Large Building Airtightness: Where We're at and Where We're Going

Impact of Large Building Airtightness Requirements Buildings XIII Conference December 6th, 2016

Lorne Ricketts | MASc, P.Eng.

1 Outline  Intro to Requirements  Measured Performance  Industry Impact  What it Is, and What it Isn’t  Airtightness vs Air Leakage

2 Why We Care

 Infiltration and Exfiltration Affect:  Building Energy Consumption – Heat Loss and Gains ($)  Indoor Air Quality - Pollutants  Building Durability - Condensation  Occupant Comfort - Thermal & Acoustics

3 Many Air Barrier Systems Available

Loose Sheet Applied Sealed Gypsum Sheathing Liquid Applied Mass Walls Membrane – Taped Joints – Sealant Filler at Joints Sealants/Membranes (concrete) & StrappingBUT, IT’S THE DETAILS THAT MATTER

Self-Adhered vapor Self-Adhered vapor Sprayfoam Curtainwall, window-wall impermeable membrane permeable membrane & glazing systems 4 BRAND

House Wrap

BRAND

Materials Components Accessories

Whole Building Airtightness

5 Standards & Qualifications

 Washington State & Seattle, ABAA Target, GSA, IBC/IECC Option < 2.0 L/(s·m²) [0.40 cfm/ft²] @ 75 Pa  US Army Corps of Engineers & IGCC < 1.26 L/(s·m²) [0.25 cfm/ft²] at 75 Pa  Passive House 0.6 ACH50 (~0.60 L/(s·m²) [0.12 cfm/ft²] at 75 Pa)  LEED, 6-sided apartment test (~1.25 L/(s·m²) [0.25 cfm/ft²] at 50 Pa)  UK (AATMA) Large Buildings ~0.70 to 1.75 L/(s·m²) at 75 Pa [~0.14 to 0.34 cfm/ft² at 75 Pa]

6 Measured Performance

7 Where We’re At – The Numbers

 Airtightness testing data was compiled in a database from the following sources:  Published literature  Industry members  Unpublished data provided by the project team

721 Airtightness Tests

584 Unique Buildings

566 Acceptable Tests for Comparison

8 Where We’re At – The Numbers

Types of BuildingsBuilding in Database Types

25% Commercial 46% MURBMulti-Family Institutional 20% Military

9% Sample of 566 buildings

9 Where We’re At – The Numbers

Location of BuildingsBuilding in Locations Database

18% 16%

Canada USA UK

66% Sample of 566 buildings

10 Where We’re At – The Numbers

AirtightnessAirtightness Vs Year of Constructionvs Year of of Construction All Buildings

20 4.0 19 Sample of 179 Buildings 18 17 16 15 3.0 14 13 12 11 10 2.0 9 8 7 6 5 1.0 4

Airtightness [cfm/ft² @ 75 Pa] 75 @ [cfm/ft² Airtightness

Airtightness Airtightness [cfm/ft² @75 Pa] Airtightness Airtightness [L/(s·m²) @75 Pa] Airtightness [L/(s.m²) @ 75 Pa] 75 @ [L/(s.m²) Airtightness 2 1 0 0.0 19451945 19551955 19651965 19751975 19851985 19951995 20052005 20152015 ConstructionConstruction of of Building Building [year] [year]

11 Where We’re At – The Numbers

AirtightnessAirtightness Vs Height vs Height of All Buildings of Building 20 4.0 Sample of 420 Buildings Individual Buildings 15 Average 3.0

10 2.0

5 1.0

Airtightness [L/(s.m²) @ 75Pa] @ [L/(s.m²) Airtightness

Airtightness [cfm/ft² @ 75 Pa] 75 @ [cfm/ft² Airtightness

Airtightness Airtightness [cfm/ft² @75 Pa] Airtightness Airtightness [L/(s·m²) @75 Pa] 0 0.0 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 HeightHeight of of Buildings Building (Stories) (Storeys)

12 Impact of Requirements

13 Impact of Requirements

14 Performance of Air Barrier Systems

5.00 1.00

4.50 Leakiest Tested 0.90 4.00 0.80 3.50 0.70 3.00 0.60

2.50 Median 0.50 WA State Requirement 2.00 0.40

1.50 0.30 Airtightness [cfm/ft² @ 75 Pa] 75 @ [cfm/ft² Airtightness

Airtightness [L/(s·m²) @ 75 Pa] 75 @ [L/(s·m²) Airtightness 1.00 0.20

Airtightness Airtightness [cfm/ft² @75 Pa] Airtightness Airtightness [L/(s·m²) @75 Pa] 0.50 0.10 Tightest Tested 0.00 0.00 Liquid Applied Sealed Sheathing Sheet Applied Curtain (10 Buildings) (11 Buildings) (28 Buildings) Wall/Window Wall/Storefront 15 54 Buildings, Oct 2015 RDH Seattle Data (15 Buildings) Impact of Testing

16 The Life of a Building

17 The Life of a Building

Upstream Effects

Material Selection Assembly Design Quality Control

18 Changes in Air Barrier System Selection

 Seeing shifts from Mechanically Attached to Self-Adhesive & Liquid Applied membranes

19 New AB/WRB Materials

 Many new self-adhered and liquid applied vapour permeable sheathing membranes available on the market

20 Changes in Quality Control

 Noticeable improvements as soon as somebody cares – specific people designated to look at air barrier  Coordination between all team members essential

Air Boss 21 Impact of Requirements Opinions of the Current Airtightness Target Does airtightness Choose one of the following statements that best represents your Aside from the cost of the test itself, do you feel that whole building opinion(< 0.40 of current cfm/ft whole² buildingat 75 Pa)air leakage target in your airrequirement leakage requirements increase increase the cost? total cost of construction? [< 2.0 L/s·m² jurisdiction:at 75 Pa]

1111%% Aside from the cost of the test itself, do youChoose feel onethat of whole the following building statements that best represents your air leakage requirements increase the totalopinion cost of of construction? current whole building air leakage target in your Okay As Is 39%39% No, or not significantly jurisdiction: Too Stringent Yes, significant Too Lenient 61%61% 33%33% 56%56% Yes, moderate Other 0% 11%

39% No, or not significantly Okay As Is Too Stringent Yes, significant Too Lenient 61% 33% 56% Yes, moderate Other 22 0%

0% Impact of Requirements

Not Beneficial and Beneficial, but Not Worthwhile 5% Not Worthwhile 11%

84% Beneficial and Worthwhile 23 The Life of a Building

Upstream Effects

Material Selection Assembly Design Quality Control

24 The Life of a Building

Downstream Effects Energy Consumption Indoor Air Quality Acoustics Durability 25 What it Is, and What it Isn’t  Airtightness vs Air Leakage

26 Airtightness vs Air Leakage

 In-service air leakage is the combination of airtightness and pressure differences created by the driving forces of airflow

Stack Effect Wind Mechanical Systems Cumulative (-5°C) (4 m/s) (5 Pa)

27 Determining Air Leakage from Airtightness

 Difficult to extrapolate from airtightness test results to air leakage ratesAirflow versus Pressure 5 1

4 In-Service 0.8 Pressure Differences

3 0.6 ²] 2 0.4

1 0.2

0 0 Leaky

-1 -0.2 Average Tight

-2 -0.4

Normalized Airflow [cfm/ft Normalized Airflow [L/(s·m²)] -3 Test -0.6 -4 Pressure -0.8

-5 -1 -100 -75 -50 -25 0 25 50 75 100 28 Pressure Difference [Pa] Only One Piece Of the Puzzle

Controls Ventilation Whole Building Equipment Airtightness Airtightness testing helps with Building modelling inputs, but doesn’t Airflows give us the whole answer.

Climate Operable

Windows Occupants 29 Summary

 Airtightness performance and testing requirements have been successfully implemented in jurisdictions such as Washington State, the USACE, and the GSA.  Target of 2.0 L/(s·m²) (0.40 cfm/ft²) at 75 Pa is common and demonstrated to be consistently achievable

 Overall perceptions of whole building airtightness testing seem positive

 Airtightness is part of the puzzle for understanding building airflows & energy efficiency, but further research required to tie directly to indoor air quality and energy savings

30 Discussion + Questions

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