Building Materials of the Future

By Larry Liang

Introduction

The kinds of materials that are used to construct our cities is an important consideration, as it is imperative that we move away from materials which have a negative impact on the environment and society. It is estimated that about 50% of all C02 emissions worldwide are due to the operation and construction of buildings, which could be reduced with the usage of better materials. In many areas of the world, building materials are not durable and also contribute to large amounts of waste which pollute the environment around the spaces they are built in.¹ This is especially true in many poorer societies which must use low quality but still environmentally damaging materials simply because they are more affordable.

To this end, we advocate the usage of sustainable, aesthetically appealing and energy efficient materials. To promote a more equitable world, these materials should be relatively affordable, but also sturdy and easily adaptable to a wide variety of climates. We look for materials that have relatively little waste and pollution in their lifecycles, as well as materials that are easily recycled and reused for future generations.

Solution

There is no one single answer to what a city should use to build. The decision depends on the specific climatic and geographic region and the socioeconomic status of the city in question. The following criteria give some general guidelines for choosing good materials, as well as provide examples of how specific materials fit these criteria. The California state government sponsored program CalRecycle defines green building materials as having satisfied the following conditions (the following is paraphrased from their website with a few modifications for readability, emphasis is original)²:

The materials contain recycled content: products with identifiable recycled content, including post industrial content with a preference for postconsumer content, preferably with minimal reprocessing. Even better, these materials could be made from salvaged, refurbished, or remanufactured components, that includes saving a material from disposal and renovating, repairing, restoring, or generally improving the appearance, performance, quality, functionality, or value. These materials should, at the end of their lifecycles, be reusable or recyclable, usually meaning that they are easily dismantled and relocated. The product packaging is another consideration: products should come enclosed in recycled content or recyclable packaging.

These materials should be natural, plentiful and/or renewable, with a focus on materials harvested from sustainably managed sources, preferably having an independent certification (e.g., certified wood). This certification should provide proof that the manufacturer utilizes sustainable practices, such as minimizing damage to the environment by restoring the harvesting site to its original state, and keeping within the maximum capacity of the land. Materials should be based on the available resources of the region. Forested regions would benefit more from using wood, deserted areas would benefit more from sand-based materials, while more sparsely vegetated regions may benefit more from prefabricated, artificial materials.

Regardless of the type of material, there should be a efficient manufacturing process: products should be manufactured with resource-efficient processes including reduced energy consumption<link to energy efficiency article>, minimal waste (recycled or recyclable product packaging), and reduced emissions of  greenhouse gases and other pollutants, compared to traditional manufacturing.

Another important standard is whether the material is locally available or can be manufactured from locally available resources. Building materials, components, and systems found locally or regionally save energy and resources in transportation to the project site.

Durability and contribution to energy efficiency are the final considerations for the impact of a material. A higher durability means that the material could be trusted to stay structurally sound for a longer time, preferably for as long as the building’s useful life, obviating the need for constant replacement and reducing costs to the owners of the buildings. Contributions to efficiency is another important topic especially in the insulation of buildings. More information on this specific topic can be found in the energy section.

Examples

Recycled metal is a standard example of a green building material. At the end of its lifecycle, steel can be recycled and made into new products and environmentally conscious structures.³ Since it is being recycled, it lessens the impact of mining and drilling for more metals. The steel industry has already implemented reuse/recycling measures, and it has managed to achieve recycling rates of up to 90%, according to a survey of steel manufacturers in the UK. Even better, the industry has also found ways to recycle the water used in the creation of steel, an example of how it maximizes resource usage efficiency. Because of these efforts, there is less demand for the creation of new steel in building construction, and the demolition of old buildings can reduce costs of new buildings because of recycling. Recycled metal was key in the construction of the British Pavilion in the Seville Expo and after the convention, it was able to be easily reused.⁴

Other more creative materials include grasscrete, which is actually a blend of concrete, grass and other flora. The resulting structure blends beautifully into the Earth, and it also lessens concrete usage in favor of plant material. There is a hidden benefit in addition to its sustainability: it helps with storm drainage and absorption, which can help fortify the structure against natural disasters. Grasscrete absorbs carbon dioxide from the air, making it a carbon sink. One can find even more examples of successful grasscrete buildings on the grasscrete website in the references of this page.⁵

Indoor heating and insulation are also important issues that building materials can help address, because they also make up a good proportion of the operational energy costs of a building. Structural Insulation Panels (SIP) are made up of panels of foam insulation sandwiched between plywood or cement panels. Studies have shown that they can save 50% of energy costs going into heating a home or office building, which typically make up a large chunk of total energy costs of a building. The material is also fire resistant and can be used in foundations, floors and walls.⁶

Conclusion

In terms of a specific plan, we advocate for a review process that determines the best building material available to a country that is also the most cost efficient. The guidelines above should drive this process, meaning that the best materials are the ones that can be recycled and reused, and which are naturally available. These three different materials discussed exemplify the central theme of reducing consumption while ensuring that the consumption that remains is sustainable and efficient. Other materials such as recycled concrete, earthbag construction, and compressed sand bricks are better for cities in poorer countries, because they require much less processing to become a viable construction material. For example, compressed sand bricks have been used in Limpopo, South Africa to great success – the housing is durable and insulative, but also fairly inexpensive due to the abundance of sand in the area.¹

It is important to remember that the kind of materials that are the most suitable for a particular city depends on the particular region they are built in – this follows from the “local availability” point from above. Cities should work within their budgets – for example, recycling steel may be expensive because of the reprocessing stage, so it may be more feasible to invest in earth-based materials which are affordable to make. It is also important to recognize the vast variety of environmentally friendly, low waste materials. These include grass bales, rammed earth, and plant-based polyurethane foam.⁶ Finally, these materials chosen by cities should try to reduce energy usage as much as possible, such as in lessening heating/cooling costs or reducing transportation emissions with locally sourced materials. With these new measures of waste reduction, recycling/reuse maximization, local sourcing, and energy efficiency, we hope to reduce the carbon footprint, consumption waste/byproducts, and natural resource demand resulting from the construction of cities.