Lesson video

Hello, I am Mrs. Adcock, and welcome to today's lesson on life cycle assessments.

We are going to be looking at, what are life cycle assessments, and how can we compare these life cycle assessments for different products to see which is the most sustainable? Today's lesson outcome is, "I can complete life cycle analysis for paper bags and plastic bags." Some of the keywords we will be using in today's lesson include, "life cycle assessment", which we shorten to LCA, "raw materials", "sustainable", "subjective", and "objective".

Here you can see each of those keywords written in a sentence.

It would be a good idea to pause the video now and read through these sentences.

You might even like to make some notes so that you can refer back to them later in the lesson if needed.

Today's lesson on life cycle assessments is split into three parts.

First of all, we are going to look at, what is a life cycle assessment? Then we will move on to analysing life cycle assessments, and we will finish today's lesson by looking at some of the problems with life cycle assessments.

Let's get started on the first part of our lesson, what is a life cycle assessment? Every product has an impact on the environment, so it doesn't matter if it's a microwave, a T-shirt, a pen, every product is gonna have some impact on the environment.

A life cycle assessment, which is abbreviated to LCA, measures the environmental impact of a product throughout its life.

The life of a product is from obtaining the raw materials through to the disposal of the product at the end of its life.

Some people say a life cycle assessment measures from the cradle to the grave, so it measures throughout the entire life cycle of a product, and looks at the environmental impact that this product has throughout its life.

Is this statement true or false? "A life cycle assessment measures the environmental impact of a product throughout its life." That statement is true.

Can you justify your answer and explain why that statement is true? Is it, A, because the life of a product is the raw materials used, and how the product is disposed of at the end of its life? Or the life of a product is from obtaining the raw materials to how the product is disposed of at end of its life? The correct answer is B.

The life cycle assessment looks at the life of a product, and that's from obtaining the raw materials right through to how the product is disposed of at the end of its life.

A is not correct, because that suggests that a life cycle assessment just looks at how the raw materials are used and how the product is disposed of at the end of its life.

We can break down a life cycle assessment into different stages, and the stages of a life cycle assessment are, first of all, looking at the extraction and processing of raw materials.

Then we look at how those raw materials are used to manufacture the product, and thinking about the packaging as well that might be used with the product.

Then we look at the use of the product during its life, and also any maintenance that is required on the product during its life.

And finally, the last stage of a life cycle assessment looks at how we can dispose of the product.

And when we are looking at each of these four stages, we are thinking about the environmental impact that this product is having.

During each stage of a life cycle assessment, the following are considered: the energy used, the water used, any pollutants that have been released, and also transportation.

We've got an image there of a lorry, because for most products, they are going to be transported at some point in their life cycle.

Time for another question.

Which of the following should a life cycle assessment or an LCA include? Should it include A, the water used? B, pollutants released? C, energy used? D, transportation? An LCA should include the water used, any pollutants that are released, any energy that's been used, and it should consider the transportation.

Now these are all included at each stage of that life cycle assessment.

Well done if you identified that all four of those answers should be included in a life cycle assessment.

The first part of a life cycle assessment considers the extraction and processing of raw materials.

Now, the raw materials are the starting materials that are used to make a product.

We should consider in a life cycle assessment if the raw materials are a renewable or finite resource.

A renewable resource is either not used up, or it can be replaced during our lifetime.

And a finite resource is one that is in a limited quantity and it cannot be regenerated or replaced during our lifetime.

We're going to look at a couple of examples here of different products, and think about the raw materials that are used.

We've got the raw materials of paper carrier bags are trees, and trees are a renewable resource.

We can grow more trees to make more paper bags.

We can see an image there of pine trees.

These are often used to make paper.

The raw material of plastic carrier bags is crude oil, and crude oil is a finite resource.

We can see an image there of crude oil.

If we were considering the life cycle assessment of a paper and a plastic carrier bag, then we would think about the raw materials, and we would consider whether they are renewable or finite resources.

A life cycle assessment considers the environmental impact during the extraction of the raw materials.

So the extraction of crude oil, which was used to make plastic carrier bags, can cause oil spills that can cause environmental damage.

The mining of metal ores, which we use to extract metal, which we use for many different applications, can damage the environment by destroying habitats.

So we can see here some of the environmental impacts of extracting those raw materials.

A life cycle assessment also considers the energy used during the processing of the raw materials.

Here we have an image showing the fractional distillation of crude oil.

Crude oil needs to be processed to make plastic, and this requires a lot of energy.

Here we can see an image of a blast furnace.

Blast furnaces can be used to extract iron from iron ores.

The extraction of metals from metal ores requires energy.

So in that first stage of a life cycle assessment, we have thought about the raw materials themselves, whether they are renewable or finite resources.

We've looked at the extraction and the processing of those raw materials, and thought about some of the environmental impacts during these processes.

Time for another question.

What are the disadvantages of using crude oil as a raw material? A, it is a finite resource? B, extraction of crude oil can cause oil spills? C, processing of crude oil uses very little energy? D, crude oil needs to be extracted from metal ores? The correct answers are, A, crude oil is a finite resource, and B, extraction of crude oil can cause oil spills.

Well done if you chose answers A and B, and got that question correct.

It is not answer C, because the processing of crude oil uses a lot of energy, and it's not answer D, because crude oil is not extracted from metal ores.

We extract metals from metal ores.

We are going to move on from the raw materials and have a think about the manufacturing process of a product.

During the manufacturing process of a product, a large amount of energy may be used to run machinery.

Manufacturing may also involve the production of waste pollutants.

These waste pollutants could be washed into water supplies, they could get into the ground, or they could be released into the atmosphere, where they can have a negative environmental impact.

In the image there, we can just see an example of a manufacturing process where large machinery is used, and this is machinery that is used during the manufacturing of felt.

When using a product, energy and water may also be used.

For example, during the use stage of a T-shirt's life cycle, it will need to be washed multiple times.

Washing machines use large amounts of energy and water.

Here we can see an image of a washing machine.

We've looked at the extraction and processing of raw materials, we've thought about the manufacturing process, and now we're thinking about the use of a product, and thinking about what energy and water might be used or pollutants may be released during the use of a product.

Finally, a life cycle assessment will consider how a product can be disposed of at the end of its life.

And there are different ways we can dispose of products, such as recycling, incineration, and landfill.

And each of these ways of disposing of a product has different advantages and disadvantages.

One benefit of recycling is it reduces the amount of raw materials that need to be extracted.

Incineration is a process where we burn the waste products, and we can use the energy released in the generation of electricity.

And landfill, one of the benefits of landfill, is that it's a convenient way to dispose of products at the end of their life.

Time for another question.

What is the correct order for the stages of a life cycle assessment? So you need to put these stages, A, B, C, and D, into the correct order.

We've got A, use and maintenance of the product.

B, extraction and processing of raw materials.

C, the manufacture of the product and packaging.

And D, disposal of the product.

The correct order for the stages of a life cycle assessment are, extraction and processing of raw materials, then C, manufacture of the product and packaging, then A, use and maintenance of the product, and finally D, disposal of the product.

So you should have B, C, A, D.

Hopefully you got those correct.

Well done if you did.

Another question for us to have a go at here.

Plastic bags are non-biodegradable, but can be incinerated to release energy.

Which part of a life cycle assessment will contain this information? Will we find this information in A, the extraction and processing of raw materials? B, the manufacture of the product and packaging? C, the use and maintenance of the product? Or D, disposal of the product? So think about, when someone's carrying out a life cycle assessment, where will they put the information that the plastic bags are non-biodegradable and can be incinerated to release energy? The correct answer is D, in the disposal of the product.

That's where we'll find information about how we can dispose of the product, such as incinerating it.

Time for a practise task.

Question one.

The table below shows the percentage of energy used at each stage in the life cycle assessment of a pair of socks.

So we can see the extraction and processing of raw materials, the manufacture of the product and packaging, use and maintenance of the product, and the disposal of the product.

And for each stage we can see the percentage of total energy used.

You need to calculate the percentage of the energy used in the extraction and processing of the raw materials.

Let's see how you got on.

The correct answer is 3% of the total energy was used in the extraction and processing of raw materials.

Hopefully you worked that out, realising that the total energy used would be 100%, so you take away the amount that was used in the manufacturing and the use and disposal of the product, and then you would have calculated the percentage of energy used in the extraction and processing stage.

Question two.

This question is about the life cycle assessment of a T-shirt.

Suggest why the use and maintenance of a T-shirt uses the highest percentage of energy.

And when you've done that for part B, you need to give two ways the amount of energy could be reduced in the use and maintenance stage.

So see if you can come up with some ideas yourself of how the amount of energy could be reduced in the use and maintenance stage of a T-shirt.

Pause the video now, have a go at answering this question, then when you come back, we'll go over the answer.

Question 2A, suggest why the use and maintenance of a T-shirt uses the highest percentage of energy.

Washing the T-shirt in a washing machine and drying in a tumble dryer uses large amounts of energy.

So when we're using our T-shirt and maintaining it, then this involves washing it and drying it multiple times.

Part B, give two ways the amount of energy could be reduced in the use and maintenance stage.

We could wash the T-shirt at a lower temperature, and we could hang it out to dry rather than using a tumble dryer.

You may have come up with some different ways the amount of energy could be reduced in the use and maintenance stage.

We have had a look at what a life cycle assessment is.

We've looked at the different stages of a life cycle assessment, and also thought about what will be measured during each of those stages.

Now we're going to move on to look at analysing life cycle assessments.

Comparing life cycle assessments helps us to identify which product has the smallest environmental impact.

When we compare life cycle assessments, we might ask, are the raw materials from a renewable resource? So if we are comparing two products, we might look at whether the raw materials are a renewable or finite resource.

Does the extraction of the raw materials impact the environment? Which product uses less energy or water in its life cycle? If a product uses less energy and less water, then it's going to have a smaller environmental impact.

What impact will any pollutants released have on the environment? For example, during the extraction of raw materials or during the manufacture process, is any carbon dioxide released? Carbon dioxide is a greenhouse gas that contributes to global warming.

Can the product be repaired, reused, recycled, or incinerated to prevent it ending up on landfill? Landfill sites release methane gas, which is another greenhouse gas.

So can we prolong the life of the product by repairing it or reusing it? Is the product biodegradable? So we're thinking about, are there ways of disposing of the product that have a smaller impact on the environment? When we compare life cycle assessments, we can then make decisions over which product has a smaller impact on the environment.

We can use the life cycle assessment of a paper and plastic bag to decide which material bags should be made from.

Here we can see some of the details from a life cycle assessment of a plastic bag and a paper bag.

If we look at the plastic bag, we can see the raw material is crude oil, and that's a finite resource, whereas paper bags, the raw material is trees.

Trees are a renewable resource.

The extraction of crude oil, used to make plastic bags, may cause oil spills.

However, cutting down trees to make paper bags can destroy habitats.

The processing stage of plastic bags requires large amounts of energy, and releases waste products.

Processing of paper bags requires large amounts of energy as well, and water, and releases waste products.

Plastic bags are strong, so they can be reused, whereas paper bags often break after one use.

However, plastic bags are non-biodegradable, and paper bags are biodegradable.

We can use this life cycle assessment to make a decision as to which material we think bags should be made from.

Time for a question.

Which of the following may we consider when comparing life cycle assessments? A, are the raw materials finite or renewable? B, will there be technological advances? C, which product is cheaper to produce? And D, what impact will any waste products have on the environment? We may consider, when comparing life cycle assessments, are the raw materials finite or renewable? And what impact will any waste products have on the environment? Well done if you chose answers A and D.

Time for our second practise task of today's lesson.

Question one.

The table below shows data from a life cycle assessment for plastic and glass bottles.

For plastic and glass bottles, we've got information on the raw materials, the carbon dioxide that is released during the manufacture per bottle, in grammes, and the energy used during manufacture measured in megajoules.

Use the information in the table and your own knowledge to decide if milk bottles should be made from plastic or glass.

Pause the video now.

Have a go at answering this question.

Give as much detail as you can in your answer, and then come back when you're ready to go over the answer.

Let's see how you got on.

Your answer may include, both plastic and glass bottles are made from finite resources.

In the manufacture of plastic bottles, 50% more carbon dioxide is released than in the manufacture of glass bottles.

However, 2.

3 megajoules less energy is used in the manufacture of plastic bottles compared to glass bottles.

Plastic bottles are often single use, whereas glass bottles can be washed and refilled.

This means that over time, less energy will be required, and less carbon dioxide released using glass rather than plastic bottles for milk.

Your answer may be different to this, but you should have used the data in the table in your answer, there should be some of your own knowledge that has been brought into your answer, and overall, you should have an evaluation as to which material you think should be used to make milk bottles.

Well done for your hard work with that question.

We have looked at what life cycle assessments are, and how we can analyse life cycle assessments to make decisions over which product may have less environmental impact.

Now we are going to move on to look at some of the problems with life cycle assessments.

The table below states the energy used during the manufacture of a plastic milk bottle compared to a glass milk bottle.

We can see that the plastic bottle uses 5.

1 megajoules of energy in manufacture, and the glass milk bottle uses 7.

4 megajoules of energy during manufacture.

This data shows that the plastic bottle uses less energy during manufacture.

So does this mean that plastic bottles are the more sustainable option? Sustainable means to carry something on over a long period of time with little or no negative impact on the environment.

It's hard for us to make a decision about the sustainability of the plastic and glass bottles when we've only got one part of the life cycle assessment.

To consider the impact a product has on the environment, we need to study the full life cycle assessment.

Some companies may use part of a life cycle assessment, or carry out a simplified life cycle assessment that shows their product off in a more favourable manner.

Another problem with life cycle assessments is that some aspects are subjective, and this means they are based on personal feelings or opinions.

The amount of energy and water used can be measured to give quantitative information.

However, it is not easy to quantify the effects of pollutants, and this means some parts of the life cycle assessment are based on personal judgement , so they are subjective, rather than being purely objective, and objective means it's based on facts, such as the amount of water and energy used that can be measured and give us quantitative information.

Time for a question.

Which of the following statements are correct? A, LCAs are purely objective.

B, LCAs contain aspects that are objective and subjective.

C, water and energy used can be quantified.

D, the effects of pollutants is difficult to quantify.

The statements that are correct are: B, that LCAs contain aspects that are objective and subjective.

So some parts are based on facts, and some parts may be based on personal feelings or opinions, or perspectives.

The water and energy used can be quantified.

That statement is correct.

And D, the effects of pollutants are difficult to quantify.

So well done if you chose B, C, and D.

They were all correct statements.

Time for our final practise task of today's lesson.

A company that produces plastic cutlery has published the life cycle assessment below for plastic and wooden cutlery.

You can see the raw materials, the average number of times that these products are used, and the disposal information.

Question one.

State two pieces of information that are missing from this LCA.

Question two, why may the company not have published the full LCA? Pause the video now.

Have a go at answering both of these questions, and then come back when you're ready to go over the answers.

Let's see how you got on.

Two pieces of information that are missing from this LCA include the amount of water and energy used, pollutants that are released, and transportation that's involved throughout all of the stages of the life cycle assessment.

Well done if you got that question correct.

Question two, why may the company not have published the full LCA? The company may not have published the full LCA as they are using the incomplete LCA to mislead in order to promote their product.

Hopefully you've got an answer that's similar to that one there.

We have reached the end of today's lesson on life cycle assessments.

Let's just summarise some of the key points that we've covered during today's lesson.

To make a product, raw materials need to be obtained and processed.

A life cycle assessment can reveal the costs to individuals or the environment at each stage of a product's life.

At the end of its useful life, a product can be repaired, recycled, incinerated, or thrown away.

Life cycle assessments are often subjective, so it is important to consider the vested interests of those reporting on their findings.

Well done for all your hard work throughout today's lesson.

I've really enjoyed the lesson, and I hope you have too, and I hope you're able to join me for another lesson soon.