3.2.5.4 - Energy demand management and sustainability

Demand reduction choices

Demand reduction should be judged by useful services, total energy use and the people affected.

Conservation avoids or reduces a service where appropriate, such as switching off unused cooling or replacing an unnecessary car trip. Efficiency provides the same useful service with less energy, through insulation, efficient motors or better equipment. These measures can lower fuel bills, import needs and pressure to construct new capacity.

Climate and buildings affect suitability. Shading can reduce solar heat gain in a hot place; insulation reduces unwanted heat transfer, helping cooling or heating. Public transport works best where routes and urban density support access. A simple universal saving percentage would ignore building fabric, behaviour and baseline conditions. US Department of Energy, home cooling mechanisms.

Costs and distribution matter. Households may be unable to afford efficient appliances even when lifetime savings are positive. Rental arrangements can separate the person paying for insulation from the person saving on bills. Grants, standards and better information can address barriers, but their implementation must be checked.

Rebound occurs when lower cost per service encourages more use. In original illustrative data, cooling initially uses 10 kWh per hour for 4 hours/day: 40 kWh/day. New equipment uses 7 kWh/hour for the same 4 hours: 28 kWh/day, a 30% technical saving. If use grows to 5 hours, consumption is 35 kWh/day, only 12.5% below the original total. A saving per hour is not the realised total saving.

Assessment compares affordability, useful access, emissions, peak demand and implementation over a stated period. Cutting energy used by an already underserved household can harm welfare. Target waste and inefficient service, while measuring both total and peak demand; shifting consumption to another time is not automatically reducing it.

Acid rain and greenhouse warming

Energy pollution affects sustainability through different mechanisms and spatial scales.

Acid deposition results when sulphur dioxide and nitrogen oxides react in the atmosphere to form acids, deposited in rain or as dry material. Fossil-fuel combustion is an important source. Deposition can acidify soils and waters, mobilise harmful substances and damage ecosystems or materials; winds can carry pollution beyond the producing region. Low-sulphur fuels, emissions controls and reduced combustion can lower precursor emissions. They do not instantly reverse accumulated damage. US EPA explanation.