KJ Tait carried out a Whole Life-Cycle Carbon (WLC) assessment for this project. The outcome of this review enabled a reduction in embodied carbon to be measured and support the BREEAM Outstanding certification.
30 Semple Street is a 7,160m2 office development located in the Exchange Business District in Edinburgh.
Although the WLC assessment covers modules A, B and C as set out in BS EN 15978 and the RICS Professional Statement, the focus of the study at this stage covered suggestions for module A, embodied carbon at practical completion. These recommendations are critical at this early stage of the project as major carbon savings can then be incorporated into the scheme.
Product Stages (module A1 to A3):
Using OneClick LCA, a baseline model was created using both the Revit model and quantities of materials provided by Structural Engineers. From this baseline, carbon savings from the proposed development were calculated.
Findings from Study
As expected, the most carbon intensive materials were those associated with the structure of the building (2.1 & 2.2.1 in chart above); concrete from floor slabs and stair core and steel from the structural framing and columns.
The largest contributor of carbon on the façade of the building was glazing (2.5.1 in chart above). It was specified in the brief that all windows would be double glazed. An analysis was done on the building to ensure that this would be the least carbon intensive option.
The IES model of the building was altered to triple glazing u-values, and savings of having triple glazing over double glazing over 20 years was compared:
After this, the carbon intensity of using double over triple glazing was compared:
With this study it was confirmed that installing double glazed windows was the least carbon intensive choice due to the high embodied carbon of triple glazing.
Measures Identified to Reduce Carbon
Estimated savings were calculated in relation to the structural element of the project, typically the largest embodied carbon element. On this project these were a higher percentage of recycled aggregate in concrete and using a much higher recycled steel content in the steel. The findings are quantified below.
The outcome of the study resulted in an agreement on improvements to be incorporated for the building design. For Stage 4 of the project, the Client can secure 6 additional points towards their BREEAM score, for a certified ‘Outstanding’ building.