icwes15 - improving the thermal performance of framed window systems. presented by miss lizette jc...

Improving the Thermal Performance of Framed Window Systems

15th Annual International Conference for Women Engineers & Scientists

Presented by Lizette McNeill

Graduate Façade EngineerAECOM Australia Pty Ltd

Thursday July 21st, 2011

OUTLINE

21 July 201115ICWES – Paper 202

The Regulation: •The BCA – Section J •The NFRC

Curtain wall facades & thermal properties

Case Studies:1.Glass only

2.Typical Frame + Glass System

3.Improved Frame + Glass System

Where to from here...?

THE REGULATION

The BCA – Section JThe NFRC

The Building Code of Australia (BCA)


• 1st edition in 1996

• Updated May 1st

• State/Territory choose to:

• Set/sub-set terminology of the BCA: 1. Sections — A, B, etc.2. Parts — A1, A2, etc.

Adopt BCA in full

Adopt certain Sections

Vary requirements through relevant Appendix

ABCB 2006, cover + contents page

BCA – SECTION J, PART J2


“The Objective of this Section is to reduce greenhouse gas emissions by efficiently using energy” (ABCB 2006a, p354)

“By referring to glazing [the thermal performance is] to be assessed for the combined effect of the glass and frame” (ABCB 2006b, p474)

Energy consumption in commercial buildings accounts for approximately 10% of Australia’s greenhouse gas emissions

(COAG 2009; CIE 2007)

Section J – Energy Efficiency

Part J2: Glazing

Where does the designer go from here…?


Hint 1: Deemed-to-satisfy (DTS) Glazing Calculators –

Hint 2: Guide to the BCA –AFRC procedures…? As adopted/derived from NFRC procedures (ABCB 2010b, p487)

National Fenestration Rating Council (NFRC)


THERM5.2

OPTICS5

“[In 1989,] heat loss through buildings accounted for 25% of all heating dollars spent in the US”

(DoE in NFRC 2003, p5)

Late 1970s Energy Crisis

NFRC established in 1991 develops

maintains regulates

Derived from ISO15099

Lawrence Berkeley National Laboratory (LBNL) developed NFRC-approved 2D thermal modelling software:

WINDOW5.2

CASE STUDIES

3 different window systems

THERMAL PROPERTIES OF GLAZING


Air movement around the systemMeasure of conductance

The LOWER, the BETTER

Ratio that measures the amount of radiant heat passing through the glass/frame

ΔT across the glazing system

Resistivity (R) of materials

U-Value (W/m2.K)

Solar Heat Gain Coefficient (SHGC)

COMMERCIAL CURTAIN WALLS


BASE CASE MODEL


6mm = glass

DOUBLE GLAZED SYSTEM with LOW-E COATING

12mm = gas infill

1. AIR

2. ARGON

“6/12/6”

CASE STUDIES


Whole of System

(WoS)

Centre of Glass (CoG)

Case Study 3. Thermally enhanced curtain wall system

Case Study 1. Glass only - window

Case Study 2. ‘Typical’ curtain wall system

‘Typical’ aluminium

frame section

‘Enhanced’ aluminium

frame section

Case Study 2. Case Study 3.

METHOD OF ANALYSIS – LBNL Software


Step 1. Create glazing - WINDOW5.2

Step 3. Re-create framed window system – WINDOW5.2

Step 2. Create frames, insert glazing - THERM5.2

RESULTS

Case Study

Type of System (Thermal

Properties)

Glass Type & Arrangement Infill

Thermal Properties

SHGC U-ValueW/m²K

1 Glass-only system (CoG)

VNE19-636/12/6

Air 0.24 1.7

Argon 0.23 1.4

2Typical framed window system

(WoS)

VNE19-636/12/6

Air 0.23 2.9

Argon 0.23 2.7

3

Thermally enhanced framed window system

(WoS)

VNE19-636/12/6

Air 0.23 2.1

Argon 0.22 1.9


WHERE TO FROM HERE…?


“panel of wall located between vision areas of windows which conceal structural columns, floors and shear walls” (CMHC 2004, pA-12)

Spandrel areas currently covered under Part J1 – Building Fabric, J1.5 Walls.

FINAL WORDS


the obstacles to reducing greenhouse gas emissions through energy efficient building design are great and many…(IPCC 2007, p390)

Through modest changes to glazing design, we can start to see the ease with which energy efficient measures can be implemented...

REFERENCES


ABCB 2006, BCA 2006 –Volume One, Australian Building Codes Board, CanPrint Communications Pty Ltd, Canberra

ABCB 2006, BCA 2006 –Guide to the BCA 2006, Australian Building Codes Board, CanPrint Communications Pty Ltd, Canberra

ABCB 2011, Energy Efficiency Glazing Calculators, Australian Government, State and Territory Governments of Australia, viewed 07 Feb 2011, <www.abcb.gov.au/index.cfm?objectid=73874810-28B9-11DE-835E001B2FB900AA>

CIE 2007, Capitalising on the building sector’s potential to lessen the costs of broad based GHG emissions cut, Centre for International Economics, Canberra, Australia

CMHC 2004, Glass and Metal Curtain Walls – Best Practice Guide Building Technology, Canada Mortgage and Housing Corporation, Canada, available online via <www.cmhc.ca>

COAG 2009, National Strategy on Energy Efficiency, Council of Australian Governments, Commonwealth of Australia

IPCC 2007, Contribution of Working Group III to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Intergovernmental Panel on Climate Change, Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA [pp 387-446]

NFRC 2003, Behind the Glass – A history of NFRC as told by the people who lived it, National Fenestration Rating Council, National Fenestration Rating Council, Silver Spring, Maryland, USA

Thank You

…. Questions?

[email protected]