**6. The Lagos HOMS project**

The predominant typology is a rectangular plan with four floors accommodating twelve (12) residential units of various sizes.

Each floor of the prototype is made up of three apartments (one bedroom, two bedrooms, and three bedrooms). There are three staircases for the combined use of the occupants. Each block, therefore, accommodates mixed-income dwelling units rather than previous government estates that have separate sections for low-income and medium-income dwellers. This prototype has been retained over the past 10 years for subsequent housing units with only minimal modifications (**Figure 1**).

The design intended to incorporate sustainable strategies such as natural ventilation, natural lighting, and use of low-impact appliances such as energysaving electricity bulbs. However, the prototype design is a very compact design and devoid of the openness required in a warm-humid tropical environment. The compact design (as indicated in **Figure 2**) is effective in optimizing building materials used in the buildings. The highly optimized floor plan has minimal circulation area. In terms of emergencies, only the staircases are the escape route as balconies are nonexistent in the buildings. Rainwater harvesting and storage for use in washing and watering plants was also intended but this was not carried through to the implementation stage. The use of ducts for plumbing pipe installation facilitates easy maintenance.

Natural ventilation and lighting were fairly achieved in the building design. However, cross-ventilation as recommended for a warm-humid tropical environment was not fully achieved. In practical terms, cross-ventilation is deemed to have been achieved when a space has window openings on at least two sides. Specifically, the living rooms of the one-bedroom apartment and the two-bedroom apartment have limited opportunity for cross-ventilation. The atrium introduced in the building is not large enough to encourage substantial air flow. No shading devices were observed

*Perspective Chapter: Promoting Circular Design Strategies in Housing Delivery in Nigeria DOI: http://dx.doi.org/10.5772/intechopen.110656*

### **Figure 1.**

*Schematic layout of a block. Source: Adapted from [91].*

**Figure 2.** *Compact arrangement of the blocks under construction. Source: [91].*

in the buildings as built. The lean-to-roof deployed for the project did not have deep overhangs to help shade the walls and openings. Meanwhile, the vegetative cover is low when compared with built-up areas of buildings and paved areas. Hence, passive design principles were not substantially applied (see **Figure 3**). The spacing between buildings is rather narrow relative to building height, which may impair effective air movement around the buildings. Hence, many of the occupants can afford to have opted for air-conditioning for thermal comfort in the buildings.

The construction materials used were conventional materials and the technology adopted was mostly *in situ* construction technology. **Table 3** depicts the materials deployed in the construction of the buildings. The buildings are made of reinforced concrete structural frames (columns, beams, and slabs) with sand-cement blocks

### **Figure 3.**

*A Section of the Lagos HOMS layout showing the closeness of the blocks. Source: [92].*


## **Table 3.**

*List of components and materials used for the work.*

as external envelopes and internal partition walls. All wall and concrete surfaces are rendered with sand-cement mortar. The roof structure is made of treated timber, while the roof covering is long-span aluminum roofing sheets. The lean-to-roof design optimized the materials used in the roofing when compared to prevailing roof designs in the study context.

Other materials include vitrified ceramic tiles for the floors and glazed wall tiles for the walls of wet areas. The ceiling is made of PVC ceiling tiles supported on timber noggins. External doors are steel doors fabricated and fixed with mortar-to-door openings. Similarly, windows are made of aluminum framed glass fabricated and fixed with mortar to the window openings. Internal doors are made of timber.

The estate road networks are paved with concrete interlocking stones. This helps to manage stormwater drainage within the estates. It also facilitates ease of maintenance

*Perspective Chapter: Promoting Circular Design Strategies in Housing Delivery in Nigeria DOI: http://dx.doi.org/10.5772/intechopen.110656*

without destroying the pavements as paving stones removed for routine maintenance can be reused in the making good process. Vegetative cover for the buildings is limited, which facilitates heat gain in the buildings emanating from the paved surroundings. As a result, residents are resorting to installation of air conditioners for indoor thermal comfort. Electricity supply is from the national grid, while water supply is from dedicated boreholes and associated storage facilities.
