The implementation of lean principles and approaches is gaining grounds in the construction industry globally. However, there is no clear understanding of the number and categories of lean practices implemented and the benefits associated with it in the planning, design and construction of building and infrastructure projects. This paper relied on a systematic review of published literature in Scopus, Science Direct and Google Scholar to identify and categorize the different lean practices implemented in the construction industry and the benefits derivable from them. Totally, 102 documents published between 1996 and 2018 were reviewed and their contents analyzed using descriptive statistics and content analysis. A total of 32 different lean practices categorised into design and engineering; planning and control; construction and site management; and health and safety management were identified. The review also found that the last planner system and just-in-time were the top two most implemented lean practices and about 20 different economic, social and environmental benefits were linked to the implementation of lean practices in the construction industry. This review is instructive that lean practices have good prospects for enhancing the productivity of the construction industry and achieving sustainable built environment, but a critical mass uptake and sustained implementation are required to attain these goals.

Abstract

Even though domestic energy can be from either renewable or non-renewable sources, the former is preferred because of its role in reducing both the operational energy intensity and carbon footprint. Given the positive role renewable energy plays in the energy mix, this paper examined the pattern of operational energy use with particular reference to the renewable and non-renewable energy content in medium and high density public residential buildings in Lagos, Nigeria. A survey research method was adopted for primary data collection while data analysis was by descriptive statistics. The study found that renewable energy use in the residential units is very low. In contrast, there was high dependence of the occupants on non-renewable direct fuel combustion through the use of fossil fuel-driven privately-owned electricity generators for electricity supply as a result of the inadequate supply from the national grid. In addition to the relatively high operational energy intensity observed in the studied buildings, the findings have implications for the safety, health and wellbeing of the building occupants as well as for carbon emissions from the buildings and for overall environmental sustainability. Recommendations to increase renewable energy use in new buildings and as retrofits in existing buildings were made.

The growing concerns over the adverse effects of buildings on the environment and the need to achieve users’ thermal, visual, acoustic, spatial and indoor environmental air quality comfort have given rise to the demand for energy efficient buildings. This paper relied on a review of 36 articles published between 2007 and 2019 to identify and categorise energy efficiency design, planning and construction applicable to office buildings. The data were randomly selected using Science Direct and Google Scholar search engines on the internet and analysed by thematic textual analysis. The results revealed 29 energy efficiency design strategies applicable for office buildings which were categorised into the three distinct phases of building projects: pre-construction (design and planning), construction and post construction stages. The strategies were further categorised into energy efficient landscape designs, site selection, building orientation, building plan and appropriate space organisation. The study also established that building envelope systems, building orientation, integration of renewable energy sources and day lighting design strategies were the most implemented in office buildings. The review concluded by highlighting the key areas of focus in energy efficiency design strategies in office buildings, the extent research has progressed on the subject and future possible directions on the topic.

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