Warm Windows

PVC pants
Men’s black PVC pants 01” by Ralph SchulzOwn work. Licensed under CC BY-SA 3.0 via Wikimedia Commons.

What exactly is ‘PVC’? And is this really a good material for window framing in New Zealand, Australia, or anywhere else in the World? These are some of the questions I put to Oleg Tolmachev, Sales Manager at Warm Windows – Cascade International.


PVC is the abbreviation for poly(vinyl chloride) which is a white powder in it’s pure form. It was ‘accidentally’ made first in France way back in 1835, and then again in Germany in 1872.

It wasn’t until the 1920s when chemists found a way to ‘plasticise’ PVC, thereby creating a flexible material that became useful. As Oleg reminded me, one such use for PVC has been for ‘fashion’. This might have contributed somewhat to a less-than-positive association with the material!

UPVC stands for ‘unplasticised’ poly(vinyl chloride). Basically, this just means it’s a rigid form. UPVC makes a useful building material because its strong, waterproof, resistant to chemicals and can withstand sunlight.

Warm Windows

UPVC windows are increasingly common in Europe and North America. Warm Windows is one of a few companies that are now supplying this technology to the New Zealand market. In fact it was Warm Windows who supplied the very high performance glazing for Murray and Lee Ann’s Passive House.

uPVC Warm Window
Warm Windows are one of the main suppliers of uPVC windows in New Zealand, and most of their work is in retrofitting old windows into existing homes.

Why should you consider uPVC? As the Warm Window site explains, the main benefits are:

  • Value
  • Comfort
  • Security
  • Energy efficiency
  • Health

Energy Efficiency of Warm Windows

UPVC window frames are up there with timber framing. The table of R-values below puts this into perspective with more typical aluminium framed windows.

 Single GlazingStandard double glazingDouble glazing with low-EDouble glazing with low-E glass & argon gas
Standard aluminium framesR0.15R0.25R0.31R0.32
Thermally broken aluminium framesR0.17R0.31R0.39R0.41
Timber & uPVCR0.19R0.36R0.47R0.50

source: http://www.smarterhomes.org.nz/design/glazing/double-glazing-glass-options/

When I walked around my own home with Oleg, he explained to me how important it is that windows close really well. UPVC windows typically lock into their frame in numerous places, ensuring not only good security, but also airtightness. This is another important reason whey they’re so good for improving energy efficiency.

Not Just Windows

Getting a good seal around doors is also really important for stopping draughts and ensuring good performance. Fortunately, Warm Windows offer a range of doors as well as windows.

warm door
Warm Windows also do doors

For more great information about different types of windows, including uPVC also check out the Window Association of New Zealand (WANZ) website.

Oleg’s Book Recommendation