In Mosman, New South Wales, windows in this 1960s apartment block were in need of an urgent upgrade. The original timber window frames were in a terrible condition with considerable wear and tear, rot damage, air leaks, and peeling paint. The single glazing also gave no reliable protection from the sun and had near-zero insulation.

Challenges presented themselves in all key areas of its current glazing:

Solar Control
Passive heat can lead to unwelcome heat entering a building on hot days. In the apartment building, the current glass let in 88 per cent of direct sun heat causing uncomfortable temperatures for occupants during summer. To try to keep cool, occupants would draw curtains and run cooling systems for long durations.

In addition, during long hot summer days, the brickwork, roof tiles, footpaths and roads absorb heat and re-radiate it outward at night time – that heat then enters the building through the glass and causes round the clock heat gain issues in summer.

Glare and Fading

Being 3mm single glazed regular clear glass, there was little protection against the strong glare affects from sunlight as well as fading factors from harmful UV rays. Blinds were often closed due to these factors.


The 3mm glass in rotting timber with obvious cracks and gaps provided virtually no insulation during colder times of the year.

Internal Condensation

Dew point is where temperature and humidity meet and condensation forms. With such glazing, it was common to see internal condensation on the glass that would eventually pool along the timber framing, adding to the mould and rotting effects of the aged timber.


Just like the impact on insulation, the glass and rotting timber allowed noise to enter inside very easily.


Retrofitting both the glass and frames to energy efficient Insulglass LowE Prime double glazing inside Kinzel Industries’ uPVC frames, brought the building into the future of energy efficiency as well as immediately and positively impacted the comfort, wellbeing and health of the tenants living inside.


  • Outer: LowE Prime Toughened
  • Spacer: Spacer with Argon Gas
  • Inner: Clear Toughened

Insulglass LowE Prime

Solar Control

The change to Insulglass LowE Prime resulted in nearly half of the direct sun heat being blocked from entering through the glass. The special silver based metal coating in the softcoat low-E glass also stopped the majority of re-radiated heat from entering inside at night on those long hot summer days – providing a more comfortable temperature level during the day and night.

Occupants now do not have to leave blinds closed all day long and demands on the cooling systems are reduced, providing a healthier living environment. According to one tenant, “The internal temperature has been reduced and is more moderate now.”

Glare and Fading

The neutral tone of Insulglass LowE Prime provided glare protection against the intense northern Sydney sun, lowering the original Visible Light Transmittance (VLT) of 90 per cent down to a more suitable 70 per cent without looking too dark or noticeable as a full tinted glass. A tenant confirmed that “glare… has been reduced significantly”.

Occupants now receive comfortable levels of sunshine and the advanced metal based coating also provides increased protection against harmful ultraviolet (UV) rays, which can fade internal wooden flooring, carpets, furniture, artwork and paint colours.


The performance of Insulglass LowE Prime exceeded expectations with a dramatic 72 per cent improvement in insulation. This allows for any heat produced inside to be retained more on those cold days and nights as well as keeping the cold from outside entering inside, resulting in a significantly lower demand for heating – “conservatively 20-30 per cent,” noted a tenant.

This effect can also be physically seen in thermal images, highlighting the before-and-after effects on a cold day. The double glazed softcoat low-E insulation also works on hot summer days by increasing the effectiveness of air conditioning – working similarly to a thermos keeping a hot drink hot (when it’s cold outside) and a cold drink cold (when it’s hot outside).

All of this results in significantly less demand for heating and supports less demand in cooling on hot days. Less energy waste and less energy costs – all year round!


Greater heat transfer from inside to out through glazing and frame as shown by the thermal imaging. Glass and frame are colder than the surrounds as indicated by purple colouring.


Heat is retained, closing the thermal wound in the wall. The silver coating of the softcoat low-E glass reflects heat back into the room. This results in increased glass temperature as indicated by the orange colours of the thermal image.

Before and after

Internal Condensation

The new Insulglass LowE Prime double glazed units increase the inside surface temperature of the glass, bypassing the dew point and virtually eliminating any internal condensation conditions – leading to healthier inside environments. “I used to frequently see condensation,” stated a tenant. “No condensation has been noticed since the new windows have been installed.”

Bigger Windows and Ventilation

Due to the high performance of the new glazing, the size of the windows could be increased without compromising performance. Multiple small windows were removed and replaced with larger full units with secured ventilation from the uPVC hardware, while the sliding doors maximised the open plan and outdoor flow to the balconies.


Transitioning from single glazed to double glazed units provided an instant positive impact on the acoustics. Intrusive noise ranged from low frequency rumbles of outside voices and low-density traffic to high frequency offenders such as chainsaws, loud music, aeroplanes and high frequency traffic. The new windows and glass doors provided over 100 per cent improvement in decibel blocking in the lower frequencies and over 50 per cent improvement in the highest frequencies. “There was a large reduction in traffic noise,” confirmed a tenant.

uPVC Frames

Combining the high performing double glazed low-E glass with uPVC frames synergised key performances such as thermal comfort. Being non-conductive, uPVC does not transfer heat in (on hot days) or out (on cold days). This, combined with Insulglass LowE Prime, results in an extremely high energy efficient window solution as well as additional benefits from the frames themselves:

Low Maintenance

No need for painting significantly reduces maintenance over their lifetime. Easy to clean too.

Tough and Durable

Reinforced with galvanised steel. Tested for ultraviolet (UV) resistance so they will not deteriorate, fade or discolour. Rot and corrosion resistant, making them ideal for coastal properties.

Bushfire Performance

Double glazed units to be used in Bushfire Attack Level 29 kW/m² (BAL 29) with some windows tested to withstand BAL 40.

Good Looks and High Security

Fusion-welded corners and unbroken lines provide simplicity and the strength of a ‘one-piece design’.

The End Result

The tenants are happy, healthier and more comfortable, and pay less on their energy bills. Apartment owners are able to attract higher rental income opportunities due to the added value the window system provides their homes. “I think the glass is performing excellently for all apartments in our unit block,” stated a tenant.

Product Details

Product: Insulglass LowE Prime

Site Address: Mosman, NSW 2088

Fabricator: Kinzel Industries

Photos: Courtesy of Kinzel Industries