Alila Villas Uluwatu, Bali
To combat climate change and intensify the actions and investments needed for a sustainable low carbon future, the Parties to the United Nations Framework Convention on Climate Change reached a landmark agreement on 12 December 2015. As this was the 21st such Conference of the Parties, it is referred to as COP21 where more than 190 nations gathered in Paris to discuss a possible new global agreement on climate change.
The central aim of the COP21 agreement is to strengthen the global response to the threat of climate change by keeping a global temperature rise this century below 2OC above pre-industrial levels and to pursue efforts to limit the temperature increase even further to 1.5OC. To achieve this temperature goal, parties must aim to reach “global peaking” of greenhouse gas emissions (GHGs) as soon as possible. The built environment plays a vital role in in how countries plan to respond to the 2015 Paris Agreement and reducing our carbon emissions and reaching global peaking of emissions.
Built environment’s greenhouse-gas-emissions
Cities are responsible for over 70 percent of global energy consumption and CO2 emissions, mostly from buildings, marking a significant opportunity to focus climate change mitigation and adaptation efforts on dense urban environments. For the built environment to tackle their respective carbon emissions, a more detailed perspective is required. The built environment’s greenhouse-gas-emissions can be broken into three areas.
1. Existing Buildings
2. New Buildings
3. Embodied Energy.
Existing Buildings: Operational Emissions
In addition to the unprecedented growth in the global building sector, nearly two-thirds of the building area that exists today will still exist in 2050. Therefore, any transition to low-carbon/carbon neutral built environment must address both new construction and existing buildings.
In order to achieve the target set by the Paris Agreement to limit the rise in global average temperature to below the 2 degree C threshold – a significant increase in the rate and depth of existing building energy efficiency improvements and the generation and procurement of renewable energy (energy upgrades) is required.Emporium Hotel South Bank, Brisbane
New Buildings: Operational Emissions
By 2060, the world is projected to add 230 billion m2 of buildings, or an area equal to the entire current global building stock. This is the equivalent of adding an entire New York City to the planet every 34 days for the next 40 years (UN, 2017).
While there have been worldwide improvements in building sector energy efficiency, as well as growth in renewable energy generating capacity, these have not been nearly enough to offset the increase in emissions from new construction. As a result, building sector CO2 emissions have continued to rise by nearly 1% per year since 2010. In order to achieve the target, set by the Paris Agreement, all new construction should be designed to high energy efficiency standards and use no CO2-emitting fossil fuel energy to operate.
Building Stock/New Buildings: Embodied Energy
Annually, embodied carbon is responsible for 11% of global GHG emissions and 28% of global building sector emissions. The embodied carbon emissions of building products and construction represent a significant portion of global emissions: concrete, iron, and steel alone produce ~9% of annual global GHG emissions; embodied carbon emissions from the building sector produce 11% of annual global carbon emissions.
Unlike operational carbon emissions, which can be reduced over time with building energy efficiency improvements and the use of renewable energy, embodied carbon emissions are locked in place as soon as a building is build. It is critical that we get a handle on embodied carbon now if we hope to phase out fossil fuel emissions by the year 2050.
Case Study - New Zealand
The 1997 Kyoto Protocol helped countries establish emissions targets for the years 2008-2012. This brought about New Zealand’s most prominent and principle response to climate change, the Emissions Trading Scheme (ETS). The ETS was established under the Climate Change Response Act 2002 and was first legislated in the Climate Change Response (Emissions Trading) Amendment Act 2008 in September 2008 (Ministry for the Environment, 2018). The NZ ETS puts a price on greenhouse gas emissions. This price on emissions is intended to create a financial incentive for businesses who emit greenhouse gases to invest in technologies and practices that reduce emissions. It also encourages forest planting by allowing eligible foresters to earn New Zealand emission units (NZUs) as their trees grow and absorb carbon dioxide.
Figure 1: Simplified diagram of how NZU trading occurs. Ministry for the Environment, 2018.
The value of total CO2 emissions quoted for New Zealand’s built environment is typically around 5% (Figure 2a) and sometimes as low as 2% (considering only direct combustion of fuels). Taken in isolation, 2-5% seems small enough to conclude that the built environment is relatively unimportant and that other sectors such as agriculture are higher priorities for emissions reduction in a country such as New Zealand. However, a recent national study into New Zealand’s carbon footprint show that these figures only consider the energy used in buildings but exclude the construction of the buildings themselves and their eventual demolition. If the full building life cycle is factored in (construction, occupation and end-of-life), the contribution of the built environment (i.e. buildings and infrastructure) increases to approximately 13% of New Zealand’s gross carbon footprint (Figure 2b). If we then adjust for the carbon footprint embodied in our exports and imports, this share climbs to 20% as shown in Figure 2c (Vickers & Fisher, 2018). This highlights the built environment as a key contributor to the national carbon emissions footprint.
Figure 2: A breakdown of New Zealand’s carbon footprint in 2015 from (a) a production perspective, (b) a life cycle perspective, and (c) a life cycle consumption perspective. Vickers, J; Fisher, B, 2018
In 2016, 85 percent of New Zealand’s electricity was generated from renewable sources (Ministry of Business, Innovation and Employment, 2017). These statistics indicate New Zealand’s building industry also needs to address the way in which buildings are designed and constructed, with care given to materials used and future deconstruction accounted for.
The uptake of photovoltaics (PV) in residential buildings has been increasing in New Zealand, this is mainly attributed to their decline in capital cost. Solar PV panels themselves have a large environmental impact through manufacturing in China using coal and transportation. In the long term, residential solar uptake is expected to actually have a detrimental effect on New Zealand’s carbon emissions by increasing the off-season demand on fossil-fuels, as it will displace new, large scale, super-low-emission wind and geothermal that would be built to meet growth demand in New Zealand (MacGregor, Dowdell, Bint, & Berg, 2018). This reinforces the importance of implementing the appropriate energy saving measures to a region such as New Zealand and other colder climates.
Most commercial buildings in New Zealand are under 650m2, with only 1 percent of commercial buildings being over 9,000m2. Tthe largest buildings in New Zealand, representing just one percent of the total building stock, are using 190kWh/m2.yr, over 20 percent more than the majority of buildings which are under 650m2. This would indicate that the largest buildings are the greatest contributors to CO2 emissions of the commercial built environment. MacGregor et al (2018) have developed 2 fundamental strategies for reducing greenhouse gas emission of commercial buildings as shown in Figure 3.
Figure 3: Building carbon reduction strategies. MacGregor et al, 2018.
Strategy 1 focuses on emissions arising from the building energy demand and supply during use. Policies and market mechanisms which reduce the demand or decarbonise the supply will help reduce the ‘business as usual’ trend line. Strategy 2 focuses on reducing the initial carbon debt incurred during design and construction through reducing the building size, choice of materials and an active effort to minimise construction waste.
Sustainable Building Planning and Designing
EarthCheck’s Building Planning and Design Standard has been developed to guide the achievement of best practice operational performance for buildings. Through reverse engineering, the Standard aids design teams to achieve location and asset specific best practice operational performance targets. EarthCheck’s Planning and Design Standards provide guidelines, tools and indicators to assist designers, architects and developers in the planning and design phases of sustainable buildings. The Standard is designed to ensure achievement of superior expected performance, meeting or exceeding current global best practice.
EarthCheck’s Planning and Design science is aligned with the international best practice for the built environment. Design Standards provide a holistic sustainability framework to guide development and refurbishment projects towards asset efficiency and business improvement. Through the BPDS, developments can make informed design decisions throughout the planning and design stages of their project to actively reduce the embodied carbon emissions and produce energy efficient buildings reducing operational carbon emissions.
Visit earthcheck.org to find out more about sustainable design.Zuri Zanzibar, Tanzania