Glossary

Acid Rain - rain which has become acidic due to atmospheric pollution.  The most important source of which is the burning of fossil fuels in motor vehicles and power stations

Air changes ? a measure of the air exchange in a building.  One air change is an exchange of a volume of air equal to the interior volume of a building.

Biomass - fuels which have been produced from organic matter such as agricultural or forest waste.  Biomass is also used to describe energy produced from waste containing a larger proportion than usual of organic matter.

Blackwater ? waste water generated from a house, usually refers to toilet waste.

Carbon dioxide ? or CO₂  - the main greenhouse gas produced from the burning of fossil fuels, such as coal, oil and gas.

Carbon Index -  this is a measure of the carbon emitted to the atmosphere from the heating and hot water used in a building.  It is measured per square metre of floor area in a year, on a log scale of 0-10.  

CHeSS ? Central Heating System Specifications guide. This provides guidance provides basic and best practice specifications for the components of domestic wet central heating systems critical to energy efficiency.  CheSS is part of the Energy Saving Trust?s Energy Efficiency Best Practice for Homes programme. 

CHP ? Combined Heat and Power systems burn fuel in an engine or boiler to drive a generator to produce electricity.  The engine also produces heat, which is recovered and used to warm homes.  This is often linked to community heating systems that provide heat and electricity to a large number of homes through a central boiler.  Biomass can be used for fuel. 

Climate change  - short-term climate variability and longer-term trends or shifts in climate caused by natural mechanisms or by human activity (see also global warming).

Chlorofluorocarbon - gases used as refrigerants, now banned in Europe and other parts of the world, due to the damage they cause to the ozone layer.

Decent Homes ? a Government established standard to ensure that all social housing meets a set decency standard by 2010.  By definition:  ?a decent home is one which is wind and weather tight, warm and has modern facilities?(ODPM 2002).  To meet this definition, homes must meet the current statutory minimum standard for housing, be in a reasonable state of repair, have reasonably modern facilities and services, and provide a reasonable degree of thermal comfort.

Fuel Poverty ? fuel poverty usually relates to a household that needs to spend more than 10% of its income on fuel for cooking and heating.

Global warming  - climate change resulting from greenhouse gas emissions causing significant environmental effects, such as severe weather, flooding, droughts and ice cap melts.

Greenhouse gases ? these are gases, such as carbon dioxide, which build up in the upper atmosphere and increase air temperature.   This is contributing to polar ice cap melt and rising sea levels.

Greywater - household water used by the sink, shower, bath or washing machine collected and re-used (usually for flushing the toilet). 

Heat exchanger ? a device used to transfer heat, often through coiled tubing, from one fluid to another.

Heat load ? the total energy needed for space heating.

Heat loss ? the amount of heat lost through the building envelope, e.g. walls, windows, roof, floors, doors.

Heat pump ? a device to transfer heat from a heat source to a heat sink.  As the heat source cools it transfers heat to the sink which then warms up.

Infiltration ? the uncontrolled movement of outdoor air into the interior of a building through cracks and gaps.  The gaps are usually found around walls, joints, windows, doors, roofs etc.

Kilowatt hour ? an energy unit equivalint to 1000watts used for 1 hour.  It might be referred to as a unit of electricity = 1 kWh.

National Home Energy Rating (NHER) ? this is an energy rating based on SAP (see below), but it also includes the energy consumed by lighting and appliances.

Ozone ? a variant form of oxygen, which forms in the upper atmosphere, to form the ozone layer. The ozone layer offers protection to the planet from the sun?s ultra-violet rays.

Ozone depletion potential ? ODP, is an indication of the potential a chemical, or groups of chemicals in a material,  has on depleting the planets protective ozone layer.   The higher the ODP the more damage the chemical does.   Materials with zero ODP should be used.

Passive gains ? the ability to access light and warmth from the sun, and natural ventilation due to the careful design of buildings and products.

Photovolataic ? the process of light conversion in to electricity.

Renewables - energy producing technologies using natural resources in an inexhaustible manner, e.g. wind, solar, wave, tidal and hydro.

SAP ? the Standard Assessment Procedure (SAP) is an energy rating for buildings.  It measures the heating and hot water yearly cost for a building, stated in a scale of 0 ?120.

Scheme Development Standards (SDS) - these set out the Housing Corporation?s requirements and recommendations for all housing projects, including the refurbishment and repair of properties that receive Social Housing Grant.  SDS concentrate on design and quality and procedural compliance issues. 

Solar collector ? a device (usually flat plates or tubes) for capturing solar energy.  Windows are a simple device, and solar hot water systems involve more complex devices, with water running through them.

Solar gain ? direct solar radiation (suns rays) passing through glazed areas to provide warmth to rooms and spaces.  Optimal gains come from south facing glazed areas.

Solar radiation ? the energy carrying electromagnetic radiation emitted by the sun. 

Solar thermal ? this often refers to hot water systems that are heated by solar energy. 

Stack effect/ventilation ? air or gas generally rises in a duct, or vertical passage, when heated.  This is due to its lower density compared with surrounding air or gas.  Passive ventilation works on these principles drawing warm moist air out of rooms.

SuDS -(sustainable urban drainage systems): SuDS can be a way of dealing with the surface water run-off, and could be apply to refurbishment opportunities.  SuDS options include lagoons and soakaways.  

Sustainable development - development that meets the needs of current generations without affecting the ability of future generations to meet their own needs. It requires a balance between economic, environmental and social impacts.

Thermal mass ? the mass of a building that can retain heat from the sun, e.g. the walls and floors of a building.  Buildings constructed of dense materials, such as bricks or concrete, have a better thermal mass than lightweight buildings, such as timber.

U value ? this is a measure of heat loss through the fabric of a building.  U values are measured as Wm2K.

Vapour barrier ? a construction material impervious to the flow of moisture and air.  Used to prevent condensation around insulation in buildings.

Watt ? a unit of power measuring the rate of flow of electricity.