3 - Improving our Environment
We all need to be aware of the effects that making and using products in everyday life can have on the world around us. Scientists are constantly looking for ways to lessen the damage we do by improving the ways we make, use and dispose of products.
Energy is expensive and should not be wasted. Energy consultants need to understand how heat is transferred.
Home owners need to show how energy efficient their house is before they can sell it.
Environmental scientists realise that pollution-free air in the home is important for our health and wellbeing.
3.1 Environmental concerns when making and using products
Candidates need to understand that:
In everyday life we rely on a vast array of products to sustain and improve our standard of living. Environmental scientists realise that making and using some products have a polluting effect on the environment during manufacture, use and disposal. Scientists, technologists and engineers working in different areas are now seeking ways to solve these problems and to make products more environmentally friendly.
Plant biologists and polymer scientists are involved in producing biodegradable plastics from plants that could be used for packaging.
Some consumers are concerned not only about the quality of products and their cost but also about the effect on the environment of their production and disposal. Consumers are often encouraged to consider the amount and type of packaging of the product.
Candidates need to:
1. Describe the main ways in which making and using products may result in increased emissions of natural greenhouse gases into the atmosphere, causing global warming, including:
(a) carbon dioxide from the combustion of fossil fuels in vehicles and power stations
(b) methane from decomposition of rubbish in landfill sites and various forms of agriculture
(c) nitrous oxide from vehicle exhausts and power stations and as a result of increased use of nitrogen-based fertilisers.
2. Explain how increased greenhouse gases absorb more long-wave radiation from the Earth and retain heat in the atmosphere.
3. Know about international agreements such as the Kyoto agreement on climate change to achieve the stabilisation of the dangerous gases carbon dioxide, methane and nitrous oxide.
4. Describe how leaching of artificial fertilisers, pesticides and herbicides causes pollution in lakes and rivers (eutrophication).
5. Explain the process of eutrophication resulting from over-use of fertilisers.
6. Explain how indicator species may be used to monitor changes in pollution levels:
(a) water pollution – bloodworm, water louse, sludgeworm, rat-tailed maggot
(b) air pollution – lichen.
7. HT only: describe the methods of degrading plastics:
(a) photo-degradable – those that degrade after prolonged exposure to sunlight
(b) oxo-degradable – an additive helps to break down the plastic, allowing access by microbes.
8. HT only: explain why plastics such as Polyvinyl Alcohol (PVOH) and Ethylene Vinyl Alcohol (EVOH) are used for plastic films for packaging and shopping bags.
Within this context, candidates should be able to use scientific data and evidence to discuss, evaluate or suggest implications of the following:
■ the environmental impact of landfill sites for the disposal of waste materials including plastics
■ the advantages and disadvantages of using plants to make plastics
■ disposal of waste material by incinerating or recycling
■ changes to the composition of water and air as a consequence of industrial activity
■ use of data gained from indicator species to evaluate the levels of pollution
■ the advantages and disadvantages of using biodegradable products in landfill.
3.2 Saving energy in the home
Candidates need to understand that:
Energy consultants advise home owners and builders of measures that may be taken to reduce the rate of heat loss in our homes. Over the past few years the parts of the building regulations that relate to energy efficiency have been revised several times in line with the need for increased energy efficiency, and to reduce the impact that buildings have on global warming. This has meant significant changes to the thickness of insulation required for buildings to help save money on utility bills and reduce effects on the environment. Energy consultants also consider the ‘payback time’ when installing energy-saving measures.
Candidates need to:
1. Describe how heat is transferred by conduction, convection and radiation in the home. Knowledge of heat transfer mechanisms should be limited to:
■ conduction – the transfer of heat energy through a substance (for example, metal) without the substance moving
■ convection – the transfer of heat energy by gases or liquids moving
■ hot objects emit heat energy by radiation.
2. Describe ways of minimising heat loss in the home (for example, insulation, double glazing, hot water tank jackets, thermostatic controls, draught excluders).
3. Know that the U-value is the measure of the rate of heat loss through a material. Candidates should be able to interpret U-value data. Any formulae required to interpret data will be given.
4. Explain the term ‘payback time’ in relation to installing energy-saving measures.
5. Explain the difference between efficiency and cost-effectiveness.
Within this context, candidates should be able to use scientific data and evidence to discuss, evaluate or suggest implications of the following:
■ the efficiency and cost-effectiveness of methods used to reduce domestic energy consumption
■ U-values of different types of material.
3.3 Controlling pollution in the home
Candidates need to understand that:
Scientists realise that clean air is something we all need for a healthy home environment. In certain circumstances indoor pollution can be more serious than outdoor pollution.
Some of the build-up of indoor pollution in today's homes is a direct result of our efforts to be energy efficient. As energy consultants strive to design homes that are more energy efficient an environment is created which is susceptible to indoor air quality problems. Air conditioning in our homes and offices means that air is recycled many times over, often with fresh air entering only when we open doors or windows. Surveyors have realised that pollution may also be caused by the type of soils beneath our homes.
Candidates need to:
1. Name some of the common pollutants in homes (dust, mould and spores, pollen, smoke, fumes from household products).
2. Name some of the common symptoms of exposure to high indoor pollution levels (asthma, headaches, tiredness, dizziness, nausea, itchy nose, sore throat).
3. Interpret hazard labels on household products.
4. State the risks associated with these hazards, and know ways of minimising these risks.
5. Explain why domestic boilers need an adequate supply of air to work efficiently.
6. Explain how incomplete combustion of fuels used in domestic boilers results in lower energy output and the formation of toxic combustion products (carbon monoxide) and soot. Balanced chemical equations for incomplete combustion are not required.
7. Know that radon is a radioactive gas and is a cause of cancer.
8. Understand that if rocks and soil beneath the home contain large concentrations of radium or uranium, radon may become a pollutant.
Within this context, candidates should be able to use scientific data and evidence to discuss, evaluate or suggest implications of the following:
■ the hazards and risks caused by using household products
■ methods of reducing pollution in the home including the use of less toxic products
■ the importance of ventilation in the home
■ the dangers of radon gas in the home.
Suggestions for practical work that could be used to support Theme 3
It is the responsibility of the centre to be aware of the health and safety implications of any practical work, and to ensure that risk assessments for practicals are carried out.
■ Demonstrate the production of solid particles by incomplete combustion using a Bunsen burner yellow flame or a candle flame to heat a boiling tube of cold water.
■ Demonstrate burning sulfur or coal in oxygen and test the pH of the gas produced.
■ Grow cress from seeds and add various concentrations of sodium metabisulfite solution to show how acid rain affects plants.
■ Investigate the effects of SO2 on growth of cress seedlings.
