Glossary A-D

pabs absolute pressure
pressure referred to a perfect vacuum. It is the sum of gauge pressure and atmospheric pressure.
absolute viscosity
the force per unit area required to produce unit relative velocity between two parallel areas of fluid distance apart; also called coefficient of viscosity
Absoluter Nullpunkt (DE) T0 absolute zero temperature
Unit: K
the zero point on the Kelvin temperature scale (-273.16°C)
Absorber (DE) absorbent
a material which extracts one or more substances form a liquid or gaseous medium which it contacts and charges physically or chemically, or both (e.g. soled absorbent: Calcium chloride, liquid absorbent: solutions of lithium chloride, lithium bromide, and ethylene glycols)
Absorber (DE) absorber
an object absorbing another object or radiation (e.g. the blackened surface within a solar collector, which absorbs the solar radiation converting it to heat. These surfaces usually absorb solar radiation but do emit a limmited amount of radiative heat because of the so-called spectral selective coatings applied to the surface)
the ratio absorbed objects or radiation. (For solar energy the ratio of absorbed to incident solar radiation on a surface)
absorptance of glazing
in this context the absorption of solar energy in the glazing material occurring throughout the thickness of a glazing material. The absorptence is the fraction absorbed related to the incident overall radiation (involving multiple reflections). The absorptence is different for different wavelengths (coloured glazing) and angles of incidence. The transmittance + absorptance + reflectance = 1
absorptance of an opaque surface
absorptance of an opaque surface: the ratio of the radiation absorbed at a surface relative to the incident radiation on that surface. The absorptance is different for different radiation waveIengths and angles of incidence. The absorptance of normally incident radiation however is always numerically equal to the emittance of the surface for the same wavelength. A black body is a theoretical perfect absorber with an absorptance of 1 for all wavelengths: a typical matt black paint has an absorptance of 0.97 for normal solar radiation and 0.95 for long-wave (thermal) radiation. For any wavelength and angle of incidence, for an opaque surface, absorptance + reflectance = 1
Absorption (DE) absorption
a process where an object absorbs another object or radiation for example a process whereby a material extracts one or more substances present in an atmospheric or mixture of gases or liquids accompanied by the material's physical and/or chemical changes
Absorptionsfaktor (DE) absorption factor
for solar radiation the fraction of solar radiation, transmitted through a glazing system that is absorbed inside the building
adaptive model, adaptive approach
for thermal comfort this is an approach to the study thermal comfort starting from the observation that there are a range of actions which occupants can take to achieve thermal comfort, and that discomfort is caused by constraints imposed on the range of actions by social, physical or other factors (see also adaptive principle). Over time this means that people are comfortable at the 'usual' or 'average' temperature which they experience
adaptive opportunity
for thermal comfort: the ability of a building to allow adaptation to broaden the band of temperatures at which the person could be comfortable. Actions might include adding or removing a layer of clothing, changing posture, or adjusting the metabolic rate. Spatial variation of temperature across the room, availability of a desk fan, and the presence of sun shading or openable windows would make the adaptive opportunities still greater. These actions either alter the temperature which is required for comfort, or alter the room temperature towards that which the occupants will find comfortable
adaptive principle
A principle which can be stated as: If a change occurs (in the thermal environment) such as to produce discomfort, people react in ways which tend to restore their comfort.
adaptive processes
The range of actions that man takes to achieve thermal comfort
aérosols (FR)
Aerosol (DE)
aerosol (ES)
aérosols (IT)
aerosoler (NO)
Aerosols are particles suspended in the atmosphere. They range in size from about 10-3 µm to about 20 µm. They are produced by natural processes or man's activities. They include volcanic dust, sea spray and its particulate products, wind generated dust, smoke from natural forest fires, particles emitted during combustion…
air barrier
for buildings a material carefully installed within a building envelope assembly to minimise the uncontrolled passage of air into and out of a dwelling
air change
One air change is an exchange of one volume of air equal to internal volume of a room or building (see also air change per hour)
air changes per hour
ventilation unit denoting the number of times a room exchanges its own total air volume with outside air per hour. For the calculation of the air permeability of a room or building this is determined (1) under natural conditions and (2) under a 50 Pascal pressure difference. (The R-2000 Home Program requires a house with 1.5 ach at 50 Pascal)
air conditioning
Control of the indoor environment by controlling the thermal characteristics (cleaning, changing the water content but mainly heating and cooling) the air supplied to the room
air leakage
the uncontrolled flow of air for instance through a component of the building envelope, or the building envelope itself, when a pressure difference is applied across the component. Infiltration refers to inward flowing air leakage and exfiltration refers to outward flowing airleakage
air movement
the movement of the air past a point, generally represented as the speed or velocity of the air measured with an anemometer
air permeability
the property of a building component to let air pass when it is subjected to a differential pressure
Luftdruck (DE) air pressure
the pressure exerted by the air. This may refer to static (atmospheric) pressure, or dynamic components of pressure arising from air flow, or both acting together
air sealing
the practice of sealing unintentional gaps in the building envelope (from the interior) in order to reduce uncontrolled air leakage
Luftdichtheit (DE) air tightness
the degree to which unintentional openings have been avoided in a building's structure
albédo (FR)
Reflektivität (DE)
albedo (ES)
albèdine (IT)
albedo (NO)
ρ albedo
Unit: 1
Ratio of the radiant flux reflected by a surface to the incident flux.
albédo (FR)
Reflektivität (DE)
albedo (ES)
albèdine (IT)
albedo (NO)
ρ albedo (relative to a pixel of a satellite image)
Unit: 1
At a given time, the albedo of an area of the earth seen by a pixel of a satellite image. The pixel value C (an integer from 0 to 255) depends on the energy radiated by the sun at that time. Therefore, the albedo ρ is computed by normalizing the pixel value with respect to the sun altitude at that time: Co is called the registration offset. It is the sum of the satellite instrument offset (a value of 5) and the contribution of the backscattering of solar radiation in the atmosphere. Eesno is the extraterrestrial normal irradiance and γs is the solar elevation.
hauteur (FR)
Stationshöhe (DE)
altitud (ES)
altezza (IT)
stasjonshøyde (NO)
h altitude
Unit: meter
Altitude of a site above sea level. In the Satel-Light database, this is the average altitude of an area of 5' longitude by 5' latitude (about 60 km² in central Europe).
hauteur angulaire (FR)
Höhenwinkel (DE)
altura angular (ES)
altezza angolare (IT)
elevasjonsvinkel (N0)
γ altitude angle
Unit: degree
Altitude angle above horizon of a point in the sky hemisphere. Also called elevation angle.
Umgebungsluft (DE) ambient air
Generally, the air surrounding an object or building
Umgebungstemperatur (DE) ambient temperature
Instrument to measure the air speed. Common electrical types are hot wire or and the hot-body anemometers. The principle used is to apply a fixed electrical current to a wire and the voltage over the wire is measured. The current heats the wire. Moving air cools the wire, decreasing the electrical resistance. This change is measured through the voltage across the wire
anisotrope (FR)
anisotrop (DE)
Having dependence on direction or angle.
American National Standards Institute
The American Society of Heating Ventilating and Air-conditioning Engineers, based in Atlanta Georgia, USA
ASHRAE scale
a set of seven descriptors of subjective warmth. Usual wording is: Cold (-3), cool (-2), slightly cool (-1), neutral (0), slightly warm (+1), warm (+2), and hot (+3)
ASHRAE/ANSI standard 55
A temperature standard proposed by ASHRAE formerly based on the Gagge's Standard Effective Temperature, but due to come in line with ISO7730 (see below) in using Fanger's PMV/PPD
attached sunspace
solar collector that doubles as useful building space also attached greenhouse, solarium. The term 'attached' specifically implies a space that shares one common wall with the associated building, such as a conservatory
auxiliary heating
the conventional (i.e. non-solar) contribution to the total load (e.g. gas boiler etc.)
an exterior, movable and usually flexible sun shading device. Protects by deflecting or diffusing solar radiation at certain angles
azimut (FR)
Azimut (DE)
acimut (ES)
azimut (IT)
asimut (NO)
α azimuth
Unit: degree
Angle between the projection of the normal of a surface onto the horizontal and true north. Measured clockwise. A surface facing east has an azimuth of 90°. A surface facing south has an azimuth of 180°. A surface facing west has an azimuth of 270°.
rétro diffusion (FR)
Rückstreuung (DE)
tilbakespredning (N0)
Act of the solar radiation being scattered in a backward direction (toward space) by the particles and the molecules of the atmosphere.
base temperature
Unit: degree-days
a fixed temperature in the definition of degree-days
beam or direct radiation
the solar radiation directly from the sun without changed angle or diffusion. Instruments for measuring direct radiation require for practical reasons a wider aperture so the measured radiation also contains radiation from the immediate region of the sky around the sun (called circum solar; see also diffuse radiation)
Bedford scale
A set of seven descriptors of subjective thermal response from Much Too Warm (7), Too Warm (6), Comfortably Warm (5), Comfortable, neither warm nor cool (4), Comfortably Cool (3), Too Cool (2), Much Too Cool (1). This differs from the ASHRAE scale in defining the central three categories as comfortable
Schwarzer Körper (DE) black body
a perfect absorber and emitter of electromagnetic radiation (light, heat etc). A black body absorbs all radiation without any reflection (see also absorption). A cavity is a perfect black body. Lampblack is close to a black body, while aluminium (polished) is a poor absorber and emitter of radiation
bright sunshine
sunshine above a certain level sufficient to be registered on a Campbell-Stokes sunshine recorder. The threshold is imprecisely defined and varies according to the type of recorder, but generally refers to sunshine bright enough to cast a shadow. Burning typically starts when the beam intensity is 200 W/m²
British Standards Institute
building orientation
Orientation of tihe building, generally used to refer to solar orientation which is the siting of building with respect to solar access. Although any building will have different orientations for its different sides, the orientation can refer to a particular room, or to the most important facade of the building
calorific value
the energy content per unit mass, per unit volume or released if reacting with usualy oxygen (burned).
candela (FR)
Candela (DE)
candela (ES)
candela (IT)
candela (NL)
candela (NO)
Kandela (PL)
candela (SE)
cd candela
Unit: lm/sr
CIE. SI unit of luminous intensity. The candela is the luminous intensity, in a given direction, of a source that emits monochromatic radiation of frequency 540 1012 Hz and that has a radiant intensity in that direction of 1/683 W/sr (16th General Conference of Weights and Measures, 1979).
candela par mètre carré (FR)
Candela pro Quadratmeter (DE)
candela por metro cuadrado; nit (ES)
candela al metro quadrato (IT)
candela per vierkante meter (NL)
candela pr kvadratmeter (NO)
Kandela na metr kwadratowy (PL)
candela per kvadratmeter (SE)
cd/m² candela per square meter
Unit: lm/(sr m²)
CIE. SI unit of luminance. A non-metric unit is sometimes used: the footlambert = 3.426 cd/m².
casula gain
See internal gains
The European Standards Institution
Schornsteineffekt (DE) chimney effect
See stack effect
The Chartered Institution of Building Services Engineers (UK)
Commission Internationale de l'Eclairage (FR)
Internationale Beleuchtungskommission (DE)
International Commission on Illumination
CIE standard source
artificial sources specified by the CIE, whose radiations approximate CIE standard illuminants A, B and C, (see CIE Publication N015)
indice de clarté du ciel (FR)
Clearness Index (DE)
indice de claridad del cielo (ES)
indice di chiarore del cielo (IT)
clearness index (NO)
kt clearness index
Unit: 1
Ratio of the global horizontal irradiance to the extraterrestrial horizontal irradiance.
Klarer Himmel (DE) clear sky, cloudness sky
clear sky in this context has two separate meanings. In the radiation Tables clear sky refers to days producing the mean maximum monthly daily global radiation on a horizontal surface. These days on average contain some cloud but the precise cloud amount is not known. In the temperature Tables, the term clear skies refers to summaries of measured temperature data for days when the mean total amount of cloud during hours of daylight was less then 2/8. Night-time temperature data for such days are related to the same 'clear' days i.e. night-time cloud cover was not taken into account
indice de ciel clair (FR)
Clear Sky Index (DE)
indice de cielo claro (ES)
indice di cielo chiaro (IT)
clear sky index (NO)
kc clear sky index
Unit: 1
Ratio of the global horizontal irradiance to the global horizontal irradiance under clear sky conditions.
a window that is placed vertically (or near vertical) in a wall above one's line of vision to provide natural light in a building
Klimakammer (DE) climate chamber
A chamber usually in a laboratory in which the environmental conditions can be changed by the experimenter, used to investigate the effects of the thermal environment on subjects
climate control
The control of the indoor climate
clo unit
Unit: clo
a unit for the insulating effect of clothing on a person. 1 clo = 0.155 (K m²)/W
heure légale (FR)
Zonenzeit (DE)
hora legal (ES)
ora legale (IT)
klokkeslett (NO)
t clock time
Unit: hours from midnight
Time used in a country, or part of a country. Usually expressed relatively to the Greenwich Meridian Time (GMT) used in the United Kingdom: GMT+3 means three hours more than GMT. In some countries, for energy saving purposes, one hour is added to clock time from the last Sunday of March, to the Saturday before the last Sunday of October. This is called daylight saving time or summer clock time, as opposed to winter clock time outside of that period.
clothing insulation
The effective insulation of clothing worn characterized as a single layer covering the whole body surface; measured in clo units
clothing surface temperature
Average temperature of the surface of the clothes for use in heat exchange calculations
nébulosité (FR)
Gesamtbewölkungsgrad (DE)
factor de nubusidad (ES)
nuvolosita (IT)
bewolkingsgraad (NL)
skydekkefraksjon (NO)
wspolczynnik zachmurzenia (PL)
molnmängd (SE)
N fractional cloud cover
Unit: 1
CIE. Ratio of the sum of the solid angles subtended by clouds to the solid angle 2π steradians of the whole sky.
indice de nuage (FR)
Bewölkungsindex (DE)
indice de nubes (ES)
indice di annuvolamento (IT)
n cloud index
Unit: 1
For a pixel in the satellite image, the ratio of the difference between the albedo ρ and the ground albedo ρg, to the difference between the cloud albedo ρc and the ground albedo. The ground albedo and the cloud albedo are calculated based on monthly values of the albedo under cloudfree and totally cloudy conditions.
Farbwiedergabe (DE) colour rendering
Colour rendering: Effect of (not nescessarily white) light on the colour appearance of objects compared to their colour appearance under a reference illuminant, usually daylight
Farbwiedergabeindex (DE) Ra colour rendering index
measure of the degree to which the psychophysical colour of an object illuminated by the test illumihant conforms to that of the same object illuminated by the reference illuminant, suitable allowance having been made for the state of chromatic adaptation
comfort chart
a chart showing effective temperatures with dry-bulb temperatures and humidities (and sometimes air movement), by which the effects of various thermal conditions on human comfort may be compared
comfort line
a line on the comfort chart showing relation between the effective temperature and the percentage of adults feeling comfortable
comfort temperature
(1) The temperature (or environment) judged by a population to be neutral on the ASHRAE scale, or Comfortable, Neither Warm Nor Cool on the Bedford scale: assumed by most workers in the field to be the desired temperature or (2) The temperature at which the greatest number of people feel comfortable
comfort vote
The subjective response given by a subject on a comfort scale such as the ASHRAE or Bedford scales
comfort zone
The range of temperature within which a subject will feel comfortable, though not necessarily neutral
Kondensation (DE) condensation
condensed liquid - in this context beads, drops or a film of water (or frost) that accumulates on the inside of facade elements, roofs or floors (usually on windows) when warm, moisture air from the interior reaches a point where the temperature (the dew point) no longer permits the air to sustain the moisture it holds
Wärmeleitung (DE) conduction
Unit: W/m²K
the heat moving from a warmer to a colder region in the same substance without mass transfer, this type of heat transfer depends on the thermal conductivity of the material
Wärmeleitfaehigkeit (DE) conductive heat transfer
Process of conduction through a material. Materials like copper or silver are good conductors
Beschränkungen (DE) constraints
factors in the physical or social environment which prevent people from taking actions to achieve thermal comfort
controlled ventilation
ventilation brought about by mechanical means through pressure differentials induced by the operation of a fan
Konvektion (DE) convection
heat transfer between a surface and adjacent fluid (usually air or water) and by the flow of fluid from one place to another. See also Forced convection, Natural convection
convective heat transfer
Process of heat transport by convective flow. With free convection the flow is caused by temperature differences is the liquid or gas. For example the air inside double glazing transports heat due to natural convection: the glazing layer on the inside is warmer than the one on the outside; the air inside the cavity moves because of this temperature difference and transports the heat. With forced convection energy is transferred due to a mechanically driven gas flow or liquid flow
Konvektor (DE) convector
an agency of convection. In heat transfer, a surface designed to transfer its heat to a surrounding fluid largely or wholly by convection. The heated fluid may be removed mechanically or by natural convection (gravity convector). Such a surface may or may not be enclosed or concealed. Apparatus for heating, in which the heat is passed on to the room by convection, due to natural air movement sometimes helped by a fan
Kühlung (DE) cooling
The process of active heat extraction for the benefit of climate control. see also direct cooling, evaporative cooling, indirect cooling, regenerastive cooling, surface cooling
cooling effect, sensible
Unit: W
difference between the total cooling effect and the dehumidifying effect
cooling effect, total
Unit: W
difference between the total enthalpy of the dry air and water vapour mixture entering the cooler per hour and the total enthalpy of the dry air and water vapour mixture leaving the cooler per hour
Kühlelement (DE) cooling element
heat transfer surface containing refrigeration fluid where refrigerating effect is desired
cooling load
The thermal energy extracted from a building to maintain a pre-determined indoor setpoint temperature
cooling medium
any substance whose temperature is such that it is used, with or without a change of state, to lower the temperature of other bodies or substances
cooling range
in a water cooling device, the difference between the average temperatures of water entering or leaving the device
Kühlwasser (DE) cooling water
water for condensation of refrigerant; condenser water
Körperkerntemperatur (DE) core temperature, deep body temperature
The temperature of the internal organs of the body, especially the brain, on the basis of which the thermoregulatory system of the body is controlled
Korrelation (DE) r correlation
An indication of the strength of the relationship between two variables characterised by the correlation coefficient (r). The value of r varies between zero (no relationship) and one (linear or exact relationship)
corresponding values
values of parameters corresponding to other parameters
Rückfluss (DE) counterflow
flow in the opposite direction in heat exchange between two fluids; the coldest portion of one meeting the coldest portion of the other
critical temperature
the saturation temperature corresponding to the critical state of the substance at which the properties of the liquid and vapour are identical
cross ventilation
flow of air through a building caused by wind-generated pressure drop across it
data logger
An instrument which accepts and stores environmental or other data electronically ready for subsequent downloading into a computer for analysis
data set
A set of subjective and physical data obtained simultaneously in a comfort survey
the process of coating the interior or exterior of a foundation wall, floor, etc., with bituminous emulsions or plastic cements. The purpose of dampproofing is to prevent or interrupt the capillary draw of moisture into the wall or floor system and to the interior of the foundation
lumière du jour (FR)
Tageslicht (DE)
luz de dia (ES)
luce del giorno; luce diurna (IT)
daglicht (NL)
dagslys (NO)
oswietlenie sloneczne
calkowite (PL)
dagsljus (SE)
CIE. Visible part of global solar radiation.
facteur de lumière du jour (FR)
Tageslichtquotient (DE)
factor de luz de dia (ES)
fattore di luce diurna (IT)
daglichtfactor (NL)
dagslysfaktor (NO)
wspolczynnik oswietlenia
dziennego (PL)
dagsljusfaktor (SE)


daylight factor
Unit: 1 or %
CIE. Ratio of the illuminance at a point on a given plane due to the light received directly or indirectly from a sky of assumed or known luminance distribution, to the illuminance on a horizontal plane due to an unobstructed hemisphere of this sky. The contribution of direct sunlight to both illuminances is excluded. (Glazing, dirt effects, etc. are included, when calculating the lighting of interiors, the contribution of direct sunlight must be considered separately). Unless stated otherwise the sky luminance distribution is assumed to be that of the CIE standard overcast sky.
degree days for cooling calculation
the sum, over a stated period of days, e.g. month, of positive values of the arithmetic difference between a stated reference 'base temperature' and the daily mean dry bulb air temperature. The base temperature for assessing cooling requirements is normally set above that used for assessing heating requirements to allow for the fact that acceptable comfort temperatures in summer are higher than those adopted for winter heating assessments
degree days for heating calculation
the product of the number of degrees below a given base temperature and the number of days when that difference occurs. The base temperature is usually defined between 15.5° to 21°C. Different base temperatures are required to estimate heating demands, frost protection, and for relating insulation standards to internal gains
Entfeuchtung (DE) dehumidification
(1) condensation of water vapour from air by cooling below the dew point, (2) removal of water vapour from air by chemical or physical methods
Luftentfeuchter (DE) dehumidifier, surface
an airconditioning unit, designed primarily for cooling and dehumidifying air through the action of passing the air over wet cooling coils
dehumidifying effect, air cooler
product of the weight of moisture condensed in the cooler by the constant 1060
Dehydrierung (DE) dehydration
(1) removal of water vapour form air by the use of absorbing or adsorbing materials, (2) removal of water from stored goods
Dichte (DE) density
Unit: kg/m3 the mass of a unit of volume of material.
descriptive scale
A subjective scale in which the subject is asked to choose between a given list of descriptions in casting a comfort vote
design heat loss
a term expressing the total predicted envelope losses over the heating season for a particular house design in a particular climate
Taupunkt (DE) dewpoint
the temperature at which a given air/water vapour mixture is saturated with water vapour (i.e. 100% relative humidity). Consequently , if air is in contact with a surface below this temperature, condensation (dew) will form on the surface
diffuse Beleuchtung (DE) diffuse lighting
a form of lighting where the light is received from a number of different directions such that a precise shadow is not formed
diffuse transmission
the type of transmission through a diffusing or translucent glazing or other material. Transmited radiation that is scattered by interaction with the glazing material
Diffusor (DE) diffuser
a device object or surface used to alter the spacial distribution of light by diffusing it
diffusion, scattering
process by which the spatial distribution of a beam of radiation is changed when it is deviated in many directions by a surface or by a medium, without change of frequency of its monochromatic components. (Note: a distinction is made between selective diffusion and non-selective diffusion according to whether or not the diffusion properties vary with the wavelength of the incident radiation.)
dilution air
the air required by some combustion heating systems in order to isolate the furnace from outside pressure fluctuations and to maintain an effectively constant chimney draft
direct method of cooling
a system in which the evaporator is in direct contact with the material or space refrigerated or is located in aircirculation passages communicating with such spaces
direct gains
the directly transmitted solar radiation absorped within a room
direct glare
glare caused by selfluminous objects situated in the visual field, especially near the line of sight
direct solar gains
See direct gains
facteur de lumière du jour directionnel (FR)
richtungsabhängiger Tageslightquotient (DE)
factor direccional de luz de dia (ES)
fattore di luce diurna direzionale (IT)
retningsavhengig dagslysfaktor (NO)
DDF directional daylight factor
Unit: 1 or %
The daylight factor at a point P due to the light received from only a patch of the sky. The sky can be divided into zones of altitude and azimuth, and the directional daylight factor can be found for each zone. The total illuminance at a point Evdp is then the sum of the products of the mean luminance of each sky zone Lvm, the subtended area of the zone Ωm sin(γm) and the corresponding directional daylight factor DDFPm
directional lighting
a form of lighting where light is received from a single direction
fraction de diffus (FR)
Diffusanteil, Diffusstrahlungsanteil (DE)
diffusfraksjon (NO)
kd diffuse fraction
Unit: 1
Ratio of the diffuse horizontal irradiance to the global horizontal irradiance.
éclairement lumineux diffus horizontal (FR)
diffuse horizontale Beleuchtungsstärke (DE)
iluminancia horizontal difusa (ES)
illuminamento orizontale diffuso (IT)
diffus horisontal belysningsstyrke (NO)


diffuse horizontal illuminance
Unit: lx
Illuminance produced by the visible part of the diffuse solar radiation on a horizontal surface on the earth.
éclairement énergétique diffus horizontal (FR)
diffuse horizontale Einstrahlung (DE)
irradiancia horizontal difusa (ES)
illuminamento energetico orizontale diffuso (IT)
diffus horisontal irradians (NO)
Eed diffuse horizontal irradiance
Unit: W/m²
Irradiance produced by the diffuse solar radiation on a horizontal surface on the earth.
facteur de réflexion diffus (FR)
Grad der gestreuten Reflexion (DE)
reflectancia difusa (ES)
fattore di reflessione diffusa (IT)
diffuse reflectiefactor (NL)
diffus reflektans (NO)
wspotezynnik odbicia rozproszonego (PL)
diffus reflektans (SE)
ρd diffuse reflectance
Unit: 1
CIE. Ratio of the diffusely reflected part of the (whole) reflected flux, to the incident flux.
rayonnement diffus du ciel (FR)
diffuse Himmelsstrahlung (DE)
radiación del cielo (ES)
radiazione diffusa dal cielo (IT)
diffuse hemelstraling (NL)
diffus himmelstråling (NO)
promieniowanie niebosklonu; promieniowanie sloneczne roz-proszone (PL)
himmelsstralning (SE)
  diffuse solar (sky) radiation
CIE. That part of solar radiation that reaches the Earth as a result of being scattered by air molecules, aerosol particles, cloud particles or other particles.
 facteur de transmission diffuse (FR)
Grad der gestreuten Transmission (DE)
transmitancia difusa (ES)
fattore di transmissione diffusa (IT)
diffuse doorlatings factor (NL)
diffus transmittans (NO)
wspólczynnik przepuszczania rozproszonego (PL)
diffus transmittans (SE)
τd diffuse transmittance
Unit: 1
CIE. Ratio of the diffusely transmitted part of the (whole) transmitted flux, to the incident flux.
éclairement lumineux direct horizontal (FR)
direkte horizontale Beleuchtungsstärke (DE)
iluminancia horizontal directa (ES)
illuminamento orizontale diretto (IT)
direkte horisontal belysningsstyrke (NO)
Evs direct horizontal illuminance
Unit: lx
Illuminance produced by the visible part of the direct solar radiation on a horizontal surface on the earth.
éclairement lumineux direct normal (FR)
direktnormale Beleuchtungsstärke (DE)
iluminancia normal directa (ES)
illuminamento normale diretto (IT)
direkte vinkelrett belysningsstyrke (NO)
Evsn direct normal illuminance
Unit: lx
Illuminance produced on the earth by the visible part of the direct solar radiation on a surface perpendicular to the sun's rays.
éclairement énergétique direct horizontal (FR)
direkte horizontale Einstrahlung (DE)
irradiancia horizontal directa (ES)
illuminamento energetico orizontale diretto (IT)
direkte horisontal irradians (NO)
Ees direct horizontal irradiance
Unit: W/m²
Irradiance produced by the direct solar radiation on a horizontal surface on the earth.
éclairement énergétique direct normal (FR)
direkt normale Einstrahlung (DE)
irradiancia normal directa (ES)
illuminamento energetico normale diretto (IT)
direkte vinkelrett irradians (NO)
Eesn direct normal irradiance
Unit: W/m²
Irradiance produced on the earth by the direct solar radiation on a surface perpendicular to the sun's rays.
rayonnement solaire direct (FR)
direkte Solarstrahlung (DE)
radiación solar directa (ES)
radiazione solare diretta (IT)
directe zonnestraling (NL)
direkte solstråling (NO)
promieniowania stoneczne bez-pósrednie; insolacja (PL)
direkt solstralning (SE)
direct solar radiation
CIE. That part of extraterrestrial solar radiation which as a collimated beam reaches the Earth's surface after selective attenuation by the atmosphere.
Zug (DE) draught
air movement causing potential discomfort
dry-bulb temperature
the temperature of a gas or mixture or gases indicated by an accurate thermometer