Rationing

Fuel shortages were a powerful incentive to energy saving in the UK in the 1940s particularly with economic growth after the war. In this discussion paper from 2005 Vilnis Vesma argues that a tapering national cap on the supply of fossil-derived fuel would still be very effective today in reducing our energy consumption and emissions.

Recuperator

Heat recovery device

Refrigerant

Volatile fluid in a chiller circuit which has a low boiling point, enabling it to absorb heat from air or water by evaporation at low temperatures and release it in a water-or air-cooled condenser. See this temperature-pressure conversion table which allows you to deduce refrigerant evaporation and condensing temperatures from measured pressures for a range of refrigerants.

Regression

Statistical technique for estimating the relationship between energy consumption and one or more driving factors. Click here for more detail.

RHI

Renewable Heat Incentive: UK subsidy for the production of heat from renewable sources such as biomass, biogass, and solar energy

RO

Renewables Obligation: support mechanism for renewable electricity projects in the UK

ROC

Renewable Obligation Certificate: tradeable instrument embodying the 'greenness' of renewable electricity; bought and sold independently of the electricity to which it relates

RoI

Return on Investment: a measure of the financial viability of a project

RoUL

Risk of Undetected Loss: method for evaluating the cost-effectiveness of supplementary metering and associated systems, in which the estimated consumption quantity in each significant branch of a utility system is multiplied by a factor representing the long-term likelihood of unexpected excess consumption. See article.