Design-build in construction industry becomes one of the project delivery method selected by owner. Light rail transit, mass rapid transit, and stadium renovation are examples of large infrastructure projects which are constructed under design-build approach to save time. In this approach, the design and construction phases are carried out simultaneously by contractor. One of the advantages for owners is that most risks are transferred to the contractors. This paper attempts to discuss contractors' perspective related to risk factors in design-build project. The aim is to understand potential risk that can lead to an unsuccessful project. A questionnaire is developed that contains six factors with 20 sub-factors related to project risks. The questionnaire is distributed and responded by both state-owned and private enterprises contractors that involved in design-build project. Data are analysed using Significance Indexes method in order to obtain the relative significance of the risk sub-factors. The result shows five influenced sub-factors including project and program management issues that may cause risk to the contractor's success under design-build project.
In an effort to support carbon footprint reduction in housing development, one approach is designing energy efficient housing. Issues such as cost efficiency and minimum environmental impact should be thoroughly considered when designing this type of housing. One of concepts found to be cost-effective and to increase the energy performance of a house is the near Zero Energy House (nZEH) concept. This concept enhances the use of natural resources, for example, sunlight exposure, climate conditions, and wind, that can minimize the use of fossil fuel energy. Housing in a tropical climate where sun exposure is year round, such as in Indonesia, can benefit from the nZEH concept. This research aimed to identify design parameters of nZEH and its best practices in tropical climates, including Indonesia. The identified design parameters will be used in the next step of the research, finding a combination of cost optimum design parameters. This study was conducted by consulting recognized experts, which included government, private sector, and academicia, who have expertise in the field of building design and energy. The results showed that the design parameters of nZEH in tropical areas include passive design, fenestration, indoor lighting arrangements, and the use of photovoltaic panels (PV).
Housing development, as part of economic development, must be supported by energy availability in order to achieve sustainable growth. One of the approaches to supporting renewable energy promotion is to design and build energy efficient housing. However, the optimal design of such buildings faces two conflicting requirements, namely the consideration of cost effectiveness and minimum environmental impact. The high costs of energy efficient buildings, such as the near Zero Energy House (nZEH), are due to the high price of the materials and equipment used, such as photovoltaic (PV) panels, insulation and other supporting materials. Indonesia is situated on the equator and benefits from sunlight throughout the year. Nonetheless, this potential has not been fully realized, as the solar-generated energy technology for housing comes at a high price. Therefore, the objective of this study is to find the cost optimum combination of validated design variables for an nZEH which suit the tropical climate conditions of Indonesia. Experiments and a case study are employed in the study to validate the design variables for an optimum nZEH design, which include building orientation, PV panels, fenestration, and passive design. The study finds that the cost optimum nZEH design achieved 72 percent site-energy savings and 21 percent savings in the total Net Present Value (NPV) of life cycle costs, with insignificant incremental initial construction costs in enhancing the design.
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