Technical Information

Glossary

UV Elimination
The percentage of ultraviolet light eliminated by the glass type, below the 380 nanometer wavelength range.
Light Transmission
The percentage of light that passes through the particular glass type, measured against 100% light outside the building.
Light Reflection
The percentage of light reflected by the exterior surface of the particular glass type.
Shading Coefficient
A measurment of the ratio of total solar heat transmission of a particular glass type compared with 3mm clear glass: the % total heat transmission of the chosen glass, divided by 87.

U Value
A measure of the rate of thermal transmittance through glass, which is directly related to the weather conditions. Usually determined using conditions established by ASHRAE(American Society of Heating, Refrigeration and Air Conditioning Engineers). The lower the U-value, the lower the thermal transmittance and hence the better the insulation.

Summer U-value
a measure of heat gain - the amount of heat transmitted into a building. Determined using the midday summer weather conditions(ASHRAE)
Winter U-value
a measure of heat loss - the amount of heat loss by a building. Determined using midnight winter weather conditions(ASHRAE winter).

r Value
Thermal resistance = r value (W/m2 / Co). r value is the opposite measurment to U value, measuring resistance to heat loss, rather than the transmission through glass. The higher the r value the better the insulation.
dB Value
Decibles are the measure of sound intensity. Two systems measure sound reduction in buildings: Sound Transmission Loss (STL) and Sound Transmission Class (STC). The higher the dB Value the better the sound insulation.
Emissivity
A materials ability to radiate energy. Used to measure effectivness of a glass coating - the lower the emissivity the better the glass performs in reducing heat transfer.
Low E
Low emissivity - refers to glass designed to reduce heat transfer. Usually non-reflective and highly transparent. Most efficient in double glazing.

Don't let your valuable fade away
Fading is the enemy of the home maker: furniture, drapes, carpets, even artworks and photos all come under attack.

But you can significantly reduce fading by careful selection of glass.

Research shows up to 92% of furniture fading is caused by solar energy: 40% UV radiation , visible light: 27%, infrared radiation(in effect heat) 25%. Some 8% comes from humidity, pollutants, etc

UV radiation fades directly, sunlight and infrared both heat the fabric which accelerates the fading process.

It makes sense to use glass which diminishes solar energy, by absorbing or reflecting the light culprits. Its like puting up a sunscreen.

UV raditaion is controlled by laminates, the PVB 'glue' interlayer absorbing up to 99% of the radiation. Tinted glasses will reflect and absorb visible light and heat. So an optimum answer is to use tinted laminate or a double glaze unit consisting of clear laminate and tinted float.

Fading Reduction
Glass Type		% fading reduction	% UV fading elimination
Clear Float	3mm	0	27
	4mm	0	30
	5mm	0	35
	6mm	0	43
	10mm	16	46
Clear Low E	4mm	20	46
	6mm	26	51
Grey Float	5mm	53	71
	6mm	60	76
	10mm	71	87
Bronze Float	5mm	51	70
	6mm	58	75
Evergreen	6mm	62	86
Stopsol SS Grey	6mm	74	85
Stopsol Bronze	6mm	84	93
Stopsol SS Dark Blue	6mm	62	79
Azur Blue/Green	6mm	41	72
Sunergy Azur Blue/Green	6mm	62	79
Sunergy Green	6mm	65	86
Comfortplus / Solar E	6mm	35	57
Panasap Dark Green	6mm	62	86
Panasap Dark Blue	6mm	45	71
Panasap Dark Grey	6mm	60	74
Clear Laminated	6.38mm	47	99
	10.38mm	49	99
Grey Laminated	6.38mm	91	99
Bronze Laminated	6.38mm	89	99

Single Glazing Performance
Glass Type		LT % light transmission	LR % light reflection	TS % total solar heat transmission	Shading coefficient
Clear Float	3mm	90	8	82	1.00
	4mm	89	8	80	0.98
	5mm	89	8	79	0.96
	6mm	88	7	76	0.94
	10mm	86	7	69	0.88
Clear Low E	4mm	83	12	68	0.84
	6mm	82	12	65	0.80
Grey Float	4mm	56	6	53	0.76
	5mm	50	6	47	0.71
	6mm	44	6	41	0.66
	10mm	28	5	25	0.55
Bronze Float	4mm	63	6	59	0.80
	5mm	59	6	54	0.77
	6mm	53	6	49	0.72
Panasap Dark Green	6mm	66	5	33	0.60
	10mm	58	6	45	0.53
Panasap Dark Blue	6mm	58	6	58	0.66
Panasap Dark Grey	6mm	16	5	52	0.60
Evergreen	6mm	66	5	33	0.60
Stopsol SS Grey Coat Out	6mm	32	30	47	0.54
Stopsol SS Grey Coat In	6mm	32	11	44	0.51
Stopsol Bronze Coat Out	6mm	21	34	40	0.46
Stopsol Bronze Coat In	6mm	21	13	27	0.53
Stopsol SS Dark Blue Coat Out	6mm	41	30	44	0.51
Stopsol SS Dark Blue Coat In	6mm	41	15	47	0.54
Azur Blue/Green	6mm	71	5	34	0.60
Sunergy Azur Blue/Green Coat In	6mm	56	7	45	0.52
Sunergy Green Coat In	6mm	55	7	42	0.48
Comfortplus / Solar E Coat In	6mm	61	10	44	0.61
Diamant / Starfire	6mm	91	8	88	1.03
	10mm	91	8	86	1.02
Clear Laminated	6.38mm	85	7	76	0.94
	8.38mm	83	7	73	0.91
	10.38mm	83	7	69	0.91
	12.38mm	81	7	66	0.85
Grey Laminated	6.38mm	42	5	51	0.73
	8.38mm	41	5	48	0.71
	10.38mm	41	5	46	0.69
Bronze Laminated	6.38mm	51	5	52	0.74

Glass: the sound barrier
We will establish the degree of insulation required: simply subtract the interior noise level required from the exterior noise level. For example, a small street records up to 70dB while a bedroom requires 35dB: 70 - 35 = 35 ... a requirment of 35dB sound insulation in the window (and walls!).

Laminated Glass
Nominal Thickness(mm)	Average STL 125-4000 Hz(dB)	STC Rating (glass)	% perceived sound reduction
6.38*	29	34	40
8.38	33	35	45
10.38	35	36	50
12.38	36	39	57
8.76 PVB Acoustic	34	37	52
7 Acoustic**	34	37	52
9 Acoustic**	36	38	56
11 Acoustic**	36	39	57
17 Acoustic**	40	42	65

Single Glass Weight
Thickness mm	Weight kg/m2
3	7.5
4	10
5	12.5
6	15
8	20
10	25
15	37.5
19	47.5
25	62.5

Annealed Glass
Nominal Thickness (mm)	Average STL 125-4000 Hz(dB)	STC Rating (glass)	% perceived sound reduction
4	25	28	10
6	27	31	25
10	30	42	65
Glass Blocks 190x190x80	40	42	65

6.38* = 6mm Laminated Glass

Acoustic** = CIP Special Laminate

*** = PVB Acoustic

Glasstech Double Glazing

Nominal Thickness
(mm)

Construction
Inner	Airgap (mm)	Outer

Average STL
125-4000 Hz
(db)

STC Rating
(class)

% perceived
sound reduction

6.38*

8.76***

13**

Typical wall of gypsum, batts and weatherboards: STL 37dB. STC 40dB.

Examples of desired noise ratings
	decibels
Bedroom	35
Living room	40
Class room, conference room	35
Private office	40
General office	50
Workshop	65

The numbers have it
In a typical single-glazed South Island window, heat loss is measured at a U value of 6.2.
With Glass Tech double glazing the heat loss is more than halved to 2.9.
Take a double glazed unit with standard glass, fill it with Argon gas, and you reduce the reading to 2.6.
Now consider additional benefits. Use Low E glass for double glazing and the heat loss drops all the way to 1.91; with Argon gass filling inside the Low E panes the heat loss is a staggering 1.61 U value.