At Harmonic Design, we’re frequently confronted with the dilemma of balancing the cost to the client with the cost to the environment. Specifying materials which contain plastics, aluminium, steel and concrete are practically unavoidable in some buildings. However, we try to rationalise each decision.
uPVC / plastic is sourced from a range of fossil fuels. As we know, the world currently has more fossil fuel stockpiled (like oil) than it actually needs, but mining companies (like Adani) are pushing to open up new areas to mine fossil fuels; ‘based on demand’.
Fossil fuels are clearly in decline as a primary power source, however big mining companies will push ahead with their fierce mining efforts because ultimately our economic choices are enabling them. uPVC products are among other plastic products helping to drive new demand for fossil fuels. Due to the weak demand for recycled plastic, and since much of the raw material within plastics come from oil and can be sourced from coal, we draw the line at plastic windows!
It tricky to navigate this rationale where on one hand we’re concerned about climate change and yet inadvertently contributing to global heating and degradation of our environment by purchasing “green” products. In consideration of this fact, and due to our research we choose to ‘black-list’ plastic windows ( although our client’s still get the ultimate say :-)
uPVC window frames in Australia have been adopted in part due to their popularity in Europe: “it’s European!” but also due to PassiveHaus increasing the popularity of ‘certified airtight windows’.
Although some local testing has occurred with uPVC products we fear that much like the ‘flammable cladding’, uPVC products are going to be very unpopular in another 10-15 years; if for no other reason than people noticing vinyl-wrap window finishes eventually discolour, crack and peal (looking degraded and requiring replacement).
In our experience you get what you pay for. Other than being thermally effective, many clients opt for uPVC windows because they’re cheap. But given that, we doubt they’ll stand the test of time. uPVC windows are generally manufactured or assembled using 50% to 100% imported materials. With such high embodied energy contained in their production and shipping, any short-term gain will likely lead to long-term pain - for the consumer and the environment.
Aluminium vs uPVC?
To defend uPVC windows some argue that aluminium windows contain more embodied energy than plastic windows. However uPVC windows (especially large sliding doors) actually contain lots of metal reinforcing (steel or aluminium), so to claim that uPVC windows contain far less embodied energy than aluminium ones is convenient at best.
uPVC in the context of building products is hard to remove entirely but in terms of ecology, PVC products are hugely problematic. By way of comparison, we prefer to specify timber windows and yet timber isn’t always suitable so what then? Due to the merits of material reuse and circular economies we’d probably specify Thermally Broken Aluminium (TB-A).
TB-A framing removes the heat transfer that occurs via thermal bridging through aluminum tubing. Whilst TB-A frames are a mix of metal outer and plastic inner, the metal frame is coupled either side of a plastic gusset (thermal break), meaning TB-A frames are easy to dis-assemble AND the metal that’s considered valuable is visible on the outside of the frame.
The economics of redundancy.
Since the iron age, metal has been recycled and redeployed and today scrap-metal is still a booming industry. On the other hand as evidenced by the lack of plastic recycling here in Australia and overseas, plastic is treated as something you throw in the bin.
uPVC window frames have metal reinforcing throughout but it’s hidden on the inside - not good for disassembly.
In both economic value and in terms of logistics, plastic windows are the opposite of Thermally Broken Aluminium. They contain lots of aluminium threaded throughout their plastic shell in which case upon demolition they aren't considered to have any intrinsic recyclable value (because it’s so cheap to source the new raw ingredients from coal or oil). Unfortunately when plastic windows come to the end of their life they will be discarded and neither the aluminum or the plastic components will be returned into their respective supply chains. We just can’t see how there’s enough incentive in Australia for uPVC windows to avoid landfill.
You can turn recycled aluminium cans into windows, but you CAN’T take PET plastic bottles and turn them into window frames -
Footnote about recycling of uPVC: We spoke in detail about all of the above with Australian Window Solutions in response to their direct promotion of their uPVC windows. They’ve said that they use Deceninck extrusions which are sourced from Belgium and that they do use high proportions of recycled PVC. Unfortunately we remain unconvinced that this resolves the issue of collection and reuse of uPVC and plastic in Australia or other parts of the world.
Materials data:
If you want to consider the predominant affect of the materials composition we’ve discussed, you can refer to the Construction Materials Pyramids below where you’ll note that Vinyl (PVC) sits towards the top of all four ‘material’s impact charts’ affecting climate change (global heating).
There are reasons why PVC has been black-listed from use in Green Star rated buildings (accreditation requires demonstration of minimal use of PVC). We’re not saying that TB Aluminium windows are 100% better than PVC. We’re saying that you can’t consider anything in isolation, and when taken in context, including embodied energy, life-cycle, reuse as well as chemical leaching in landfill, uPVC windows are potentially doing more harm than good.
Harmonic Design deeply considers the building materials we choose to specify and as a pathway towards true sustainability we’re motivated to find environmentally ethical solutions so we’ve added plastics to the list of materials that we avoid.
Acidifciation potential (refers to the compounds that are precursors to acid rain)
Eutrophication potential (refers to the impacts on terrestrial and aquatic environments due to over-fertilisation or excess supply of nutrients impacting quality of drinking water, fisheries & recreational water bodies)
Global warming potential (refers to the rise of global temperatures)
Photochemical ozone creation potential (also known as summer smog) refers to emission of substances to air).
Further to above mentioned, PVC has been black-listed from use in Green Star rated buildings (because accreditation requires demonstration of minimal use of PVC). See attached data for reasons why.
These diagrams are inspired by a food pyramid, illustrating what we should consume least at the top of the pyramid.
Image SOURCE: https://materialepyramiden.dk/
Acidification Potential
Eutrophication Potential
Global Warming Potential
Photochemical Ozone creation potential