Introduction
The potential impact of climate change and global warming is without doubt one of the most life-threatening challenges that face humanity. Central to this challenge is our dependence on fossil fuels as the primary source of energy – the major contributors of greenhouse gases (GHGs) including carbon dioxide (CO2) – and the extensive use of non-renewable resources.
It is now widely recognised that the climate systems are warming: there is also medium confidence that other effects of regional climate change on natural and human environments are emerging, although many are difficult to discern due to adaptation and non-climatic drivers. Global GHG emissions due to human activities have grown since pre-industrial times, with an increase of 70 per cent between 1970 and 2004. Anthropogenic warming could lead to some impacts that are abrupt or irreversible, depending upon the rate and magnitude of the climate change, including severe species loss.
Nevertheless, a wide range of adaptation options is available, although a more progressive rate of adaptation than is currently evident is required. Given an increase in adaptation rates, many impacts can be reduced, delayed or avoided. There is thus a causal relationship between climate change mitigation and sustainable development: sustainable development can reduce vulnerability to climate change by enhancing adaptive capacity and increasing resilience.
The construction and maintenance of the built environment has a fundamental role to play in this challenge: green materials and technologies for new and existing buildings could considerably reduce CO2 emissions while simultaneously improving indoor and outdoor air quality, social welfare, energy security, and ecological goods and services.
Background
The built environment is where the majority of the world’s population now reside: one out of every two people live in a city (UN 1996). Global population has expanded more than sixfold since 1800 and the gross world product more than 58-fold since 1820. As a result, the ecological footprint (EF) of humanity exceeds earth’s capacity by about 30 per cent. If we continue on the same development trajectory, by the early 2030s two planets will be required to keep up with humanity’s demand for goods and services.
In 2013, the global building stock was 138.2 billion m2, of which 73 per cent was in residential buildings (Bloom & Goldstein 2014:2). It is forecast that the commercial and residential segments will experience compound annual growth rates (CAGRs) in the next 10 years of 2,1 per cent and 2,2 per cent respectively (Bloom & Goldstein 2014:3).
Overall it is projected that the total building stock will grow to 171.3billion m2 at a GAGR of 2,2 per cent over the next decade (Bloom & Goldstein 2014:3).
Most of the growth is expected to occur in China, where nearly 2.0 billion m2 are added to the commercial and residential building stock every year. However, North America and Europe are each likely to make a significant contribution to the total building stock (Bloom & Goldstein 2014).
Interestingly enough, Bloom & Goldstein claim that commercial, residential, and industrial buildings are responsible for 47 percent of global greenhouse gas (GHG) emissions and 49 percent of the world’s energy consumption (2014:1).
As stated earlier, the construction industry plays a critical role in the growth of the economy through its creation of immovable fixed assets. Because of this role Government has declared the construction industry a national priority (Cidb 2012:10).
Gross Fixed Capital Formation (GFCF) for the residential sector fell -2,2 percent year-on-year in Q4: 2011 based on constant 2005 prices, from R24,83 bn to R24,29 bn. The non-residential sector fell by 1,3 percent year-on-year in Q4: 2011, to R37,08 bn from R37,56 bn in Q4: 2010. GFCF in construction works rose 2,3 per cent year-on-year in Q4: 2011, the highest growth rate over the past seven quarters with investment in construction works increasing to R110,36bn in Q4: 2011 from R107,89bn in Q4: 2010 (Industry Insight 2012:18).
The total GDP for South Africa in 2013 was approximately R3,3 trillion of which the non-residential sector contributed 1,41 per cent directly, 1,55 percent indirectly, and 2,39 percent induced (SAPOA 2014:51).
During 2013 the real estate sub-sector contributed R1,32 billion to the fixed capital stock of South Africa, while the gross fixed capital formation added R97,856 million to this figure over the same period, representing 20,9 percent and 14,95 percent respectively of the whole economy (SAPOA 2014:15). Of this capital formation, R69,697 million or 71,2 percent, is attributable to non-residential buildings (SAPOA 2014:15).
It is also a significant consumer of resources especially materials, energy and water: globally the construction industry is responsible for about 50per cent of all materials used, 45 per cent of energy generated to heat, cool and light buildings and a further 5per cent to construct them, 40 per cent of water used (in construction and operation), and 70 per cent of all timber products that end up in construction
The construction industry has traditionally been a slow adopter of new technologies in general, mainly due to the perceived associated risks ( Woudhuysen and Abley, 2004). The building sector in particular is reluctant to adopt new technologies due to potential buyer resistance ( Woudhuysen and Abley, 2004). Thus, the sector undertakes most of its work with conventional technologies.
Green technologies really came into consideration with the emergence of the formal green building movement lead by the British Research Establishment (BRE), and Professors’ Feist and Adamson in the late 1990s. This saw the release of green building systems such as British Research Establishment’s Environmental Assessment Method (BREEAM), and the Passivhaus concept respectively. Since then a number of new green building systems have emerged, including the Green Star® system as adopted by the Green Building Council of South Africa (GBCSA).
The introduction of these systems has heightened interest in green building, and in the technologies they use. While much of the technology remains conventional to meet some of the performance requirements, green technology is required.
High Performance Green Building
Because buildings are often used for centuries, the rapid pace of development increasingly means that it is impossible to imagine the demands that future uses will place on buildings. Consequently, products and systems should be chosen that make adaptation easier. While aesthetic appeal will always be a component of building design, the real challenge is to create built environments that are durable and flexible, appropriate in their surroundings and provide high performance with less detrimental impacts.
The current generation of‘green’ buildings already offer significant improvements over conventional buildings inasmuch as they consume less energy, materials, and water; provide demonstrably healthier living and working environments; and greatly enhance the quality of the built environment, including the neighbourhood. However, these improvements are offered through the use of existing materials and products, design approaches, and construction methods. Because of this conventional approach to design and construction, it remains difficult to incorporate truly innovative technologies into current construction practice.
Good design is fundamental to sustainable construction. Decisions made at the initial design stage have the greatest effect on the overall sustainability impact of projects. The issues to be faced by radical
Prudent use of natural resources results in both greater industry efficiency and a restricted usage of natural materials. Practices such as materials recycling, waste minimisation, local product resourcing, land decontamination, and construction- and demolition-waste disposal make sound business sense and encourage good construction housekeeping. Application of the principles of ‘lean construction’ and life-cycle assessment is equally important.
The characteristics of high-performance green building as suggested by Fujita Research (2000) include:
1. Optimal environmental and economic performance;
2. Integrated processes, innovative design and increased efficiencies to save energy and resources;
3. Satisfying, healthy, productive, quality indoor spaces;
4. Employing lean construction methodologies and tools to improve waste management and reduce the environmental impact of construction waste;
5. Increasing the emphasis, at R&D stage, of whole-building design, construction and operation over the entire life cycle;
6. Fully integrated approach including teams, processes and systems;
7. Renewal engineering methods;
8. Management and business practices;
9. New standards, open buildings, advance jointing and assembly techniques, process engineering;
In High Performance construction, the key issue is how the choice of construction products and methods can create scope for reducing burdens.
Green Materials
The market for building materials is predicted to grow steadily into the foreseeable future. The primary driver for growth by sheer volume is the ongoing government investment in new buildings and other physical infrastructure in developing countries such as South Africa. At the same time, the demand for building materials is shifting towards environmentally preferable or “green” materials due to consumer demand; and an ever growing number of mandatory environmental regulations and standards.
Green materials use is predicated on the replacement of future flows of conventional building materials with “green” materials. From an environmental perspective, “green” materials would need to be those materials with the least “embodied effects”, where the word embodied refers to attribution or allocation in an accounting sense as opposed to true physical embodiment. In the building community, the tendency is to refer only to “embodied energy” (Trusty and Horst, 2006). However, as implied by the comprehensive list of effect categories (Table 1) typically investigated in a Life Cycle Assessment (LCA) study, all the extractions from and releases to nature are embodied effects, and there are also embodied effects associated with the making and moving of energy itself (known as pre-combustion energy).
Until the 1970s, the construction industry sector made little attempt to establish objective and comprehensive methods for environmental assessment and improvement of buildings. The concept of Sustainable Construction which is “The creation and operation of a healthy built environment based on ecological principles” (Kibert, 1994) was first mooted in the wake of the 1987 Brundtland Report and the 1992 Rio Accords. Starting with the launch of the Building Research Establishment Environmental Assessment Method (BREEAM) in 1990, a large number of building rating systems have been developed around the world to provide the basis for putting sustainable construction into practice.
Green Technologies
Green technologies in the building sector can be defined as those technologies which reduce the environmental impact of building on the environment. These technologies would either reduce environmental impact through the development of more environmentally sustainable materials and products, or through the generation and/ or conservation of resources such as energy and water.
Conclusion
The construction industry sector is the largest documented user of materials by weight. The market for building materials is predicted to grow steadily into the foreseeable future driven by ongoing investments in built infrastructure and the consumer demand for “green” products.
Source: Green Building Handbook: Materials ad Technology
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