New Zealand Metal Roofing Manufacturers (NZMRM), as does every industry that wants to survive, is continuously looking at the sustainability of their products and member companies. We have been operating a Sustainability Subcommittee since 2006, which looks at issues affecting the sustainability of our products and industry. It has been proactive in promoting the sustainability benefits of MRM to various external bodies, including Metals NZ, and the NZ Green Building Council. We are members of the Sustainable Steel Council.
We have discussed elsewhere and will again the very sustainable operation of New Zealand Steel, our primary source of material, and how it is in this respect a world leader.  The manufacturer obviously concerns primarily the beginning of the usually long life of steel cladding, its manufacture as brand new coil, painted or unpainted.
What is not always well known is the other end of the life of steel and indeed all metal cladding – its ability to be recycled and its actual level of recycling.  In fact metal used in cladding (and elsewhere of course) is able to be recycled indefinitely with no loss of quality (unlike any other material), and actually is recycled to a very high degree, not least because the processing energy cost of recycling is significantly less than that of making virgin metal.

An ongoing issue for us in New Zealand and our environmental credentials, not always well understood, is the difference between recycled content of a product and its own ability to be recycled at the end of its life.   In this area New Zealand is different to many other countries.

In this article, we provide information from world sources and specifically New Zealand sources to discuss the generic recyclability and recycling of metal, in particular steel, and about the unique system and cycle operating in New Zealand, which works well for all parties.   What follows has been taken from a number of sources and all data, volumes, numbers etc. are derived from published information so are only as accurate as the sources.    We deal primarily with steel, which is by far the main material used for metal building cladding, but many of the comments also apply to aluminium, certainly at world level.

Recyclability vs recycling
It is important to separate these two similar sounding operations. Steel is the ultimately recyclable material.  Its quality is unaffected by recycling and recycled steel is as good as new, but has much less embodied energy. All steel products have the ability to be recycled, but the degree to which they are recycled and the ease of doing so does depend on how much they are mixed with other materials and the difficulty of recovery from the other materials.  Reuse of material similarly depends on its quality at the end of the life of whatever contains it. Structural steel is very reusable and also quite easily recycled.  Steel cladding can be reused depending on its condition (and may end up on a lower quality building) but is more easily recycled (and is much easier to melt than structural steel). Steel used as reinforcing in concrete is fairly easy to recycle although as this requires the destruction of the concrete it is difficult to recover.

Steel used in motor car bodies is highly contaminated with other materials. In spite of this variability steel for recycling is a valuable resource and 85-90% of steel used in construction is recycled globally.   Over 60% of all steel used globally is subsequently recycled.

The ability to be recycled
A number of common materials can be recycled in the sense of being removed from a form which is no longer needed and then converted into something else. A number of products themselves are able to be reused once the item into which they are incorporated is no longer required.

Metals in various forms, glass, plastics, paper, timber, fabrics and others are able to be reused in some way, and we are all familiar with the recycling programmes of local councils – unheard of 20 years ago but now common – in which various materials are left outside to be “recycled”. We have the idea that they are reused in some way without being very aware of what this might be. For a number of materials collected in this way recycling is actually not possible currently.

In fact, to varying degrees nearly all these – apart from metals – are either not actually reused in a recognisable way or are degraded during reprocessing from the original form or quality (often referred to as “down cycling”).  Nearly all non-metals even if reused as part of a new or similar product are in a product of lower quality or value with reduced physical or aesthetic properties.
Metal and specifically steel cladding (which after all is what we make and sell) can both often be reused in the original form but more importantly it can be recycled into product indistinguishable from the original, totally undegraded and capable of being recycled indefinitely.   Steel cladding is generally unmixed with anything other than metal coating and paint and has thin sections and so is one of the most easy to recycle steel products, compared with e.g. reinforcing steel buried in concrete.  
Throughout its history steel has always been recycled and all steel contains a proportion of recycled material from 10 – 100%, so that any steel currently in use actually has some content that may have been used many times and be 100’s of years old.  

Recycling levels
Because of the factors discussed above - and below – (no loss of quality, scrap required for efficient function of steel mills, much lower energy content), steel has a very high level of recycling – typically up to 90% of all steel embodied in buildings and in artefacts which have ended their useful life ends up being recycled into fresh steel ready to start as good as new, into a long new useful life.

In the case of building cladding, quite a lot can actually get reused (rather than recycled as material) although generally in a lower value role – e.g. steel roofing from an office might end up in a fence or a farm shed. The actual percentage of steel which is recycled obviously depends on the application, so that steel which can be reused when a building is taken down is different to steel in a crushed motorcar body or an old fridge, but overall it is very high.
In the USA in 2013 98% of structural steel was recycled; and 81% of all steel.

Steel manufacture and recycling
Today, steel is nearly all made by one of two processes world-wide.  
The Basic Oxygen Furnace (BOF) is the main method for converting iron metal made from iron ore into steel.
It needs to use some recycled steel for efficient running and will use from 10-25% of recycled material.  

This may be in-plant scrap (“pre-consumer recycle” or “home scrap”) or bought-in scrap metal that is derived from steel items past their usefulness (“post-consumer recycle”). Typically a BOF unit will use all its own in-house scrap and some bought-in material.

The Electric Arc Furnace (EAF) can also convert iron into steel but is the main way of consuming scrap steel materials (post-consumer), and the process requires a minimum level of at least 30% scrap to function.  EAF units run from 30 to 100% scrap. A number of mills with EAF only use scrap steel as a raw material.

Because steel is a durable material and is used mainly in quite long-life products (unlike packaging materials) and is also in increasing demand, the amount of scrap available (even at very high recycling rates) is not sufficient to feed the demand and so virgin steel continues to be made from iron ore.  Many global steel companies have both types of furnace and are able to take in and reuse large amounts of scrap steel – typically as much as they can get, because reprocessing scrap steel requires less energy than making new steel.

It is worthy of note that the embodied energy aspect of Life Cycle Assessment of steel requires that both new manufacture and reuse are considered, so that all steel has a multi-level energy cost reflecting the fact that any new steel made will almost certainly be recycled many times way into the future and so the energy required to make it progressively decreases as it is successively recycled.

The New Zealand scene
Globally then, steel mills making all sorts of steel products use both recycled (pre- and post-consumer scrap) and virgin iron made from iron ore. The proportion varies from mill to mill; some only use scrap and others use smaller amounts of it in their mix. Overall a very high level of recycling is achieved.

New Zealand (of course) is different.
New Zealand Steel (now part of Bluescope Steel, an Australian manufacturer also operating throughout Asia) started manufacturing steel at Glenbrook (approximately 60km south of Auckland, the biggest market) in 1963. After many decades of research, a process had been developed to process the local ironsand in a unique process, which has a small ‘ecological footprint’, and the Glenbrook plant was built to use this process. After various changes in technology (and ownership) New Zealand Steel now uses the BOF process and makes all new steel from iron with only about 12% in-plant waste (pre-consumer scrap) added. From 2014 on the New Zealand steel industry consists of this one manufacturing plant at Glenbrook.

This New Zealand Steel plant manufactures a variety of steel products, from coil for roll-formed roofing and framing and metal joinery to reinforcing bars and wire rods. The coil may be metal-coated with zinc (galvanised steel) or aluminium/zinc (Zincalume ®), and may be painted on a coil-coating line or unpainted. The steel cladding materials NZMRM members use and supply primarily come from NZ Steel, with a small amount imported from Asian mills.
Type of scrap steel used in NZ

Home scrap (also known as circulating or internal scrap) is the residue left from the steelmaking, rolling and finishing operations and includes croppings, offcuts and material rejected by quality inspection procedures. This internal scrap usually accounts for about 10% of total crude steel production in an integrated steelworks. NZ Steel uses only the BOF process which can use a maximum 20% of scrap in its metallic charge. Thus NZ Steel uses only its own “home scrap” in its steelmaking process.  No post-consumer recycle (PCR) is used here as is this not needed in this steel-making process.

All post-consumer scrap steel generated and collected in New Zealand is exported as a valuable resource for steel plants elsewhere which use the Electric Arc Furnace (EAF) process which can be based entirely on scrap because the furnace is suitable for heating, rather than the BOF process which is a complex chemical reaction.

In purchasing steel made in New Zealand you can be sure it has been made with maximum recyclability.  New Zealand has a high level of recovery of steel products either for reuse or recycling at Pacific Steel.  All good, you might think, but there is one problem with this very neat system.  

Energy rating systems
For a number of years there has been an increasing global demand for energy efficient buildings.  Typically this starts with office buildings and then extends to institutions like schools, and finally to domestic dwellings. The methods of rating buildings is (of course) different in different countries but generally the system looks at the derivation of the raw materials used, the transportation of materials and of people to the building, the energy used during construction of the building and during its life, the water used and processed, and finally the ability to be reused or recycled at the end of the building’s life.

This is only a summary, and you can find more details easily on the internet. There are some well-known rating systems including BREEAM (early 1990’s) in the UK, Casbee in Japan, and LEED (2000) in the United States. These are of varying ages and levels of development and New Zealand has been a rather late starter in this area.

In 2003 Australia developed a system called the Green Star Rating (initially for new office buildings only, but rating systems for other buildings exist, and the intention is that all new buildings will eventually be covered by this system - sooner rather than later).  

In 2007 New Zealand followed suit with a very similar Green Star NZ rating system, managed by the NZ Green Building Council.  Until recently both of these have been somewhat different to either BREEAM or LEED in their regard for the recycled content of steel.
Without going into the somewhat complicated details – BREEAM and LEED credit for “sustainable sourced and used” steel. To achieve points with either Green Star system required the steel used in a building to have a high recycled content - “Up to two points are awarded where it can be demonstrated that the percentage of all steel used in the design has a post-consumer recycled content greater than x % as follows - 1 point = 60% by mass and 2 points = 90% by mass”.  

Exactly what this means (read it again) is not clear to me, but it is clear that steel manufactured by New Zealand Steel contribute no points to the total. Neither is there any recognition of distance travelled, either way (i.e. no penalty for long distance and no benefit for short distance).  What this means for NZ is that cladding made in NZ receives no points. Imported cladding from 10,000 kms away, painted with paint of unknown quality, and sourced from a plant or country with no known sustainability credentials, can get two points if it is made in an EAF. It is recognised elsewhere that both systems complement each other and should not be regarded differently. If there was no BOF process there would be no new steel to be recycled.

NZMRM and NZ Steel through Sustainable Steel Council and directly have been objecting to this rating method ever since it was first published in the mid-2000s.   Now we are seeing some possible movement to our advantage.

The Green Building Council of Australia recently changed its view on this methodology and no longer requires recycled content as its sole means of assessment and instead looks for “sustainably sourced” steel which has been defined in several ways for the plant and for the product. The direction this is heading in is called Environmental Product Declaration (EPD) which is a sort of externally monitored self-certification process.  This is a well-established process globally and the methodology and certification authorities exist. This is now how most international environmental rating systems work.

The NZ Green Building Council which operates the NZ Green Star rating system now intends to review all Material Credits (which contribute to the overall Greenstar rating of the building) and publish in some common format later in 2015.   NZMRM and New Zealand Steel through Sustainable Steel Council have commented extensively on the proposed Steel Credit (Mat-8) and suggested it be aligned with the Australian steel credit, and recognise EPD as the primary rating option.  The significance of this for NZ-made steel in NZ Greenstar rated buildings is quite significant as it now means that (assuming our suggestions are accepted and we follow Australia) it will be possible to obtain points toward your Greenstar building rating by using new, New Zealand made, steel products in its construction. Quite how this will work is as yet unclear, but it seems likely it will revolve around the actual steel manufacturing plant and process, more than how it is actually used.  We still have to work on this.

Regardless of the Green Star rating system issue, steel is the most recyclable and recycled building material in the world. You can use it or design for its use in buildings confident that  this in some way contributes to the sustainability of New Zealand as a whole. In the near future you should be able to obtain Greenstar points for its use as well.

Updated from an article
in Scope 18.