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Green building glossary

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

D

Daylight

A natural source of light, daylight consists of sunlight, cloud diffused sunlight, both reflected by the ground and adjoining surfaces.

Daylight transmittance

The ratio of the amount of light transmitted through a window divided by the amount of light incident on its outside surface.

Daylighting design

The use of controlled natural lighting methods indoors, through the use of skylights, windows and reflected light.

Decarbonisation

When applied to an economy, refers to the phasing out of its dependence on (carbon-containing) Fossil fuels.

Deforestation

The conversion of forested areas to non-forest land use such as arable land, urban use, logged area or wasteland; historically, this meant conversion to grassland or to grainfields.

Defuturing

Activities, processes and products which reduce, rather than enhance, the possibility of a future which can be sustained.

Degree days

The difference between the average daily temperature and the CIBSE degree day baseline temperature. This measure is used to estimate building energy needs. It is also a quick way to compare the severity and character of a climate. A heating degree day is counted for each degree below 15.5o reached by the average daily outside temperatures. For example, if, on a given day, the daily average temperature outdoors is 12 oC, then there are 3.5 degrees below the 15.5 oC. Thus, there are 3.5 heating degree days for that day. Reverse this process (degrees above 15.5 oC) to calculate Cooling Degree Days.

Demand Side Management

The planning, implementation, and monitoring of utility activities designed to encourage consumers to modify patterns of electricity usage, including the timing and level of electricity demand. It refers only to energy and load-shape modifying activities that are undertaken in response to utility-administered programs.

De-regulation

The process of removing or reducing regulation. It is often employed in connection with the liberalisation process for privatised industries. The term is sometimes used erroneously to describe the movement of publicly owned companies and industries in to the private sector.

Desertification

The transformation of arid and semi-arid land into desert, generally due to overgrazing, Deforestation, poor irrigation and tilling practices, Climate change, or a combination of these factors.

Design criteria

A set of standards agreed by the developer, planners and regulators that the proposed system should satisfy.

Detention basin

A vegetated depression which is normally dry, except after storm events, constructed to store water temporarily to attenuate flows; may allow Infiltration of water to the ground.

Development gap

The economic and consequent social divide between richer countries such as the USA and poorer countries such as Bangladesh.

Dieback

General name for a significant decline in tree health and numbers, especially native trees; caused by a variety of agents, including insect attack, disease, pollution and human-induced changes to the environment.

Diffuse pollution

Pollution arising from land-use activities (urban and rural) that are dispersed across a Catchment, or Sub-catchment, and do not arise as a process effluent, municipal sewage effluent, or an effluent discharge from farm buildings.

Dioxins

A general term that describes a large group of chemicals that are highly persistent in the environment. The most toxic compound is 2,3,7,8-tetrachlorodibenzo-p-dioxin or TCDD. Dioxins are generally formed as unintentional by-products of industrial processes involving chlorine (such as waste incineration, chemical and pesticide manufacturing and pulp and paper bleaching), but also during the combustion of Biomass, such in wood stoves.

Disposable culture

Communities where no real Recycling or consumer item repairs are carried out; the USA demonstrates such a culture, whereas India is famous for its re-use of items.

Distortionary subsidy

A subsidy that creates an unintended distortion in the allocative efficiency of the local or Global economy.

Distributed generation

A new trend in the generation of heat and electrical power. The Distributed Energy Resources (DER) concept permits consumers who are generating heat or electricity for their own needs (like in hydrogen stations and Microgeneration) to send surplus electrical power back into the power grid, a process also known as net metering, or share excess heat via a distributed heating grid.

District energy or heating

Heating provided from a central boiler, or a number of heat stations, to serve a network of pipes that supply heat to a number of buildings. Such schemes may be fuelled by a range of sources, both fossil and renewable and some schemes are multi-fuelled. The buildings served may be a mix of housing, public and commercial buildings.

DJSI

Dow Jones Sustainability Index. Created in 1999, DJSI indexes were the first of its kind, listing companies according to their Sustainable development performance.

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