1.2

212

23

Elev

ato

r

11 Story Building


Ventilate

Seal

Ventilate

Air sealing treatments

Focus on leaks between units (not exterior)

Seal as much is practical – 3 to 8 hours/unit. Average cost of about $700/unit

Blower door test to monitor total leakage

Use visual/smoke puffer diagnostics sometimes aided by blower door. Tried IR in limited cases

Total and shared leakage

CFM50/unit

Existing After Treatments

Total Shared Total Shared

Duplex 2409 466 1881 601

8-plex 1032 475 916 307

12-plex 918 507 769 247

138 unit 641 90 639 88

New 4 story 1150 25 900 20

11 story 556 120 417 108


Modest overall reductions in leakage between apartment units – but some were significant

Range Median

Duplex: small change

8-plex: 21 to 44% 35%

12-plex: 14 to 70% 55%

New 138-unit: 0 to 23% small change

New 4-story: 0 to 20%

11-story: 0 to 56% 23%


Mechanical ventilation observations

Often provided only by occupant-operated (highly intermittent-typically off) bath fans

Many bath fans are better noise-generators than air movers, even when new

Apartment bath fans are not maintained (corrosion, dirt)

Apartment exhaust flows are rarely balanced

Continuous ventilation in code

“Old” Codes • Kitchens: 0 CFM OR 100+ CFM

• Baths: 50 CFM

2012 International Mech. Code • Kitchens: 25 CFM

• Bathrooms: 20 CFM

ASHRAE 62.1 -2010

5 cfm per person + 0.06cfm/sq ft

Kitchens: 50 cfm

Kitchenettes: 0.30 cfm/sq ft

Toilets: 25cfm

Corridor supply choices

Minimum 0.05 cfm/sq ft corridor area (IBC)

Minimum 0.06 cfm/sq ft corridor area ASHRAE 62.1-2010

Supply all ventilation to corridor & exhaust from units

Original design flow (typically higher)

Confirm with local code official

Ventilation treatments – for study

Install effective (and quiet) exhaust fans with capacity of at least 30 to 45cfm

Convert intermittent exhaust to continuous exhaust

Balance exhaust air flows to reduce ventilation driving force between units

Ventilation treatments Quiet, Continuous Ventilation

Constant Air Regulator

Quiet Ceiling Exhaust Multi-point

Ventilation rate increased substantially

60% Increase *only one unit with added fan


Duplex: 28 (12 to 43) 43 (35 to 50)

8-plex: 38 (19 to 58) 50 (26 to 79)

12-plex: 38 (23 to 75) 73 (57 to 157)

New 138-unit: 26 (15 to 47) 41 (31 to 53)

11-story: 28 (18 to 79) 69 (45 to 124)

4-story*: 45 (26 to 61) 48 (22 to 88)

Average 34 54

Median Ventilation Rate (cfm)

min to max


Cleaner air, same transfer rate

Original ventilation system may be a direct path

for smoke transfer (11 story, 138 unit, 4 story

ducts)

More smoke is captured near source

Dilution reduces concentration in nonsmoker’s

or receiver’s unit

Effect of Treatments: Air Transfer

Fraction of Incoming Air From Adjoining Units


Top-floor: 16% (2 to 26%) 13% (0 to 42%)

Mid-floor: 5% (1 to 20%) 2% (0 to 12%)

Lowest-floor: 2% (1 to 4%) 7% (1 to 19%)


Effect of Treatments

65% of the units had decreased air transfer

60% increase in ventilation rate

80% of tenants: SHS drift was less frequent and

less severe

Rooftop fan

with multiple

inlets

8-Plex Building 1 fan serves 4 units

25 26 28 26

23 26 27 24

47 28 32 53

26 17 9 32

Before

After

Non-smoker’s fan pulls from smoker’s

open plumbing chase

Open

between

tubs

Neighbor’s

bathtub

Why do our clothes smell like smoke?

Is better good enough?

+ Unit #3 contaminants in unit #7 decreased by

factor of five

+Fraction of air from unit #3 to #7 reduced from

11% to 6%

+Unit #3 ventilation rate increased 158%

+ Marked reduction of SHS odors per tenants

+ Will owners pay for it? Who can do the work?

Ongoing Success: 67 Buildings in

Condo Complex of Tested 8-plex

+ Condo Maintenance team trained to respond to

smoke complaints in additional buildings.

+ Smoker is back-charged for repair costs

+ 20 additional units have been completed to date

+ 15 more units are scheduled

+ Huge improvement in livability

+ Common areas air quality improved

Details of Ongoing work

+ Typical complaint has smoker on lower level with fan off and large bypasses venting smoke into chases.

+ Non-smoker on upper level often had higher exhaust fan flows which increased airflow from chase into unit. Stack effect enhances this flow in winter.

+ Seal major bypasses, 1-4 person hours

+ Ventilation modifications

+ Nonsmoker: replace fan damper with CAR

+ Smoker: remove fan damper and omit CAR for higher capture.

+ Typical flows are 25cfm in nonsmoker and 75cfm in smoker’s unit.

Existing Conditions

Practical & Effective Work

Rooftop fan with multiple inlets: high

rise case study

Many residents said fans didn’t work

PRV Fan on roof –

top of vent chase

Duct chase

Inside details

Not sealed

Vent louvers opened by dial

Inlet register on bathroom

wall or ceiling

FL

OO

R0 1 2 3 4 5 6 7 8 9 10 11 12 14 15 16 17

11 3 3 3 3 3 3 0 3 3 3 3 -1 3 3 0 3 3

10 3 3 3 3 3 3 3 3 3 3 3 -1 2 3 0 3 3

9 3 3 3 2 2 3 3 3 3 3 3 -1 2 3 0 0 2

8 2 3 3 0 2 3 2 3 3 3 -1 0 0 3 2 2 2

7 2 3 2 1 2 3 2 1 3 2 2 0 2 3 2 0 2

6 2 2 2 2 2 1 2 2 2 0 2 0 0 2 -1 0 2

5 2 2 2 3 -1 2 -1 2 2 0 0 2 2 2 -1 2 0

4 0 2 2 0 3 2 1 2 2 1 2 1 0 0 0 -1 0

3 1 -1 2 -1 2 2 2 1 2 1 0 2 1 0 0 0 0

2 2 0 2 -1 2 2 0 2 -1 2 0 0 2 2 0 2 0

1 2 2 2 2 2 2 0 0 2

Unit Number

Each apartment duct in shaft

Obstructs flow from below

Roof slab over top unit at shaft entry into fan baffle

Drywall joints open between

restrictions.

No suction left for design flow.

Ventilation System Problems

+ Restrictions caused most of the air to be

drawn from upper apartments

+ Duct leaks also reduced flow from lower

apartments and caused air to be drawn

from unknown sources

Floor Press Flow Notes

11 -74 28

10 -45 27

9 -15 14

8 -10.8 14

7 -9.5 10

6 na

5 +1.2 + stinks

4 +0.1 + smoker

3 +0.3 + stinks

2 -2.8 4

1 -5.3 8

Exhaust duct provided direct route for

smoke transfer

Smoke blew in my face as I tested the

CAR in the 5th floor with the roof fan on.

I called the office to postpone

the post installation tracer gas test

Solutions worked through

on 4 shafts

+ Remove minimum of central duct restrictions, provide 3” sub ducts to upper 2 floors.

+ Install constant air regulators or designed orifice plates on inlets in apartments.

+ Seal drywall ductwork with Aeroseal technology. Test and adjust to balance flows at low prv speed.

Thanks to Don Stevens for noticing fire code issue

Floor Press Flow

11 -74 28

10 -45 27

9 -15 14

8 -10.8 14

7 -9.5 10

6 na

5 +1.2 + stinks

4 +0.1 + smoker

3 +0.3 + stinks

2 -2.8 4

1 -5.3 8

floor Press Flow (203cfm)

11 -102 25

10 -54 20

9 -53 21

8 -59 21

7 -54 21

6 -39 19

5 test -28 16

4 smoker -23.5 15 (39, 75open)

3 test -23.8 15

2 -23.4 15

1 -23.4 15

Before After car/cut

Total flow 506cfm, 81% leaks Unit flow 93, none from lower 5 floors

Aeroseal=> equal flow in every unit

221cfm from units 279cfm total

Better results when run past normal residential stop point to reach 0 leakage

Sub duct or fire damper required

Fire damper requires steel framework not

present in this shaft. Rebuilding is required –

cost prohibitive in this case.

A sheet metal sub duct extending 22” above fan

inlet is allowed in building code. 3” diameter

will provide less restriction to shaft air flow.

Remove restrictions in 2 top inlets and

provide 3” sub ducts

3” sub duct in place after Aeroseal

3” orifice plate allows balancing with CAR , or tape to desired flow at lower stack pressure with less noise at top.

Floor Car P

pre

Unit cfm

Car P Aero

Unit Cfm

11 -74 28 -75 21

10 -45 27 -65 20

9 -15 14 -63 20

8 -10.8 14 -56 20

7 -9.5 10 -52 20

6 na -49 20

5 +1.2 + -42 20

4 +0.1 + -42 20

3 +0.3 + -42 20

2 -2.8 (4) -42 20

1 -5.3 (8) -44 20

Fan flow 506 93 280 221

First shaft

Aeroseal

Sub duct

repair

and CAR

installation

Looks

promising

What does this cost,

who pays, who can do it? •Licensed mechanical contractor required for all duct alterations.

•Aeroseal franchisee required for duct sealing. (Maint. prep ok)

•Performance contractor/ consultant for design, balancing, QC

•$300 per unit or $3,200 for 1 shaft minimum, $5,000 for 2 shafts

•Changes to the building are an Association responsibility.

•Airsealing in unit is responsibility of individual condo owner

Individual supply and very low

leakage required for best control

If an occupant opens a window to let smoke out air can

come in and blow smoke into adjacent units.

At 30F we measured a lower unit change pressure from

from -0.7pa to hall to +24pa to hall by opening 1 window.

Some flow still came in from under the kitchen kickboard

@+2pa to hall. The occupant complained about

intermittent smoke. Total air leakage down to 283cfm50

after work.

Some individuals may not tolerate any smoke transfer, a large improvement may not be enough.

Hidden chase openings often difficult to access

Add mineral wool fire-safing to high rise shaft openings

Seal with listed fire barrier

138 unit, little connection pre

324 323 322 321

601 9 17 574 3 622

+/-1 +/-13 +/-3

1 44

224 +/-7 223 222 +/-4 221

21 688 71 33 661 65 654

+/-7 +/-4

28 -4 2 64

124 +/-14 Guest +/-12 123 +/-15 122 +/-12 121

609 35 390 37 606 51 664 93 683

+/-8 +/-2 +/-8

Guarded-Zone Measured Air Leakage Rates

734

680

-13

+/-11

Oaks: Pre-Treatment

unit #

total leakage

unit/unit leakage

leakage precision

Low leakage between units

Foam plumbing openings

Seal baseboard behind tack strip

Seal ductwork from registers

Vent blocked : View inside smokers

fan duct in attic.

Vent blocked: Roof damper frozen shut

on same fan

CARs in fan duct in attic, smokers

open for higher flow

2 point system over guest and 224

3 point systems over 23(s) and 22

stacks

Unit flow Unit flow Unit flow

323 24cfm 322 25cfm

224 21cfm 223 20cfm 222 22cfm

G uest 26cfm 123 28cfm 122 20cfm

All ducts and bypasses in joist space

in 4 story

Aeroseal ducts in joist chase

Individual conditioning:

+ Duct fresh air intake to return with fan recycler and mech. damper

+ Point source exhaust

Wall behind baseboard open

Floor Edge Open To Joist space

New continuous duty fan in kitchen:

source of odor complaint.

Airsealing in unit above and source

unit credited with 90% reduction of

odor.

Baseboards, pipes, recessed lites

Cook below opens windows when cooking- negates fan effect.

Recommendations

Seal large openings between units

Balanced, 30 – 45cfm continuous exhaust

ventilation

Consider extra ventilation in smoker’s unit


Additional slides

Kitchen option for cooking source In different project after work

Cooking moisture was an issue in 15% of units

Continuous kitchen fan option needed

VenMar developed (UL) a quiet continuous

range hood

Kitchen option for cooking source Quiet Range Hood

Replace existing fans with continuous quiet range hood

Lo or high speed, no off

Less than 20 watts consumed at 34 cfm

High: 100,175 , or 225cfm

Additional Information

Canada Mortgage and Housing Corporation

Fact Sheet: Solving Odour Transfer Problems in Your Apartment

http://www.cmhc.ca/en/co/reho/reho_002.cfm

2-part Foam Seals Plumbing Chase Stop Vertical Air Transfer In Plumbing Wall

Patched, primed

Inject Foam Along Top of Wall

12-plex

Shared leakage reduced about

50% from 507 to 247 cfm50

Easy air flow is possible through

framing around pipes, etc

Note – Improvements are possible. Managing expectations is

important.

air sealing and ventilation improvements for multifamily buildings

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