Stephanie McDonald explains how plasterboard has undergone several changes in response to sustainability concerns.
Sustainability in the building industry has largely been about two key aspects – design and materials selection. With the introduction of rating systems such as Green Star and NABERS, the spotlight is now even stronger on using environmentally friendly products.
Plasterboard, as a virtually ubiquitous building product, is worth its fair share of attention. There are several environmental benefits to plasterboard. The product has low toxicity, according to David Baggs, CEO at ecospecifier, and is a relatively benign product which does not require a large amount of energy to manufacture. Bill Thompson, R&D manager at CSR and representative of the Gypsum Board Manufacturers of Australasia (GBMA) on the Building Products Innovation Council (BPIC), says it is also a low impact product because:
• of its high strength-to-weight ratio and the use of strong recycled paper outer surfaces
• the plaster core is made from reserves of gypsum
• the manufacturing process involves low temperature dehydration, so it is not as energy intensive as other building products.
Thompson says the two biggest sustainability impacts associated with plasterboard have been the introduction of the Building Code of Australia and the need to minimise the environmental impacts associated with the manufacture and distribution of the product. “The plasterboard industry has always focused on waste and energy minimisation as a means to reduce manufacturing costs,” he says.
“From a previously internal manufacturing focus, this approach has over recent years extended to understanding and minimising impacts from the ‘cradle to grave’ – in other words, from the extraction of raw materials, their transport, conversion to finished products, installation and finally end-of-life disposal.” This cradle to grave approach is one the plasterboard industry has actively pursued. In 2007, the GBMA published the findings of a life cycle assessment of plasterboard and found the two main negative impacts related to global warming potential and water depletion, according to Thompson. “Global warming potential reflects the amount of greenhousegases emitted of the product’s life cycle,” he says. “In the case of plasterboard, 61 per cent of the greenhouse gases arise from thermal energy consumed in the manufacture using natural gas, 17 per cent is from electricity consumption and the remainder is associated with the manufacture and transport of raw materials.”
Plasterboard waste is 100 per cent recyclable; waste must be separated, clean and with low levels of contamination, including nails, screws, wood, steel, plastic and insulation.
In order to help offset environmental impacts, the industry has taken steps to reduce these impacts. Around 2.7kg of carbon dioxide was released from each sqm of plasterboard in the 1970s, according to Thompson. However, he says emissions have dropped by 63 per cent to less than 1 kg of carbon dioxide per sqm as a result of changing from indirect oil-fired process heating to direct fired natural gas heating with heat recovery systems.
Judy Hollingworth, CEO of Good Environmental Choice Australia, says companies are also increasingly becoming more responsible in their gypsum extraction, increasing the recycled content of the core and backing paper and using low VOC adhesives to join the paper and core. Some companies are also participating in recycling programs to take back and reuse post-consumer waste. “The core is crushed and reprocessed into new board and the paper can be utilised for soil reclamation,” Hollingworth says. “Environmental improvements to post-use phases facilitate the conservation of resources and reduce demand for virgin resources.
This in turn reduces impacts of items for use within residential, commercial and government environments and forms a major manufacturing sector in Australia.” CSR Gyprock recycles waste back into the manufacturing process and also recycles waste generated from the installation process. Its paper has also been upgraded to retain its strength whilst being made from 100 per cent recycled waste, and impact, sound and fire resistant products now use waste flyash from powerstations.
“Plasterboard weights have [also] reduced significantly over the last 20 years by control of the core structure and chemistry. Reduced product weight requires less energy in manufacture and transport as well as requiring less raw materials,” Thompson says. However, there are some concerns with plasterboard from an environmental viewpoint. The material can be easily damaged by knocks and bumps, but on the upside, it can often also be easily fixed. Some plasterboard products can also be easily damaged by water contact.
Baggs says from a sustainability point-of-view, one of the most important aspects of specifying plasterboard is where companies source their gypsum from – recycled versus non-recycled.
“You’ve also got different types of plasterboard where you’ve got the paper facing with the gypsum core and then you’ve got others which have the fibre distributed right through the entire matrix, a bit more like fibre cement type material, but it’s still plasterboard and that’s a more durable product,” Baggs says.
Potential water damage can also be an issue when it comes to plasterboard. “Anything that would improve [the product’s] moisture resistance and its integrity in contact with water would be good,” Baggs says. He says one approach to improve the water resistance of plasterboard is to pre-coat the boards to seal the product’s faces. However, careneeds to be taken to ensure any pre-sealed plasterboard products have been sealed using low VOC products.
This means there may be a trade-off with some plasterboard products – some products may have a higher recycled content, but may be more easily damaged and vice versa, while others may not have a high recycled content, but are more impact resistant and therefore more durable. Baggs says sustainability credentials can vary between companies, which is why using accredited rating schemes can be a useful guide when specifying plasterboard.
For example, two of BGC Plasterboard’s panel boards are accredited by GECA, which is manufactured using a gypsum core covered with a linerboard that is wrapped around the gypsum to protect the core.
The range includes water resistant boards, fire resistant boards and Impactboard, which can be used in high traffic areas where walls might be knocked and damaged. BGC’s Enviroboard is also manufactured using a higher level of recycled content than standard plasterboard – at least 11 percent of the gypsum in Enviroboard Commercial and Enviroboard Ultimate has been recycled, comprising 100 per cent recycled paper liner. Specifying plasterboard products which have been certified also ensures they aren’t coming from overseas where problems have been experienced with radon emissions, according to Baggs. He says when it comes to plasterboard, “The products with high recycled content are going to perform better overall from an environmental point-of-view.”
