The Mastic Asphalt Council (MAC), representing about 100 of the UK’s mastic asphalt manufacturers, contractors and suppliers, made the bold claim in January that the industry was the first to work towards what it calls "CarbonZero status".
Around 60,000 tonnes of mastic asphalt is laid in the UK every year. The material is a mixture of limestone and bitumen, and is used mainly to waterproof flat roofs and bridges. The term does not include asphalt used for road surfaces such as Tarmac.
Making mastic asphalt is energy-intensive. Raw materials are melted at 230°C before processing to produce blocks for melting or ‘hot lay’ deliveries to sites in heated vehicles.
Launching the initiative at London’s Barbican Centre on 18 January, MAC director John Blowers said that for every tonne of the material "made and laid" the Council’s members will offset 165 kilograms of carbon dioxide.
Offsetting will be done through voluntary emission reductions schemes: an energy efficient light bulb scheme in Kenya and a project in East Africa to replace kerosene lamps with solar-powered lanterns. More controversially, money will also be invested in a UK tree-planting scheme - the benefits of which have been subject to considerable debate (ENDS Report 384, p 24 ). Mike Rigby, director of the offsetting firm involved, Co2balance, said the projects were "new and fully additional".
Alongside concerns about the validity of investing in UK afforestation projects, some language used by the MAC is unclear.
A statement saying the work will allow customers to use a product "with no discernable carbon footprint" is questionable because the offsetting projects will not deliver savings for another four years. When asked if the statement was likely to mislead John Blowers said: "I don’t think it is misleading. I think ‘discernable’ is the right word to use."
Also optimistic is the MAC’s statement: "With help from experts at Co2balance, members first evaluated all their processes… and cut as many unnecessary CO2 emissions as possible."
On closer questioning, the MAC admitted that general advice produced by Co2balance had been sent to members but it is not known how many have acted on it.
Many environmental experts believe that, without first reducing energy use, the practice of carbon offsetting is questionable.
Co2balance’s Mr Rigby was firm in his belief that the project had taken the right approach: "Let’s get firms carbon neutral from day one and then work on a consultancy basis to reduce emissions. Otherwise it would be years before firms started to think about tackling residual emissions."
There is also little evidence that all MAC members are aware of how much CO2 they produce. While the MAC claimed "members first evaluated all their processes", it later said that CO2 emissions from just "5-10%" of the membership had been evaluated. The sample was a mix of firms of different sizes and covered manufacturing, manufacturing and installation, or just installation.
Co2balance used the data to generate an average CO2 figure for each tonne of asphalt produced and installed. The offset requirements are based on this figure.
It is also notable that the energy used in the extraction and processing of raw materials, or their delivery to manufacturing sites, was not included in the calculations.
The MAC’s members already report monthly tonnage sales to the council and are charged a membership levy for each tonne sold - the costs of offsetting are simply being added to that. This has worked out to be "less than 1% of the price of a tonne of asphalt", Mr Blowers said. However, neither the council nor Co2balance could provide any data to back this up.
The MAC said all companies in the industry operated in essentially the same way, which justified the sampling rate: "We really couldn’t see the benefit of doing any more. They all melt and lay asphalt in exactly the same way."
However, the low offset price adopted by the industry and the uncertainty about actual emissions might act as disincentives to investigate and reduce emissions further.
Mr Blowers disagreed: "This is only the start. We are already looking to reduce the remelt temperature by 30°C, which will save something in the order of 10-15% of energy costs. Contractors will equally have a saving on the remelt. That’s a really significant development and it’s been given a boost through the initiative… we’ve been able to bring it through much quicker."
He added that with energy costs continuing to increase, the industry would be continuously looking to reduce its overheads.
A spokesman for the Green Building Council cautiously welcomed the scheme, saying "At least it shows that the industry is willing to engage with the issue."
John Tebbit of the Construction Products Association said more firms were looking at offsetting "even if it might not be the best option in the long run" because more clients were asking for it.
He added that the BRE’s Green Guide, which attempts to cut through industry greenwash, does not take into account offsetting when assessing the environmental performance of construction products.