BRANZ. Welcome to BRANZ



  BU629 ALF 4.0

ALF 4.0 (Annual Loss Factor) is an online tool for determining the building performance index (BPI) of a house design.  BU629 image.JPG

The calculator can be used to demonstrate that a specific house design complies with New Zealand Building Code clause H1 Energy efficiency.

ALF 4.0 is an updated and completely redesigned version of the older ALF 3.2 calculator. This bulletin replaces Bulletin 555 A guide to ALF 3.2.

This bulletin covers: 

  • Getting started
  • Entering data to find the BPI
  • Results and reports
  • Improving/optimising energy efficiency in design
  • Energy cost and moisture
  • Using ALF 4.0 for existing houses
  • ALF 4.0 web browser requirements