Engineering Greenhouses - MA

The science background section provides teachers with in-depth information about the phenomena students explore in this unit on climate. Below is an excerpt of the science background section on engineering greenhouses.

Effects of Climate Change

Climate change is a central focus of scientists around the world because of the wide-ranging impacts a changing climate will have on regions all over the planet.

The Intergovernmental Panel on Climate Change (IPCC) is a group of scientists from around the world who assess current understanding and the potential impacts of climate change. The IPCC reports that the world’s surface air temperature has increased by an average of 0.6 degrees Celsius (1 degree Fahrenheit) during the 20th century. Furthermore, the group predicts that temperatures are likely to increase even more during the 21st century. These findings are significant because even a 1-degree change can cause changes around the world.

The following are some changes that are expected with the rising temperatures:

• Sea levels are rising, a result of both the melting of glaciers and the expansion of water with heat.
• Arctic sea ice is melting, which may eventually lead to global changes in water circulation, as well as the increased warming of the Arctic because water absorbs 80 percent of sunlight, about the same amount that the cover of sea ice used to reflect.
• Oceans are warming, which has a major impact on marine ecosystems. For example, about a quarter of the world’s coral reefs have died in the last few decades. Many of them were affected by coral bleaching, a process tied directly to warming waters.
• Extreme weather, such as increased flooding, stronger storms, and increased droughts, will increase around the world.

Engineering a Solution

Now that climate scientists have identified the problem of climate change and understand possible causes, some engineers are trying to come up with solutions to slow Earth’s warming. One problem that some engineers tackle is how to grow different kinds of plants year-round.

Their solution is often a greenhouse—a structure that is similar to how Earth is warmed. The design plays an important role in how well the structure is able to regulate the temperatures inside. Radiant heat from the sun enters the greenhouse through its transparent covering of glass or plastic and starts to warm the objects, soil, and plants inside. The heated surface warms the air above it, and through convection, heats the rest of the greenhouse. Because the greenhouse is tightly sealed, all of the air remains relatively warm. If even a small window is opened, the temperature will become cooler.

The world’s largest greenhouse is located in Great Britain, and houses thousands of plant species from all over the world. Called the Eden Project, it is home to two massive greenhouses consisting of adjoining domes. The first dome mimics the climate of tropical rainforests, while the second dome mimics the climate of Mediterranean farms.

The first designs of the Eden Project biomes were drawn on a napkin over a drink in a pub. Over time, the design evolved to mimic giant bubbles because of bubbles’ ability to settle anywhere, even on uneven surfaces. The engineers also wanted to use the fewest possible materials when building the domes. They decided to look to nature for inspiration, and the engineering skills of bees. They designed the domes of the Eden Project using hexagonal shapes, just like honeycombs, which provide for a strong structure with minimal materials. The different biomes are designed to keep the inside air temperatures within a very specific range. Engineers used a variety of methods to achieve this. For example, the domes are made of a double-layered insulating material that traps air in between the two layers, acting as a thermal blanket.