**7. Conclusions and recommendation**

This chapter underscored the importance of circular economy as the preferred direction for all human activities. The advantage of circular economy with particular reference to the built environment was highlighted. Specifically, given the impact of the built environment in terms of resource use and waste generation, circular economy principles were adjudged to be the panacea. Given the importance of housing in the overall built environment, circular economy offers positive prospects. The relevance of circular strategies in housing delivery within a developing country context such as Nigeria becomes more apparent. With housing deficit running into millions, the resource implication of bridging the deficit is huge. Adoption of circular design strategies can effectively mitigate the negative resource implication of bridging the housing deficit.

The study also evaluated an urban public housing program in Lagos, Nigeria's most populous and urbanized city. It was found that opportunities exist for the adoption of circularity in housing delivery given the huge housing need. Adoption of modern methods of construction, which will incorporate the circular design principles of standardization, prefabrication, modularity, reuse, and design for disassembly, was identified as good approach to reducing the housing deficit. However, the prevailing building procurement process followed a rudimentary process of wet or *in situ* construction. Similarly, the design of the buildings did not incorporate innovative processes that would facilitate modern methods of construction. In order to move the housing delivery process toward circularity in the study area, modern construction technology should be adopted. As an active player in the housing delivery process, the public sector can play an important role in the uptake of modern technology in building design and construction process. In this respect, the building procurement process should benefit from digital technology.

The importance of renewable materials was also highlighted in the chapter. Renewable materials can be brought into the material mix due to the high cost of housing procurement using conventional materials. A number of renewable materials are found in the study area that can be used for housing development. There are materials such as SCMs that can reduce the quantity of Portland cement deployed in the construction of the buildings. Incidentally, these SCMs can be obtained from byproducts of both industrial processes and as wastes from agricultural processing. In this respect, wastes from other processes are utilized as inputs into building materials for housing development, thereby promoting circularity. Also, the use of mortar-less interlocking blocks can reduce the use of high-impact Portland cement. Interlocking clay bricks stabilized with cement have also been found to be very useful in the study context.

Energy use accounts for a large proportion of resources used in housing, especially at the use/operational level. Renewable energy use is on the increase, driven by the need for cleaner and low-impact energy. As a result, public housing projects are increasingly adopted renewable energy to mitigate the waste associated with conventional energy supply. Even though renewable energy was not factored into the housing projects, residents and building occupiers have commenced energy retrofits using solar photovoltaic installations.

Hence, going forward, energy efficiency strategies that incorporate solar photovoltaic installations with other building components are desirable. Mini-grid PV networks can be considered for estates.

Finally, the adoption of passive and regenerative principles in housing design should be emphasized. Housing design should conform to context in order to maximize natural attributes through passive design principles. This can help to reduce overall environmental impact of the buildings and reduce the need for the use of high-impact equipment and accessories. In a similar vein, green infrastructure is a way of promoting regenerative principles in housing design. The preponderance of hard landscaping in the housing programs informs the need for green infrastructure incorporation. However, given the limited land area available in the study area for housing development, conventional green infrastructure may not be feasible. Hence, while increasing occupancy per unit area in response to estimated deficit, it is desirable to explore the adoption of green roofs as a way of recapturing the natural green areas displaced by the construction of buildings and other infrastructure.
