AA600_3_ThermalCalculations.pdf

AA600 SERIES Thermal Assessment ISSUE B D6003 - 1

Thermal Measurement, Assessment and Reference Tables

APRIL 2002

(Updated June 2002)


CONTENTS 1.0 Introduction Pg D6003-3 2.0 The Methods Pg D6003-3

2.1 Reference Tables 2.2 Simplified Calculation Methods 2.3 Computer Simulation 2.4 Measurement of Thermal Performance by Physical Testing

3.0 Comparisons of Thermal Assessment Methods Pg D6003-6 APPENDIX A: Reference Tables Pg D6003-7 1.0 Tables A1 to A6 of indicative window U-values APPENDIX B: Pg D6003-8 1.0 Sample Calculation to BS EN ISO 10077-1

2.0 Calculating Uframe Values APPENDIX C: Assessments to prEN ISO 10077-2 Pg D6003-15 APPENDIX D: Comparisons of Thermal Assessment Methods Pg D6003-21 APPENDIX E: List of References Pg D6003-22 APPENDIX F: Tables of 600 Series Uf values Pg D6003-24


THERMAL MEASUREMENT, ASSESSMENT AND REFERENCE TABLES

1.0 INTRODUCTION

U-values may be determined by several means • Indicative values given in tables • Simplified calculation methods using hand held calculators or by

using spreadsheets • Detailed calculations by means of computer simulation • Physical testing. Whichever method is used it should be noted that obtaining better values than those from a physical test should not be possible and the more simplified the method the more conservative should be the values obtained and greater the possible error. It should also be noted that, while calculated U-values are acceptable for Building Regulations, test results in accordance with the appropriate measurement standards should be preferred when available. Further details and guidance on using the above methods can be found in the relevant British Standards and other reference documents listed in Appendix E.

2.0 THE METHODS

2.1 Reference Tables Reference tables can be found in; • Building Regulations Document L2 for windows with metal

frames, Tables A2 & A3 page 35, based on a nominal 25% frame area. These cover glazing emissivities and widths of spacer bars for differing thermal break widths.

• BS EN ISO 10077-1 Annex F, tables F1 & F2 based on frame areas of 25% and 30%. These cover glazing centre pane U-values and Uframe values which can be calculated using this document.

Further more detailed reference tables can be found in Appendix A of this document covering aluminium windows and doors with a fraction of the frame area of 20%, 25% & 30%.


2.2 Simplified Calculation Methods;

• BS EN ISO 10077-1, Thermal performance of windows, doors and shutters – Calculation of thermal transmittance – Part 1: Simplified method. This Standard provides a simplified method of calculating whole window U-values requiring only basic dimensions of the window framing and thermal barrier and combining data from tables in the document. A detailed calculation of this method can be found in Appendix B.

• CAB - Setting the Standard No 3: A guide for the assessment of thermal performance of aluminium windows. This guide provides a more comprehensive method for assessing differing types of window construction and needs to be combined with the tables on Linear Transmission contained in BS EN ISO 10077-1 to calculate whole window U-values. Alternatively values of linear transmittance can be derived from BS EN ISO 6946 -Thermal performance of buildings and building components – Thermal resistance and thermal transmittance – Calculation method.

2.3 Computer Simulation

• prEN ISO 10077-2, Thermal performance of windows, doors

and shutters – Calculation of thermal transmittance – Part 2: Numerical methods for frames. This standard provides a more detailed method for assessing frame and whole window values by use of computer simulation software. This method can be used to calculate Uframe values for use with BS EN ISO 10077-1 where a simulation with an insulated panel with thermal conductivity λ = 0.035W/(mK) conductance is performed to obtain a Uf value. This standard can also be used to determine whole window U-values by assessing glazing in place of an insulated panel, this is achieved by combining the above simulations to derive a figure for the linear transmittance of the perimeter of the glazing. The whole window U-value can then be calculated as in BS EN ISO 10077-1.


• ISO DIS 15509, Thermal performance of windows, doors and

shading devices – Detailed calculations. Known as the “edge method” this method is found to be a much simpler procedure than prEN ISO 10077-2 and is a preferred method by the UK aluminium window industry. This method has the advantage of being suitable for assessing structural sealant glazing systems and curtain wall applications.

More detailed guidance on the above methods can be found in the CAB Guide “Setting the Standard No. 6, Thermal properties of Aluminium Fenestration Products and the Building Regulations – AD L1 & L2”.

2.4 Measurement of Thermal Performance by Physical Testing.

• BS EN ISO 12567-1, Thermal performance of windows, doors

and shutters – Determination of thermal performance by hot box method – Part 1 Complete windows and doors. This method tests a complete glazed window assembly but to pre-determined sizes to reduce the amount of work re-calibrating the hot box. The “standard” sizes for windows and doors are specified in the Window and external pedestrian door product standard pr EN 14351 and are as follows:

Windows - 1.23m wide x 1.48m high Single leaf doors - 1.0m wide x 2.0m high – no side or top panels Double leaf doors - 2.0m x 2.0m – equal split, no side or top panels Sliding leaf doors - 2.0m x 2.0m – equal split one fixed one slider

However the size and configuration of the test sample should be representative of those to be installed in the building. For buildings having to comply with ADL2 of the Building Regulations a window of the size stated above as a single opening pane is deemed to be representative of typical commercial windows. For dwellings further details can be found in the Glass and Glazing Federation, Data Sheet 2.2, 2002.


• Pr EN 12412-2 Windows, doors and shutters –

Determination of thermal performance by hot box method – Part 2: Frames. This Standard tests the frame material of the window by placing profiles side-by-side or back-to-back and infilling the glazing rebates with insulation to derive a Uframe value that can be used to calculate whole window U-values by use of BS EN ISO 10077-1 above.

3.0 COMPARISONS OF THERMAL ASSESSMENT METHODS

All the methods/standards above strive to produce an overall window U-value but differ in their approaches and for this reason it is not possible to directly compare the separate elements of, for example frame and glazing edge derived by the differing methods. In the case of condensation prediction Uframe values derived by BS EN ISO 10077-1 or pr EN 10077-2 with insulated panels should not be used, as they will give lower frame U-values than will be found in reality with glazing units. The CAB publication- Setting the Standard No. 3 provides useful information on assessing surface condensation risk of aluminium windows. For reference a comparison of the values derived from the different methods can be found in Appendix D.


APPENDIX A Reference Tables 1.0 Thermal transmittance of windows

Tables A1 to A6 give typical values for metal windows calculated to BS EN ISO 10077-1 using the linear thermal transmittances from annex E in the same document. Values for the frame (Uf) for fraction of the frame area of 20%, 25% and 30% of the whole window area and glazing centre-pane U-values (Ug) are given in the tables from which the average window U-value in W/(m²·K) can be derived.

Tables A1 to A3 show single and double-glazing uncoated or coated glass, air or gas space.

Tables A4 to A6 show triple-glazing uncoated or coated with two low emissivity coatings, air or gas space.

Appendix A Table A1

Thermal Transmittances for Aluminium Windows and Doors with fraction of the Frame area 20% of the whole window/door area.

Type of Ug UfGlazing W/(m²·K) W/(m²·K)

Frame Area 20%

2.5 2.6 2.7 2.8 2.9 3 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 4 4.2 4.5 5 6 7Single 5.7 5.1 5.1 5.1 5.1 5.1 5.2 5.2 5.2 5.2 5.2 5.3 5.3 5.3 5.3 5.3 5.4 5.4 5.5 5.6 5.8 6.0Double 3.3 3.3 3.4 3.4 3.4 3.4 3.4 3.5 3.5 3.5 3.5 3.5 3.6 3.6 3.6 3.6 3.6 3.7 3.8 3.9 4.1 4.3

uncoated 3.1 3.2 3.2 3.2 3.2 3.3 3.3 3.3 3.3 3.3 3.4 3.4 3.4 3.4 3.4 3.5 3.5 3.5 3.6 3.7 3.9 4.1Ψ = 0.06 2.9 3.0 3.0 3.1 3.1 3.1 3.1 3.1 3.2 3.2 3.2 3.2 3.2 3.3 3.3 3.3 3.3 3.4 3.4 3.5 3.7 3.9

2.7 2.9 2.9 2.9 2.9 2.9 3.0 3.0 3.0 3.0 3.0 3.1 3.1 3.1 3.1 3.1 3.2 3.2 3.3 3.4 3.6 3.8

Double 2.3 2.6 2.6 2.6 2.7 2.7 2.7 2.7 2.7 2.8 2.8 2.8 2.8 2.8 2.9 2.9 2.9 2.9 3.0 3.1 3.3 3.5coated 2.1 2.4 2.5 2.5 2.5 2.5 2.5 2.6 2.6 2.6 2.6 2.6 2.7 2.7 2.7 2.7 2.7 2.8 2.8 2.9 3.1 3.3Ψ = 0.08 1.9 2.3 2.3 2.3 2.3 2.4 2.4 2.4 2.4 2.4 2.5 2.5 2.5 2.5 2.5 2.6 2.6 2.6 2.7 2.8 3.0 3.2

1.8 2.2 2.2 2.2 2.3 2.3 2.3 2.3 2.3 2.4 2.4 2.4 2.4 2.4 2.5 2.5 2.5 2.5 2.6 2.7 2.9 3.11.7 2.1 2.1 2.2 2.2 2.2 2.2 2.2 2.3 2.3 2.3 2.3 2.3 2.4 2.4 2.4 2.4 2.5 2.5 2.6 2.8 3.01.6 2.0 2.1 2.1 2.1 2.1 2.1 2.2 2.2 2.2 2.2 2.2 2.3 2.3 2.3 2.3 2.3 2.4 2.4 2.5 2.7 2.91.5 2.0 2.0 2.0 2.0 2.0 2.1 2.1 2.1 2.1 2.1 2.2 2.2 2.2 2.2 2.2 2.3 2.3 2.4 2.5 2.7 2.91.4 1.9 1.9 1.9 1.9 2.0 2.0 2.0 2.0 2.0 2.1 2.1 2.1 2.1 2.1 2.2 2.2 2.2 2.3 2.4 2.6 2.81.3 1.8 1.8 1.8 1.9 1.9 1.9 1.9 1.9 2.0 2.0 2.0 2.0 2.0 2.1 2.1 2.1 2.1 2.2 2.3 2.5 2.71.2 1.7 1.7 1.8 1.8 1.8 1.8 1.8 1.9 1.9 1.9 1.9 1.9 2.0 2.0 2.0 2.0 2.1 2.1 2.2 2.4 2.61.1 1.6 1.7 1.7 1.7 1.7 1.7 1.8 1.8 1.8 1.8 1.8 1.9 1.9 1.9 1.9 1.9 2.0 2.0 2.1 2.3 2.5

Appendix A Table A2



Frame Area 25%

2.5 2.6 2.7 2.8 2.9 3 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 4 4.2 4.5 5 6 7Single 5.7 4.9 4.9 5.0 5.0 5.0 5.0 5.1 5.1 5.1 5.1 5.2 5.2 5.2 5.2 5.3 5.3 5.3 5.4 5.5 5.8 6.0Double 3.3 3.3 3.3 3.3 3.4 3.4 3.4 3.4 3.5 3.5 3.5 3.5 3.6 3.6 3.6 3.6 3.7 3.7 3.8 3.9 4.2 4.4

uncoated 3.1 3.1 3.2 3.2 3.2 3.2 3.3 3.3 3.3 3.3 3.4 3.4 3.4 3.4 3.5 3.5 3.5 3.6 3.6 3.8 4.0 4.3Ψ = 0.06 2.9 3.0 3.0 3.0 3.1 3.1 3.1 3.1 3.2 3.2 3.2 3.2 3.3 3.3 3.3 3.3 3.4 3.4 3.5 3.6 3.9 4.1

2.7 2.8 2.9 2.9 2.9 2.9 3.0 3.0 3.0 3.0 3.1 3.1 3.1 3.1 3.2 3.2 3.2 3.3 3.3 3.5 3.7 4.0

Double 2.3 2.6 2.6 2.6 2.7 2.7 2.7 2.7 2.8 2.8 2.8 2.8 2.9 2.9 2.9 2.9 3.0 3.0 3.1 3.2 3.5 3.7coated 2.1 2.4 2.5 2.5 2.5 2.5 2.6 2.6 2.6 2.6 2.7 2.7 2.7 2.7 2.8 2.8 2.8 2.9 2.9 3.1 3.3 3.6Ψ = 0.08 1.9 2.3 2.3 2.3 2.4 2.4 2.4 2.4 2.5 2.5 2.5 2.5 2.6 2.6 2.6 2.6 2.7 2.7 2.8 2.9 3.2 3.4

1.8 2.2 2.2 2.2 2.3 2.3 2.3 2.4 2.4 2.4 2.4 2.5 2.5 2.5 2.5 2.6 2.6 2.6 2.7 2.8 3.1 3.31.7 2.1 2.1 2.2 2.2 2.2 2.2 2.3 2.3 2.3 2.4 2.4 2.4 2.4 2.5 2.5 2.5 2.6 2.6 2.8 3.0 3.31.6 2.0 2.1 2.1 2.1 2.1 2.2 2.2 2.2 2.2 2.3 2.3 2.3 2.4 2.4 2.4 2.4 2.5 2.6 2.7 2.9 3.21.5 2.0 2.0 2.0 2.0 2.1 2.1 2.1 2.1 2.2 2.2 2.2 2.2 2.3 2.3 2.3 2.4 2.4 2.5 2.6 2.9 3.11.4 1.9 1.9 1.9 2.0 2.0 2.0 2.0 2.1 2.1 2.1 2.1 2.2 2.2 2.2 2.2 2.3 2.3 2.4 2.5 2.8 3.01.3 1.8 1.8 1.9 1.9 1.9 1.9 2.0 2.0 2.0 2.0 2.1 2.1 2.1 2.1 2.2 2.2 2.2 2.3 2.5 2.7 3.01.2 1.7 1.8 1.8 1.8 1.8 1.9 1.9 1.9 1.9 2.0 2.0 2.0 2.0 2.1 2.1 2.1 2.2 2.2 2.4 2.6 2.91.1 1.7 1.7 1.7 1.7 1.8 1.8 1.8 1.8 1.9 1.9 1.9 1.9 2.0 2.0 2.0 2.0 2.1 2.2 2.3 2.6 2.8

Appendix A Table A3



Frame Area 30%

2.5 2.6 2.7 2.8 2.9 3 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 4 4.2 4.5 5 6 7Single 5.7 4.7 4.8 4.8 4.8 4.9 4.9 4.9 5.0 5.0 5.0 5.0 5.1 5.1 5.1 5.2 5.2 5.3 5.3 5.5 5.8 6.1Double 3.3 3.2 3.3 3.3 3.3 3.4 3.4 3.4 3.4 3.5 3.5 3.5 3.6 3.6 3.6 3.7 3.7 3.8 3.8 4.0 4.3 4.6

uncoated 3.1 3.1 3.1 3.2 3.2 3.2 3.2 3.3 3.3 3.3 3.4 3.4 3.4 3.5 3.5 3.5 3.6 3.6 3.7 3.9 4.2 4.5Ψ = 0.06 2.9 3.0 3.0 3.0 3.0 3.1 3.1 3.1 3.2 3.2 3.2 3.3 3.3 3.3 3.3 3.4 3.4 3.5 3.6 3.7 4.0 4.3

2.7 2.8 2.8 2.9 2.9 2.9 3.0 3.0 3.0 3.1 3.1 3.1 3.1 3.2 3.2 3.2 3.3 3.3 3.4 3.6 3.9 4.2

Double 2.3 2.6 2.6 2.6 2.7 2.7 2.7 2.8 2.8 2.8 2.9 2.9 2.9 2.9 3.0 3.0 3.0 3.1 3.2 3.3 3.6 3.9coated 2.1 2.4 2.5 2.5 2.5 2.6 2.6 2.6 2.7 2.7 2.7 2.7 2.8 2.8 2.8 2.9 2.9 3.0 3.0 3.2 3.5 3.8Ψ = 0.08 1.9 2.3 2.3 2.4 2.4 2.4 2.4 2.5 2.5 2.5 2.6 2.6 2.6 2.7 2.7 2.7 2.8 2.8 2.9 3.1 3.4 3.7

1.8 2.2 2.3 2.3 2.3 2.3 2.4 2.4 2.4 2.5 2.5 2.5 2.6 2.6 2.6 2.7 2.7 2.7 2.8 3.0 3.3 3.61.7 2.2 2.2 2.2 2.2 2.3 2.3 2.3 2.4 2.4 2.4 2.5 2.5 2.5 2.6 2.6 2.6 2.7 2.8 2.9 3.2 3.51.6 2.1 2.1 2.1 2.2 2.2 2.2 2.3 2.3 2.3 2.4 2.4 2.4 2.4 2.5 2.5 2.5 2.6 2.7 2.8 3.1 3.41.5 2.0 2.0 2.1 2.1 2.1 2.2 2.2 2.2 2.3 2.3 2.3 2.3 2.4 2.4 2.4 2.5 2.5 2.6 2.8 3.1 3.41.4 1.9 2.0 2.0 2.0 2.1 2.1 2.1 2.2 2.2 2.2 2.2 2.3 2.3 2.3 2.4 2.4 2.5 2.6 2.7 3.0 3.31.3 1.9 1.9 1.9 2.0 2.0 2.0 2.1 2.1 2.1 2.1 2.2 2.2 2.2 2.3 2.3 2.3 2.4 2.5 2.6 2.9 3.21.2 1.8 1.8 1.9 1.9 1.9 2.0 2.0 2.0 2.0 2.1 2.1 2.1 2.2 2.2 2.2 2.3 2.3 2.4 2.6 2.9 3.21.1 1.7 1.8 1.8 1.8 1.9 1.9 1.9 1.9 2.0 2.0 2.0 2.1 2.1 2.1 2.2 2.2 2.2 2.3 2.5 2.8 3.1

Appendix A Table A4



Frame Area 20%

2.5 2.6 2.7 2.8 2.9 3 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 4 4.2 4.5 5 6 7Triple 2.3 2.5 2.6 2.6 2.6 2.6 2.6 2.7 2.7 2.7 2.7 2.7 2.8 2.8 2.8 2.8 2.8 2.9 2.9 3.0 3.2 3.4

uncoated 2.1 2.4 2.4 2.4 2.4 2.5 2.5 2.5 2.5 2.5 2.6 2.6 2.6 2.6 2.6 2.7 2.7 2.7 2.8 2.9 3.1 3.3Ψ = 0.06 2.0 2.3 2.3 2.3 2.4 2.4 2.4 2.4 2.4 2.5 2.5 2.5 2.5 2.5 2.6 2.6 2.6 2.6 2.7 2.8 3.0 3.2

1.9 2.2 2.2 2.3 2.3 2.3 2.3 2.3 2.4 2.4 2.4 2.4 2.4 2.5 2.5 2.5 2.5 2.6 2.6 2.7 2.9 3.11.8 2.1 2.2 2.2 2.2 2.2 2.2 2.3 2.3 2.3 2.3 2.3 2.4 2.4 2.4 2.4 2.4 2.5 2.5 2.6 2.8 3.01.7 2.1 2.1 2.1 2.1 2.1 2.2 2.2 2.2 2.2 2.2 2.3 2.3 2.3 2.3 2.3 2.4 2.4 2.5 2.6 2.8 3.0

1.6 2.0 2.0 2.0 2.0 2.1 2.1 2.1 2.1 2.1 2.2 2.2 2.2 2.2 2.2 2.3 2.3 2.3 2.4 2.5 2.7 2.9

Triple 1.7 2.1 2.1 2.2 2.2 2.2 2.2 2.2 2.3 2.3 2.3 2.3 2.3 2.4 2.4 2.4 2.4 2.5 2.5 2.6 2.8 3.02 panes 1.6 2.0 2.1 2.1 2.1 2.1 2.1 2.2 2.2 2.2 2.2 2.2 2.3 2.3 2.3 2.3 2.3 2.4 2.4 2.5 2.7 2.9coated 1.5 2.0 2.0 2.0 2.0 2.0 2.1 2.1 2.1 2.1 2.1 2.2 2.2 2.2 2.2 2.2 2.3 2.3 2.4 2.5 2.7 2.9Ψ = 0.08 1.4 1.9 1.9 1.9 1.9 2.0 2.0 2.0 2.0 2.0 2.1 2.1 2.1 2.1 2.1 2.2 2.2 2.2 2.3 2.4 2.6 2.8

1.3 1.8 1.8 1.8 1.9 1.9 1.9 1.9 1.9 2.0 2.0 2.0 2.0 2.0 2.1 2.1 2.1 2.1 2.2 2.3 2.5 2.7

1.2 1.7 1.7 1.8 1.8 1.8 1.8 1.8 1.9 1.9 1.9 1.9 1.9 2.0 2.0 2.0 2.0 2.1 2.1 2.2 2.4 2.61.1 1.6 1.7 1.7 1.7 1.7 1.7 1.8 1.8 1.8 1.8 1.8 1.9 1.9 1.9 1.9 1.9 2.0 2.0 2.1 2.3 2.51 1.6 1.6 1.6 1.6 1.6 1.7 1.7 1.7 1.7 1.7 1.8 1.8 1.8 1.8 1.8 1.9 1.9 2.0 2.1 2.3 2.5

0.9 1.5 1.5 1.5 1.5 1.6 1.6 1.6 1.6 1.6 1.7 1.7 1.7 1.7 1.7 1.8 1.8 1.8 1.9 2.0 2.2 2.40.8 1.4 1.4 1.4 1.4 1.5 1.5 1.5 1.5 1.6 1.6 1.6 1.6 1.6 1.7 1.7 1.7 1.7 1.8 1.9 2.1 2.3

Appendix A Table A5



Frame Area 25%

2.5 2.6 2.7 2.8 2.9 3 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 4 4.2 4.5 5 6 7Triple 2.3 2.5 2.6 2.6 2.6 2.6 2.7 2.7 2.7 2.7 2.8 2.8 2.8 2.8 2.9 2.9 2.9 3.0 3.0 3.2 3.4 3.7

uncoated 2.1 2.4 2.4 2.4 2.5 2.5 2.5 2.5 2.6 2.6 2.6 2.6 2.7 2.7 2.7 2.7 2.8 2.8 2.9 3.0 3.3 3.5Ψ = 0.06 2.0 2.3 2.3 2.3 2.4 2.4 2.4 2.5 2.5 2.5 2.5 2.6 2.6 2.6 2.6 2.7 2.7 2.7 2.8 2.9 3.2 3.4

1.9 2.2 2.2 2.3 2.3 2.3 2.3 2.4 2.4 2.4 2.5 2.5 2.5 2.5 2.6 2.6 2.6 2.7 2.7 2.9 3.1 3.41.8 2.1 2.2 2.2 2.2 2.2 2.3 2.3 2.3 2.3 2.4 2.4 2.4 2.5 2.5 2.5 2.5 2.6 2.7 2.8 3.0 3.31.7 2.1 2.1 2.1 2.1 2.2 2.2 2.2 2.2 2.3 2.3 2.3 2.3 2.4 2.4 2.4 2.5 2.5 2.6 2.7 3.0 3.2

1.6 2.0 2.0 2.0 2.1 2.1 2.1 2.1 2.2 2.2 2.2 2.2 2.3 2.3 2.3 2.3 2.4 2.4 2.5 2.6 2.9 3.1


1.3 1.8 1.8 1.9 1.9 1.9 1.9 2.0 2.0 2.0 2.0 2.1 2.1 2.1 2.1 2.2 2.2 2.2 2.3 2.5 2.7 3.01.2 1.7 1.8 1.8 1.8 1.8 1.9 1.9 1.9 1.9 2.0 2.0 2.0 2.0 2.1 2.1 2.1 2.2 2.2 2.4 2.6 2.91.1 1.7 1.7 1.7 1.7 1.8 1.8 1.8 1.8 1.9 1.9 1.9 1.9 2.0 2.0 2.0 2.0 2.1 2.2 2.3 2.6 2.81 1.6 1.6 1.6 1.7 1.7 1.7 1.7 1.8 1.8 1.8 1.8 1.9 1.9 1.9 1.9 2.0 2.0 2.1 2.2 2.5 2.7

0.9 1.5 1.5 1.6 1.6 1.6 1.6 1.7 1.7 1.7 1.7 1.8 1.8 1.8 1.8 1.9 1.9 1.9 2.0 2.1 2.4 2.70.8 1.4 1.5 1.5 1.5 1.5 1.6 1.6 1.6 1.6 1.7 1.7 1.7 1.7 1.8 1.8 1.8 1.9 1.9 2.1 2.3 2.6

Appendix A Table A6



Frame Area 30%

2.5 2.6 2.7 2.8 2.9 3 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 4 4.2 4.5 5 6 7Triple 2.3 2.5 2.6 2.6 2.6 2.7 2.7 2.7 2.7 2.8 2.8 2.8 2.9 2.9 2.9 3.0 3.0 3.0 3.1 3.3 3.6 3.9

uncoated 2.1 2.4 2.4 2.5 2.5 2.5 2.5 2.6 2.6 2.6 2.7 2.7 2.7 2.8 2.8 2.8 2.8 2.9 3.0 3.1 3.4 3.8Ψ = 0.06 2 2.3 2.3 2.4 2.4 2.4 2.5 2.5 2.5 2.6 2.6 2.6 2.7 2.7 2.7 2.7 2.8 2.8 2.9 3.1 3.4 3.7

1.9 2.2 2.3 2.3 2.3 2.4 2.4 2.4 2.5 2.5 2.5 2.6 2.6 2.6 2.6 2.7 2.7 2.8 2.9 3.0 3.3 3.61.8 2.2 2.2 2.2 2.3 2.3 2.3 2.4 2.4 2.4 2.5 2.5 2.5 2.5 2.6 2.6 2.6 2.7 2.8 2.9 3.2 3.5

1.7 2.1 2.1 2.2 2.2 2.2 2.3 2.3 2.3 2.3 2.4 2.4 2.4 2.5 2.5 2.5 2.6 2.6 2.7 2.9 3.2 3.51.6 2.0 2.1 2.1 2.1 2.2 2.2 2.2 2.2 2.3 2.3 2.3 2.4 2.4 2.4 2.5 2.5 2.6 2.6 2.8 3.1 3.4


1.3 1.9 1.9 1.9 2.0 2.0 2.0 2.1 2.1 2.1 2.1 2.2 2.2 2.2 2.3 2.3 2.3 2.4 2.5 2.6 2.9 3.21.2 1.8 1.8 1.9 1.9 1.9 2.0 2.0 2.0 2.0 2.1 2.1 2.1 2.2 2.2 2.2 2.3 2.3 2.4 2.6 2.9 3.21.1 1.7 1.8 1.8 1.8 1.9 1.9 1.9 1.9 2.0 2.0 2.0 2.1 2.1 2.1 2.2 2.2 2.2 2.3 2.5 2.8 3.11 1.7 1.7 1.7 1.8 1.8 1.8 1.8 1.9 1.9 1.9 2.0 2.0 2.0 2.1 2.1 2.1 2.2 2.3 2.4 2.7 3.0

0.9 1.6 1.6 1.7 1.7 1.7 1.7 1.8 1.8 1.8 1.9 1.9 1.9 2.0 2.0 2.0 2.0 2.1 2.2 2.3 2.7 3.00.8 1.5 1.6 1.6 1.6 1.6 1.7 1.7 1.7 1.8 1.8 1.8 1.9 1.9 1.9 1.9 2.0 2.0 2.1 2.3 2.6 2.9


APPENDIX B 1.0 Sample Calculation to BS EN ISO 10077-1

The following example shows how to calculate the average U-value in W/(m²·K) for a 603 Tilt-Turn window. The window configuration is shown opposite in fig.1 and consists of a Tilt-Turn vent adjacent to a Fixed Light separated a centrally placed vertical muntin.


The thermal transmittance of a window Uw in W/(m2·K) is calculated using the following equation: Uw = Ag.Ug + Af.Uf + lg.Ψg Ag + Af Where: Ag is the visible area of the glazing, in m². Ug is the centre-pane U-value of the glazing in, W/(m2·K). Af is the area of frame, in m². Uf is the thermal transmittance of the frame, in W/(m2·K). lg is the perimeter length of the glazing edge, in m. Ψg is the linear thermal transmittance due to the combined thermal effects of glazing, spacer and frame, in W/mK. The first step is to look-up the Uf values from the Tables in Appendix F. An example of how to calculate the Uf value is also provided following this example. The Uf values are as follows; Frame & Vent Profiles 698-202 & -215 Detail D6031-03 = 2.91 W/(m2·K) Frame Profile 698-202 Detail D6006-02 = 2.92 W/(m2·K) Muntin & Vent Profiles 698-242 & -215 Detail D6031-12 = 2.98 W/(m2·K) The 24mm Glazing unit consists of two 4mm panes of glass and a 16mm aluminium spacer bar (4-16-4), air filled cavity and a normal emissivity coating of En = 0.2 giving a centre pane U-value of 1.8 W/(m2·K). Note: where available use centre-pane values to two decimal places. The other values are as follows; Ag = 1.410 x 1.027 + 1.482 x 1.099 = 3.077m². Ug = 1.8 W/(m2·K). Af = 0.763m². Uf = 2.93 W/(m2·K) lg = 10.036m. Ψg = 0.08 W/(m·K) Note: Values of the linear thermal transmittance�are given in table E.1 of BS EN ISO 10077-1 and for metal windows are: • 0.06 W/(m·K) for double or triple glazing, uncoated glass with air or gas

filled space or • 0.08 W/(m·K) for double glazing with low emissivity, triple glazing with two

low emissivity coatings with air or gas filled space.


Uw = 3.077x1.8 + 0.763x2.93 + 10.036x0.08 3.077 + 0.763 Whole window U-value = Uw = 2.23 W/(m2·K) rounded to 2.2 W/(m2·K) The spreadsheet calculation follows:

603Uf Window 1.6 x 2.4 Central Vertical Muntin with Vent/fixed-light

m² W(m2·K) % Total AreaTotal Area 3.84 U-Value = 2.23

Frame Area Uf LHS 0.347 2.91 1.010 9.04%RHS 0.224 2.92 0.654 5.84%Muntin Area 0.192 2.98 0.572 5.00%Total Frame Area 0.763 Frame Conductance = 2.237 19.88%Average frame U-value 2.931 Glass Area Centre Pane U-value LHS 1.448 1.8 2.607 37.71%RHS 1.629 1.8 2.932 42.41%

100.00% m Ψ

Linear Transmittance 10.036 0.08 0.803 m²

Check Area 3.84 Total Conductance 8.578


2.0 Calculating Uframe values

BS EN ISO 10077-1 provides the method to calculate Uframe values. Using the example frame and vent shown in fig. 2, the Uf value is obtained as follows;

Uframe = 1 Rsi. Af/Adi + Rf + Rse. Af/Ade

Where; Af = Profile sightline Adi = Developed internal dimension Ade = Developed external dimension Rsi = Internal surface resistance in m2·KW = 0.13 m2·KW Rse = External surface resistance in m2·KW = 0.04 m2·KW Rf = Frame Thermal Resistance in W(m2·K)

Note: Rf = 1 - 0.17

Ufo

Ufo = Thermal resistance of metal frames W(m2·K)

This value can be obtained from Figure D.4 in BS EN ISO 10077-1 or from the table B1 below. The length of the thermal break is taken as the smallest distance between opposing metal sections.

Table B1

TB Length 4mm 8mm 12mm 16mm 20mm 24mm 28mm 32mm 36mm Ufo 4.00 3.55 3.20 2.95 2.75 2.62 2.56 2.52 2.50

Note: In the following example the frame sightline and developed internal and external dimensions are used to simplify the calculation and obtain a generic Uf value . BS EN ISO 10077-1 requires projected frame areas to be used in the calculation the difference to the results is insignificant in terms of the calculated whole window U-value.


Af is the profile sightline = 90mm (largest dimension on internal or external face)

Adi is the developed internal dimension = 123mm Ade is the developed external dimension = 99mm Rsi is the internal surface resistance = 0.13 m2·KW Rse is the external surface resistance = 0.04 m2·KW Ufo is the thermal resistance of metal frames = 2.68 W/(m2·K)

Rf = 1 - 0.17 = 0.203 W/(m2·K)

2.68

Note: The Ufo value has been taken as the average of the 25mm thermal break on the frame and the 20mm thermal break on the vent = 25+20/2 = 22.5mm

1 Uframe = 0.13x90/123 + 0.203 + 0.04x90/99 = 2.99 W/(m2·K)


APPENDIX C 1.0 Assessments to prEN ISO 10077-2 This standard specifies a method for the calculation of the thermal

transmittance (Uf ) vertical frame profiles, and the linear transmittance (Ψ This latter property is used to characterize the edge effects due to glass or other material infill.

This standard also contains tables of thermal conductivity

(λ -value) for selected materials. Users of this standard will need to verify the suitability of the

calculation program used by carrying out calculations on examples given in this standard to within allowable deviations from the values given in the text.

1.1 Thermal transmittance of the frame section

The following diagrams show outputs from a typical thermal analysis program for the example shown in fig 1, Detail D6031-02.

Figure 3 shows an assessment for a frame and vent glazed with an insulated panel with a thermal conductivity λ = 0.035W/(mK). Note: the visible panel and glazing width is 190mm as set out in the standard.

Figure 4 shows the same detail but glazed with a 24mm DGU with a centre-pane U-value calculated at 1.77 W/(m2·K).


Fig 3 Showing the window glazed with an insulated panel of conductivity λ = 0.035W/(mK). This gives a U-factor of 1.800 W/(m2·K) for the elevation shown.


Fig 4 Showing the window glazed with a with a 24mm DGU with a centre-pane U-value calculated at 1.77 W/(m2·K). This gives a U-factor of 2.447 W/(m2·K) for the elevation shown.


Thermal transmittance of the frame (Uf ) is given by:

Uf = Lf2D – Up • bp

bf Where: Uf is the thermal transmittance of the frame section, in W/(m2·K) Lf

2D is the thermal conductance of the section shown in fig 3 i.e. = height of frame in m x U factor in W/(m2·K)

= 0.285 x 1.8 = 0.513 W/K Up is the thermal transmittance of the center of the panel in W/(m2·K)

and is calculated as follows: Up = 1 RT Where RT = Thermal resistance of the panel, in W/(m2·K) and is calculated as follows: RT = Rse + Rsi + d = 0.04 + 0.13 + 0.024 = 0.856 W/(m2·K) λ 0.035 (d is the thickness of the panel = 24mm) Therefore: Up = 1 = 1.169 W/(m2·K) 0.856 bf is the projected width of the frame section, in m and is equal to = 0.095m bp is the visible width of panel in m, and is equal to = 0.190m Therefore:

Uf = 0.513 – 1.169 x 0.190 = 3.06 W/(m2·K) 0.095


1.2 Linear thermal transmittance

The linear thermal transmittance (Ψ describes the additional heat flow caused by the interaction of the frame and the glass edge, including the effect of the spacer.

Linear transmittance (Ψ is given by:

Ψ = LΨ²D – Uf • bf – Ug • bg

Where: Ψ is the linear thermal transmittance, in W/(m2·K) LΨ

2D is the thermal conductance of the section shown in fig 4 i.e. = height of frame in m x U factor in W/(m2·K) = 0.285 x 2.447 = 0.697 W/K

Uf is the thermal transmittance of the frame section, in W/(m2·K) and is equal to = 3.06 W/(m2·K).

Ug is the thermal transmittance of the glazing, in W/(m2·K) and is equal to = 1.77 W/(m2·K)

bf is the projected width of the frame section, in m; bg is the visible width of the glazing, in m.

Therefore:

Ψ = 0.697 – 3.06 x 0.095 – 1.77 x 0.190 = 0.07 W/mK

The remaining values have been calculated as follows:

Detail D6006-02 Uf = 3.05 W/(m2·K) Ψ = 0.07 W/mK

Detail D6031-12 (Alt) Uf = 3.11 W/(m2·K) Ψ = 0.07 W/mK

As shown in Appendix B above the thermal transmittance of a window Uw in W(m²·K) is calculated using the following equation:

Uw = Ag.Ug + Af.Uf + lg.Ψg Ag + Af

Uw = 3.077x1.77 + 0.763x3.07 + 10.036x0.07 3.077 + 0.763 Uw = 2.21 W/(m²·K) rounded to 2.2 W/(m2·K)


The spreadsheet calculation follows; 603 Simulation Window 1.6 x 2.4 Central Vertical Muntin with Vent/fixed-light

m² W(m2·K) % Total Area Total Area 3.84 U-Value = 2.21

Frame Area Uf LHS 0.347 3.06 1.062 9.04% RHS 0.224 3.05 0.683 5.84% Muntin Area 0.192 3.11 0.597 5.00% Total Frame Area 0.763 Frame Conductance = 2.343 19.88% Average frame U-value 3.070 Glass Area Centre Pane U-value LHS 1.448 1.77 2.563 37.71% RHS 1.629 1.77 2.883 42.41%

100.00% m Ψ

Linear Transmittance 10.036 0.07* 0.703 m²

Check Area 3.84 Total Conductance 8.491 *Note: Had the calculated linear transmittance figure been different for each detail then each edge length and its linear transmission would need to be summed separately.


APPENDIX D 1.0 Comparisons of Thermal Assessment Methods

As can be seen from the previous appendices the calculation of window U-values can produce slightly differing component values but the whole window U-values are similar if rounded to one decimal place. The use of reference tables and simplified calculations are adequate for most situations but for larger projects computer assessments may lead to savings on glazing units being more accurately specified.

An overview of the results is shown below with the centre-pane U-value required to achieve a whole window U-value of 2.2 W/(m²·K).

Method Average Uf value W/(m²·K)

% Frame area

Glazing centre-pane

U-value W/(m²·K)

Ψ W/mK

Whole window U-value W/(m²·K)

Reference Tables 3 19.88% 1.7 0.08* 2.2 BS EN ISO 10077-1 2.93 19.88% 1.8 0.08 2.23 prEN ISO 10077-2 3.07 19.88% 1.77 0.07 2.21

* Note: The linear transmission figure of 0.08 W/mK is included for in the reference tables.


APPENDIX E List of references British Standards – calculation methods BS EN ISO 6946 Thermal performance of buildings and building components – Thermal resistance and thermal transmittance – Calculation method and draft amendment EN ISO 6946/prA1

BS EN ISO 10077-1 Thermal performance of windows, doors and shutters – Calculation of thermal transmittance – Part 1: Simplified methods

prEN ISO 10077-2 Thermal performance of windows, doors and shutters – Calculation of thermal transmittance – Part 2: Numerical methods for frames

BS EN ISO 10211-1 Thermal bridges in building construction – Heat flows and surface temperatures – Part 1: General calculation methods.

BS EN ISO 10456 Building materials and products – Procedures for determining declared and design values

BS EN ISO 13789 Thermal performance of buildings – Transmission heat loss coefficient – Calculation method

ISO/DIS 15099 Thermal performance of windows, doors and shading devices – Detailed calculations

BS EN 673 Glass in building – Determination of thermal transmittance (U-value) – Calculation method

BS EN 12524 Building materials and products – Hygrothermal properties – Tabulated design values

British Standards – direct measurement of U-value

BS EN ISO 8990 Thermal insulation – Determination of steady-state thermal transmission properties – Calibrated and guarded hot box

pr EN 12412-2 Windows, doors and shutters – Determination of thermal performance by hot box method – Part 2: Frames.

BS EN ISO 12567-1 Thermal performance of windows and doors – Determination of thermal transmittance by hot box method – Part 1: Complete windows and doors


Other documents

Technical Standards for compliance with the Building Standards (Scotland) Regulations 1990 as amended: Part J: Conservation of Fuel and Power. The Stationery Office, 2001.

Approved Document L1: Conservation of fuel and power in dwellings: 2002 Edition. The Stationery Office 2001.

Approved Document L2: Conservation of fuel and power in buildings other than dwellings: 2002 Edition. The Stationery Office 2001.

Limiting thermal bridging and air leakage: Robust construction details for dwellings and similar buildings, TSO, 2001

CIBSE Guide Section A3, 1999 Edition

SAP 2001 The Government’s Standard Assessment Procedure for Energy Rating of Dwellings, 2001 Edition, BRECSU

Guide for assessment of the thermal performance of aluminium curtain wall framing. Council for Aluminium in Building, 1996

Guide to good practice for assessing heat transfer and condensation risk for a curtain wall, Centre for Windows and Cladding Technology (under revison)

Setting the Standard No. 3: A guide for the assessment of thermal performance of aluminium windows. Council for Aluminium in Building, 1999

A route map to Part L, British Fenestration Rating Council (www.bfrc.org)

Data Sheet 2.2, Glass and Glazing Federation, 2002


APPENDIX F 1.0 Tables of 600 Series Uf values

The following pages show the Uframe values for use when calculating whole window u-values to BS EN ISO 10077-1 as shown in the example in Appendix B. The values have been calculated for 24mm thick glazing units but as a guide can be used for any glazing infill between 20 and 28mm thick.

AA600_3_ThermalCalculations.pdf

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