Developers and contractors don’t have to spend a fortune to create and operate buildings that reduce impact on the environment.
As the debate over global warming gathers momentum, developers and builders are coming under increasing scrutiny for their practices, but what some might view as a threat could be an opportunity.
In fact, there are lots of opportunities to reduce greenhouse gas emissions in the construction and operation of buildings. This fact has propelled Australia and some other countries to adopt a green building rating system, and it’s something Thailand could emulate, says Andrew Mercer, managing director of Boral Thailand Concrete & Quarries.
Such a rating system could help companies that have environmentally friendly profiles because they could ask the landlord for the rating of the office building they plan to move into.
The key to making buildings green, says Mr Mercer, is not just the design and specification of the materials for construction but also their operation. "There are two aspects to a building. When I build a building I can build it in a way that is sustainable, that is green, I don’t pollute, I don’t use materials that have high energy intensity and therefore high greenhouse gas intensity."
Once a building is built, he continues, it will probably stand for 30 to 50 years, during which it will use a lot of energy if it has not been well-designed and the right materials with insulating properties have not been selected.
This underscores the importance of Australia’s green-star rating system, which has up to seven categories including how a building relates to transport and infrastructure, its energy use and lighting systems. "There are some extra points available for innovation -- the total number of points is compared against a scale," explains Mr Mercer, who has been Boral for 20 years.
The first Australian building to achieve a six-star rating is Council House 2 in Melbourne, the equivalent of the BMA headquarters in Bangkok. "This happens to be the first building that achieved the six-star rating in terms of concrete used and cement that has a high alternative energy component."
Mr Mercer explains that cement is important because the cement industry worldwide accounts for 1-2% of all greenhouse gases. "Producing cement is quite greenhouse gas-intensive even though it is not energy-intensive."
This is so because limestone, which is a major constituent of cement, is mostly carbon dioxide and when one heats it to turn it into cement the carbon dioxide goes up the chimney stacks.
Mr Mercer calculated that cement production in Thailand over the last three to four years has been around 40 to 45 million tones. "So from 40-45 million tonnes of cement you get around 40 to 45 million tonnes of carbon dioxide. Even the most efficient cement producers in the world can’t get below 0.8 of a tonne of carbon dioxide per tonne of cement produced."
Carbon dioxide emissions can be reduced by using cement substitutes. "So when I make my concrete I use cement, sand, crushed stone and water. If I take the cement, it’s the thing that produces all the carbon dioxide, and replace some with fly ash, which is waste from burning coal in a power station rather than dump that and make a mess somewhere, that actually improves the concrete.
"So we don’t just get a green concrete but a better concrete, it’s more durable. It flows better through the concrete pump when you are pumping it up the top of a building, it reduces cracking, shrinkage, it has better durability."
While green concrete is available in Thailand and some developers are using it, Mr Mercer noted that cement manufacturers, while using some fly ash, are reluctant to jeopardise their chances of selling as much cement as possible.
A related development that is starting to have an impact on green buildings is lightweight concrete.
"If we make a lightweight concrete, we achieve a much better insulation against the heat transfer through the walls, through the floor and that helps us with energy use in the building," explains Mr Mercer. "Lightweight concrete also helps the building designer reduce the amount of materials he has to use in the building, because if he has lightweight concrete walls rather than heavyweight materials he needs to use less concrete in the foundation."
Lightweight blocks are catching on in Thailand but greater potential exists for lightweight concrete cast on the site or formed into panels.
Most of the precast walls in Thailand are heavyweight but they could be lightweight panels that would have much better thermal properties. For example, he says, if insulated glass is used in the window in a lightweight wall, then that wall’s energy heat transfer would be one-fifth of the traditional heavyweight concrete panel with an ordinary window.
On the operation side, meanwhile, there are great cost-saving opportunities that do not cost much money, the most obvious examples being more efficient lightbulbs and air-conditioning systems.
"So there are a whole range of things about a building that give you the opportunity to reduce the amount of energy used. You can choose fittings, and the right materials that are insulating."