Glossary S-Z

saturated air
moist air in which the partial pressure of water vapour equals the vapour pressure of water at the existing temperature. This occurs when dry air and saturated water vapour coexist at the same dr -bulb temperature
saturated temperature
of a fluid, the boiling point corresponding to a given pressure; evaporation temperature, condensation temperature
saturation ratio
the ratio of the specific humidity of humid air to that of saturated air at the same temperature and pressure, usually expressed as a percentage
saturation pressure
the saturation pressure for a pure substance for any given temperature is that pressure at which vapour and liquid, or vapour and solid, can coexist in stable equilibrium
flexible materials used on the inside of a building to seal gaps in the building envelope thereby preventing uncontrolled air infiltration and exfiltration
selective coating
finishes applied to materials to improve their performance in relation to radiation of different wavelengths: for example those applied to solar absorbers would seek to have a high absorptance of solar radiation and a low emittance of long-wave (thermal) radiation, while those for glazing have a high transmittance to solar radiation and high reflectance of long wavelengths
selective absorber
a surface absorbing essentially all incident solar radiation (short wave high temperature source), while emitting a small fraction of thermal radiation (long wave low temperature source)
semantic differential
A technique for obtaining a value for subjective response in which the subject is asked to denote the intensity of a stimulus by choosing a subdivision between two extremes
semi-enclosed sunspace
a sunspace that shares common walls with the associated building
sensible heat
heat which is associated with a change in temperature in contrast to a heat interchange associated with a change of state (latent heat)
sensitivity date
date that express the dependence of the heating performance of a passive solar heating system on individual parameters of the system design
SI unit
(Systeme International d'Unites) the International System of Units being adopted throughout the world
skin temperature
The average temperature of the skin surface
skin wettedness
A theoretical measure of the coverage of the skin by sweat needed to explain the rate of evaporation of sweat as a proportion of the total skin surface area
ciel serein normalisé CIE (FR)
klarer Himmel nach CIE (DE)
cielo despejado patron CIE (ES)
cielo sereno secondo CIE (IT)
heldere-hemelstandaard van de CIE (NL)
CIE standard klar himmel (NO)
niebosklon bezchmurny znormalizowany CIE (PL)
CIE standard för klar himmel (SE)
  sky, CIE standard clear
CIE. Cloudless sky for which the relative luminance distribution is described in CIE Publication N°22 (1973). Example:
ciel couvert normalisé CIE (FR)
bedeckter Himmel nach CIE (DE)
cielo cubierto patron CIE (ES)
cielo coperto secondo CIE (IT)
betrokken-hemelstandaard van de CIE (NL)
CIE standard overskyet himmel (NO)
nieboskton pokryty znormalizowany CIE (PL)
CIE standard föt mulen himmel (SE)
  sky, CIE standard overcast
CIE. Completely overcast sky for which the ratio of its luminance Lvγ in the direction at an angle γ above the horizon to its luminance Lvz at the zenith is given by the relation: Lvγ=Lvz (1+2sinγ)/3
ciel nuageux (FR)
bewölkter Himmel (DE)
cielo nublado (ES)
cielo nuvoloso (IT)
skyet himmel (NO)
  sky, cloudy
Sky condition corresponding to a cloud index larger than 0.6.
ciel intermédiaire (FR)
mittlerer Himmel (DE)
cielo intermediario (ES)
cielo intermediario (IT)
delvis skyet himmel (NO)
  sky, intermediate
Sky condition corresponding to a cloud index larger than 0.15 and smaller than 0.6.
ciel ensoleillé (FR)
klarer Himmel (DE)
cielo soleado (ES)
cielo soleggiato (IT)
solrik himmel (NO)
  sky, sunny
Sky condition corresponding to a cloud index smaller than 0.15.
lumière du ciel (FR)
Himmelslicht (DE)
luz del cielo (ES)
luce dal cielo (IT)
hemellicht (NL)
himmellys (NO)
olwietlenie sloneczne rozproszone (PL)
himmelsljus (SE)
CIE. Visible part of diffuse sky radiation.
pente (FR)
Neigungswinkel (DE)
pendiente (ES)
pendenza (IT)
helningsvinkel (NO)
β slope
Unit: degree
Angle of a plane with respect to the horizontal. A horizontal surface has a slope angle of 0°. A vertical surface has a slope angle of 90°.
sol-air temperature
the hypothetical temperature which would give the same temperature distribution and heat flow in a building element that would result from the impact of the actual combination of the absorbed short wave radiation, long wave exchange with sky and ground, forced convection due to wind at the given external air temperature . It is used to assess transfer of heat through a specific building element of a given surface colour. Different sol-air temperatures are encountered on differently orientated surfaces for materials of the same surface properties
solar aperture
that portion of the solar wall covered by glazing
azimut solaire (FR)
Azimuthwinkel der Sonne (DE)
acimut solar (ES)
azimut solare (IT)
solasimut (NO)
αs solar azimuth
Unit: degree
Azimuth angle of the sun. Measured clockwise with respect to true north.
solar collector
A device for capturing solar energy, ranging from ordinary windows to complex mechanical devices.See also flat plate collector, focussing collector
constante solaire (FR)
Solarkonstante (DE)
constante solar (ES)
constante solare (IT)
zonneconstante (NL)
solarkonstant (NO)
stala sloneczna (PL)
solarkonstant (SE)
solar constant
Irradiance produced by the extraterrestrial solar radiation on a surface perpendicular to the sun's rays at mean yearly sun-earth distance (150 Million km). Eesno = 1367 W/m² (Final report No.590 of the Commission for instruments and methods of observation: CIMO-VIII of the World Meteorological Organization, Mexico City, October 1981).
déclinaison solaire (FR)
Deklination der Sonne (DE)
descline solar (ES)
declinazione solare (IT)
solens deklinasjon (NO)
δs solar declination
Unit: degree
Angle between the sun's rays and the earth's equatorial plane. Declination values are positive when the sun is north of the equator (March 20 to September 23) and negative when the sun is south of the equator. Its maximum and minimum values are +23.45 and -23.45°.
hauteur du soleil (FR)
Sonnenhöhenwinkel (DE)
altura del sol (ES)
altezza del sole (IT)
solhøyde (N0)
γs solar elevation
Unit: degree
Angle between the centre of the sun's disc and the horizon. It is only approximately the angle of the centre of the sun above the horizon, because near the horizon the apparent position of the sun is affected by refraction in the atmosphere.
solar fraction
the percentage of the total heat load supplied by the solar heating system, including useful losses from the storage
solar gain
Heat from the sun, entering a room through transparent surfaces (kW/m²)
angle horaire du soleil (FR)
Stundenwinkel der Sonne (DE)
ángulo horario del sol (ES)
angolo orario del sole (IT)
solens timevinkel (NO)
ωs solar hour angle
Unit: degree
The angle at which the earth must turn to bring the meridian of the given point directly under the sun. Negative in the morning: sun coming from the east. Positive in the afternoon: sun going west. This angle increases by 15° an hour.
angle horaire du soleil au lever et au coucher (FR)
Stundenwinkel der Sonne bei Sonnenaufgang und Sonnenuntergang (DE)
ángulo horario del sol al amanecer y al anochecer (ES)
angolo orario del sole all alba e al tramonto (IT)
solens timevinkel ved soloppgang og solnedgang (NO)
ωso solar hour angle at sunrise and sunset
Unit: degree
The solar hour angle at sunrise and sunset.
solar load ratio (SLR)
ratio of solar gain to building load used in SLR correlations
rayonnement solaire (FR)
Solarstrahlung (DE)
radiación solar (ES)
radiazione solare (IT)
zonnestraling (NL)
solstråling (NO)
promienioiwanie sloneczne (PL)
solstralning (SE)
  solar radiation
CIE. Electromagnetic radiation from the sun. On average, 98% of the sun's radiation reaching the earth falls in the spectral range between 0.29 µm and 4 µm.
solar savings fraction (SSF)
the ratio of the solar savings to the energy requirement of the reference nonsolar building
solar spectrum
the radiation emitted by the sun outside the atmosphere approximates to that emitted by a black body at 6000K. At the surface of the earth, the majority of the radiation falls within a range of wavelengths from 300 to 2500 nm and typically about ha1f the energy comes in the form of visible light (380 to 700 nm wavelength). Ultra violet radiation has wavelengths shorter than 380 nm and only forms a very small proportion of the spectrum. Due to water vapour and carbon dioxide and other absorbing gases in the atmosphere, several bands of long wave radiation are substantially removed
solar time
a time scale based on the movement of the sun, such that noon is when the sun is at the highest of its arc and is true south, as opposed to local standard time
angle solaire zénithal (FR)
Sonnenzenitwinkel (DE)
ángulo solar zenital (ES)
angolo solare zenitale (IT)
solens senit vinkel (NO)
ξs solar zenith angle
Unit: degree
Angle between the centre of the sun's disc and the vertical: π/2-γs.
angle solide (FR)
Raumwinkel (DE)
ángulo sólido (ES)
angolo solido (IT)
romvinkel (NO)
Ω solid angle
Unit: steradian
Area intercepted on a unit sphere by a conical angle originating at the sphere center.
solid state
one of three states of matter characterized by stability of dimensions, relative incompressibility , and molecular motion held to limited oscillation. [note the term solid state is often used to talk about solid-state semiconductors
sound insulation
The ability of building elements to reduce the sound level between internal spaces, or between outdoors and indoors. In HVAC systems: acoustical treatment of fan housings, supply ducts, space enclosures, and other parts of system and equipment to isolate vibration or to reduce noise transmission
specific heat
the amount of heat required to raise the temperature of a unit mass of any substance one degree as a fraction of that required to raise the temperature of unit mass of a standard substance one degree (usually water at 15°C)
specifiy heat capacity
a measure amount of energy required to raise a unit mass or volume of a material through a unit temperature change. (kWh/kg.K, J/kg.K. kWh/m3.K, J/m3.K)
specific volume
the volume of a substance per unit mass; the reciprocal of density
efficacité lumineuse relative spectrale (FR)
Spektrale Lichtausbente (DE)
eficiencia luminosa espectral relativa (ES)
fattore spettrale di visibilita (IT)
relatieve spectrale ooggevoeligheid (NL)
spektral lysvirkningsgrad (NO)
skutecznosc swietlna widmowa wzgledna (PL)
spektral ljusverkningsgrad (SE)
v(λ) spectral luminous efficiency (of a monochromatic radiation of a given wavelength)
Unit: 1
CIE. Ratio of the radiant flux at wavelength λm to that at wavelength λ such that both radiations produce equally intense luminous sensations under specified photometric conditions and λm is chosen so that the maximum value of this ratio is equal to 1. The values used for the spectral luminous efficiency in photopic vision can be found in the CIE publication N°86 (1988). They are also recommended by the International Committee of Weights and Measures. Example in photopic vision:
display or specification of the components of the radiation considered in terms of intensity and wavelength. (Notes: (l) there are line spectra, where the spectrum consists of a finite number of 'lines' at particular wavelength(s) and continuous spectra where there is an infinite number of wavelengths with no sudden discontinuities of intensity. Some spectra exhibiting both these characteristics. (2) this term is also used for spectral efficiencies [excitation spectrum, action spectrum]
specular reflectance
proportion of incoming radiation which undergoes specular reflection
specular reflection
reflection at a surface where the angle of reflection (more or less) equals the angle of incidence (as happens in a mirror)
spherical irradiance
quantity defined by the formula ... where d_ is the solid angle of each elementary beam passing through the given point and Le its radiance at that point. (Unit: W/m²)
spray pond
arrangement for lowering the temperature of water in contact with outside air by evaporative cooling of the water. The water to be cooled is sprayed by nozzles into the space above a body of previously cooled water and allowed to fall by gravity into it
stack effect
the tendency of air or gas in a duct or other vertical passage to rise when heated due to its lower density in comparison with that the surrounding air or gas. In buildings, the tendency towards displacement (caused by an increase in temperature) of internal heated air by unheated outside air, due to the difference in density of outside and inside air. See Convective heat transfer
standard air
dry air at a pressure of 101.325 kPa at a temperature of 20°C. The density is than 1.2041 kg/m3
standard conditions
a set of physical, chemical or other parameters of a substance or system which defines an accepted reference state or forms a basis for comparison
steady conditions
an operating state of a system, including its surroundings, in which the extent of change with time of all the significant parameters is so small that no important effects on the performance can be observed or measured
steady-state model (of thermal comfort)
A theoretical model of thermal response based on climate chamber measurements in conditions which are held constant in time
stéradian (FR)
Steradiant (DE)
estereorradian (ES)
steradiante (IT)
steradiaal (NL)
steradian (NO)
steradian (PL)
steradian (SE)
sr steradian
CIE. SI unit of solid angle. Solid angle that, having its vertex at the centre of a sphere, cuts off an area of the surface of the sphere equal to that of a square with sides of length equal to the radius of the sphere (ISO, 31/1-2.1, 1978).
A person taking part in a comfort survey
subject population
A group of people who form the basis for a comfort survey
subject sample
A sample of the subject population who participate in the survey
subjective response
The sensation caused by a physical stimulus (generally a comfort vote)
facteur de correction de la distance terre soleil (FR)
Exzentrizitätskorrektur (DE)
factor de corrección de la distancia sol-tierra (ES)
fattore di correzione della distanza terra sole (IT)
korreksjonsfaktor for sol-jord avstand (NO)
r sun-earth distance correction factor
Unit: 1
Ratio between the daily value of the sun-earth distance and its mean yearly value (150 Million km). Its value is computed according CIE publication N°85 (1989): Where J is the day of the year also called the Julian day (from 1 to 365, or 366 if the year is bissextile).
lumière solaire (FR)
Sonnenlicht (DE)
luz solar (ES)
luce solare (IT)
zonlicht (NL)
sollys (NO)
oswietlenie sloneczne bezposrednie (PL)
solljus (SE)
CIE. Visible part of direct solar radiation.
surface film conductance
the rate of heat flow per unit area under steady conditions between a surface and a fluid for unit temperature difference between the surface and fluid [in W/m².K]
sunshine (possible percentage)
the actual number of hours of sunshine expressed as a percentage of the maximum possible duration for the month (or other period)
durée d'ensoleillement (FR)
Sonnenscheindauer (DE)
tiempo de insolación (ES)
soleggiamento (IT)
gesommeerde zonneschijnduur (NL)
solskinnsvarighet (NO)
csas trwania naslonecznienia (PL)
solskenstid (SE)


sunshine duration
Unit: hour
Sum of time intervals within a given time period (hour, day, month, year) during which the irradiance from direct solar radiation on a plane normal to the sun direction is equal to or greater than 120 W/m². This limit has been set by the World Meteorological Organization in 1981, before this date, it was 200 W/m².
durée astronomique d'ensoleillement (FR)
astronomische Sonnenscheindauer (DE)
tiempo de insolación astronómico (ES)
soleggiamento astronomico (IT)
astronomische zonneschijnduur (NL)
astronomisk solskinnsvarighet (NO)
czas trwania naslonecsnienia astronomiczny (PL)
astronomisk solskenstid (SE)


sunshine duration, astronomical

Unit: hour
CIE. Sum of the time intervals within a given time period during which the sun is above an even, unobscured horizon. This is equivalent to the period during which the solar elevation is greater than 0. The sun is actually hidden only when the solar altitude is below about -0.84° due to the apparent radius of the sun (0.27°) and atmospheric refraction.
durée possible d'ensoleillement (FR)
mögliche Sonnenscheindauer (DE)
tiempo de insolación posible (ES)
soleggiamento possibile (IT)
maximale zonneschijnduur (NL)
mulig solskinnsvarighet (NO)
czas trwania naslonecsnienia mozliwy (PL)
möjlig solskenstid (SE)


sunshine duration, possible (at a particular location)
Unit: hour
CIE. Sum of the time intervals within a given time period during which the sun is above the real horizon, which may be obscured by mountains, buildings, trees, etc.
durée relative d'ensoleillement (FR)
relative Sonnenscheindauer (DE)
tiempo de insolación relativo (ES)
soleggiamento relativo (IT)
relatieve zonneschijnduur (NL)
relativ solskinnsvarighet (NO)
czaq trwania naslonecznienia wzgledny (PL)
relativ solskenstid (SE)


sunshine duration, relative
Unit: 1 or %
Usually, this is the ratio of the sunshine duration to the possible sunshine duration within the same period. This requires to know the local topography at the location. Since there is no way to obtain this information for all locations covered by Satel-Light, we use the ratio of the sunshine duration for unobscured horizon, to the astronomical sunshine duration.
see attached sunspace or semienclosed sunspace
suntempered building
a minimal solar building derived from a conventional building by orienting its long axis east-west and placing a substantial fraction of its window area on the south side
surface cooling
method used to cool air or other gas by passing it over cold surfaces
surface resistance
With the transition from air to material and material to air a surface resistance has to be overcome. It has two components, the surface resistance for convection/conduction Rc whose value depends on the rate of air flow over the surface and radiative surface resistance for long wave radiation heat transfer Rr whose value depends on the surface emittance and the surface temperature. These two components are assumed to act in parallel so that the overall surface resistance Ro is give by I/Ra = I/Rc + I/Rr
survey (comfort survey, field survey)
An experimental investigation of subjective responses of a group of subjects in the field, generally assumed to be undertaken in such a way as to disrupt the normal pattern of the subject's lives as little as possible, and to leave subjects to decide their own dress and activity, use of environmental controls and so on
sweat rate
the rate at which sweat is produced by the body
systematic errors
Errors in the underlying assumptions of a theoretical comfort model which are temperature-dependent, and will therefore give rise to errors in its predictions
the thermal state of matter with reference to its tendency to communicate heat to matter in contact with it
temperature swing
The range of temperature, usually between day and night
temperature standards
Recommended values for temperature (and other environmental parameters) in buildings or rooms, values generally defined by the expected use of the room
thermal break
a material of low conductivity used in an assembly to prevent flow of heat by conduction from one side of the assembly to the other . Often used to refer to materials used for this purpose in the frame of metal windows
thermal bridge
Non- or relative low-insulated connections between indoor and outdoor environment and may compromise the effect of thermal insulation: for example, framing members in insulated frame walls or metal ties in cavity wall and panel construction
thermal comfort
The study of the relationship between man's thermal sensation and the stimulus in the form of the thermal environment in conditions of moderate heat stress (generally taken to include thermal discomfort)
thermal conductance
rate of heat flow through a body per unit area from one of its bounding surfaces to the other for a unit temperature difference between the two surfaces, under steady conditions [e.g. W/m².K]. See also U-Value
thermal conduction
process of heat transfer through a material medium in which kinetic energy is transmitted through the material from particle to particle without displacement of the particles
thermal conductivity
rate of heat flow through unit area and unit thickness of a homogeneous material under steady conditions when a unit temperature gradient is maintained in the direction perpendicular to area. Materials are considered homogeneous when the value of the thermal conductivity is not affected by variation in thickness or in size of the sample within the range normally used in construction. (W/m².K)
thermal experience
The different thermal environments experienced by a subject taking account of the order in which they occurred
thermal insulation
a material having a relatively high resistance to heat flow and used principally to retard heat flow
thermal mass
the ability of a building to accumulate heat effectively. A construction with a low thermal mass is heated quickly; a construction with a big thermal mass is heated slowly. This way construction with a big thermal mass, like concrete or brick, can store heat or cold and release it many hours later. 'Primary thermal mass' receives direct sunlight; 'secondary thermal mass' is in sight of the primary thermal mass and so receives radiative and convective energy from the primary thermal mass; 'remote thermal mass' os hidden from view of both the primary and secondary thermal mass and so receives energy by convection only.See Heat accumulation
thermal performance
the characteristic way in which a building reacts to the thermal climate
thermal resistance
The thermal resistance (the reciprocal of thermal conductance - see above), denoted by R, of a construction layer is the quotient of thickness and conductivity. A construction layer with a high thermal resistance is a good insulator; one with a low thermal resistance is a bad insulator (m².K/W)
thermal resistivity
the reciprocal of thermal conductivity. (m².K/W)
thermal storage mass
building elements, usually masonry or water in containers, designed to absorb solar heat during daytime hours for release later when heat is needed
thermal storage volume ratio
ratio of the volume of thermal storage material to the projected area
thermal transmittance
the thermal transmission through 1 square metre area of a given structure (e.g. a wall consisting of bricks, thermal insulation, cavities, etc .) divided by the difference between the environmental temperature on either side of the structure. Usually called 'U-value'. (W/m².K)
free convection from a warm zone (sunspace or Trombe-wall air space) to a cool zone through openings in a common wall
thermocirculation vents
openings in a common wall between cool and warm zones through which thermocirculation occurs. The vents are arranged in pairs, one of each pair near the floor and one near the ceiling
the various physiological means by which the core temperature is regulated: vasoregulation, sweating and shivering
the angle of a plane relative to a horizontal plane
time sampling
sampling by time of day; a wide time sample is necessary if the full experience of subjects is to be represented
light which enters through the top part of intrior space such as clerestories, light wells or skylights
facteur total de trouble (FR)
Trübungsfaktor (DE)
factor total de turbidez (ES)
fattore totale di torbidita (IT)
troebelheidsfactor (NL)
total turbiditetsfaktor (NO)
wspotczynnik zmetnienia (weslug Linke) (PL)
turbiditetsfaktor (SE)
TeL total turbidity factor (according to Linke)
Unit: 1
Ratio of the vertical optical thickness of a turbid atmosphere to the vertical optical thickness of the pure and dry atmosphere (Rayleigh atmosphere), related to the total solar spectrum: Where δR is the optical thickness with respect to Raleigh scattering at the air molecules, δA, δz, δw are the optical thicknesses with respect to Mie scattering and absorption at the aerosol particles, to ozone absorption, and to water vapor absorption respectively.
 facteur de transmission (FR)
Tansmission (DE)
transmitancia (ES)
fattore di transmissione (IT)
transmittans; transmisjonsfaktor (NO)
τ transmittance (for incident radiation of given spectral composition, polarization and geometrical distribution)
Unit: 1
Ratio of the transmitted radiant or luminous flux to the incident flux in the given conditions.
transverse sampling
A method of choosing a population sample for a survey by taking one or a few comfort votes from a large number of subjects (cf longitudinal sampling)
trombe wall
a thermal storage wall of masonry placed between the solar aperture and the heated space. Heat is transferred into the space by conduction through the masonry and, if vents are provided, by natural convection
heure solaire vraie (FR)
Wahre Sonnenzeit (DE)
hora solar verdadera (ES)
ora solare vera (IT)
sann soltid (NO)
ts true solar time
Unit: hours from midnight
True solar time differs from clock time. It is specific to a location. At 12:00 solar time, the sun is exactly south. The difference between true solar time and clock time is due to (1) differences between the site longitude λ and the standard meridian (the reference for clock time), (2) the equation of time ET and (3) summer time (one hour), if applied: ts=t+λ/15-GMTzone+ET/60-summer
Dämmerung (DE)
Period of incomplete darkness before sunrise and after sunset. Three different kinds of twilight are defined: civil twilight, nautical twilight, astronomical twilight.
twilight, civil
Twilight occuring while the sun is between the horizon and 6° below. The horizon is visible, as well as the brightest stars. This is the time when streetlights are switched on and cars begin using their head lights.
twilight, nautical
Twilight occuring when the sun is between 6 and 12° below the horizon. During this time, the horizon is visible and most of the stars. The best time for a sailor to use a sextant to take star sights.
twilight, astronomical
Twilight with the sun being between -12 and -18°. The horizon is no longer visible. If the sun is even lower, total darkness is the result.
U value
the thermal conductance of a composite building element: see thermal transmittance
ultraviolet radiation (UV)
electromagnetic radiation having wavelengths shorter than visible light (<380 nm). This invisible form of radiation is found in solar radiation and plays a part in the deterioration of plastic glazings, paint, and furnishing fabrics. It is also the major carcenogen in sunlight
usual temperatures
If the adaptation processes are working satisfactorily then we expect people to be comfortable in the environments they are accustomed to, for they will have had adequate opportunity to adjust the temperatures to suit their requirements, and to modify their living patterns to suit the temperatures. It follows that knowledge of these 'usual' environments would provide thermal comfort information of a basic kind
useful solar energy
the amount of solar energy contributing to the total heat load. It is expressed in absolute figures (kWh) or per unit collector area (kW/m²)
vapour pressure
the pressure exerted by the molecules of a given vapour (e.g. water)
indice de variabilité (FR)
Variabilitätsindex (DE)
variabilitetsindeks (NO)
σ3 variability index
Unit: 1
Root mean squared deviation between the clear sky index at time t and the clear sky indices at time t-Δt and t+Δt:
vascoregulation, vascoconstriction, vascodilation
The physiological mechanism by which the body regulates the supply of blood to the periphery of the body to reduce heat loss from the skin (vasoconstriction) or enhance it (vasodilation)
the process of supplying or removing air by natural or mechanical means to or from any space. Such air may or may not have been conditioned
ventilation losses
the heat losses associated with the continuous replacement of warm, stale air by fresh cold air
vertical shadow angle, profile angle
the angle between the direction of the sun resolved in a vertical plane perpendicular to the face of the solar aperture, on the normal of the solar aperture. This angle is used to predict the effect of shading devices in sectional drawings
that property of semifluids, fluids and gases by virtue of which they resist an instantaneous change of shape or arrangement of parts. It is the cause of fluid friction whenever adjacent layers of fluid move with relation to each other
rayonnement visible (FR)
sichtbare Strahlung (DE)
radiación visible (ES)
radiazione visibile (IT)
zichtbare straling (NL)
synlig stråling (NO)
promieniowanie widzialne (PL)
synlig stralning (SE)
visible radiation
CIE. Any optical radiation capable of causing a visual sensation directly. There are no precise limits for the spectral range of visible radiation since they depend upon the amount of radiant power reaching the retina and the responsivity of the observer. The lower limit is generally taken between 360 nm and 400 nm and the upper limit between 760 nm and 830 nm.

visual performance
performance of the visual system as measured for instance by the speed and accuracy with which a visual task is performed
volumetric heat capacity
a measure of the ability of a unit of volume of material to store heat, namely, the heat stored in a unit of volume of material per degree of temperature rise (J/m3)
volumetric heat loss coefficient, G value
the total heat loss of a dwelling (through the fabric and ventilation), divided by the heated volume and the temperature at which the loss occurs. (W/m3.K)
water wall
a thermal storage wall of water in containers placed between the solar aperture and the heated space . Heat is transferred into the space by conduction and convection through the water
wet-bulb temperature
thermodynamic wet-bulb temperature is the temperature at which liquid or solid water, by evaporating into air, can bring the air to saturation adiabatically at the same temperature. Wet-bulb temperature (without qualification) is the temperature indicated by a wet-bulb psychrometer constructed and used according to specification.see also evaporative equilibrium
wind speed
the speed of the air measured in accordance with the recommendations of the World Meteorological Organisation, normally measured ten metres above ground level (m/s)
plan utile; plan de travail (FR)
Nutzebene (DE)
plano de trabajo (ES)
piano utile (IT)
werkvlak (NL)
arbeidsplan (NO)
plaszczyzna robocza (PL)
arbetsplan (SE)
work plane
CIE. Reference surface defined as the plane at which work is usually done. In Satel-Light, this plane is a horizontal plane 0.80 m above the floor and limited by the walls of the room.
angle zénithal (FR)
Zenitwinkel (DE)
ángulo zénital (ES)
angolo zenitale (IT)
senitvinkel (NO)
ξ zenith angle
Unit: degree
Angle between a point in the hemisphere and the vertical: π/2-γ.