# Waste Management in a Sustainable Circular Economy as a Part of Design of Construction
## 2 Theoretical Background
### Quantifying of Construction and Demolition Waste  
A prerequisite for the implementation of successful waste management is the quantifying of construction and demolition waste (CDW) [51]. Many methods for the quantifying of CDW are known. CDW is generated from different construction activities. The primary activities that generate CDW are:  
* Construction of new buildings [52; 53; 54; 55; 56];
* Demolition of buildings [56; 57];
* Civil and infrastructural works [58]. Methods for the quantifying of CDW may have a general use or use for a specific project. Very essential methods are intended for the project estimation level [52]. An effective national CDW management policy can be supported by the methods for quantifying CDW on the regional estimation level [59]. Authors [PERSON] et al. [52] have identified and classified 57 methods for quantifying CDW. They have processed a three-level classification according to the waste generation activities, estimation level, and particular methodology. The methodology principles determine the level of use. The methods were divided into five groups based on the approach to quantifying CDW:  
* Site visit method: direct measurement [60], indirect measurement [53; 61; 62];
* Generation rate calculation method: per capita multiplier [63; 64], financial value extrapolation [64], area-based calculation [65; 66];
* Lifetime analysis method: building lifetime analysis [53; 56], material lifetime analysis [67];
* Classification system accumulation methods [55; 65];
* Variables modelling method [64]. The accuracy and clarity of each method varies. The methods require different input data, which are not always available, and therefore, their relevance cannot be verified. Limitations of quantifying CDW are mainly a lack of actual data and a lack of verification. The CDW quantification methods can be classified according to their construction activities and estimation levels (Table 1). Figure 1: Life cycle of building and life cycle of construction materials vs. circular economy and supply chain. Site visit quantification methods are based on a visit to a specific construction site where construction or demolition waste is generated [53; 60; 61]. The direct method determines the amount of waste based on the spatial dimensions of a place's stockpiled CDW. The indirect method consists of counting the number of trucks for waste transport and the volume of each container. The generation rate calculation methods are the most used methods for CDW quantification. The principle of this methodology is to obtain the rate of waste generation (coefficient) per specific unit (e.g., kg/m\({}^{2}\), m\({}^{3}\)/m\({}^{2}\)) by a different type of multiplier [63; 64; 65; 66]. It has a general use; one critique of this method is the absence of suitable databases for the rate calculation. The lifetime analysis method is used for demolition waste quantification. A building's lifetime analysis considers the age of the building, which often determines the need for demolition work [53; 56]. National material flow databases are essential for applying the material lifetime analysis method. The database determines the amount of purchased building material for a given region [67]. The lifetime analysis methods are not generally applicable to every construction project and region. This methodology has researched and designed these databases for the United States only. The classification system accumulation method comes from the idea of generation rate calculation methods. It is focused on the CDW quantification for a specific waste type and the specific building structure of an element [55; 65]. The variables modelling method consists of modelling various variables that arise during construction or demolition activities. These variables include construction time, construction site conditions, weather, material storage, or labor experience. The importance and frequency of these variables affect the generation of construction waste [64].