Cladding Products
Timber Based Cladding Products
Composite Cladding Products
Composite cladding materials employ a wide variety of organic and inorganic industrial residues to produce sheet and board like cladding materials. The most well known variant of such products are wood-plastic composites. These materials use Polyvinyl chloride and wood powder to create an extremely durable, consistent and user-friendly cladding material.
The long life of these products make them very attractive to commercial clients (XXX).
Examples of products available in Australia and New Zealand today:
InnoWood (read environmental product declaration here). (Uses 52.5% wood powder + 38.2% polyvinyl chloride (PVC) + 5.8% calcium carbonate)
Euro Selekta Clad (see the product here). (Composition not declared).
Weo Composite (see the product here). (Uses 60% sawdust + 40% high-density polyethylene (HDPE))
Many composite cladding products can be recycled into like-for like products. InnoWood declares (as of 2018) that approximately 7.5% of its feed-stock is post-industrial InnoWood material and that this figure would be higher if it wasn’t for their materials long-life performance. Likewise the Weo Composite cladding product reportedly contains “95% recycled content" and is “100% recyclable”.
The difficulty with wood fiber composites and recycling is that once combined with wood powder it is immensely difficult to recover the Polyvinyl chloride or HDPE (XXX). This is a barrier to high-value recycling and makes handling the products very challenging for established plastic recycling schemes.
Fibre Cement Cladding Products
(And Fibre Cement Composite’s).
Fibre Cement Cladding products are well established in New Zealand and Australia under the James Hardie brand name. Fibre cement products are known for their durability and capacity to create large smooth cladding panels, as well as weatherboard profiles. Fibre cement products are popular in commercial construction as they are inherently fire resistant.
Fibre cement cladding solutions are in most cases nail-fixed to the structural frame, or nail fixed to structural cavity battens.
Fibre cement sheet requires specific personal protective equipment to be used safely. When cutting a fine dust is produced that can be toxic if inhaled.
Fibre cement sheet cannot be recycled into a like-for-like product, nor into other high-value materials.
For this reason, unless a highly effective circular fixing solution is used, fiber cement cladding products should not be used.
High density fibre cement products are manufactured in Europe and often come with surfaces pre-finished.
Aluminium Cladding Products
The use of Aluminum cladding materials has grown significantly over the past two decades. Modern manufacturing methods mean that extruded Aluminium profiles can be created and greatly reduced costs to produce an almost zero maintenance cladding product that is resistant to rot, decay, fire and insect attack. Aluminium can also be recycled time and time again with minimal losses in quality. Recycling reportedly uses approximately 5% of the energy required to create virgin Aluminium. Thus, with all of these qualities many argue that Aluminium is an ideal Circular Economy product.
Yet current methods of Aluminium production are hugely energy intensive and produce large quantities of Carbon Dioxide gas. Mining Bauzite ore (the worlds primary source of aluminum) can also be disruptive to natural ecosystems.
To put the environmental impacts of Aluminium building products into perspective we have compared these products with engineered timber cladding materials (i.e. finger jointed lumber, thermally modified cladding and the like).
Streamlined LCA Analysis - Engineered Timber vs. Aluminium
Extruded Aluminium: Embodied Energy: 201 Mj/Kg | Global Warming Potential (CO2): 14.15 kg/kg
Engineered Wood: Embodied Energy: 9.5 Mj/Kg | Global Warming Potential (CO2): -1.16 kg/kg
Source: Alcorn, A. 2010. Global Sustainability and the New Zealand House. Doctoral Dissertation, Victoria University of Wellington (pg. 180 and 245)
The data on its own is telling. There is a 2000% increase in the quantity of energy required to manufacture Aluminium weatherboards vs. timber boards. Likewise, there is a 13 fold (or 1300%) increase in CO2 emissions per unit of Aluminium manufactured vs. timber.
You can then convert these generic values into a comparison of the material when actually used on a building:
Engineered Timber vs. Aluminium Cladding (per meter square)
Extruded Aluminium: Embodied Energy: 1053.2 Mj/Kg | Global Warming Potential (CO2): 74 kg/kg
Engineered Wood: Embodied Energy: 68.4 Mj/Kg | Global Warming Potential (CO2): -8.3 kg/kg
N.B. In this calculation we assume that 1m2 of Aluminum cladding weighs 5.2kg and 1m2 of Timber cladding weighs 7.2kg. These figures are based on real world products of 200mm wide weatherboards.
Based on this analysis you could comfortably say that per m2 of cladding Aluminium produces 74kg of CO2 vs timber which sequesters 8.3kg. All these figures assume a single life/use of the product.
Examining the cyclic use of these products is also important and must take into consideration life cycle potential, reprocessing emissions and transportation.
It is frequently reported that recycling Aluminium uses '5% of the energy required to manufacture aluminum from ore' . With that in mind, and by using the previous embodied energy figures, recycling Aluminium uses approximately 10 Mj of energy per kg.
To quantify the benefits of this recycling one approach is to look at the point at which reusing a product with higher embodied energy becomes better than the embodied energy costs of using a new product each time. If we do this for timber vs. Aluminium cladding and assume a lifespan of 25 years it would take (roughly) 750 years (30 use cycles) for you to be 'embodied energy neutral' when using recycled Aluminium products vs. using new timber products every time. And, more importantly, at this stage you would have produced 181kg of C02 per kg of Aluminium used - vs. sequestering 250kg of carbon by using timber. (Although this isn't entirely fair given that timber no longer in use will biodegrade and release the sequested carbon back into the soil and eventually the atmosphere. That said, the above model assumes no timber reuse which is rare).
With these figures in mind we prioritize the use of timber cladding products over Aluminium at this time. Yet, it is important to note that upon the advent of improved Aluminium production and recycling technologies this balance could shift.