scope:

This publicly available specification(PAS) has been prepared to provide guidance on the selection of insulation levels and window options to improve the energy efficiency of houses beyond the minimum required by the New Zealand Building Code. The PAS also identifies the insulation levels required by NZS 4218 to meet the minimum requirements of the New Zealand Building Code. Recommendations for designers, builders and homeowners on the use of insulated (typically double-glazed) windows, and increased levels of insulation in the roof, walls, windows and floors of homes are introduced. Because the Better and Best insulation options described exceed the minimum requirements of the New Zealand Building Code, they are suitable as a means of compliance with the Building Code.

This PAS is not intended to be a comprehensive design guide, and does not deal with window size, orientation and or shading in any detail. However, a design checklist is provided in Appendix A. For more guidance see Energy-wise design for the sun, or contact the Energy Efficiency and Conservation Authority (EECA). The BRANZ Annual Loss Factor (ALF) computer model can also provide a useful means of more accurately evaluating the effect of different insulation levels on a specific house design, as it takes into account window size and orientation.

This document is a general guide to a relatively complex issue. It provides general "rules of thumb" rather than detailed solutions tailored to individual design problems. It is recommended that, where possible, when addressing energy efficiency issues the owners of buildings, both new and existing, should engage the services of a designer experienced and expert in the design and specification of mass, glazing and insulation.