In the distant past, the environmental impact of construction was typically self-evident.
As most buildings and heritage brickwork were constructed with local materials, you could simply look around the local area to see the environmental impact, but as construction became much more sophisticated and more efficient, it also became far more impactful to the environment.
Particularly during the rise of statement architecture in the wake of the revitalisation of Bilbao, architecture and construction relies even more on exotic, rare and ecologically expensive materials, each of which has a particular cost to the environment that gets more expensive to pay by the day.
Whilst the typical case for traditional methods is aesthetic, this article will instead explore the environmental case of exploring old, traditional and local building techniques that worked for centuries, by looking at the impact of the building materials we use now.
How Do We Measure Environmental Impact?
For as much as our building materials of choice have changed as a society, how we explore the environmental impact of construction decisions has become more complex and more sophisticated over the years.
As both medicine and climate science have evolved and as production and manufacturing, in general, have become more industrialised, the implications of the construction world post-Industrial Revolution are both greater and more greatly understood.
The effects of chlorine and bromine gases on the ozone layer, primarily caused in construction by aerosol propellants and agents used to create plastic foams, led to several international agreements being put in place to phase out the use of chemicals blamed for causing holes in the ozone layer.
As well as this, the primary modern measurement of the environmental impact is greenhouse gas emissions, which is the amount of carbon dioxide, methane, nitrous oxide and fluorinated gases emitted through the construction process.
Whilst initially only focused on the gases (primarily carbon dioxide) produced during construction were factored into early legislation and surveys into environmental impact, there is also an increased focus on the lifetime embodied emissions of a building.
This is the greenhouse gases emitted from initial mining and sourcing of the raw materials, transportation, refinement, construction, the entire lifespan of the building’s use and finally its demolition, leading to a shift in the philosophy of some of the materials we use.
A greenhouse gas is a gas in the atmosphere that absorbs heat energy and redirects it back to Earth, creating increased temperatures in a similar way to how a greenhouse functions, hence the commonly used term greenhouse effect.
Cement’s Climate Impact
For at least a century, cement and concrete have been the blight of restorers and heritage construction, but the primary reason for this is that it is often incorrectly used to repoint stone walls, something that due to its lack of permeability typically leads to long-term damage.
In this case, cement and its solid composite byproduct concrete are not only the most environmentally impactful construction materials on the planet but one of the greatest contributors to climate change of any kind, with seven per cent of all carbon emissions being the result of cement and concrete.
This is due to a lot of factors throughout the life of cement and concrete. Producing concrete not only takes a lot of energy that is often generated through the use of polluting fossil fuels, but the chemical process itself has carbon dioxide as a byproduct.
Also, when concrete and cement structures are demolished, it releases concrete dust, a dangerous air pollutant.
However, one caveat is that the reason why it is such a big carbon emitter is because aside from water it is the most commonly used substance in the world.
Expanding Foams
Whilst insulation previously consisted of the inherent properties of wood and naturally-derived construction materials such as wattle and daub, modern insulation typically relies on sheets of fibreglass or expanding foams such as polyurethane.
Whilst better than the previously commonly used asbestos, expanding foams tend to be harmful whilst they are curing, causing breathing issues and blurred vision, leading to asthma with long enough exposure.
However, far more concerning is that closed-cell expanding spray foam products typically relied on blowing agents that were derived from hydrofluorocarbons (HFCs) as well as chlorofluorocarbons (CFCs), both of which are significant contributors to global warming and ozone depletion.
Many of these agents have been phased out or are in the process of being phased out, but with less polluting and more effective alternative insulation, spray foam is a material where the cost may not possibly be worth it.
Gypsum Plasterboard
Mixed from paper and gypsum, plasterboard (also known as plaster of Paris) is a commonly used material in construction, typically mixed with a range of chemicals to increase its strength and longevity.
It is primarily used for its versatility but it also has significant embodied emissions costs due to production, transportation and waste. People are far less aware than other materials that gypsum can be recycled and create a closed-loop system using recycled paper.
It can also cause problems when plasterboard is mixed with other forms of waste, so it is best to separate and recycle gypsum whenever possible.
Unlike a lot of the materials mentioned above, which would require significant changes to how they are manufactured and used in order to become less environmentally impactful, plasterboard simply needs a more holistic approach to waste management and transportation, although lath and plaster could be used as an alternative.
Chemical Treatments
Many, if not most of the construction materials used today, even if they are otherwise far more environmentally conscious, rely on chemical treatments and additives either for regulatory reasons or to ensure they last longer than they otherwise would.
This can become an issue when it comes to recycling, as it can inadvertently lead to the contamination of recyclable materials such as metals and wood.
This has become an increasing issue for textiles as there is an increased awareness of persistent organic pollutants, which when sent to landfill can pollute soil, which in turn ends up in water supplies and can cause contamination.
This highlights that environmental awareness is not just about specifics but a holistic view of the impacts the materials we use can have, and often the most effective solution is one that has been used much longer than the materials that are standard today.
