Written by Karl Smith (Imperial College London)
We live in a post COP21 World. It’s now more than two months since the nations of the world agreed (in article 2) to work towards limiting global warming to 1.5 °C (above pre-industrial levels). But what does that mean? Have we been saved or submerged in the wake of what happened in Paris?
The COP21 Agreement
The 1.5 °C agreement is, in fact, an encouraging outcome. Before Paris, even an agreement on a 2 °C limit was far from a certainty. But what chance of success without a clear road-map for achieving the 1.5 °C limit? The COP21 pledges include a commitment to help developing countries to adapt to climate change and also, transition to clean energy – by providing finance. However, this commitment, like the 1.5 °C limit, is not legally binding. But do we need to be forced into taking action?
The Challenge of Meeting COP21
We do not have much room, or time, for inaction. 2015 marked the year in which the average global temperature reached 1 °C above pre-industrial levels. Moreover, humans’ appetite for meat, though largely in decline in the west, is increasing in countries such as China. Animal farming generates more greenhouse gas emissions than all of the world’s vehicle exhaust emissions. Moves to switch to clean energy are being more than offset by our growing taste for animal products. Rising consumption is compounded by a growing population – today’s 7.1-7.2 billion is expected to top 11 billion by 2100 (UN data).
Capitalising Upon our Cities
Revolutionising the built environment could be crucial to achieving COP21’s ambitions. Why? We live in an urbanised world. In 2014, 54% of the world’s population lived in urban areas. This figure is predicted to reach 66% by 2050 (UN data). And our urban centres use a lot of energy.
A 2009 publication calculated that China’s urban areas consumed 75% of the energy produced across the country. Is this a lot? Yes, when you consider that China is the largest single contributor to global carbon emissions – 28%, against the EU’s 10%.
Within the EU, households use 26.8 % of all (final) energy consumed and the service industry consumes 13.8% (Eurostat data – 2013). If we change the focus from decarbonising the entire world to decarbonising our urban centres, then we can go a long way towards achieving COP21’s target.
Making the Case for Decarbonising the Built Environment
So what can COP21 compliance do for us? Apart from the obvious benefit of preventing unchecked climate change, decarbonising cities can:
- Reduce energy bills. Improving building insulation is crucial to reducing energy use. Within the UK, around 60% of domestic energy use is employed for heating (UK government data – 2013). Lowering our energy use lowers our energy costs. It’s a simple win-win.
- Improve energy security. Cities are in a strong position to become self-sufficient for power. They can hence become better insulated against both geo-political events and also, the increased risk of power black-outs that countries like the UK face due to increased demand and the closing down of coal plants and end-of-life nuclear plants.
- Improve health. Reducing our meat consumption and making more use of our bodies for urban travel – whether on foot or on bicycle – can enhance health and well-being.
COP21 – Benefiting Green Building Businesses
For the green building industry, COP21 presents a compelling opportunity to increase coverage of energy saving/low carbon technologies. The built environment sector is a major energy end-user, which represents a great scope for achieving major carbon savings via small scale interventions – there’s a lot of low hanging fruit to be plucked (e.g. improving building insulation).
The greater use of energy and building standards may be crucial to informing and educating clients/consumers on the energy, carbon and cost savings of low-carbon pathways. So will the setting of targets by city/local governments. For example, mandating that new build developments are zero/low-carbon, setting energy efficiency targets for existing targets.
Multi-functional Benefits – The Case for Green Roofs
If someone gives you 100 Euros to spend, would you spend it on something that delivers only one benefit, or many? Within the built environment sector, green infrastructure – green roofs and walls, urban trees etc. – is very much a multi-benefit intervention.
With respect to decarbonising building stock, green roofs: 1) provide a thermal insulating layer, reducing energy use for heating; 2) keep buildings cool in the summer, so reducing the need for energy intensive, air conditioning. The cooling effects stems from their having a lower solar receptivity than conventional roofing materials, plus the self-cooling mechanism of evapotranspiration that the roof’s vegetation employs. Additional benefits? They enhance the building’s aesthetic properties, boost local biodiversity, provide the potential for food production and act as a sponge/buffer a storm water, so reducing the risk of rainfall run-off induced flooding.
In short, vegetation delivers a range of benefits to humans that are termed ‘Ecosystem Services’. In addition to the green roof benefits listed, these services include: decontamination of air and water; provision of shading; improved human health and well-being. The Imperial College London led, Climate KIC funded, Blue Green Dream project, has focussed on quantifying these benefits and producing tools to enable their simulation for optimised design and planning.
Gearing up for a Green Future
The prospect of cities that are green in every sense is surely irresistible to any ambitious and forward thinking city. We could wait for this greening to happen via the trickle-down effect of post-COP21, new/tightened building and planning guidelines/recommendations. Or, in tandem with municipal governments and authorities, we could seize upon the clear economic, environmental and societal benefits outlined here to instigate a step change in the decarbonisation of the built environment.
I’m sure that the Eurbanlab community would agree that this is not the time for waiting. If the climate is changing, then so should we. This is one race that we cannot afford to lose.
This article was written by Dr. Karl M. Smith (Imperial College London)
for the Featured Articles series.