Four everyday green dilemmas: what's really better for the environment?

With the UN's annual climate change conference, COP26, fast approaching, the UK government's COP26 spokeswoman Allegra Stratton this week announced a set of 'micro-steps' that people at home could adopt to be more eco-friendly.

The campaign, dubbed 'One Step Greener', has been met with mixed enthusiasm, with some praising the approach and others criticising a perceived diversion from the bigger green issues facing the government.

Suggestions included not rinsing dishes before putting them in the dishwasher, using bars of soap instead of shower gel, and freezing bread to avoid food waste. The campaign's aim is to complement the work being done by government and businesses, and nudge the public towards a bigger market for 'green goods' and cleaner technology.

While the ultimate key to reducing the UK's carbon emissions remains firmly in the hands of government and big businesses, there's no doubt that there are small changes we can make to our everyday lives to reduce our own personal environmental impact.

However, as anyone who's attempted it can attest, trying to live more sustainably can be complex. There's often not a simple answer, and deciding what's the 'greener' choice usually depends on a multitude of factors.

Below, we've looked into four common 'eco-friendly' decisions you might be making at home, to try to ascertain what's really best for the planet.

Hear expert Which? researchers get to the heart of what it means to be a sustainable consumer: head to the Which? Investigates podcast

1. What's greener, a shower or a bath?

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However you choose to bathe, you're going to need both water and heat.

Taking a shower might seem inherently more efficient, but that really depends on your shower and your habits. Some power showers can pump out more water in five minutes than it would take to fill a bath.

According to Waterwise, the average standard shower uses around 12 litres a minute. The average amount of water used to fill a bath is around 80 litres. That equates to a shower of about six and a half minutes - not long if you're pondering life's great questions or belting out classic hits.

Using an eco or aerated shower head can significantly reduce your water usage. Our research has found eco shower heads that reduce your water use to around six litres a minute, meaning you could shower for more than 13 minutes and still not use the same amount of water as the bath.

Then there's the heating to consider. Whether you choose a shower or bath, your carbon footprint will depend on whether you're using renewable energy or fossil fuels.

Few providers are currently using green gas, but if you're using an electric shower powered by renewable electricity, your impact will be considerably lowered.

If your energy sources are non-renewable, then you're better off with water heated by a gas boiler, which is generally more carbon-efficient than heating water with electricity.

So short showers, powered by renewables, are the way to go.

If you do have a bath, you can reclaim some of the energy you have used by leaving the warm water in the tub to heat up the air in your home.Then once it's cooled down, use it to water the plants.

Find out more: how to buy the best eco shower head

2. Should you use single-use plastic bags or long-life alternatives?

We can all agree that using plastic bags once and throwing them away isn't good. But for long-life alternatives to be greener, they must be used multiple times.

A 2019 report by Greenpeace UK and the Environmental Investigations Agency found that in one year the 10 companies that represent over 90% of the grocery retail market sold 525m single-use carrier bags and 1.58bn of the heavier-duty resuable ones.

This equates to one long-life bag per household per week, which suggests they aren't being reused as often as they should.

Because of the extra plastic used, these bags generally need to be used a minimum of between four and 12 times (depending on the type of bag) to make them more environmentally friendly than their single-use counterparts.

So you really do need to reuse them to make it worthwhile.

The materials used to make them can make a difference to their impact, too. Some are made from recycled materials. Others are made in fully closed-loop systems - Marks and Spencer's 'bags for life' are made from its operational plastic waste and can be returned to store to be recycled into more bags.

Paper isn't the answer either. Because paper bags are heavier, more emissions are used to transport them. Plus, they must come from a reputable sustainable supply chain to avoid risks of deforestation.

And while cotton tote bags don't cause pollution or end up in the oceans in the same way as plastic bags, the toll they have on natural resources and climate change is high.

A 2018 Danish study looked at the various environmental impacts of different types of bag and found that an organic cotton bag must be used 149 times before it levels with the impact on climate change of a single-use plastic bag (an ordinary cotton bag needs using 52 times). When they factored in the impact of some methods of cotton production on ozone depletion the reuse figure became much, much higher - between 7,100 and 20,000.

Related: Find out what supermarkets are doing about plastic and which supermarkets stock packaging-free products.

3. Is non-dairy spread better for the environment than butter?

It's commonly known now that cows can have a significant impact on the environment.

A 2018 study by Poore and Nemecek found that the average greenhouse gas emissions per litre of cow's milk in Europe was 2.2 kg CO2eq, compared with 0.9 and 1.0 for oat and soya milk alternatives. Plant-based milk alternatives also generally do better for land use and water use.

But while dairy butter is just made from milk, vegan 'butter' contains other ingredients that can have environmental impacts you should consider.

A study comparing the life-cycle assessments of 212 plant-based spreads with butter (Liao and Gerichhausen, 2020) found that plant-based spreads had lower climate, water and land impacts than butter.

But some plant 'butters' contain oils that are tied up in significant land-use change, such as palm oil. The study found that in a hypothetical worst-case scenario, the climate advantage of choosing a plant-based spread would be wiped out by the damage caused by the land-use change.

If you're choosing a plant-based spread, check that any palm oil in it is certified sustainable. Palm oil certified by the Roundtable of Sustainable Palm Oil (RSPO) is not without its critics, but many believe it's still the best way forward for sustainable palm oil.

Some plant-based spreads use coconut oil instead, but coconut farming can also come with environmental baggage - choosing organic or Fairtrade can mitigate against some of these concerns.

Read more about:plant-based 'milk' alternatives and how they compare with dairy, both nutritionally and environmentally.

4. Glass bottles, aluminium cans or plastic bottles?

You might assume glass bottles and aluminium cans are both better for drinks than single-use plastic, because these materials are easily and widely recycled, and have been for a long time.

In fact, a 2020 University of Southampton life-cycle assessment of beverage packaging (Brock and Williams) found that glass and recycled glass bottles had the most environmental impact in every drinks category they studied. Much of that impact is made up of the extraction of the composite materials used, the energy needed to melt the materials down into glass and the emissions caused by the melt.

But there was always a better option than single-use plastic.

Aluminium can be endlessly recycled, so 100% recycled aluminium cans were found to be the best option for containing pressurised beverages, Tetra Pak-style cartons were the best option for fruit juice, and milk cartons (that don't contain aluminium) were the best for milk.

For carrying your own drinks around, a reusable bottle is always a good bet. According to Green Alliance research, a reusable container designed to be refilled with water only has to be topped up 15 times to have a lower carbon impact than a single-use plastic one.

Head to our guides to the best reusable water bottles for 2021, and the best reusable coffee cups and travel mugs.

What can and can't be recycled? Our guide to how to recycle in the UK.