LCA and Embodied Carbon

Embodied carbon means all the CO2 emitted in producing materials. It is estimated from the energy used to extract and transport raw materials as well as emissions from manufacturing processes. The embodied carbon of a building can include all the emissions from the construction materials, the building process, all the fixtures and fittings inside as well as from deconstructing and disposing of it at the end of its lifetime.

It can be used to compare the environmental impacts of different building materials, designs and construction processes. It can help to identify elements which are carbon-intensive and promote alternative options which reduce the amount of CO2 released. It can be used to design policies that reduce the CO2 emissions from the construction sector.

Used together with the operational carbon (i.e. the carbon emitted due to use of the building for heating, cooling, equipment use etc), the embodied carbon can be included as part of a whole life cycle analysis (LCA) to understand the overall impact of the building on the environment over its whole life cycle.

DesignBuilder provides 2 methods to calculate environmental impact of the building construction (as opposed to its operation):

• One Click LCA.
• Embodied Carbon.

Technical Note: Geometry Conventions in One Click LCA Carbon Assessments

 

In general, we advise that you use the 2-Outer Zone geometry and surface areas option when carrying out Carbon calculations. This is because:

 

1. The 2-Outer setting typically provides a more realistic assessment of the material quantities than the 1-Inner alternative option. In particular, depending on how the blocks have been drawn and whether any fixed thicknesses have been applied, the 1-Inner option may result in vertical gaps between floors and horizontal gaps between zones on the same level. This may result in an underestimate of the surface areas in the DesignBuilder embodied carbon results.
   
   

2. When exporting the model to One Click LCA, DesignBuilder v7.3 uses an intermediate gbXML file to supply the model geometry, constructions, glazing etc. The gbXML format effectively uses 2-Outer geometry, regardless of the Zone geometry and surface areas setting. Unless the model has been created using zero thickness surfaces, this will result in the One Click LCA surface areas being different from those used in the internal DesignBuilder calculation, which can cause confusion.

One Click LCA Integration

The recommended way to carry out a complete Building Life Cycle Assessment, is through our native integration with One Click LCA ®, a powerful yet easy to use LCA and LCC platform. The integration enables DesignBuilder users to:

• Transfer their DesignBuilder energy models quickly and easily to One Click LCA for additional materials analyses.
• Achieve BREEAM Mat 01 LCA and LCC credits
• Acheive LEED v4 and v4.1 LCA materials credits.
• Use One Click LCA’s material database to get a true picture of the carbon & LCA performance.

Note: The One Click LCA integration uses the material names selected in the DesignBuilder model, mapping those to known certified data contained in the extensive One Click LCA database. The embodied carbon data entered in the DesignBuilder Materials database is not used in these analyses.

For more information on the integration see: One Click LCA DesignBuilder Integration Help Article.

Note: You should contact One Click LCA to obtain a licence to access their online system from DesignBuilder.

Embodied Carbon Results

DesignBuilder also provides a basic report of the embodied carbon and equivalent carbon data for the building on the Embodied Carbon tab of the Cost and Carbon screen. The carbon data covers only bulk construction and glazing materials and not lighting, HVAC and other building services.

The calculation is made by summing the embodied carbon data for each surface in the model, calculated using construction material layers and the embodied carbon data for each material.

The materials and constructions inventories are equivalent ways of showing the same data, but broken down in different ways. The total for the building is shown at the bottom.

Note: Embodied carbon calculations for models where the zone multiplier is used are not always 100% accurate because the embodied carbon for internal surfaces between multiplied zones and adiabatic component blocks can be over-estimated.

Note: The embodied carbon for glazing and PV panels can be defined on the Carbon tab of the Model options dialog.

An example Embodied carbon report is shown below.