uPVC Use In NZ vs. Other Countries

We got a good question recently: Why doesn’t uPVC have a larger market share in NZ? The rest of the world has adopted uPVC, why not New Zealand?

The primary answer is that there is a blind trust by the public that the building code is all that one needs to know when building a home. Homeowners therefore don’t investigate any reason to go beyond Building Code minimums.

Citizens trust that the government is watching out for them and therefore treat the minimum Building Code as a goal to aspire to.  As a result, a vast majority of citizens build only to minimum Building Code. What we need to keep in mind is that the intent of the Building Code is to set a minimum legal requirement before a home can be considered habitable.  Habitable doesn’t sound like a high bar. BRANZ even states that the Building Code is a bare minimum and “should be exceeded”.

The knowledge that there is anything better than minimum building code isn’t common though.  Here is an example. The minimum Building Code recently updated window requirements to include double glazing.  Nearly everyone that I talk to at building trade shows (hundreds and hundreds of random people) think that double glazed aluminium windows are as good as you can get.  They are very wrong. That isn't even the best aluminium window available.  That is just the minimum. People look at the minimum Building Code as a goal instead of the minimum requirement that it is intended to be.

Is this blind trust in the NZ Building Code warranted? The truth is that NZ Building Code is dramatically outdated. We in NZ are still installing items that were phased out a half century ago in other first world countries. This is evident with the Organisation for Economic Co-operation and Development (OECD) conclusion that the NZ Government “should consider modernising the Building Code; its standards are less stringent than those of many OECD countries”. Please keep in mind that some OECD countries are historically third world and developing countries.

In both Europe (UK included) and the US, over 80% of all new windows are uPVC, with much of the balance being wood. There are also a few composite windows thrown in, but there are virtually no aluminium windows for new residential builds. The main driver for this is because all European countries and the US have higher energy performance requirements for windows in residential buildings that aluminium windows just can’t meet. The aluminium itself transmits too much energy out of the home, even with the upgrades of added thermal breaks.

So, why doesn’t NZ use more uPVC?  Most New Zealanders (and possibly legislators) don’t know how our Building Code and building materials compare to other countries, and don’t know that NZ is so far behind.

Another reason is that many homeowners are very focused on immediate cost when building, even at the expense of quality, health, and comfort. Many compare the short-term expense of an item vs. how many square meters of house they could get for the same cost difference. Many don’t plan on what they need to get the most out of the home that they can afford.  Therefore, the least expensive item is often chosen instead of the most appropriate item.

For this reason, most aluminium manufacturers often don't even educate their customers about these more expensive thermal upgrades like Low-E glass, argon fill, or thermal breaks.  It is less expensive to build a poor thermally performing window than a good performing one, and the least expensive option is often chosen by the customer.  This focus on immediate cost at the expense of performance is why legislation had to be used to force double glazing onto the market. That is also why many homeowners don’t get better performing windows now, even if they are aluminium.

A recent interview with an aluminium manufacturer determined that 99% of homeowners purchase the bare minimum performing window. This short-term cost reduction comes at the expense of long-term comfort and long-term economical gains. These thermal upgrades pay for themselves in energy savings over a short time. This doesn’t even include the fact that homeowners are happier in homes with better insulating windows, homes that are more comfortable, drier, and have healthier occupants.

To quantify the long term gains of better performing windows, BRANZ stated in a 2014 paper that if New Zealanders already installing windows would choose more efficient wood or uPVC windows instead of aluminium windows, they would save over $730,000,000 in heating bills over the first 20 years alone and prevent the release of 660,000 tonnes of CO2 into the atmosphere. This doesn’t even count the additional community cost benefits like reduced healthcare.

Why such an impact? Simply put because current double-glazed aluminium windows allow 8x more heat loss compared to the same area of wall space. That directly translates to 8x more heating expense required to get a room to the same temperature! uPVC windows perform much better thermally and dramatically reduce that heating deficit.

To summarize, the simple reasons why aren’t uPVC windows more common are a general lack of public consideration on the long term savings of energy efficiency and blind but misplaced belief that the Building Code is current, is a goal to achieve instead of a bare legal minimum, and has the best public interest at heart.

2 thoughts on “uPVC Use In NZ vs. Other Countries”

  1. Loved reading this article. We are originally from the UK where UPVC double glazed windows have been standard since the 1980’s. It is far superior to the total rubbish that is aluminium double glazing. It’s the equivalent of slapping 2 pieces of bread together and calling it a sandwich! It has no substance and no filling and thus very few thermal properties. We have lived in 2 houses that had new aluminium double glazing and we had dripping water all down the windows and frames during the coldest months of the year and we live in Auckland! A builder friend has recently installed UPVC in a house and his comment was that it was very expensive….. He was very surprised when I explained to him that the UK and Europe had moved away from Aluminium decades ago… it just isn’t effective! Having read the story of window issues in a 6 year old apartment building currently receiving remedial work at Stonefields in Auckland, serious questions need to be asked!

    1. Sarah,

      We thank you for your input and completely agree with you. uPVC just hasn’t caught on in NZ and this is mostly due to a very outdated building code. The NZ govt has recently realized this after a 2017 international report stated that our new housing won’t conform to any country in the OECD’s minimum housing standards. Yes, our building code is so outdated that our houses don’t meet any OECD country’s requirements. In response, MBIE has recently asked for public comments on possibly bringing NZ building code thermal performance standards to half of what they currently are internationally for similar climates. This doesn’t mean that they are going to improve window and insulation standards to cut the current deficit in half (halving the distance between current performance and international code), they are proposing improving window thermal performance in NZ so it achieves only 1/2 of international accepted levels. Yes, current double glazing thermal performance is less than half of acceptable international values! That is why our NZ houses are cold and damp. Your UK homes have had minimal thermal performance requirements that have been over 2x what NZ builds. This is one reason why our standard window offers 2.5x the thermal performance of a standard aluminium window.

      Again, we thank you for your comment and input.

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