A model for early construction cost prediction is useful for all construction project participants. This paper presents a combination of process‐based and data‐driven model for construction cost prediction in early project phases. Bromilow’s “time‐cost” model is used as process‐based model and general regression neural network (GRNN) as data‐driven model. GRNN gave the most accurate prediction among three prediction models using neural networks which were applied, with the mean absolute percentage error (MAPE) of about 0.73% and the coefficient of determination R² of 99.55%. The correlation coefficient between the predicted and the actual values is 0.998. The model is designed as an integral part of the cost predicting system (CPS), whose role is to estimate project costs in the early stages. The obtained results are used as Cost Model (CM) input being both part of the Decision Support System (DSS) and part of the wider Building Management Information System (BMIS). The model can be useful for all project participants to predict construction cost in early project stage, especially in the phases of bidding and contracting when many factors, which can determine the construction project implementation, are yet unknown.

Bitni element svakog ugovora za građevinski projekt su troškovi kao bitni element pa točnost predviđanja troškova može utjecati na izvršenje projekta, a također i na poslove onih koji su uključeni u projekt. Podaci za objekte...

PurposeIntegrating the aspects of sustainability into facilities design has become a designers’ challenge, and the early design phase is seen as the most important in implementing sustainability into facilities design. Therefore, this paper aims to analyze the factors that influence sustainability assessment of preliminary design of facilities and predicts sustainability assessment depending on those factors. Design/methodology/approachData were collected by survey questionnaire distributed to project managers using a six-point Likert scale. Obtained data were modeled with general regression neural network (GRNN) using DTREG software. In total, 27 factors were chosen for determining the most accurate predictive model, and their importance was computed. FindingsThe six most important factors for sustainability assessment of facilities design are: work experience, work on several outline design proposals, resolving issues between stakeholders, prioritization of participants in the design phase, procurement management and defining projects’ program and goals. The predictive model that was used for prediction of the sustainability assessment was shown to be highly accurate, with MAPE (mean absolute percentage error) amounting to 2.58 per cent. Practical implicationsUsing the same approach, assessment of every other factor for the preliminary design can be predicted and the factors that are most influential to its sustainability can be obtained. Originality/valueThe paper supports the sustainability improvement of the preliminary design of future facilities’ projects, as well as support during the decision-making process.

The pursuit of sustainable construction practices has become imperative in the modern era. This paper delves into the research of the properties and application of a genetaly specific material called “red clay” from the locality "Crvena Mogila" in Macedonia. A series of laboratory tests were conducted to evaluate the physical, mechanical and chemical properties of the material. The tested samples show that it is a porous material with low density, high water absorption, and compressive strength in range of 29.85 - 38.32 MPa. Samples of composite wall blocks were made with partial replacement of natural aggregate with red clay aggregate. Two types of blocks were produced with dimensions of 390x190x190 mm, with 5 and 6 holes. Average compressive strength of the blocks ranges from 3.1 - 4.1 MPa, which depends on net density and the number of holes. Testing showed that these blocks have nearly seven times lower thermal conductivity than conventional concrete blocks and nearly twice-lower conductivity than the full-fired clay bricks. General conclusion is that the tested red clay is an economically viable and sustainable material with favorable physical, mechanical and thermal parameters, and can be used as granular aggregate in the production of composite ceramic blocks.

The pursuit of sustainable construction practices has become imperative in the modern era. This paper delves into the research of the properties and application of a specific material called “red clay” from the locality “Crvena Mogila” in Macedonia. A series of laboratory tests were conducted to evaluate the physical, mechanical, and chemical properties of the material. The tested samples show that it is a porous material with low density, high water absorption, and compressive strength in range of 29.85–38.32 MPa. Samples of composite wall blocks were made with partial replacement of natural aggregate with red clay aggregate. Two types of blocks were produced with dimensions of 390 × 190 × 190 mm, with five and six holes. The average compressive strength of the blocks ranges from 3.1 to 4.1 MPa, which depends on net density and the number of holes. Testing showed that these blocks have nearly seven-times-lower thermal conductivity than conventional concrete blocks and nearly twice-lower conductivity than full-fired clay bricks. The general conclusion is that the tested red clay is an economically viable and sustainable material with favourable physical, mechanical, and thermal parameters and can be used as a granular aggregate in the production of composite ceramic blocks.

Determining the participation of each type of works in the total construction costs for the building is a useful issue, particularly in the early stage of the project. Therefore, data has been collected for fifteen residential buildings built in Macedonia. Buildings have reinforced concrete structures, one underground level and four to seven levels above the ground. The participation of each type of works in the total construction costs for each building was calculated. Their average participation is: earth works 3,02 %, concrete and reinforced concrete works 41,55 %, masonry works 10,84 %, roofing works 2,44 %, plastering 14,67 %, painting 0,76 %, floor works 12,95 %, insulation works 4,22 %, doors and windows 9,55 %. Although the values presented are approximate, they can be used to roughly predict costs of each type of work for residential buildings with reinforced concrete structure.