‘Green walls’ in Nigeria

A novel approach for tackling high indoor temperatures and producing a stream of income for families in Nigeria has been developed and tested by researchers at Cardiff University.

The team, consisting of experts in architecture and business, has developed affordable and environmentally friendly vertical greening systems, commonly known as green walls, which have the potential to bring both health and economic benefits to low-income families across Africa.

Green walls are vertical structures that are covered in plants, often supported by a metal or wooden frame that holds soil or another growing medium.

They have risen in popularity in recent years and are used in many residential and commercial buildings around the world, not only for their aesthetic appeal but also for their ability to reduce temperatures, provide crops for food and economic gain and increase biodiversity.

In their study, the team adopted a ‘responsible innovation approach’ by jointly developing appropriate green wall technology with the community of Agege, a large shanty town in Lagos, Nigeria. Materials were locally sourced and the community was strongly involved in designing, building and maintaining the prototypes.

Two different green walls, one constructed from affordable high-density polyethylene (HDPE) and the second from environmentally friendly bamboo, were installed outside two residential houses in Lagos.

The green walls were filled with a range of edible and medicinal plants and secured to the outside walls of occupied rooms in both houses.

Internal air temperatures, relative humidity and wall surface temperatures were recorded for each of the rooms adjacent to the green walls, as well as for comparable rooms with no green walls installed.

The green walls were shown to reduce internal air temperatures within the adjacent room by an average of 2.3°C, with occupants inside reporting to be comfortable 90%–100% of the time, against 23%–45% in the control room.

The co-authors of the study, Dr Clarice Bleil de Souza, Dr Julie Gwilliam and Dr Oluwafeyikemi Akinwolemiwa, stated that: “It’s clear from these results that vertical greening systems can bring both thermal comfort and economic benefits, with the possibility to grow food and medicinal plants in overcrowded areas in Africa potentially offering the most significant positive impact.”

The researchers also performed a full cost analysis taking into account the cost to buy materials, build the green walls and then maintain them over a number of years.

Co-author of the study Professor Luigi De Luca, from the Cardiff Business School, stated that: “Both prototypes could be very profitable and repay the investments relatively quickly even allowing some loss of yields from the plan. However, it’s also possible that residents may want to consume the produce themselves rather than sell them on, especially considering that a high proportion of expenditures in low income groups in Nigeria are on food and drink.”

“There are many more improvements and issues to consider in order to make this a viable and more affordable for families in Africa, but the development of this product roadmap will hopefully propel efforts to make this system a reality and provide a lasting change for families across the continent.”