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Take home comfort to another level.

Low E Double Glazing

THE LOW E RANGE FROM METRO PERFORMANCE GLASS. Technology that’s clearly superior. The glass you choose can make a huge difference to the comfort of a house and the size of its energy bills. That’s why it pays to choose Low E glass from the experts in performance glass. Because windows are a key design factor for the insulation of houses, Metro offers a range of window glass with high-tech coatings that create the optimum conditions inside. Simply select the Low E glass that delivers the right level of performance and enjoy a more comfortable home.

Choose the level of Performance you need. Metro’s aim is to increase the performance of windows in housing. That is why only Metro has developed a range of Low E IGUs, in addition to our classic and custom range, to suit your requirements and budget.

LowE LowE Medium Clarity Low E Glass

High Clarity, Low Haze Low E Glass, includes Argon Gas

Xcel Xcel

High Performance and High Clarity, Low Haze Low E Glass, includes Argon Gas and Thermal Spacer

The Metro Performance Rating To help you select the right glass type, we have introduced a unique Performance Rating across our Low E range. This provides you with good, better and best options. The final Rating represents the performance of the glass across seven key measures.


Clear IGU Low E Plus Low E Max Low E Xcel

Heat Loss

Heat Gain






Overall Performance Rating

Low E is a High Performance Glass Low E is an abbreviation of “Low Emissivity”, which is the ability to radiate absorbed energy Low E glass has a unique Low Emissivity coating designed to reflect long wave radiation from the glass itself and from inside or outside the house. Low E coated glass is best used in Insulating Glass Units (IGUs) and it can be used on surface two or three depending on the glass combination and performance required. Low E coatings on surface two are often called “Solar Low E” as they reduce the solar gain (heat gain) into the building, and these provide best year round performance in NZ Climates. (See Diagram 1).

Improved insulation reduces heat loss and creates a warmer, dryer, comfortable and energy efficient house + Windows are a key design factor for the insulation of houses. + Modern houses with 2009 code insulation will lose 45% of the space heat through single glazing, and this is reduced to 33% with a standard IGU and less than 28% with Low E IGUs. + Low E IGUs improve on the minimum performance of windows (R 0.26) in housing and small buildings as required by the NZ Building Code. + By improving window insulation performance you will have a warmer, dryer, more comfortable home and save on heating costs in winter and cooling cost in summer. + The measurement of heat loss is known as the U Value, so lowering the U value of glazing reduces heat loss. + Raising the R value of the window system reduces heat loss.

How Low E works Incident Solar Energy

+ Reduced heat loss saves on heating costs. + The larger the windows, the more window area (m2), the more the heat loss.

[Diagram 1]

Reflected Solar Energy

ected ared iation

Transmitted Solar Energy / Solar Heat Gain

Transmitted Solar Energy / Heat Loss Reflected Infrared Radiation

> >



n Incident Infrared Radiation SURFACE 1



Benefits of Low E IGUs + + + +

Less heat loss More insulation Less condensation More comfort

+ + + +

Less heat gain Less glare Less fading More energy savings

+ With Low E glass and thermal frames the heat loss is further reduced. + Reducing heat loss enables the room temperatures to be raised and maintained. + Argon gas is better than air for insulation.

Control the sun and reduce heat gain + The sun will allow heat gain into a house but may cause overheating. + Overheating is common on East, North and West elevations that face the sun. + Heat gain from the sun can reduce heating costs. + Temperatures in excess of 24°C with relative humidity over 60% humidity are considered muggy and uncomfortable. + Heat Pumps are being used to cool houses in summer and IGUs make them more efficient by keeping the cool air inside. + Modern house design with no eaves often suffer from overheating. + Solar heat gain is measured by the Solar Heat Gain Coefficient (SHGC) or Shading Coefficient (SC) – the lower the value the better the shading. + Low E glass used on surface 2 of the IGU can be used to reduce solar gain. + Solar Low E glasses are best at reducing solar gain while maintaining insulation and high visibility. + It is more expensive to cool air than to heat it, so IGUs are crucial in hot climates.

Less condensation with increased comfort + Low E IGUs make the internal glass temperature warmer and therefore reduce the onset of condensation on the inner glass surface. + Internal condensation is not common on Low E IGUs if the temperature and humidity are normal, but at times can be seen at the edge area of the unit or on the frames if these are not thermally efficient. + Minimum room temperatures are recommended to be 16°C at night and 18°C during the day. + Higher room temperatures around 20°C to 22°C are considered as comfortable and help reduce condensation. + Condensation is a function of the thermal performance of the window, Relative Humidity (RH) and indoor and outdoor temperature. + Higher performance windows provide more comfort and less condensation. + RH levels should be less than 75% for healthy living. + Thermal spacers in IGUs will reduce the edge area condensation and are recommended for thermal frames. + The key comfort zone is 20°C to 22°C and 40 to 60% RH. + External Dew – Low E IGUs are so efficient they can sometimes cause the outer panes to dew as the outer pane surface is colder due to less heat loss. + If this occurs it indicates the IGUs are working well in insulating the building. The lower the U value of the IGU (higher R Value) the more likely this will occur.

+ In hot climates the windows and doors are often closed and the HVAC turned on to cool the house.

Control the suns radiation and reduce fading + The suns radiation causes fading and damage to fabrics and materials. + The main cause of fading is Ultraviolet Light (UV). + Clear glass normally allows most of the UV to enter a building. + Low E glass can reduce fading. + Fading is best measured by the Fading Reduction Coefficient (FRC) as it compares the damaged weighted transmission (Tdw-K) over the full UV range. + The UV elimination percentage will provide a guide to fading but can be misleading, some products may eliminate 99% of UV but they will still allow fading. + Control the sun to control fading.

Additional Benefits of IGUs

Allow visibility while reducing glare + Day light is fundamental to human health and wellbeing. + Providing natural light and an awareness of the outside is a NZ Building Code requirement. + Daylight is directly related to the Visible Light Transmission (VLT) of the glazing. + High levels of sunlight are usually associated with higher levels of solar heat gain. + Large areas of clear glass can let in too much light and create glare. Solar control Low E glasses work like sunglasses and control the VLT and thus glare inside the home. + Glare is often worse with a white cloudy (diffuse light) sky and can also be a problem on the south elevation. + Low E glass coatings reduce the VLT and thus glare depending on the type. Solar Low E products are best to reduce VLT and glare. + Some Low E coatings can create a light blue haze in transmission as they interfere with the light. + Sputter coatings are best to reduce haze. + Xcel Low E coatings are applied to extra clear glass to maintain a high VLT (79%), similar to classic clear glass IGUs.

The Metro Performance Rating (MPR) does not include sound control, safety and security features in the rating, as the Low E glass does not affect the performance, so these are additional benefits you get when selecting from the Low E IGU range.

Control noise for a quieter environment + IGUs reduce the sound transmission compared to single glazing so they make the environment quieter and more comfortable. + By using thicker glass and or glass panes of different thickness the acoustics are improved. + Special acoustic glasses can be included in the IGU if required.

Be safe and secure in your home + Toughened Safety Glass will be used to comply with NZS 4223 Part 3 – Human Impact Safety Requirements, where required, either as the Low E outer pane or clear inner pane. + Toughened Safety Glass is ideal for safety, strength and temperature resistance. + Toughened Safety Glass is ideal for high impact areas such as doors. + Laminated Safety Glass can be used for safety and security if required.

Call 0800 545 800 Contact your local Metro representative for more information about our range of Low E IGUs. Metro Direct Whangarei 28 Porowini Ave Whangarei (09) 438 9399

Metro Direct Hamilton 32 The Boulevard Te Rapa Park, Hamilton (07) 850 6371

Metro Performance Glass Central Auckland 17-19 Patiki Road Avondale, Auckland (09) 815 1199

Metro Performance Glass Bay of Plenty 88 Portside Drive Mt Maunganui, Bay of Plenty (07) 575 5503

Metro Performance Glass South Auckland 24-36 Lady Ruby Drive East Tamaki, Auckland (09) 274 1030

Metro Direct Napier 9 Niven Street Onekawa, Napier (06) 843 3777

Metro Direct Palmerston North 193 John F Kennedy Drive Palmerston North (06) 354 2071 Metro Direct Taranaki 159 Gill Street New Plymouth (06) 758 8366

Metro Performance Glass Christchurch 700 Halswell Junction Road Hornby, Christchurch (03) 348 4184 Christchurch Glass 35 Hammersmith Drive Wigram Park, Christchurch (03) 343 5103

Metro Performance Glass Wellington 18 Jamaica Drive Grenada North, Wellington (04) 232 9920

Metro Direct Cromwell Ree Crescent, Cromwell, Central Otago (03) 445 4530

Metro Direct Nelson 146 Tahunanui Drive, Nelson (03) 546 5365

Metro Direct Dunedin 140 Portsmouth Drive Dunedin (03) 477 9485


Metro Performance Glass LowE  

Take comfort to another level, Metro LowE glass is creating a new standard in glazing. Available at Elite windows and doors.

Metro Performance Glass LowE  

Take comfort to another level, Metro LowE glass is creating a new standard in glazing. Available at Elite windows and doors.