Statsbygg GHG calculation tool for construction, Norway
In 2006 Statsbygg, the Norwegian government’s building commissioner and property manager, started to develop a comprehensive model for calculating the greenhouse gas (GHG) emissions of buildings.
Klimagassregnskap.no is a free, web-based and holistic model which calculates the lifetime GHG emissions of the building, covering the materials used in construction, emissions from the construction phase, energy use in the operation phase as well as transport of goods and people who use the building. In March 2011 version 3 was launched, which includes also greenhouse gas emission calculations of a reference building.
The tool assists in identifying the sources of emissions and estimating their amount, and can be therefore used to provide a comparison of different options. Service life, material types and the electricity mix have all been demonstrated to play an important role in the calculations.
The model is now used by a number of actors in the construction industry in Norway, with several hundred user accounts and projects, and experiences show that emissions can be reduced by 30–50% compared with the reference/current practice. Statsbygg aims to use the tool to set targets in all of its procurement activities, and requires designers and contractors to use the tool throughout the entire project. Two major government sponsored construction programs aimed at developing carbon neutral urban areas, “Fremtidens Byer” (Future Cities) and FutureBuilt, require greenhouse gas calculations to be carried out using klimagassregnskap. The tool is also used for the greenhouse gas calculation section in the Norwegian adaptation of BREEAM (BREEAM NOR). The utilisation of the tool begins at an early stage, and the GHG impacts of at least two alternative project solutions are analysed to enable ambitious energy goals to be set. Good choices for design and materials must be made as early as possible in the project, often before detailed data exists for the project. Additionally, it is recommended to specifically request materials with lower embedded carbon emissions, together with appropriate documentation. Again experiences demonstrate that such products are available if actively demanded, and that such demands help to encourage more environmentally friendly production methods, such as energy efficiency or recycled materials, and greater availability of documentation on products.
A few practical examples of application:
- For the extension of The high North Research Centre for Climate and the Environment (Framsenteret) in Tromsø, the tool was used to assist in determining the target energy requirements.
- For the construction of Oslo’s new National Museum GHG emissions, calculated using Klimagassregnskap, formed part of the evaluation of the architectural competition, where the overall target was to achieve a 50% GHG reduction.
- For the papirbredden II Knowledge park development in Drammen, consisting of both office and educational buildings, the buildings were required to meet passive house and A-energy class criteria. In addition, climate friendly construction materials and good bicycle parking conditions are required. Klimagassregnskap was used in the preliminary project phase as well as during design and construction. The calculation revealed that the highest emissions came from the concrete and underground structures. A new assessment was carried out on the positioning of axes and columns, which led to the conclusion that the number of columns could be reduced. An assessment was also carried out on the use of prefabricated elements such as basement floors instead of in situ casted structures. This resulted in a considerable reduction in the use of concrete.
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