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Green building glossary

A glossary of words and phrases used in green construction and sustainable development.

R

Radon

An odourless gas that passes from some soil types into buildings and may cause cancer.

Rainwater harvesting or rainwater use system

A system that collects rainwater from where it falls rather than allowing it to drain away. It includes water that is collected within the boundaries of a property, from roofs and surrounding surfaces.

Rammed earth

A wall-building technique, by which a mixture of earth, water, and usually a small amount of cement, is very forcibly tamped inside formwork. The resulting wall has high mass, so it works well in hot climates. It often needs no exterior or interior covering, thus saving materials.

Recurrence interval

The average time between Runoff events that have a certain flow rate, e.g. a flow of 2 m/s might have a recurrence interval of two years in a particular catchment.

Recycled rain water

See – Greywater

Recycling

The process by which discarded materials are collected, sorted, processed and converted in to raw materials which are then used in the production of new products. Material that would otherwise be destined for disposal but is diverted or separated from the waste stream, reintroduced as material feed-stock, and processed into marketed end-products.

Regulatory impact analysis

The ex-ante analysis of the effects of proposed regulations, or the ex-post assessment of an existing one.

Rehabilitation

Action to restore, regenerate, renovate or improve a building, site or Catchment; usually involving improvements to remedy past adverse environmental or social impacts.

Remediation

The action or measures taken to lessen, clean-up, remove or mitigate the existence of hazardous materials existing on a property to such standards, specifications or requirements as may be required by statutes, rules or regulations.

Renewable energy

The use of energy from a source that does not result in the depletion of the earth's resources whether this is from a central or local source.

Renewable energy certificate (REC)

A certificate that represents a unit of Renewable energy generated that can be used to verify the fulfilment of an obligation to source a certain percentage of renewable generation as required in Renewable Portfolio standard schemes.  Trading may be allowed so that companies that under-achieve their obligation can buy certificates from those who have over-achieved.

Renewable portfolio standard (RPS)

A market based mechanism devised by Nancy Rader and Richard Norgaard for the American Wind Energy Association in 1996. It obliges supply companies or consumers to purchase a specific amount of electricity from Renewable energy sources. The key goal of such a mechanism is to minimise the costs of increasing renewable energy capacity through the stimulation of competition to fulfil obligations. The RPS mechanism is also known as a quota or obligation mechanism.

Renewable resource

A resource that is capable of being replenished through natural processes or its own reproduction, generally within a time-span that does not exceed a few decades. Technically, metal-bearing ores are not renewable, but metals themselves can be recycled.

Reserve

In geology, a reserve refers to an estimated quantity of a natural material (mineral, rock, gas or liquid) in the ground that has been explored to the extent that the probability of producing the material from it economically is reasonably assured.

Resource

Any substance of use to humans; renewable such as water, or finite such as oil.

Resource rent

The financial surplus, after deducting production costs, associated with the extraction or harvest of a Natural resource.

Retention pond

A pond where Runoff is detained (e.g. for several days) to allow settlement and biological treatment of some pollutants.

Re-use

The recovery of components to be re-used in future buildings without the requirement for recycling.

Runoff

Water flow over the ground surface to the drainage system. This occurs if the ground is impermeable, is saturated or if rainfall is particularly intense.

R-value (RSI)

A unit of thermal resistance, the opposite of thermal conductance. The higher the R value, the greater the insulating quality. The SI units for thermal resistance are Km²/W. R-values are commonly used to characterise thermal insulation materials in buildings. In this context, the unit is often written as RSI (for R-value Système International), and a specific value such as 5.53 may be indicated as RSI–5.53, but may also simply be written as R5.53. One tenth of an RSI is known as a tog.

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