### BACS Auditing Schemes  
In terms of overall building performance auditing methodologies and evaluation criteria, schemes on national and international levels have been developed and presented in the last years dealing with whole-level building certification, including DGNB [23], LEED [24], and BREEM [25]. Nevertheless, very few similar schemes are discussed and presented when it comes to the specific building automation and control systems auditing and evaluation. In this context, one of the very popular BACS design evaluation schemes presented recently is the 'eu.bac System' methodology [26]. This BACS auditing and evaluation methodology have been implemented in multiple countries in Europe, with a drastic increase in the buildings being audited and commissioned. It is the product of the European Building Automation and Controls Association (eu.bac) which represents a large group of leading building automation and control equipment manufacturers and traders in Europe [27]. The eu.bac methodology in BACS evaluation is based on the very well established European standard EN15232 \"Energy performance of buildings--the impact of Building Automation, Controls and Building Management\" [28], which classifies buildings into multiple classes associated with the corresponding level of automation and control, ranging from A (best) to D (worst). The eu.bac methodology thus evaluates multiple building services, including various domains and technical aspects. Figure 1 shows a caption of multiple services listed under the heating system domain as part of the eu.bac system methodology. While the eu.bac methodology has demonstrated plenty of positive impacts in terms of evaluating BACS design, it only considers the impact of the design with respect to a single criterion, energy efficiency.  
Recently, a first-of-its-kind instrument, 'IBACSA' for building automation and control systems auditing and smartness evaluation, was developed and launched to serve as a basis for initial and retro-commissioning of the BACS in various buildings and facilities [29]. The instrument is also driven by the requirements and regulations set by the European standard EN15232 for building automation and control but with a more holistic approach in terms of the impact criteria considered. IBACSA methodology employs a hybrid quantitative-qualitative multi-criteria assessment framework and aims at evaluating the BACS design on the level of eight different building domains. Such multi-criteria assessment frameworks have been employed in various studies in the literature and shows major positive impacts in terms of evaluating and assessing building automation systems design and overall building performance [30; 31; 32]. The considered domains are as follows: Heating, Hot Water, Cooling, Ventilation, Lighting, Dynamic Envelope, Electricity and Monitoring and Control. Thus, as part of the building automation and control system evaluation and assessment, IBACSA evaluates a list of services under each of the eight domains mentioned, summing up to 60 services in total. The services evaluation is a functionality selection process, where the user will select for each service, the level of control functionality associated with a list of choices provided by the tool. The higher the service functionality selected, the larger the number of points accrued for that service.  
As the user selection of the corresponding services is completed, the instrument will provide a comprehensive assessment of each of the eight building domains against five impact criteria, (1) energy efficiency, (2) maintenance and fault prediction, (3) energy flexibility, (4) comfort and (5) information to occupants [29]. A points-based grading score is used to quantify the effect of functionalities on the five considered impacts. The number of points claimed for each functionality level are determined by a scale ranging from 0 to 3 points.