By TAN CHENG LI firstname.lastname@example.org
Going passive is the simplest way to make buildings green.
WANT to green your home or building? Forget about the eco-blings, those stuff like photovoltaic cells, wind turbines, building automation, smart lighting systems, and what not. Sure, shiny solar panels on the rooftop will impress neighbours and shout “This is a green building” but it is pointless generating green energy or using automated controls of lights, blinds and appliances if the structure itself is an energy-guzzler due to poor design.
Before spending huge sums on these green gizmos, make sure the building does not require much electricity in the first place – what is known as “passive buildings.” In our tropical climate, these would be structures that are shaded and insulated from the heat as air-conditioning is a major reason behind soaring electricity bills.
Green building consultant Gregers Reimann shares that in one building in Jakarta, Indonesia, energy savings of 40% was achieved by making its facade airtight. Before retrofitting works, leaky doors, windows and partition gaps had led to over-use of air-conditioning.
“Most people, when they think green, they think of solar panels. That should be the last thing to do,” says the energy engineer from IEN Consultants.
Architect and sustainable building advocate Dr Tan Loke Mun shares the same view. Tan says the preferred way to green a structure is to first look at “passive cooling” by employing measures such as shading, building orientation and erecting walls that provide thermal insulation.
“Installing solar panels is an additional cost. For walls, you have to build them anyway and you’re already incurring cost, so you might as well use the greenest material possible. It’s the low-hanging fruit. Walls keep the heat out right from the start and provide passive cooling for 24 hours. So you won’t need more electricity for cooling. It’s a no-brainer. Otherwise, you’ll be spending money to cool down the house,” says Tan, who had been involved in developing the Green Building Index (GBI), Malaysia’s certification scheme for buildings that have a lighter environmental imprint.
High carbon load
The construction industry is terribly unkind to the planet; it depletes raw materials, guzzles energy, and leaves behind waste and greenhouse gases.
“It is known that buildings consume up to a third of the world’s resources, emit 40% of global greenhouse gases, use up 12% of its freshwater, and generate 40% of its solid waste. Thus embracing sustainable construction is not only the responsible course of action, it is the only rational course of action we must pursue,” says Thirukumaran Jallendran, a board member of the Malaysia Green Building Confederation, an industry group that promotes eco-friendly construction technology and practices.
Though more carbon is emitted during the lifetime of a building, the carbon footprint from the construction itself needs fixing, too. This “embodied CO2” – the CO2 that is released in the manufacture of construction materials and during construction – has to be minimised right from the start when designing the building and during construction (such as by choosing green materials) for once a structure is up, the opportunity for the saving is lost.
While using green construction materials and installing energy-efficient equipment and solar cells are both critical for making green buildings, the former should be priority, asserts Matthias Gelber whose company makes eco-products.
“Low-carbon footprint materials, passive cooling and positioning of the building are low or zero-cost options and represent an immediate CO2 emission saving. The others are for the long-term.”
Tan points out several aspects of green materials: “They must be green in their production such as have recycled content or are made from waste materials, use minimal natural resources and energy, and generate little waste. The distance between the production and construction site should also be considered to limit the carbon footprint from transportation. In terms of performance, they must have good insulation and acoustic values to create better indoor environment.”
Building with less
Environmentally preferable building materials are those that are fabricated with less energy and have recycled content or are made from renewable resources while at the same time function as well as existing materials.
Construction materials consisting of recycled content include drywall (uses recycled paper and post-industrial gypsum), plastic lumber (uses plastic waste), clay roof tiles (uses factory rejects) and glass tiles (uses waste glass). Metals such as steel and aluminium also have high recycled content due to expensive virgin materials.
In some green types of building blocks, wood fibres and waste materials such as fly ash (from coal plants) and slag (waste from steel mills) are used to reduce the need for concrete. (See story on P4)
When it comes to material-selection, Gelber says the considerations include products that have low CO2 and insulate at the same time, are free of formaldehyde and volatile organic compounds, and offer value for money. “Recycled content is good but what is the point of that if there is no improvement in CO2 reduction?” He adds that measurements on the carbon profile of construction materials should be simplified and standardised so that people can better distinguish between the green and not-so-green products.
Another consideration to green a building, adds Reimann, is to not over-design. “A lot of buildings are over-designed, for instance, with many big beams, to be on the safe side. If you have good structural engineering, you can trim the design and use 40% less steel and cement. Another thing is to use high-strength concrete which can carry two to three times the weight of conventional concrete. This will also trim down material use.”
Yet another green option for the construction sector is the salvage and reuse of demolition debris but that is uncommon here. Recycling construction waste reduces greenhouse gas emissions by minimising the need to extract and process raw materials, and the environmental impact of waste disposal. In Singapore, used concrete is crushed and reused. In Germany, construction waste is banned from the landfill and has to be reused. In Malaysia, demolition waste is mostly illegally dumped.
One green building material is a traditional one: good old clay bricks. In recent years, these have lost out to the cheaper cement bricks. Clay bricks have good thermal insulation and so, keep homes cool. Houses these days, however, are mostly constructed with cement bricks which trap heat and easily dispenses it, thus warming up home interiors. This is why when you enter an old house built of bricks, it is cooler compared to a typical terrace house in any one the housing schemes that make up our suburbs.
Tan says the insulation property of clay bricks improves by building cavity walls (double brick walls with a cavity in between). “Brick walls are maintenance-free and minimise material usage as you do not need to plaster and paint them,” adds the architect, whose GBI-platinum-rated home features a few raw brick walls. Clay bricks can nudge up their green quotient if the production process is made greener, such as by using cleaner fuel for firing and anti-air-pollution equipment, and recycled content.
Choices of green building materials are certainly more varied now but many builders are still unfamiliar with them. It is mostly architects and developers eyeing GBI rating for their projects, who seek such products. Most housing schemes and high-rises still rely on cheaper materials which do not prevent heat build-up in interiors.
Tan says that in Europe, such materials are used as the law requires it. “Here, because there are no laws, not many developers use such materials although some have been in the market for 15 to 20 years. But people are getting more aware of the need to use such materials. They are a bit more costly but the price difference is catching up, and the benefits are there.”
The use of green materials is an important criteria to be certified under GBI, according to Malaysia Green Building Confederation president Von Kok Leong. “It rewards those who use materials which have recycled content, are reuseble and recyclable, and sourced from within the region. The higher the recycled content, the more points are given. We also encourage the use of Malaysian timber that has been certified as sustainably produced.”
Von says current building bylaws and codes need to be upgraded to meet higher standards on building performance, so this indirectly requires the use of greener materials.
“We have to encourage designers to introduce the new, green materials, developers to accept them, contractors to use them, and purchasers to ask for them.”
The European Parliament last year announced new energy standards that will require all new buildings constructed in Europe after 2020 to be nearly carbon-neutral. This means buildings must have zero-carbon emissions – they must remove as much CO2 from the atmosphere as they put in.
Reimann reckons Malaysia, too, needs to move in such a direction if it wants to stifle growth of its carbon footprint. “The world cannot go green without transforming the way it builds. In the quest to reduce greenhouse gas emissions, the building sector has been identified as the sector with the biggest and cheapest potential for doing so.”
And consumers buying new homes, too, should make it a point to understand how the choice of bricks, building blocks and concrete can affect their comfort and ultimately, the world’s climate.