Glossary
Units and physical quantities
British Thermal Unit (BTU)
Anglo-American unit of thermal energy. 1 BTU corresponds to approx. 1.055 kJ or 0.293 Wh.
BTU/h
Unit of heating or cooling capacity. 1,000 BTU/h corresponds to approx. 293 W.
Degrees Fahrenheit (°F)
Temperature unit used mainly in the USA.
Degrees Celsius (°C)
Internationally used unit for stating temperatures.
Kelvin (K)
SI unit of thermodynamic temperature, also used to state the colour temperature of light.
Watt (W) / Kilowatt (kW)
Units of power, for example for heating and cooling capacity.
Watt-hour (Wh) / Kilowatt-hour (kWh)
Units of energy or energy consumption.
Watts per square metre (W/m²)
States a power or radiant power relative to an area, for example solar irradiation.
Nanometre (nm) / Micrometre (µm)
Units of length used to state wavelengths. 1 µm corresponds to 1,000 nm.
Lux (lx)
Unit of illuminance. 1 lux corresponds to 1 lumen per square metre.
Lumen (lm)
Unit of luminous flux, i.e. the light output as weighted by the human eye.
Candela (cd)
Unit of the luminous intensity of a light source in a particular direction.
Wavelength
Describes the spectral position of electromagnetic radiation and is used to distinguish between UV, visible and infrared radiation.
Illuminance E (lx)
States how much light falls on a given surface.
Luminance L (cd/m²)
Describes the perceived brightness of a luminous or illuminated surface.
Luminous Intensity I (cd)
States how strongly a light source emits light in a particular direction.
Luminous Flux Φ (lm)
Describes the total visible light output of a light source.
Luminous Energy Q (lm·s)
Describes the quantity of light emitted over a given period of time.
Luminance Coefficient RL
Ratio of luminance to illuminance and thus a measure of the photometric effect of a surface.
VLT – Visible Light Transmittance
States the proportion of visible light that passes through a material.
Colour Temperature (K)
Describes the colour impression of light from warm to cool and is stated in kelvin.
CRI / Ra – Colour Rendering Index
Characteristic value for the natural rendering of colours under a light source. A value of 100 corresponds to a very high colour rendering quality.
Lightfastness
Describes the resistance of a material to colour changes caused by exposure to light.
Solar shading and thermal protection
Shading Coefficient (SC)
Characteristic value for solar heat gain compared with a reference glazing. The lower the value, the greater the solar shading effect.
SHGC – Solar Heat Gain Coefficient
States the proportion of incident solar energy that enters the interior as heat. The lower the value, the better the heat protection.
Total solar energy transmittance (g-value)
States the proportion of incident solar energy that passes through the glazing into the interior.
g_tot value
Total solar energy transmittance of a combination of glazing and solar shading. The lower the value, the lower the solar heat gain.
TSER – Total Solar Energy Rejected
States the proportion of total solar energy that is held back by the system and does not enter the interior.
U-value / Thermal transmittance
Characteristic value for heat transfer through a building component. The lower the value, the better the thermal insulation.
R-Value
Characteristic value for thermal resistance, used mainly in North America. The higher the value, the better the insulating effect.
Emissivity
Describes the ability of a surface to emit thermal radiation.
Fc value
Reduction factor describing how much a solar shading device reduces solar heat gain compared with glazing without solar shading.
Irradiance (W/m²)
States how much radiant power falls on a given surface.
Solar Control
Targeted control of incident solar radiation to reduce heat gain and glare while making the best possible use of daylight.
Solar Heat Gain
Solar energy that enters the interior, particularly through glazing, and contributes to heating it.
Secondary heat gain
Proportion of absorbed solar energy that is subsequently released into the interior as heat.
Cooling Load
Cooling capacity required to maintain the desired room temperature under given conditions.
Thermal Comfort
Describes how comfortable the occupants perceive the thermal conditions of a room to be.
Solar spectrum and radiation
Solar spectrum
Spectral distribution of solar radiation. For glazing and solar shading, the range from approx. 300 to 2,500 nm is typically considered.
UV radiation
Short-wave radiation invisible to the human eye. It is divided into UVA, UVB and UVC and can damage materials, colours and surfaces, among other things.
UVA (approx. 315 – 400 nm)
Long-wave UV radiation that can penetrate deep into materials and skin and contributes significantly to ageing and fading effects.
UVB (approx. 280 – 315 nm)
Higher-energy UV radiation that causes sunburn, among other things, and can damage materials.
UVC (approx. 100 – 280 nm)
Very high-energy UV radiation that is almost completely absorbed by the Earth's atmosphere and does not normally reach the Earth's surface.
Visible light (approx. 380 - 780 nm)
The part of the electromagnetic spectrum that can be perceived by the human eye.
IR radiation (approx. 780 nm – 1 mm)
Infrared radiation invisible to the human eye, which accounts for a significant proportion of solar and thermal radiation.
NIR – Near Infrared (approx. 780 – 1,400 nm)
Near-infrared range directly adjoining visible light and containing a significant proportion of solar energy.
SWIR – Short-Wave Infrared (approx. 1,400 – 3,000 nm)
Short-wave range of infrared radiation.
MWIR – Mid-Wave Infrared (approx. 3,000 – 8,000 nm)
Mid-wave range of infrared radiation.
LWIR – Long-Wave Infrared (approx. 8,000 – 15,000 nm)
Long-wave infrared range, associated in particular with thermal radiation from surfaces.
Solar Position
Position of the sun in the sky, which influences the angle of incidence and intensity of solar radiation on a façade.
Optical and material properties
Transmission
Proportion of incident radiation that passes through a material.
Reflection
Proportion of incident radiation that is reflected by a surface.
Absorption
Proportion of incident radiation that is taken up by a material and converted into heat, among other things.
Solar transmission
Proportion of total incident solar radiation that passes directly through a material.
Solar reflection
Proportion of total incident solar radiation that is reflected by a material.
Solar absorption
Proportion of total incident solar radiation that is absorbed by a material.
Spectral Selectivity
Ability of a material to transmit, reflect or absorb different wavelengths of solar radiation to different degrees.
Shade Film
Flexible film material for solar shading systems such as roller blinds or other movable shading solutions.
Reflective Shade Film
Solar shading film with a reflective surface or layer for increased rejection of incident solar radiation.
Non-Reflective Shade Film
Solar shading film with low visible reflection for applications where a subtle optical effect is desired.
Multi-Layer Shade Film
Solar shading film made up of several functional layers that combines different optical and technical properties.
Blackout
Opaque material for blocking light. Complete darkening of a room also depends on the design of the solar shading system.
Light and visual comfort
Glare Control
Reduction of disturbingly high brightness and contrast levels to improve visual comfort.
Clear View
The ability to maintain as clear a visual connection to the outside as possible despite solar shading.
Daylight Quality
Describes the quality and usability of natural light in the interior, including brightness, uniformity and colour rendering.
Daytime Privacy
Privacy protection in daylight, the effect of which depends on the material, lighting and the light conditions inside and outside.
Visual Comfort
Pleasant visual conditions without disturbing glare, extreme contrasts or insufficient lighting.
Buildings, glazing and systems
Interior Solar Shading
Solar shading system on the room side of the glazing for controlling solar radiation, glare and daylight.
Window Film
Film that is applied permanently and directly to glazing.
Glazing
Glass construction of a window or façade, whose properties influence heat and radiation transfer, among other things.
IGU – Insulating Glass Unit
Glazing consisting of two or more panes of glass with sealed cavities between them to improve thermal insulation.
Low-E / Low-Emissivity
Term for materials or surfaces with low emissivity and therefore reduced exchange of long-wave thermal radiation.
Low-E Coating
Thin coating on glass to reduce heat exchange through long-wave infrared radiation.
Retrofit
Subsequent improvement or modernisation of existing buildings, glazing or solar shading solutions.
HVAC – Heating, Ventilation and Air Conditioning
Collective term for the heating, ventilation and air-conditioning technology of a building.
Building Automation
Automated control and networking of technical building functions such as solar shading, lighting and air conditioning.
Building Simulation
Computer-aided calculation of the thermal and energy performance of a building under defined conditions.
Thermal Glass Breakage
Glass breakage resulting from high temperature differences and the resulting thermal stresses within a pane of glass.
Façade Orientation
Orientation of a building façade, which influences the timing, duration and intensity of direct solar radiation.
Sustainability and building certification
LEED – Leadership in Energy and Environmental Design
International rating system for sustainable, energy-efficient and healthy buildings.
WELL – WELL Building Standard
International certification system focusing on the health and well-being of building occupants.
BREEAM – Building Research Establishment Environmental Assessment Method
International rating system for the sustainability and performance of buildings over their life cycle.
DGNB – Deutsche Gesellschaft für Nachhaltiges Bauen (German Sustainable Building Council)
German certification system for the holistic assessment of the sustainability of buildings and urban districts.
C2C – Cradle to Cradle Certified
Product standard for assessing material health, circularity and other sustainability criteria.
HPD – Health Product Declaration
Standardised declaration of product ingredients and associated health information.
EPD – Environmental Product Declaration
Verified environmental product declaration with information on the environmental impact of a product over its life cycle.
Declare
Transparency label for building products with information on ingredients and potentially hazardous substances.
UL GREENGUARD Certification
Product certification for low chemical emissions and better indoor air quality.
USGBC – U.S. Green Building Council
US non-profit organisation for sustainable building and developer of the LEED rating system.
Standards
EN 410
Determination of the luminous and solar characteristics of glazing.
EN 13120
Performance and safety requirements for internal blinds.
EN 13501-1
European classification of the reaction to fire of construction products.
EN 14500
Test and calculation methods for the thermal and visual properties of solar shading systems.
EN 14501
Classification of the thermal and visual performance of solar shading systems, e.g. with regard to glare control, daylight and view to the outside.
ISO 105-B02
Test method for assessing the lightfastness of materials under artificial daylight.
ISO 9001
International standard for quality management systems in companies.
ISO 14001
International standard for environmental management systems in companies.
ISO 52022-3
Calculation method for the solar and luminous properties of solar shading in combination with glazing.
DIN 4102-1
Classification and testing of the fire behaviour of building materials.
DIN 4108-2
Requirements for thermal insulation and summer heat protection of buildings.
ASTM E903
US test method for determining the solar transmission, reflection and absorption of materials.
NFPA 701
US test method for assessing the flame propagation of textiles and films.
California Title 19
Californian fire safety regulations for flame-retardant materials, textiles and films.