Cost and environmental impacts reduction through building compactness

Purpose: The central motivation for this study was to examine alternatives against the apartment area reduction as a safe way to reduce construction costs, adopted by many construction companies. From the building economic compactness index concept, it was studied the cost and environmental impacts (material consumption, embodied energy – EE and CO2 emission). Design/methodology/approach: The research strategy takes advantage of a case study aiming to investigate the relation between design characteristics related to area (m²) and building economic compactness index (%) with cost (Research Stage 1) and with environmental impacts: (Research Stage 2). The study involved real data from social housing projects, chosen in terms in terms of very similar features like size, area and constructive method (constants), however, with dissimilar compactness (variable). Findings: The lack of direct relation between area and cost signs the importance of including the cost of vertical plans considered in the economic compactness building. The higher the economic compactness index, the lower the cost, the lower the amount of material, EE and CO2 emission parameters. However, due to the wide range of EE and CO2 values available, the reduction in the amount of materials achieved by increasing building economic compactness index may not be reflected in EE and CO2 gains. Research limitations/implications: As the limitation of this study, it must be taken into account a limited number of case buildings and the fact that the analysis is dependent on the reliability and accuracy of the data provided by constructors and the available information of EE and CO2 emission. As well discussed in the literature, the consistent database is a great challenge for the construction sector. Originality/value: There might be alternatives to higher areas with relatively low-cost increments since results from buildings with the same area present different cost estimative and suggest a strong relationship with the economic compactness index. The large variation of EE and CO2 emission data indicates that reductions obtained by compactness increase may be impaired if the construction materials are produced with high levels of EE and CO2 emission. Thus, there must be an integrated effort on the part of designers (design and material specification) and manufacturers (material production), since isolated solutions may not be enough.