Defining a reference building according to LEED v4, to enable comparison of LCA alternatives

Abstract: In this thesis the possibility of defining a general reference building, or so-called Baseline Building representing Swedish multi-family dwellings is investigated. The scope of the research is limited to analyze the multi-family dwellings of 3-8 stories. If succeeded the results should represent a general Baseline Building according to the new LEED v4 credit, Building Life-Cycle Impact Reduction. The credit requires a whole building life-cycle assessment to be carried out in order to evaluate environmental effects cause by the building design. However difficulties occur when developing a Baseline Building since no reference point is known. This leads to uncertainties when trying to improve the building design, since the reference point contains major variations. A suggested Baseline Building was derived by analyzing five questions from surveys conducted on the Swedish building stock, during 2000-2009. These questions considered the building shape, structural components, and manufacturing method of the structural component, façade material and roofing material. Through the statistical analysis it was concluded that the most common building shape consisted of two building shapes, Apartment Block and Building Block. The choice of structural element consisted of partly prefabricated concrete elements for both building shapes. Furthermore plaster was found to be the most common façade material and metal sheet the most common roofing material. Despite this, no general Baseline Building that covered all building elements was obtained through the statistical review, due to high variations in greenhouse gas emissions caused by different construction types. The results should instead be used as material suggestions for the building envelope and structural elements of a Baseline Building. The results from the investigation are intended to guide project teams in selecting appropriate materials in an early design stage regarding the Baseline Building design. As the final step sensitivity analysis were conducted by defining different construction and material types of a Baseline Building design and analyzed in a simplified LCA tool. From the LCA study we could conclude that the structural elements affected the LCA results the most. In conclusion the structural elements should be analyzed in early design phase through a “what if” scenarios to improve the LCA outcome.