Container Homes, A Good Environmental Choice?

Research is paramount if you want to make an environmental difference.

Container homes have quickly gained popularity around the world as a sustainable solution. It is one of the few trends and concepts that has been unquestionably celebrated as an epitome of sustainable modular architecture by the design and construction fraternity. However, the criticisms of this practice are also not scarce. Like any innovation, the claim that it is sustainable is debatable at best, even though, on the surface, it looks like an environment friendly idea. 

Containers are some of the most durable modular structures in existence today. However, it entails two factors that cannot be disregarded: 100% recyclability and intended lifecycle. The strength and durability, containers offers, argues that it is NOT an environmental choice using it for shipping container homes. Instead, it is better to use its 100 % recyclable quality for shipping or to produce new secondary steel and reduce the need for primary steel in the market.

The table below indicates the aspects that make container homes a good environmental choice and the ones that don’t.

Ecofriendly whenNot ecofriendly whenIf reusing a container that is not fit for shipping anymore (damaged/ broken before its life span ended)Pulling a container too early out of its intended cycle. (Create a demand for a new one)
If the container is readily available to a nearby place/ port thus saving the transport emissions When the container is being shipped from across the continent, utilizing a large amount of fuel and increasing the carbon footprint.
Depending on what is it alternative for. E.g. If the shipping container home is replacing an RCC home, multistorey building that would have required a large amount of steel, then it is a better option.orIf it is replacing a shed that was supposed to be built with new steel beams insteadWhen using a new container, right out of the factory.
If you know that the container you used was not going to be sent for recycling, or it is not feasible to send it for recycling due to logistical reasons.Pulling it from the recycling chain
If the container is replacing the need for new 8000 lbs steel for a multi-level structure.When only one time used container is pulled for conversion into a home.
If you live in a tornado or hurricane-prone areaWhen used for a function that does not need as much steel, and strength as a container offers.

What is a good environmental choice?

In order to determine if shipping container homes are a good environment choice, the definition of good environment choice needs to be clear. A choice that would help reduce the carbon footprint, utilize less energy compared to the conventional ways and thus reduce the dependency and use of fossil fuels and non-renewable resources is a good environment choice. 

In case of building a home, a good environment choice would be in the areas of building material, appliances, size, sources of energy. 

‘Cargotecture’ mainly falls in the category of building materials, because it is essentially providing a structurally strong envelope for the home, while the rest of the factors needs to be introduced from scratch. To understand if reusing a shipping container for a home envelope is a good environment choice, let’s explore the cargotecture in detail.

The reality of ‘cargotecture’

Green Future notes in an article that the patent for converting shipping containers into habitable spaces was first filed by Phillip C. Clark in 1987, but it took some decades for the rest of the world to catch up to his foresight. On the surface, the reuse of discarded shipping containers seems like a noble and environment friendly idea. It suggests that cargotecture is saving these abandoned containers from going to landfills.

However here are some red flags of cargotecture that could unwind some gruesome consequences if gained enough momentum to change the supply and demand of steel and shipping containers.

  1. Most articles, companies and blogs that facilitate shipping container homes by information or materials recommend that new or one-time used shipping containers are the best for conversion into a home. These suggestions are based on the fact that the used shipping container could have exposure to toxic chemicals, and thus avoiding them will be safe.
  2. The average life of a shipping container when they are fit for shipping is 10- 12 years. However, Cargotecture leads to a lot of containers being pulled away from their intended life cycle just 1 year after they have entered the cycle and thus creating demand for new steel containers.
  3. As shipping containers are made of steel, they tend to have a greater heating and cooling effect due to varying climates. This requires strong insulation. Unfortunately, none of the sustainable insulation methods is suitable for shipping container homes, as they either do not provide enough R-value, ergo insulation, or occupies a lot of space within the already limited width of the container. As a result, maximum users end up using non-ecofriendly polyurethane spray foam insulation, which is considered best for shipping container insulation. 
  4. Even though people are using shipping containers for all types of habitable spaces, including commercial, residential, institutional, cultural etc. The hype of shipping containers and tiny homes have coincided, thus leading to a lot of people employing shipping containers for tiny homes. But If considered rationally, In an ideal case of conventional building, a tiny home would never require the amount of steel that a shipping container is built of. Thus, utilizing a heavy steel envelope for a tiny home often becomes a waste of the qualities and strength that a shipping container offers. The reuse of shipping containers is not proportionate to its strengths and qualities, thus making it a waste of material.

What happens to Shipping Containers after they are discarded?

This question lies at the root of determining if we are really saving the earth and the space in the landfills by reusing these containers as homes.

Once the container has served its life in the transport industry, ideally, they are sent to a scrap yard, where they are crushed, dismantled, shredded into smaller pieces and then sent for recycling along with all the other scrap metal from cars, sheds, utensils etc.

Shipping containers are made of Corten steel, which is a copper chromium alloy steel and is 100% recyclable indefinitely. This means it can be recycled numerous times without losing its value. Of course, recycling steel utilizes a lot of energy and does leave a carbon footprint, but that energy consumption and carbon footprint are less than that needed for the manufacture of primary steel from iron ore. (The next section shall put forward some specifics to prove this.)

However, it would be wrong to assume that all of the shipping containers are sent for recycling regularly. Shipping containers are heavy, require space and a lot of transportation. Oftentimes, it seems logistically more feasible to send the discarded container to a landfill, rather than a faraway or congested scrap yard. Hence, the fate of shipping containers being in landfills begins. However, this is a case-based scenario, and cannot be generalized to support a trend.

Reuse is a great way to reclaim such shipping containers, but it should be these discarded containers, and not the ones still in the shipping cycle. 

Let’s analyze if recycling these containers is a good environment choice?

Recycle v/s Reuse

Iron and steel are the second largest energy-consuming industry in the world. Production of steel, cement, automobiles and other manufactured products is responsible for about 20 percent of global carbon emissions. As shipping containers are manufactured of steel, they fall in this category, thus contributing to the 20 percent. 

Let us understand the energy consumption in manufacturing steel, 

  1. From iron ore (Primary steel)- It requires 6806 kWh energy and around 1.6 tons of iron ore per ton of steel produced. A shipping container contains 4 tonnes of steel; therefore, it takes approximately 27,224 kWh energy to manufacture 1 shipping container from scratch.
    • From recycling (Secondary steel)- As David Cross of points out, it takes only around 8000-11000 kWh energy to recycle a single 4 ton of steel shipping container.
    • Reusing/Converting into home- It takes around 400 Kwh to convert a 20 ft shipping container into a home.

It is evident from the above information the energy required for recycling steel is significantly lower than the energy used in the manufacture of primary steel plus the energy used to extract and process the iron ore. In fact, a research paper by Clare Broadbent shows that for every 1 kg of steel scrap that is recycled at the end of the products life, a saving of 1.5 kg CO2-e emissions, 13.4 MJ primary energy and 1.4 kg iron ore can be achieved. This equates to 73, 64 and 90 %, respectively, when compared to 100 % primary production. Moreover, over 1,400 kg of iron ore, 740 kg of coal, and 120 kg of limestone are saved for every 1,000 kg of steel scrap made into new steel.

Indeed, reusing and converting shipping containers requires a lot less energy, but in the long run, is it healthy to deprive the recycling industry of large quantities of recyclable steel that comes from these discarded shipping containers? Especially with the shipping and cargo industry booming and growing continuously?

The recyclability of steel is its biggest asset.  The Environmental Protection Agency estimates that secondary steel production uses about 74% less energy than the production of steel from iron ore. When looking at the bigger picture, it is important to consider, if our actions are pulling a significant amount of steel from this cycle, and that too for a function that wouldn’t require this quantity of steel if built conventionally. 

Reuse: Yes, Reuse of a shipping container uses way less energy and contributes a lot less to the carbon footprint,  (only 400kwh to be exact) but it also pulls some valuables steel from the chain of recycling, thus reducing the materials available for secondary steel, putting more pressure on the primary steel industry. Therefore the instances of reuse should be carefully chosen.

When can ‘Cargotecture’ prove a boon?

Cargotecture is indeed a brilliant idea, but the point of this article is that this idea needs to be implemented mindfully, for functions that actually require them, and which will justify the strength and qualities of the shipping container. 

Let’s have a look at some instances, where shipping container homes might make sense:

  1. If you live in a region where wood is scarce and an unorganized timber industry, then you might be saving a considerable number of trees by opting for a shipping container home.
  2. In a disaster-prone area: Shipping containers have proved worthy and extremely resistant in high scale tornadoes and hurricanes. 
  3. Disaster relief temporary housing. For temporary housing, these containers can be the quickest and strongest means to provide relief and shelter to affected areas.
  4. Storage units- Reusing shipping containers as a temporary storage unit for construction sites or backyards could be a good idea, as they are temporary and eventually those shipping containers will end up in the recycling chain.
  5. Before deciding to build with shipping container, and getting influenced by the hype of environment-friendly cargotecture, compare it with:
    • Most accepted construction practice in your area
    • Availability of shipping container. Most of the shipping containers are manufactured in South Asia and then shipped. If you are using a new shipping container, make sure you don’t import it from another continent, otherwise, you are using a lot of valuable fuel even before your house is built
    • If you live near a port and have access to a good quality one-time used container, this might be a good option. However, keep in mind that pulling a one-time used container from its intended life actually creates more demand for new shipping containers in the shipping cycle. So, put some thought into the decision.
    • Damaged Shipping Container: In my opinion, using a damaged shipping container, which is not fit for shipping and withholding saltwater environments, can be efficiently converted into a home with some treatments. 
    • Make sure you use eco-friendly insulation. However, this will not be possible if you live in a region with extreme climates. As eco-friendly insulation options do not offer the high R-value that products like polyurethane spray foam offers.
    • A shipping container is used for its structurally strong envelope and modular quality. It is often prefabricated in factories. If you are buying a prefabricated shipping container home, make sure that the factory is following sustainable methods and discarded shipping containers in the process. 

Ways to ensure you are making an eco-friendly choice.

If you have decided to reuse a shipping container for your home because you care about the environment, and believe that this will be an eco-friendly choice, ensure this checklist to analyze if you are making the right choice?

  • How many times has the container been used?

Shipping containers generally have a life span of 10-12 years, when they are fit for shipping. Then they are discarded.

If you are using it only one or two times the used container, then you are creating room for another new one, which is not environment friendly.

  • Is the shipping container you are buying being pulled out of its recycling opportunity?

This is an on-ground question.

The answer to this question depends on how far is the recycling facility, and do the owners send it or are they just going to let the discarded container sit on land for years. If that is the case, then reusing it is the best option, because you are saving a lot of chemical sludge from draining into the ground through that container.

  • Is buying a new shipping container worth it?

It is possible that you may still feel that buying a new shipping container is your best bet, but make sure you don’t buy it from someone who is shipping it from across the continent. That is just a waste of fuel and energy and added carbon footprint because of your home.

Final Words:

‘Cargotecture’ is without a doubt a brilliant idea. However, we have made this mistake before, when plastic was invented. Reckless use of plastic has led to a catastrophic condition of the oceans and world today. It is time we learn that all good concepts are not good in every situation and think about their application mindfully.

If used mindfully, considering the context and various factors discussed above, then shipping containers can be an environment friendly option. However, employing the technique just because of the trend and hype could be misleading and actually do more harm than gain to the environment.