Master Thesis - Environmental Engineering - 2019
Reducing the amount of construction and demolition waste is essential for a sustainable future. This thesis strives to enable companies and decision makers to set up a systematic and economically feasible reuse and recycling plan for construction and demolition waste. For that purpose, a holistic database of the in-use type and amount of construction materials stocked in existing buildings - “in-use-stocks”- was modelled. To do so, a quantification of the building stock in Denmark is targeted which subsequently will lead to the amounts of waste, its spatial distribution and approximate time of occurrence. In order to model building stocks, both material intensity data and floor area data are needed.
The first part of the thesis focuses on the development of a material intensity database for Residential building (RB) and non-residential building (NRB) material intensities. Data were then derived from the resulting RB material intensities, Ecoinvent inventory data and Swedish non-residential building material intensities. The RB stock was modelled with 30 archetypes (3 end-uses x 10 time cohorts), and each archetype’s material intensities were calculated through the analysis of 2 to 3 sample buildings.
In the second part, the dynamic stock driven model of the Danish building stock is executed to obtain the amount and spatial distribution of building materials over the five Danish regions. The building stock floor area per region and archetype from Statbank are combined with the lifetime data to obtain the obsolete building stock, the future demand. Obsolete materials of refurbishments are considered via application of a fixed rate to the still in-use building stock per year.
The third part focuses on the evaluation of drivers and barriers of bricks and concrete regarding their end- of-life management e.g. reuse, recycling, upcycling or downcycling to ensure that interested stakeholders are provided with all necessary information.
The obsolete material stock in the regions of Denmark is estimated with 11,76 mio ton in the year 2020 and expected to decrease to 10.5 mio tons. The demand is exceeding with 12.12 mio tons in 2020 and 11.3 mio tons in the year 2050. Main drivers are bricks and concrete. Furthermore, has been found that the major driver in the direction circular economy of bricks and concrete is the coming supply shortage of building aggregates. Laid out in all resource plans of the Danish regions. One major barrier is the not established trust in reused and recycled materials.