20 Nov 2023
We can create green skyscrapers that reduce energy use, carbon emissions, and waste while creating healthier indoor environments.
Skyscrapers have long been symbols of wealth, prestige, and technological innovation. As African cities continue to grow at astounding rates, skyscrapers seem likely to become more common sights in the urban landscapes of the continent. However, the traditional skyscraper model comes with immense environmental impacts.
As architects and engineers in Africa, we have an opportunity to take a more sustainable approach right from the start. By implementing eco-friendly design principles and features, we can create green skyscrapers that reduce energy use, carbon emissions, and waste while creating healthier indoor environments. As leaders in the building industry, we can drive change across Africa and beyond through demonstration.
Why Traditional Skyscrapers Are Not Sustainable
The typical skyscraper is far from an environmentally friendly building. These towering structures require tremendous amounts of energy, materials, and other resources to construct, operate, and maintain - leading to immense environmental impacts.
Glass-and-steel buildings demand massive amounts of electricity for interior and exterior lighting, heating, ventilation, air conditioning, elevators, and other systems. The higher the skyscraper, the more energy is needed to pump water and move people vertically.
Keeping immense towers constantly lit and climate-controlled night and day consumes staggering quantities of energy - the Empire State Building in NYC uses more power annually than 40,000 average U.S. homes! This immense electricity consumption results in high greenhouse gas emissions from fossil fuel power plants.
Tall towers also generate incredible amounts of waste. The construction industry is responsible for nearly 70% of all non-industrial waste streams. Building skyscrapers consumes vast quantities of materials - a 100 story tower can require well over 100 thousand metric tons of concrete and steel.
The mockup, forming, fabrication, transportation, and installation processes create immense material losses. Once built, cleaning, maintaining, repairing, and upgrading such vast structures leads to constant waste generation. While some materials can be recycled or reused, much of this waste ends up burdening landfills.
Skyscrapers also monopolize vast amounts of water. Conventional cooling towers, boilers, water pumps, wastewater conveyance systems, and plumbing fixtures consume incredible volumes. Without careful conservation systems in place, water usage per floor area is often much higher than in smaller buildings.
Unfortunately, the materials most commonly used to build skyscrapers also have sizable carbon footprints. The production processes for steel and concrete generate massive carbon dioxide emissions - cement production alone accounts for 8% of global CO2 emissions due to extreme heat requirements. Using these unsustainable materials at monumental scales to build ever-taller towers boosts emissions tremendously.
In addition to harming the planet, traditional skyscrapers can also negatively impact human health and comfort. Keeping immense indoor volumes heated, cooled, and ventilated takes huge amounts of energy. Often times, sealing the towering structures entirely from outdoor conditions also seals out sunshine, fresh air, and connections to nature that people fundamentally need.
These confined indoor environments - reliant on mechanical ventilation, lighting, climate control, and dysfunctional building forms - may foster poor air quality and psychosocial issues that contribute to health problems ranging from respiratory diseases to depression.
Clearly, the standard skyscraper model comes with immense environmental baggage in terms of energy, emissions, resource consumption, waste, and even human health. As builders, designers, and architects, we have an obligation to approach these towers in better ways.
Sustainable Skyscraper Design Principles
However, skyscrapers don't have to be energy-guzzling symbols of excess. By thoughtfully implementing smarter sustainable design, we can drastically reduce their environmental impact. There are three core principles green skyscrapers should build upon:
Making skyscrapers highly energy efficient is the most impactful sustainability strategy. Carefully optimizing building orientation, architectural layouts, forms, and materials can dramatically cut lighting, heating, cooling, and ventilation needs. Installing smart meters, lighting controls, and building automation systems allows for fine-tuned energy management.
There are many features that can further curtail skyscraper energy use:
Window-to-wall ratios below 50% reduce heat loss and solar heat gain.
Low-emissivity coatings on windows reflect infrared light.
External movable shades and fins block intense sun when needed.
High albedo materials on the roof and exterior prevent heat absorption.
Superior insulation, air sealing, and heat recovery ventilation curb heat loss.
Elevator, conveyance, and lighting upgrades enhance efficiency.
Swapping old HVAC, pumping, and compression systems for new high-efficiency models.
Incorporating on-site renewable energy systems into the design is also key. Solar PV panels, wind turbines, geothermal wells, and waste-to-energy conversion can sustainably offset much of a tower's energy load. Excess renewable power can even be fed into the grid.
Water Conservation & Waste Minimization
There are also many ways to slash water usage and waste:
Low-flow plumbing fixtures sharply cut indoor potable water use.
Rainwater harvesting provides free irrigation and non-potable water.
Greywater recycling repurposes wastewater from sinks/showers.
Smart landscape irrigation with native plants saves water outdoors.
Composting organic waste on-site reduces hauling emissions.
Low-impact construction methods and materials cut waste.
Using prefabricated and modular building components made of recycled materials minimizes construction waste. Optimizing architectural plans to standard material sizes further eliminates excessive resource use. Implementing responsible waste sorting, diversion, and reuse programs on the jobsite also prevents valuable materials from burdening landfills.
Healthy & Comfortable Indoor Environments
Sustainable towers should provide welcoming, tranquil, and healthy spaces for occupants. Design choices that directly impact indoor environmental quality carry major implications for human health, comfort, and productivity.
Providing abundant natural daylight, dynamic exterior views, and connections to outdoor green spaces enhances mental well-being. Good ventilation and optimized air flow allows proper fresh air circulation. Using non-toxic, ethical construction materials prevents off-gassing and contamination. Acoustic controls minimize disruptive noise pollution within the tower. Thermal comfort systems maintain optimal humidity and temperatures.
By thoughtfully incorporating each of these principles, we can design skyscrapers that uplift people's health and happiness while conserving tremendous amounts of resources.
Bringing Green Skyscrapers to Africa
Sustainable skyscrapers like these demonstrate how pushing the envelope of eco-design leads to incredibly ambitious green buildings. They tackle environmental problems head-on while providing healthier, more inspiring spaces to inhabit.
As demand for urban development across Africa grows exponentially in the coming decades, high-density cities will have to build upwards. Ambitiously sustainable skyscrapers like those outlined here represent a path forward that uplifts people's well-being rather than degrading the planet.
Africa has an opportunity to lead the charge in green skyscraper innovation. By creatively integrating forward-thinking sustainable technologies into super-tall landmarks early on, the building industry here can drive change across continents. As architects and engineers on the forefront of the next era of urbanization, we must push the boundaries of sustainable design to maximize our positive impact.
The time has come for skylines to go green.