2.13. Topic 10: The look-up table with R-values for vertical windows and doors in housing misses some common glazing types

2.13.1. Reason for the change

With all compliance pathways for the H1 energy efficiency insulation provisions, designers need to determine the thermal resistance (R-value) of the proposed building elements that form part of a building’s thermal envelope. For vertical windows and doors in housing, an easy way for designers is to look up the R-value of common types of glazing from a Table E.1.1.1 in Appendix E of Acceptable Solution H1/AS1. 

Industry feedback and recent BRANZ analysis suggest that the current table do not cover some common types of glazing with certain thermal performance characteristics. This can make it difficult for designers and Building Consent Authorities to establish whether a building complies with the H1 energy efficiency insulation provisions.

2.13.2. Proposed changes

The proposed changes involve amendments to Acceptable Solution H1/AS1 Energy Efficiency for all housing, and buildings up to 300m2 to enable the use of the look-up table for vertical windows and doors in housing for more common types of glazing.  

They include:

• Adding rows to Table E.1.1.1 in Appendix E of H1/AS1 for windows and doors that have double glazing units with Ug-values of 2.9, 1.2 and 1.0 W/(m2 K), and triple-glazing units with a Ug-value of 
  2.1 W/(m2 K)
• Removing rows for uncommon double-glazing units with a Ug-value of 0.9 W/(m2 K), and triple glazing units with a Ug-value of 1.89 W/(m2 K).

For more details of the proposed wording in H1/AS1, please refer to Appendix A.

Appendix A: Proposed changes to Acceptable Solution H1/AS1 [PDF, 4.4 MB]

2.13.3. Questions for the consultation Topic 10

10-1. Do you support amending Acceptable Solution H1/AS1 as proposed to make it easier for designers and Building Consent Authorities to establish whether a building complies with the H1 energy efficiency insulation provisions by enabling the use of the look-up table for vertical windows and doors in housing for more common types of glazing?

• Yes, I support it.
• Yes, with changes.
• No, I don’t support it.
• Not sure/no preference.

10-2. Please explain your views.

< 2.12. Topic 9: The look-up tables with R-values for slab-on-ground floors do not cater for some common situations | 2.14. Topic 11: Acceptable Solution H1/AS1 and Verification Method H1/VM1 include obsolete provisions and definitions, and outdated references to documents and tools >