Carbon Emission Targets

In 2015, nations across the world came together to negotiate the Paris Agreement, a historic framework underpinned by the long-term goal to stop global temperatures from rising above 2°C. In an effort to further ensure the prevention of irreversible climate change, governments also included an ambitious target to limit temperature rise to 1.5°C, which would require emissions to peak by 2020 and fossil fuels to be phased out by 2055.

The Built Environment

These requirements warrant two critical considerations for evaluating carbon reduction strategies: How much energy can a strategy potentially save? And, what is the timeframe for realizing these savings? Since some reduction strategies result in an initial increase of carbon emissions, we need to pursue initiatives that can produce a net reduction within a critical 10 to 20 year timeframe. In short, we need strategies that produce large savings fast.

The built environment is a critical source of savings. As an end user of fossil fuels, the built environment accounts for more emissions than any other sector, producing nearly half of total global greenhouse gas (GHG) emissions.  The current gold standard for reducing emissions from buildings is to build new, zero net energy (ZNE) buildings – super efficient buildings powered by renewable energy sources. This is an important step to realize a carbon neutral built environment, but there is a problem with this strategy: building new, ZNE buildings will generate substantial emissions.

Two other sources of emissions may be even more important to address in the short term: embodied emissions from building materials, products and construction processes, and operating emissions from existing buildings.

Embodied Emissions

Making building materials and products cause greenhouse gas emissions. Activities such as mining, driving trucks, running factories, and combining chemicals result in emissions to the air, earth and water. Embodied carbon is the sum impact of all the greenhouse gas emissions attributed to the materials throughout their life cycle (extracting from the ground, manufacturing, construction, maintenance and end of life/disposal).

Significant progress has been made to understand how to reduce operational emissions. However, there is a gap in our knowledge and effort toward reducing embodied emissions. The Carbon Leadership Forum is working to bridge that gap to enable a comprehensive understanding of all emissions from buildings throughout their life cycle.

Life Cycle Approach

Environmental Life Cycle Assessment (LCA) is a standardized method used to quantify environmental impacts of buildings from material extraction and product manufacturing through use and end of life and disposal.