Energy efficient

Windows and doors play an important role for thermal insulation of a building. With well-targeted measures you can exploit great energy saving potential. Due to the characteristics of PVC-U, Homerit PVC-U windows & doors have excellent thermal insulation properties. The material itself has lower conductivity than  metal frames and  the multi-chamber system gives Homerit PVC-U windows & doors further insulation ability.

PVC-U windows are used in 80% of the world, and have been used for more than 50 years. PVC-U is much more energy efficient than aluminium. At 25°C aluminum thermal conductivity is 205 w/mk while PVC thermal conductivity is only 0.19 w/mk.

In a letter to BUILD magazine published in 2006, Ken Miller – former President of the UK Federation of Master Builders wrote:  “After all, the Europeans have been building far longer than us and it’s about time we took a leaf out of their book. … Otherwise New Zealand will continue to build shoddy, leaking, damp and inefficient homes for years to come.” To download a full copy of his letter, click here < Look to other countries to build wisely>.


In addition to standard double glazing we can provide  five types of Low E double glazing and one Low E triple glazing options. Low E coating can further improve thermal insulation.

On 29 November 2021 MBIE published new Building Code – H1 Energy Efficiency Acceptable Solution H1/AS1.  To download a full copy, click here < Building Code H1/AS1 Fifth Edition >. 

Minimum construction R-values for windows and doors will be R0.46 for most of the country, R0.50 for lower South Island for building consent applications submitted after 2 November 2023.

R-values of Standard Size Homerit PVC-U Windows

Glazing Ug (W/M²K) R-value (M²K/W)
2.63 0.41
2.27 0.46
2.02 0.50
1.60 0.58
1.30 0.67
1.10 0.74
1.00 0.78
0.90 0.82
0.60 1.00
  • R-values are from BRANZ Appraisal No. 543[2022] for a standard window
  • Ug of classic double glazing is 2.63W/M²K
  • Ug of double glazing with high performance Low E and Krypton gas can reach 0.9W/M²K
  • Ug of triple glazing with high performance Low E and argon gas can reach 0.6W/M²K
  • R-value of aluminium windows with classic double glazing is 0.26W/M²K
  • R-value of thermally broken aluminium windows with classic double glazing is 0.32W/M²K

For Homerit BRANZ appraisal certificate and technical literature, visit  < BRANZ appraisal No. 543 >. 


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