Understanding Zimbabwe’s green building and sustainable design sector

from Energy and Power Insider Issue 5

Roaring Success For Enlit Africa 2023

The terms ‘green building’ and ‘sustainable design’ are often thrown around but what do they actually mean and how do they relate to energy and power consumption? How do these concepts help to regulate and define a better use of natural resources and impact on our environment and our lifestyles? The terms are often used interchangeably but there are subtle differences. Green buildings tend to focus only on the environmental impact of the construction process and the finished structure, whereas sustainable design focuses on the three interrelated principals of ‘people, planet, profit’. However, a good, sustainable, architectural design – which incorporates a number of engineering features – will produce a green building. Green building incorporates methods and materials that that lead to structures that are environmentally responsible and resource-efficient throughout a building’s life cycle, from site selection to demolition or reuse. The choice of building materials that are recycled or recyclable also makes a building more sustainable.

Some of the main features of green building and sustainable design are:

1. Energy efficient windows. Buildings, whether homes, offices or apartment blocks should incorporate features that reduce the demands on outside energy supplies.

Large windows, for example, reduce the need for electrical lighting. The placement of window openings is important too. In Zimbabwe north facing windows get the best natural sunlight in winter helping to keep interior spaces warm - while in summer north facing windows get less sunlight reducing the need for cooling. Carefully placed windows can also provide cross ventilation so there’s no need for air conditioning in summer.

2. Water recycling. Buildings that incorporate grey water recycling reduce the demand for water and ensure that water is used most efficiently and effectively. Although most of the more sophisticated water recycling and purifying systems produce water that is safely drinkable, most systems recycle the water for things like filling up the toilet cistern, water for washing and bathing or for use on the garden. A number of cluster homes and townhouse complexes in Zimbabwe are now incorporating recycling systems as the demand for water in urban areas increases.

3. Rain water harvesting. Rain water is an important resource that usually literally runs down the drain. For the average house the water collected from the gutters and drainpipes can be stored in tanks that will provide water through at least part of the dry season. The water can be used for washing and bathing – although it might not advisable to drink it without further purifying. Roofs collect dust and debris that need to be filtered out however, it’s a great resource for watering the garden or the vegetable patch.

4. Solar and renewable energy. Solar geysers help to reduce the demand for electricity quite dramatically. They’re easy to install and require little or no maintenance. Solar panels can be used to directly power up appliances during daylight or to charge up batteries – through an inverter –to supply power at night. Excess power generated can even be fed directly in to the national grid for a credit and also to reduce pressure on the grid. In Europe and other parts of the world geo-thermal systems are used for heating and cooling although this has yet to be fully embraced in Zimbabwe.