Much debate surrounds the question of whether civil engineering can ever be truly sustainable. The answer depends very much on what your definition of sustainability is, CH2MHill global water sustainability director Jay Witherspoon tells Marissa Lynch.
Sustainability is incredibly hard to define. The term can vary from building to building or from energy source to energy source and experts may also be conservative or liberal with their own definitions.
For CH2MHill director vice president and global water sustainability director Jay Witherspoon, the definition is not the issue, rather, it can be the jumping off point to let companies decide how sustainable they want to be.
“The problem with sustainability is that you can define it in so many different ways,” he says. “What we do is lower the risks of the unknown…some of the risks are climate change, economic downturns or customer practices and you have to sort through those and then prioritise how you negotiate it.”
He says most people he works with are most concerned about making sure ageing infrastructure and facilities can still be made sustainable.
“The problem with sustainability is that you can define it in so many different ways”
Witherspoon believes achieving sustainability is all about taking one step at a time, or as he describes it, a “phased approach”.
“We do it on a social and economic basis to show the economic impacts for them…then we look at the actual cost and return on the investment. If they want carbon neutrality, you will have to question the real economic cost,” he says.
“Sustainability will give you return on investment for the future, but phased over time technologies will be invented which will make that choice more viable. Twenty five years from now you will be able to be completely sustainable.But it’s best to begin with a phased approach.”
For Witherspoon, the relationship between embedded carbon and operating carbon is an interesting one - by decreasing the embedded carbon in a project, you can significantly help to increase its sustainability at quite a small cost. Embedded carbon, he says, is an item’s carbon content that can be measured at every stage of its production and distribution, from source to build.
“People have to make a decision, for example how much green concrete they will use to replace the Portland cement,” he says.”You do pay a premium but through the opex [operating expenditure], you will make it
up about 10 to 15 years down the line.”
When building a “business as usual” structure, concrete will take up the largest percentage in the total carbon footprint of the building, measuring about 59%.
“We are in a water crisis now and soon this will lead to scarcity. This will quadruple over at least this generation’s lifetime”
Witherspoon says that green cement is most often being used to make up about 10% to 15% of the mix, although some projects have used up to 50%.
Using green concrete can save up to a third of total carbon emissions, although the cost of green concrete is about 10% to 12% more than Portland cement.
Part of the solution
Having green concrete is just part of the sustainability solution.Witherspoon says it’s very difficult for an entire city to become sustainable, although attaining the ideal can come close if a city is built from the ground up.
This was plan for one of the world’s more famous sustainable cities, Masdar in Abu Dhabi. While its sustainable aspirations have been dramatically scaled back in recent months (NCE 26 May), and it has many detractors, it still stands as an exemplar from which others can learn.
For this project, CH2MHill used its thorough series of key performance indicators (KPIs) that are able to be tweaked depending on the client’s specifications.
When Witherspoon began work on Masdar, the developers had chosen a plethora of KPIs that were far from normal.
“Initially there was a requirement for some pretty crazy things, such as one that said that all citizens would have to practice yoga once a week.”
Instead, CH2MHill refocused the vision of the city and created new KPIs around energy, water, waste, materials, logistics and transportation, social and economics.
“We took their old KPIs and remodelled them bottom up and top down,” Witherspoon says.
“We came up with new KPIs from their vision and goals and outcomes. We used risk assessment models and picked the ones with higher consequences and increased probability.”
One of the easiest sustainability solutions implemented in Masdar was being able to reduce domestic energy consumption (or plug loads) something which any individual can do easily as well.
“One of the best options is reducing plug load and reducing heating and cooling,” he says. “You can do things like switch lights to LEDs and supplement with renewable energy which can get you down to the 10% of business as usual level. It’s very hard and costly to go beyond that, to get to zero carbon emitted.”
Masdar, he says, will be an exemplary sustainable model city when it is finished.
Other solutions to increase sustainability depend largely on one very unpredictable factor: climate change.
Witherspoon says that for those working in industries such as agriculture, the effects of climate change could eventually be detrimental for business.
Despite the unknowns about exactly what areas climate change will impact, Witherspoon says CH2MHill has some pretty reliable models that it is using to help its clients become future proof.
One of these clients is a sugar cane grower in Queensland, Australia. In future, there is a very high chance that the areas in far North Queensland that currently have an ideal climate for growing cane will no longer be viable.
“We are helping a sugar cane manufacturer in Queensland. It has been manufacturing sugar for 150 years and it is starting to wonder if it will be in business for another 50,” he says.
“It wants a predictive tool to reduce the future risks and future company costs and we are looking at the locations and benefits. We know that in future, there will be a lot more rain to deal with.”
Sugar cane shift
According to figures, for the cane grower, there will be about a 15% band shift in the soil and water conditions.
Witherspoon says his client is already thinking ahead and investing in the future.
“He’s changing his harvesting approach and buying property in areas that may be better for it in future,” he says.
According to their climate maps and data, even city planners will have to change their thinking. With increased rain events likely in places like Australia, infrastructure will have to be constructed to meet new design codes to cope with an increase in flooding and extreme weather events.
However, city planners are not the only ones that need to change their thinking, Witherspoon says.
In order to be sustainable, people must understand that their own attitudes must change as well. “We react too slowly and really only react to extreme events,” he says.
“We are in water crisis now and soon will move to water scarcity. This will quadruple over at least [this generation’s] lifetime. We’ll need to use at least 50% to 70% of wastewater for agricultural development and we will need smarter and better technologies. You have to look at things like growing dates in the desert - that just doesn’t make sense. There are also several things to do such as 100% reuse of irrigation, farming and cooling and we need to look at the relationship between water and energy. We call that the water energy nexus,” he says.
“That shows us how to optimise water wastage to water reuse. And there needs to be a change in attitude - already in the Thames we have toilet water going in there and London takes its water from there and it is treated.
There’s not much difference to recycling and reusing water at a very high treatment quality.”
Inevitably, the key is to start early and phase in the sustainable approach that will be taken - no matter what your definition of sustainability really is.