Dr Mahendra Gooroochurn, Senior Lecturer, University of Mauritius talks about circular homes amid climate change. According to him, it will come as a great motivation and pride for each one of us that our individual homes can become the backbone for climate action.
It is clear that climate change has become a matter of concern at planetary, national, community and boiling down to personal levels as we observe dramatic changes in our climate and environment, and exacerbated by natural calamities. If we have been doubting whether climate change is actually happening in our modern civilization, there remains no ambiguity: climate change is a reality and they are here to stay.
There remain systemic difficulties in permeating national policies at a grassroots level. This explains the growing frustration, especially from our younger generation, as they see an already uncertain world tending to become increasingly inhabitable with global warming, pollution, and loss of biodiversity. While it requires important strategic decisions at the national level by the government to mitigate and adapt to climate change, it is equally the onus of each member to bring his or her share, but how? Any such initiative needs to be demonstrable to the general public, simple in language to both explain the effect of climate change and how the measures address the issues and can be cost-effective.
One such avenue is our home, and reimagining it using the three pillars of a circular economy (depicted in Figure 1) to transform it into a circular one, a circular home. Indeed it will come as a great motivation and pride for each one of us that our individual homes can become the backbone for climate action. As our homes become more sustainable, the benefits get amplified in the community and subsequently at the national level. Let’s first consider the three highly insightful pillars making up the circular economy (CE) framework as proposed by the Ellen McArthur Foundation, namely (1) design out waste and pollution, (2) keep products and materials in use, and (3) regenerate natural systems, and transposing them directly onto one energy, materials, and water measure each.
That is, the design out waste and pollution principle will relate to the energy aspect, the keep products and materials in use will relate to the materials aspect, and the regenerate natural systems principle to the water aspect. This may seem a rather simple solution, and the whole purpose is to keep it simple, although more elaborate, highly comprehensive approaches can be considered at the risk of being turned down. The three measures chosen are based on the specific context of Mauritius and are deemed to be of high priority in our combat against climate change.
A. Design out waste and pollution – Reduce greenhouse gas emissions by providing comfortable houses with little or no requirement for air-conditioning. The major concern to be addressed for the tropical context of Mauritius is thermal comfort, as we experience warmer summers, driving the installation of more air-conditioning equipment. Unfortunately, air conditioning systems consume significant amounts of electricity, hence contributing to worsening global warming. Therefore the energy dimension of our circular home will focus primarily on how to achieve thermal comfort in our homes without the need for air-conditioning as far as possible using passive design principles.
The sun has a low angle of elevation in the morning and the evening and a higher angle of elevation during the day, meaning the sun in the east (morning) and west (evening) is close to the horizon and hence can penetrate through window panes along these orientations to cause significant heat gains and hence thermal discomfort in warmer regions such as coastal areas. On the other hand, the sun at noon (in the north direction) is almost on our heads. Although it can penetrate partially through windows facing north, simple overhangs or eaves over the windows can block unwanted solar radiation. This also means overhangs and eaves are not effective along with the east, north-east, north-west, and west, where the sun has a low angle of elevation. Trees and vertical shading devices such as external fins and internal blinds or curtains are needed for shading window panes along these low elevation orientations.
Another major source of heat gains in our concrete homes is the roof, which is generally flat, hence irradiated by the sun throughout the day, irrespective of its position, and causes significant heat discomfort. Hence every means should be expended to shade the roof, by simple solar shades, roof terraces, cool roofs, or more costly but highly sustainable green roof systems. Clearly, allowing our homes’ walls, floors, and ceilings to be heated and then employing massive amounts of air conditioning energy to cool them is not very intelligent. To improve thermal comfort further, natural ventilation should be favoured, supported by low-power ceiling fans in every occupied room in your house.
B. Keep products and materials in use – Value our materials and prevent them from becoming waste. An estimated 500,000 tonnes of annual solid waste is landfilled, with 80% originating from houses, hence a circular home with no waste generated can go a long way to solving our solid waste management challenges. The third and final dimension of the circular home is the materials dimension, which aims to divert an increasing amount of the annual 500,000 tonnes of solid waste sent to landfills, of which 80% come from our households. The primary consideration should be the segregation of the organic and inorganic streams, following which the vast amount of possibilities for making good use of these valuable material streams (clearly no more waste!) illustrated in the butterfly diagram below can be considered. Before considering recycling on the right-side (blue) industrial cycle, sharing, maintaining, reusing, and refurbishing should be privileged. In addition to relying on central collection facilities to implement segregated waste collection, community-based solutions for composting, sharing of obsolete products, and producing craft and art items from these material streams can be sought, including business offerings based on these ideas, and services and products.
C. Regenerate natural systems – Give rainwater its natural path and avoid disturbing ecosystems. Before our homes were constructed, the plot of land allowed water to seep into the ground without undue water accumulation, replenishing the underground water aquifers and feeding the boreholes we rely on heavily for our potable water demand. With the construction of impermeable, hard surfaces made of concrete, the pathway for rainwater has been significantly disturbed. If each home manages its rainwater run-off at the source, this can significantly prevent floods at the neighbourhood level.
A 100 mm rainfall event will generate 10,000L of run-off for a single 100 m2 home, now imagine the deluge this will cause in a neighbourhood. But does rainwater have to take such a negative dimension? Not if the rainwater is allowed to take its natural course into the ground or harvested at every home to serve non-potable ends such as gardening and car washing of the household. With the more frequent occurrence of short duration, high-intensity rainfall events in Mauritius, it is clear that each household dealing with its rainwater run-off can contribute massively at the neighbourhood level, providing improved resilience to prevent flash floods while reducing the use of potable water.
It will come as a strong motivation for each one of us that we can have a highly beneficial and impactful influence on our climate action agenda, where our homes can become key cornerstones of sustainable communities around our island in the making of a sustainable Mauritius. The target should be zero energy, zero run-off, and zero waste homes by integrating further measures around the three main measures presented in this article.