A form of energy.

Glass incorporating metal particles which absorb solar radiation passing through the glazing; a proportion of this heat is then re-radiated outwards. The total heat transfer through the glass is thus reduced compared with standard glazing. As its operation depends on absorbing the incident radiation, heat-reflecting glass itself heats up, and some of this heat re-radiated into the internal space, which can cause discomfort to people near windows.

A part of a building element or assembly which due to its high conductivity transfers heat rapidly through the element. Also known as Thermal Bridge. 

The transmission of heat through a medium such as a building material or building element.

Heat input to the interior of a building eg from the sun through windows, from equipment such as lights and computers, and from inhabitants’ metabolic function (see useful heat gain).

The passage of heat through building elements from interior to exterior.

Heating/cooling equipment which operates by taking heat at a low temperature from a medium such as water or air, and transferring it at a higher temperature by means of a condenser;  for cooling, from inside a building to outside, for heating, vice versa.

Glass with a surface film of transparent reflective aluminium which reflects a percentage of the incident radiation; different grades reflect given percentages of total radiation, from 20% to 85%. It can be useful for privacy as well as for heat control; it should be remembered that from the lit side such glass appears to be a mirror, so at night can give a false sense of security while giving a clear view from outside. (As it does not depend on absorbing the incident radiation heat-reflecting glass is more effective than heat-absorbing glass).

The capacity of high thermal mass materials to store energy (heat) to reduce the impact of heat inputs (eg the sun) on internal temperatures in a building in the hot season (see ‘Difference between temperature and heat’).

The capacity of high thermal mass materials to store energy (heat), in particular solar energy through windows, to later re-radiate into the building; generally utilised during winter to sustain a comfortable internal temperature,  eg overnight. Also known as Thermal Storage.

Masonry or brick cavity construction, generally on a concrete slab, which provides thermal storage capacity for passive solar design. 

Radiation above approx. 5 micrometres (including the visible spectrum and solar radiation): both polished aluminium and white paint are good reflectors at these frequencies.

The energy balance attained by a healthy (human) body between its deep body temperature, its skin temperature and the temperature of its ambient environment (Also Homeostatic Balance).

The evaporation and condensation of water on a global scale. In simple terms evaporation from bodies of water on the earth’s surface (rivers, lakes and the sea) leads to the formation of clouds which results in precipation, filling the bodies of water. Deforestation, pollution and global warming are likely to change the patterns of precipitation (type, magnitude, periodicity and location) and cause serious problems for eco-systems and human settlements, activities and economies.

The pressure at a point in a liquid, caused by the height above that point of a column or storage tank of liquid connected directly to it (as in a header tank).

Extreme over-heating of the human body above normal temperature.

Extreme cooling of the human body below normal temperature.