Low-carbon buildings are buildings designed and constructed to release very little or no carbon at all during their lifetime.
Buildings and climate change
What are low-carbon buildings?
Low-carbon buildings (LCB) are buildings which are specifically engineered with GHG reduction in mind. So by definition, a LCB is a building which emits significantly less GHG than regular buildings.
There is no emissions threshold under which a building would qualify as a LCB. But to be genuinely “Climate Change neutral”, a LCB would have to achieve at least 80% GHG reduction compared to traditional buildings. According to the Stern Review on the Economics of Climate Change, our emissions would have to be reduced by 80% compared to current levels in order not to exceed the Earth’s natural capacity to remove GHG from the atmosphere. By comparison, a regular building releases about 5,000 kgCO2e/m2 during its entire lifetime (though it varies a lot, depending on the project type and where it is located).
Low-carbon buildings technology
GHGs are released in the atmosphere during each stage of a building's life:
- Building construction
- Building operation
- Building renovation and deconstruction
GHG reduction calculations should consider all stages of the building life: construction (incl. renovation and deconstruction) and operation.
GHG emissions associated with buildings construction are mainly coming from:
- Materials manufacturing (e.g., concrete)
- Materials transport
- Demolition wastes transport
- Demolition wastes treatment
The construction, renovation, and deconstruction of a typical building is on average responsible for the emissions of 1,000-1,500 kgCO2e/m2 (around 500 kgCO2e/m2 for construction only).
Strategies adopted by LCB to reduce GHG emissions during construction include:
- Reduce quantity of materials used
- Select materials with low emissions factors associated (e.g., recycled materials)
- Select materials suppliers as close as possible from the const
- Divert demolition wastes to recycling instead of landfills or incineration
GHG emissions associated with buildings operation are mainly coming from:
- Electricity consumption
- Consumption of fossil fuels on-site for the production of electricity, hot water, heat, etc.
- On-site waste water treatment
- On-site solid wastes treatment
- Industrial processes housed in the buildings
Fossil fuels include natural gas and propane.
Depending on the region where the building is located and the building energy mix, operation emissions can vary from 0 to over 100 kgCO2e/m2 per year.
LCB usually achieve less than 10 kgCO2e/m2 per year.
Strategies adopted by LCB to reduce GHG emissions during operation include:
- Reduce energy consumption
- Switch to renewable energy sources
Renewable energy sources include:
- Low-impact hydro
- Biofuels (under certain conditions)
- Wave and tidal
Indirect GHG reductions
There are three main sources of indirect GHG reductions available for buildings:
- Green power
- Carbon offsets
- GHG reductions from the selling to the grid of clean electricity produced on-site
These GHG reductions can be used by building owners to offset the emissions which can not be reduced otherwise or to achieve specific GHG target, for example “carbon neutrality”.
Note: building emissions should always be reported in GHG inventories prior to and independent of any indirect GHG reductions. GHG emissions trades should be reported separately in a different section of GHG inventories.
For this reason, it is recommended to reduce buildings emissions by adopting the strategies listed in previous paragraphs rather than using GHG emissions trades.
Low-carbon buildings today
LCB, as part of “green buildings”, are developing very rapidly. Recent examples include:
- Aldo Leopold Foundation Headquarters, Fairfield (USA)
- Kroon Hall, Yale University’s School of Forestry & Environmental Studies (USA)
- Sustainable Energy Technology Center, The University of Nottingham, NingBo (China)
- Mud Decisions, Bangalore (India)
Existing low-carbon buildings standards
The Low-Carbon Buildings Method TM 2011, Buildings Construction, A Simplified Methodology for Estimating GHG Emissions from Buildings Construction
- U.S. EPA. 2008. Inventory of U.S. Greenhouse Gases Emissions and Sinks: 1990-2006, p. ES8.
- IPCC. 2007. Climate Change 2007 Synthesis Report, p. 59.
- The Stern Review, Final Report, Chapter 8.