Glass data

Glass Type

HL BS CL EPG
The different glass types shown below are the most common in practice and they include predefined glass data, such as Ug-value, solar factor, solar absorption, transmission, light transmission, and light reflection in accordance with ISSO 8, Table 7. You may enter your own available glass data. Please make sure not to set percentages, but rather factors, in Vabi Elements.

Type	U_g	g-factor	Transmission (D) energy	Absorption (ABS) energy	Reflection (R) energy	Transmission (D)LTA (τ_v) light	Reflection (R) (ρ_v) light	Absorption (ABS) Light
Single Glass	5,37	0,81	0,77	0,12	0,11	0,89	0,08	0,03
Attachments Window	2,80	0,70	0,62	0,23	0,15	0,80	0,14	0,06
Double glazing	3,20	0,70	0,62	0,23	0,15	0,80	0,14	0,06
HR glass	2,00	0,66	0,57	0,25	0,18	0,80	0,12	0,08
HR + glass	1,52	0,62	0,53	0,26	0,20	0,80	0,12	0,08
HR + + glass	1,10	0,58	0,47	0,30	0,23	0,80	0,12	0,08
Triple glazing	0,80	0,50	0,47	0,34	0,19	0,64	0,19	0,17
User defined

ISSO Publicatie 32 (2011) bijlage D

Uitgangspunten temperatuursimulatieberekeningen, fysische materiaalgegevens

ISSO-digitaal

NEN 1068:2012 Bijlage E

Warmtedoorgangscoëfficiënt van beglazing, zonder meerekening van randeffecten

BRISwarenhuis

U_g value

[W / m². K] HL BS CL EPG
The U_g-value represents the thermal transmission of the glass. This is the transmission of heat in Watt per unit of time and per m² at a temperature difference of one Kelvin between inside and outside. This thermal property should be measured in accordance with EN 673:2011, perpendicular to the surface. Well-insulated glass is characterized by a low U_g-value.

g-waarde (g_gl;n)

[factor] CL BS EPG
The g-value (solar gain), is the ratio between the incoming and the striking solar radiation. This is a property of a glass system and a measurement of the total amount of solar energy transmitted through the glass system. The value is between 0 and 1. The higher the g-value, the more heat enters the room. This glass property must be measured in accordance with NEN-EN 410: 2011, and is the solar heat gain in the event of a vertical incidence.

Please note that the ZTA (Zontoetredingsfactor A) is in many cases different than the g value of glass. The ZTA was used in the Netherlands to indicate how much solar radiation can enter through the glass. Internationally, people do not use ZTA, but the g-value of glass.

1. ZTA, this value applies at an angle of 45°.

2. g_gl;n, This value applies at an angle of 90°, so perpendicular to the glass. This value is specified by the European standard EN 410.

The g_gl;n is always higher than the ZTA, because the sun entering perpendicular tot he glass gives less reflection. Vabi Elements Building simulation corrects the values for the whole year with the actual sun levels and the associated reflection.

The new Dutch calculation standards also no longer ask for the ZTA, but for the g-value (g_gl;n). This makes the input of the glass data more in accordance with international standards and methodologies, and the glass data of the manufacturers can be entered better.

Energy

Transmission energy

CL BS
This is the direct energy transmission [α_e, TE%] and indicates the percentage of energy that is transmitted through the glass. This is the part of the directly transmitted solar energy, in other words the transmitted solar radiation relative to the total striking solar radiation. The higher the τ_e value, the more light is transmitted. This glass property must be measured in accordance with NEN-EN 410: 2011

If the transmission [τ_e] is not known, but the absorption [αe] and energy reflection [α_e] are, then the value of the transmission can be deduced from the following formula:

Absorption energy

CL BS
Energy absorption [α_e, AE1%+AE2%] is the part of the solar energy absorbed by the glass. This glass property must be measured in accordance with NEN-EN 410: 2011. The higher the absorption, the more energy is absorbed.

If the absorption [αe] is not known, but the transmission [τe] and energy reflection [ρe] are, then the value of the absorption can be deduced from the following formula:
.

Reflection energy

CL BS
Energy reflection is the percentage of energy that is reflected by the glass. The higher the reflection, the more energy is reflected.

Light

Transmission light licht (LTA)

CL BS
This is the light entry factor [τ_v, TL%] or light transmission and gives the ratio between the incoming and the striking visible solar radiation with a perpendicular angle of incidence. his coefficient is used to determine the light in the room and is used to switch the lighting. The higher the LTA value, the more visible light and heat enters. This glass property must be measured in accordance with NEN-EN 410: 2011.

Reflection light

[factor] CL BS
The visible reflection [ρ_v, RLe%], or light reflection, indicates the percentage of visible light that is reflected by the glass. The higher the reflection, the more light is reflected. This glass property must be measured in accordance with NEN-EN 410: 2011.

Make sure that the light reflection [ρ_v] is different from the energy reflection [ρ_e] of glass.

Absorption light

Light absorption is the part of the light absorbed by the glass. The higher the absorption, the more light is absorbed.