Global warming and infrastructure construction

Global warming and infrastructure construction

How can construction align with the goals of a low-carbon economy?

Definitions
  • Sustainable construction aims to minimise environmental impact and maximise both economic viability and the social benefits (e.g. employment/empowerment) of construction
  • Sustainable design aims to design buildings and infrastructure that work within environmental limits and are profitable and healthy places to live, work and use

Barriers to change
  • Economic viability is often prioritised (by both private and public clients) over environmental and social considerations
  • Sustainable construction/design can be hampered by uncertain economic environments, rapid urbanisation, lack of effective spatial planning, lack of skills and integration of project teams
  • A ‘compliance’ engineering culture, that assumes – often wrongly – that sustainability will cost more money; and client unwillingness to pay higher up-front capital costs for potential savings in the long term

References

Du Plessis, C, Sustainable Construction in Developing Countries
DEFRA, Construction waste

Global warming impacts of the construction industry

  • Economic: construction industries have complex links to most sectors of every nation's economy, playing a key role in determining its social and economic progress
  • Social: construction provides opportunities for employment and skills development as well as the socio-economic benefits of the buildings and infrastructure themselves (housing, transport links etc). But consider also factors such as the health and safety risks of construction and use and migration of labour force for large construction programmes
  • Environmental: construction impacts ecosystems, depletes natural resources and leads to CO2 emissions (see example)

Example: the UK construction industry’s CO2 emissions impact

  • Through the UK Climate Change Act 2008, the UK government is committed to a 34% reduction in CO2 emissions by 2020 and 80% by 2050
  • Since building use contributes about 52% of the UK’s CO2 emissions and construction contributes another seven percent, the construction industry is a major focus for change
  • The waste going to landfill from the UK construction industry in 2004 was about 100 million tonnes, roughly equivalent to one house being buried in the ground as waste for every three built

Design and construct to minimise environmental impact and optimise socio-economic viability

Now: engineer’s influence at design stage:
  • Choice of locally available resources (materials and labour);
  • Recyclability of materials and systems (benefit from a contractor’s input and owner involvement as they are often more informed of material availability and recycleability)
  • Efficient structural, electrical and mechanical systems
  • Informed decisions about demolition/deconstruction and preservation (design in adaptability to reduce need for demolition at end of primary use period)
Longer term: development of the construction industry to embrace sustainable design and construction requires:
  • Human resource development:Professionals: professional bodies to set membership standards and CPD; and higher education to focus on sustainable construction
  • Small businesses: appropriate procurement strategies for engaging and developing SMEs
  • Materials and technology development: e.g. Reduce waste through prefabrication and recycling/re-use. (see box)
  • Corporate development: Businesses to position themselves to access the global market for low-carbon goods and services, projected to be worth £4.3 trillion by 2015
  • Perception change: Governments can incentivise private sector compliance and research through legislative controls, such as carbon pricing (tax, trading), planning and building regulations and requiring compliance with environmental assessment procedures (e.g. BREEAM, CEEQUAL, LEED, measuring factors such as site development, water and energy efficiency, solid waste and emissions management, materials selection, indoor environmental quality etc)

Considerations for the selection of building materials:

Construction materials can account for 40% of a building’s lifetime CO2 emissions. So use efficient structural systems and materials:

  • Timber: renewable, biodegradable, non-toxic, energy efficient. Specify lumber certified as sustainably harvested
  • Concrete: cement production contributed approx. 7% of global CO2 emissions in 1998. Reduce cement content by substituting fly ash (by-product of coal burning) or blast furnace slag
  • Masonry: use thermal mass properties to reduce heating/cooling requirements. Consider also recycled content (fly ash, slag cement, silica fume, recycled or salvaged aggregates), adobe (less than 1/6 the production energy of concrete blocks) and interlocking masonry (saving mortar)
  • Steel: already a highly recycled building material, consider designing for de-constructability of a building, to aid re-use of materials (e.g. bolted over welded connections)

Further reading

BIS, The Strategy for Sustainable Construction
Journal of Construction in Developing Countries