A knowledge-based decision support system for roofing materials selection

Varieties of materials are available for roof housing construction but selecting the appropriate material is a complex and ponderous task. In order to choose the right material, a multitude of performance criteria would need to be considered. This research aims to develop a knowledge-based decision support system for material selection (KDSMS) to facilitate the selection of optimal material for different sub elements of roof design. This model consists of a knowledge base and databases to store different types of roofing materials with their corresponding performance characteristics. Knowledge is elicited from domain experts and extensive literature review. The proposed system employs the use of TOPSIS (Technique of ranking Preferences by Similarity to the Ideal Solution) multiple criteria decision making method, to solve the materials selection and optimisation problem where initial cost, maintenance cost, thermal performance and sustainability criteria are considered among others. The proposed system is currently being developed for the housing sector in Northern Ireland. This paper presents and explains the framework of the proposed system

A knowledge-based decision support system for roofing materials selection and cost estimating: a conceptual framework and data modelling

A plethora of materials is available to the modern day house designer but selecting the appropriate material is a complex task. It requires synthesising a multitude of performance criteria such as initial cost, maintenance cost, thermal performance and sustainability among others. This research aims to develop a Knowledge-based Decision support System for Material Selection (KDSMS) that facilitates the selection of optimal material for different sub elements of a roof design. The proposed system also has a facility for estimating roof cost based on the identified criteria. This paper presents the data modelling conceptual framework for the proposed system. The roof sub elements are modelled on the Building Cost Information Service (BCIS) Standard Form of Cost Analysis. This model consists of a knowledge base and a database to store different types of roofing materials with their corresponding performance characteristics and rankings. The system s knowledge is elicited from an extensive review of literature and the use of a domain expert forum. The proposed system employs the multi criteria decision method of TOPSIS (Technique of ranking Preferences by Similarity to the Ideal Solution), to resolve the materials selection and optimisation problem. The KDSMS is currently being developed for the housing sector of Northern Ireland

Performance evaluation of the Petroleum Trust Fund Educational and Health Infrastructure Rehabilitation Programme in North Western Nigeria

The government of Nigeria removed the subsidies on the prices of petroleum products in 1994 and set up the Petroleum (Special) Trust Fund (PTF) to use some of the extra revenue to rehabilitate infrastructure nationwide. This evaluation was carried out to provide an assessment of the programme in view of its scrapping in 2000. The Earned Value Technique was used to analyse the projects in terms of the time, cost, quality and other objectives using data obtained from PTF and the consultants. The study concludes that the programme suffered no cost overruns and the quality of work was generally satisfactory, but the programme suffered a time overrun of 38,5%. At the end of the scheduled completion period 72,6% of the projects were behind schedule while 17,6% were at zero completion

Tender evaluation methods in construction projects: A comparative case study

A review of tender evaluation practices from around the world revealed the inadequacy of the ‘lowest bidder’ criterion for contractor selection. In response to this inadequacy, many countries have introduced qualifications to this cri terion and established procedures for the evaluation process. The objective of the qualifications is to select a suitable contractor whilst fostering compet itiveness. Using a multi criteria decision making (MCDM) approach, the study identified eight contractor attributes from the literature, which are thought to be indicators of contractors’ capability to execute a contract and meet certain project specific criteria. Employing a case study project, the tenders of eight contractors short listed for the project were evaluated with the attributes using the “lowest bid”, multi attribute analysis (MAA) and analytic hierarchy process (AHP) methods. The results showed that the two multi criteria decision making methods indicated the selection of contractors other than what the ‘lowest bidder’ criterion indicated. Comparing the results of the MAA and AHP meth ods, it is evident that the two methods differed very little in their ranking of the contractors. This implies that the more complex nature of AHP and the extra efforts it requires have only a minor influence on the final ranking of contrac tors and seems to suggest that the extra cost of using AHP is not justified