Lesson Notes By Weeks and Term v5 - Grade 12

Lesson Video

This page supports the lesson note with a companion video and a short classroom-ready summary.

For class groups and homework, share this lesson page so learners also get the summary, objectives, and full lesson context.

Performance objectives

• Define sustainable construction and its key principles.
• Analyze the environmental impact of construction materials.
• Evaluate the sustainability of a construction project.
• Describe sustainable techniques for the South African context.
• Discuss the economic and social benefits of green building.

Lesson summary

Sustainable construction is a crucial aspect of modern Civil Technology, especially in South Africa. Our rapidly growing population and infrastructure demands place enormous pressure on our natural resources and ecosystems. Without sustainable practices, we risk depleting these resources, causing irreversible environmental damage, and jeopardizing the well-being of future generations. Think about the impact of informal settlements lacking proper sanitation and infrastructure, or the environmental damage caused by mining operations to obtain construction materials.

Lesson notes

2.1 Defining Sustainable Construction: Sustainable construction, also known as green building, focuses on minimizing the environmental impact of buildings and infrastructure throughout their entire lifecycle.

This includes: Design: Optimizing building orientation for natural light and ventilation, incorporating passive solar design principles, and minimizing the building's footprint.

Materials: Selecting locally sourced, recycled, and renewable materials with low embodied energy (the total energy required to extract, process, manufacture, and transport a material).

Construction Processes: Employing efficient construction techniques that minimize waste, reduce water consumption, and prevent pollution.

Operation and Maintenance: Designing for energy and water efficiency, utilizing renewable energy sources, and implementing sustainable maintenance practices.

Deconstruction and Demolition: Planning for the eventual deconstruction or demolition of the building to maximize material recovery and minimize waste sent to landfills. 2.2 Environmental Impact of Construction: Embodied Energy: The total energy required to create a building material, from raw material extraction to manufacturing and transportation. High embodied energy materials, like aluminum and steel produced with coal-fired power, contribute significantly to greenhouse gas emissions. Choosing locally sourced materials drastically reduces transportation energy.

Example: Producing 1 ton of steel has significantly higher embodied energy than producing 1 ton of timber from sustainably managed forests. Learners can research embodied energy figures for common construction materials.

Carbon Footprint: The total amount of greenhouse gases released into the atmosphere as a result of a construction project. This includes emissions from material production, transportation, construction processes, and building operation.

Example: Using concrete with a high cement content increases the carbon footprint. Substituting a portion of the cement with fly ash (a waste product from coal-fired power plants) reduces the carbon footprint and diverts waste from landfills. This is particularly relevant in South Africa where coal-fired power is a major source of energy.

Waste Generation: Construction and demolition activities generate significant amounts of waste, including concrete, wood, metal, and plastics. This waste often ends up in landfills, contributing to environmental pollution and resource depletion.

Example: Traditional bricklaying often involves cutting bricks, leading to significant waste. Using modular brick designs or pre-fabricated wall panels can reduce waste and improve construction efficiency. 2.3 Sustainable Construction Techniques (South African Context): Rainwater Harvesting: Collecting and storing rainwater for non-potable uses such as irrigation, toilet flushing, and laundry. This reduces reliance on municipal water supplies, especially important in water-stressed regions of South Africa.

Example: A household in Cape Town can install a rainwater harvesting system to collect rainwater from the roof and store it in a tank. The harvested water can then be used to water the garden, wash the car, and flush toilets, reducing the household's water bill and conserving water resources.

Use of Recycled Materials: Incorporating recycled materials into construction projects, such as recycled concrete aggregate, recycled plastic lumber, and recycled steel. This reduces the demand for virgin materials and diverts waste from landfills.

Example: Using recycled concrete aggregate as a base material for roads or as fill in construction projects reduces the need to mine new aggregate and reduces landfill waste. Many South African companies now specialize in processing recycled construction materials.

Green Roofs: Installing vegetated roofs that provide insulation, reduce stormwater runoff, improve air quality, and create habitats for wildlife. This is particularly beneficial in urban areas with limited green space.

Example: Installing a green roof on a commercial building in Johannesburg can help to reduce the building's cooling load, improve air quality, and create a more aesthetically pleasing environment. Green roofs can also contribute to stormwater management by absorbing rainwater.

Passive Solar Design: Orienting buildings to maximize solar gain in winter and minimize solar gain in summer, reducing the need for artificial heating and cooling. This involves careful consideration of building orientation, window placement, and shading devices.

Example: In the southern hemisphere, a north-facing building will receive more direct sunlight during the winter months. Designing a building with large north-facing windows and appropriate shading devices can help to passively heat the building in winter and reduce the need for artificial heating.