Definitions - r

R-Selection

Rapid growth and occupation through early reproduction, short life spans, low biomass, and lots of offspring. See K-Selection.

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R-value

The R value or R-value is a measure of thermal resistance used in the building and construction industry. The bigger the number, the better the building insulation's effectiveness. R value is the reciprocal of U-value. Often used as a measure of bulk insulation products, such as a roof insulation Batts.

Original Wikipedia entry

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Radiant Barrier

A device designed to reduce or stop the flow of radiant energy.

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Radiant Floor Heating

A heating system that warms the floor, which radiates heat to the whole house. Often either electrical or hot water based.

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Radiation Inversion

An increase in temperature with height due to radiational cooling of the earth's surface. Also called a nocturnal inversion.

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Radiative Forcing

A change in the balance between incoming solar radiation and outgoing infrared radiation. Without any radiative forcing, solar radiation coming to the Earth would continue to be approximately equal to the infrared radiation emitted from the Earth. The addition of greenhouse gases traps an increased fraction of the infrared radiation, radiating it back toward the surface and creating a warming influence.

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Rainshadow

An area of diminished precipitation on the lee (downwind) side of a mountain or mountain range.

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Rainwater Harvesting

Rainwater harvesting refers to the act of 'keeping' rainwater that falls on your roof for use later. This implies that the a certain amount of plumbing is done to collect the water to a central tank, then plumbing is done to provide the water where needed. Also overflow plumbing needs to be done for when the tank is full.

This is often done to reduce a building's dependence on piped 'town water' or to provide fresh water where town water is not available. The water so collected is suitable for drinking as long the roof is clean and the water tank is rated for potable water storage.

See here for an online calculator to work out the amount of water you can harvest and the size of tank you need in relation to your water usage.

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Rapidly Renewable

Rapidly renewable materials include those that replenish faster than hardwoods. Bamboo and cork fall into this category.

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Recovered Energy

Reused heat or energy that otherwise would be lost. For example, a combined cycle power plant recaptures some of its own waste heat and reuses it to make extra electric power.

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Recovered Material

Fragments of products or finished products of a manufacturing process, which has converted a resource into a commodity of real economic value, and includes pre-consumer and post-consumer material but does not include excess resources of the manufacturing process.

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Recycling
Recycling

Recycling involves processing used materials into new products to:

  • Prevent the waste of potentially useful materials,
  • Reduce the consumption of fresh raw materials,
  • Reduce energy usage,
  • Reduce air pollution (from incineration),
  • Water pollution (from landfilling) by reducing the need for "conventional" waste disposal, and,
  • Lower greenhouse gas emissions as compared to virgin production.
Recycling is a key component of modern waste management and is the third component of the "Reduce, Reuse, Recycle" waste hierarchy.

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Redox Cell

The redox (reduction–oxidation) cell is a reversible cell in which electrochemical components are dissolved in the electrolyte. Redox flow batteries are rechargeable.


Typically they are able to be deeply discharged and recharged to full without ill effect on the lifetime of the battery or its capacity. Also they can be left indefinitely in a charged state, making them ideal with stand by power situations.

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Reforestation

Total dry weight of all living organisms that can be supported at each tropic level in a food chain.

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Refurbished Product

A product that has been completely disassembled and restored to its original working order while maximizing the reuse of its original materials.

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Relative Ecological Sustainability

Ability of an ecosystem to maintain relative ecological integrity indefinitely.

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Relative Humidity

Relative humidity is a term used to describe the amount of water vapor in a mixture of air and water vapor. It is defined as the partial pressure of water vapor in the air-water mixture, given as a percentage of the saturated vapor pressure, under those conditions

The relative humidity of air thus changes not only with respect to the absolute humidity (moisture content) but also temperature and pressure, upon which the saturated vapor pressure depends. Relative humidity is often used instead of absolute humidity in situations where the rate of water evaporation is important, as it takes into account the variation in saturated vapor pressure.

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Remanufactured Product

Any product diverted from the supply of discarded materials by refurbishing and marketing said product without substantial change to its original form.

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Renewable Energy

Energy obtained from sources that are essentially inexhaustible, unlike, for example, the fossil fuels, of which there is a finite supply. Renewable sources of energy include wood, waste, geothermal, wind, photovoltaic, and solar thermal energy.

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Resident Fish

Fish species that complete their entire life cycle in freshwater. Non-anadromous fish. An example is rainbow trout.

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Resource Efficiency

A practice in which the primary consideration of material use begins with the concept of "Reduce - Reuse - Recycle - Repair" stated in descending order of priority.

This concept may be applied in everyday life to help promote a sustainable society. In design, begin by reducing the amount of material that is specified; find ways to reuse materials, recycle products or product waste; specify products made from recycled materials; and repair or restore products instead of replacing them.

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Retorting

The heating of oil shale to get the oil out from it.

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Reverse Graffiti

A form of outdoor advertising with a clean is green message.Essentially it is created by power washing a message into a dirty surface such as a side-walk or an outdoor concrete wall. A specific form of green graffiti.

How legal such graffiti is depends on the laws in force for the area concerned. Some local governments require any form of advertising to require prior permission before placement. Also careful consideration needs to be given to the effect of power cleaning on the actual material being cleaned, it could well promote breaking down the exposed surface quicker than would have otherwise being the case.

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Rewilding

Rewilding is the act of reintroducing species to areas where they previously went extinct. The assumption being that by them being reintroduced it makes the areas more 'wild' and therefore natural compared to what it was previously.


Rewilding needs to be undertaken very carefully as some are suggesting reintroducing species that were equivalent to the locally extinct species but not the same. This could have unintended consequences, as the presence of introduced species could have altered the ecosystems sufficiently to make the reintroduction of an extinct species no longer viable. Also native species could be thriving with the introduced species.

There is also discussion about the reintroduction of apex predators into areas where there is no apex predators - again, the eco system needs to be sufficiently robust to support such a change. 

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Riparian Area

An area of land directly influenced by water. An ecosystem that is transitional between land and water ecosystems. Riparian areas usually have visible vegetative or physical characteristics reflecting the influence of water. River sides, lake borders, and marshes are typical riparian areas.

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Riparian Buffer

Riparian areas that are managed to protect the aquatic and riparian ecosystem. A riparian buffer protects water quality and temperature, habitat along the banks, upland habitat for aquatic and riparian species, and some or all of the floodplain.

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Riparian Rights

The rights of water use possessed by a person owning land containing or bordering a water course or lake.

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Roll Cloud

A rotating, cigar-shaped cloud that sometimes precedes a thunderstorm. Often seen in UFO photographs.

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Rough Fish

Fish not prized for sport or eating, such as gar and suckers. Most are more tolerant of changing environmental conditions than are game or food species.

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