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Windows are portals for light, temperature, air flow and views. Choices can be made in size, orientation, opening type and direction, frame material, glass type and treatment, number of glazing layers, and quality of seals. It is vital that each element is understood, designed and used appropriately to maximise the benefits of these qualities and minimise their disadvantages.

Consider what qualities are needed for each living space and from each window. Also consider how all the windows work together as a whole house system.

And, as always, make responsible choices with all components in regard to their life cycle – from womb to tomb.

Generally Accepted Approach

Ordinary windows can represent a major source of unwanted heat gain in summer and significant heat loss in winter.

Frames and seals can be ill-fitting and allow draughts.

Inappropriate orientation of glazing can make the indoor environment uncomfortable in terms of light, temperature, air flow and views.

High embodied energy, and green house gas (GHG) issues in some materials e.g. aluminium, glass from overseas (issues of manufacture and transport miles).

Laminated glass often ends up in land fill as it is harder to recycle. However Visy DO recycle it if people dispose of it through the correct channels (ask at your recycling depot).

Biodiversity issues (destruction of, or an erosion of habitat and/or biodiversity values) if ‘Bad Wood’ used in framing. (www.goodwoodguide.org.au‎)

Choices for Bull Street

Windows and doors will be manufactured locally.

Glazing: Triple Glazed with energy tech or Sol tech ‘Smart Glass’. 4mm clear / 12mm Argon gap / 4mm clear smart glass / 12mm Argon gap / 4mm clear Smart glass – float glass manufactured in Dandenong by Viridian Glass, Vic (159km). Processed in Clayton, Vic. (146.8km).

Frames: recycled timber or FSC certified Australian timber

Timber Treatment: Quantam Aquaoil, Seaford, Vic. (175.4km) / E Colour – E0 Poly Clear, Byron Bay (1631km) / or Hymes UVEX Timber Primer, Ballarat (79.4km). All are high performing products, rated zero VOC and manufactured in Australia.

Seals: All units designed and built to withstand winds in excess of 120km. Gasket seals.

Summary of Research & Choices

Frames: (ref: ecospecifier). Compared to PVCu. non-verified timber, and aluminium, FSC-certified timber has the most positive outcomes in terms of GHG (production of greenhouse gases, ozone-depleting chemicals), Health (products or emissions during production or use that directly impact on human health) and Biodiversity (destruction or an erosion of habitat and/or biodiversity values, e.g. threatened species or species loss).

Its potential shortcoming is in the area of Life-Cycle Issues (durability and maintenance). Therefore this must be addressed with informed choice of timber to use (durability) and its treatment (maintenance).

Biodiversity is regulated if FSC-certified timber is used, or the timber is classified as ‘Good Wood’ under the terms of the Greenpeace Good Wood Guide www.goodwoodguide.org.au

The windows at Bull Street are framed with Cypress Macrocarpa (comm. Golden Cypress) that have been culled from public areas in and around the Ballarat area. These trees would normally be chipped but Grand Design Windows have negotiated with the Council to use the timber, milling and seasoning it in their own kiln to Crosby Architects’ design specifications. Cypress Macrocarpa is a high performing thermal product, durable, insect repelling and locally sourced.

Seals – Deventa seals, made in Holland (best on market)

Hardware – Roto, made in Austria and Hungary (best on market)

Screws – Spax, made in Germany (best on market)

Sealants – Ramseur  GE Silicone RTV120 Series Neutral Cure (best on market)

Glass – Viridian Glass, energy tech or Sol tech ‘Smart Glass’ of which are made in Australia. (Viridian do import some of their products so it is important to check) made from sand (mined in Lang Lang 209km), Soda Ash (very small quantity. Imported), and Dolomite (Australian)

Details of research

Energy efficient windows will make your home more comfortable, dramatically reduce your energy costs and help to create a brighter, cleaner, healthier environment. (ref: www.wers.net for Cooling and Heating Climate information)

To enable the selection of high performance in different areas of Australia, WERS (Window Energy Rating Scheme www.wers.net) has split the country into three main areas that each require different window properties to achieve the best results. Castlemaine is classified as ‘Mixed Climate Zone’.

Mixed Climate Zones

The priority in a mixed climate is to keep heat out of the home, except during a relatively mild winter season, when ‘free’ solar heat gain and retention of warmth in the house become important. Heat gain or loss takes three forms; radiant heat transfer, conductive heat transfer and heat transfer via air infiltration. Ideally, mixed climates call for strong solar control on east and west windows, but deliberate use of free sunlight admitted by northerly windows. This means different glazing solutions.

In a mixed climate (temperate), coloured green on the WERS climate map, the best results are obtained from windows that insulate well (low U-value), admit plenty of free solar energy (high solar heat gain coefficient) on the north during cooler months, but limit solar heat gain from the east and west (low solar heat gain coefficient). Ideally, northerly windows should be protected by correctly sized eaves. This will provide protection from summertime heat and glare while still allowing sun penetration in winter.

When selecting a window product from WERS, look for products with a balanced heating and cooling Star Rating.

Radiant Heat Transfer

Radiant heat gain occurs when solar energy is transmitted through the glass. In addition, some solar energy enters indirectly. This occurs when the glass (and frame) are exposed to sunlight and heat up. Some of this heat is transferred inside by conduction and convection (air currents).

On the east and west, the best way to stop radiant solar heat gain is to shade the glass, but this is not always possible. In addition, shading systems sometimes interfere with the view, reduce natural light, inhibit ventilation or add cost to the window system. Every situation is unique. An easier alternative is to select a window with at least four cooling stars – that is, follow the guidelines for a cooling climate.

To the north, the windows should be shaded in summer by correctly sized eaves. To maximise the benefit of free heat from the winter sun, look for windows with at least three heating stars. In other words, follow the guidelines for a heating climate. This will also ensure that beneficial winter sun is admitted.

Conducted Heat Transfer

In a mixed climate, windows with at least four heating stars, on all sides of the house, will ensure that unwanted heat losses or gains are minimised. This means the windows must have a low U-value. Insulating glass units (IGUs) with some sort of low-e coating and an argon gas fill between the panes give the lowest U-values; as low as 1.8, compared with at least 5 in the case of a single-glazed clear window. A frame with a low U-value assists in reducing the whole-window U-value. Frames that use thermal breaks or composite metal / timber (wood) design, or timber or uPVC frames, outperform standard aluminium windows. This performance difference shows up in the WERS stars.

Infiltration Heat Transfer

The final way that heat enters or leaves the home is through gaps and cracks around sashes and frames. When a window is shut it should be shut. WERS-rated windows must satisfy Australian Standard AS 2047 for air infiltration performance. Most easily exceed it and achieve air leakage figures below 1 litre per second per square metre of window area. Look for windows with good weather seals. Traditionally, those with ‘compression’ seals, as fitted to awning and casement windows, tended to have superior long-term infitration performance. However, recent advances in some sliding window seals have reduced the gap.


Viridian glass is the only float glass manufactured in Australia. The facility is in Dandenong (Float glass manufacture) 158km from Castlemaine. Processing is in Clayton, Vic. where float glass is processed into laminates and high performing glass.

Viridian source some products from overseas, currently patterned glass, low E coated, perforate glass, green glass & mirrors (dual sourced from Australia & OS), Super heavy weight, and Super clear (low iron)

95 Greens Road
Dandenong VIC 3175
Ph: 1800 810 403
Direct: +61 3 9212 2222

Viridian have a comprehensive Environmental Covenant and were the first manufacturer to sign a sustainability covenant with the EPA


Eco-Priorities (ref: http://www.ecospecifier.com.au/)

The following issues relate to both potential positive and negative issues associated with each product class:

Priority Order PVCu Timber – Non FSC Timber – FSC, recycled or equivalent Aluminium
1 GHG + / Health GHG+ GHG + GHG / Health
2 Life-Cycle + (Durability) Biodiversity + Biodiversity + Durability +
3 Recyclability + Life-Cycle (Maintenance) Life-Cycle (Maintenance) Recyclability +
4 Resources  (Finite) Resources  (Renewable) Resources  (Renewable) Resources (Abundant)
Issues of concern/Red Lights?* Yes – Health Yes – Biodiversity No Yes – GHG


Table Key

GHG – Production of greenhouse gases, ozone-depleting chemicals.
Life-Cycle Issues
 – Durability and maintenance.
 – Destruction or an erosion of habitat and/or biodiversity values, e.g. threatened species or species loss.
 – Toxic and/or persistent and/or bio-accumulative emissions to the environment.
 – Products or emissions during production or use that directly impact on human health.
 – The use of raw resources, e.g. oil, metal ores.
+   Indicates an overall positive outcome.
*   Issues that are of high concern and are a potential eco-design basis for not using the product.

Thermal considerations for window frames include:

  • A significant part of the thermal energy transmission can be through the frames. Another significant energy pathway is the porosity of the construction including sealing.
  • Timber and PVCu are approximately thermally equivalent and provide high level of energy efficiency compared to a Standard aluminium frame.
  • Standard aluminium frames can have a poor energy performance. To become more energy efficient aluminium frames need to be improved through performance enhancing design features or through the use of thermal breaks.
  • US Green Building Council research has shown that the majority of even Thermally Broken Aluminium frames are relatively poor compared to timber or PVC and all aluminium consistently shows greater environmental and human health impacts than other frames types.


Quantum Aqua Oil -Family owned and run, tel: 9776 8831, Seaford, Vic. 175km. All quantum aquaoil & timber plus finishes are formulated from vegetable derived resinated oils sourced entirely from renewable resources and are made using the very minimum of volatile organic compounds (VOC’s) that do not have a petrochemical base. Manufactured on site in Seaford, Vic. and tested in Alpine and Coastal Areas.

Haymes UVEX Timber Primer – local business, Ballarat.

Ecolour paints have Zero Volatile Organic Compound (VOC) outgassing. The Carbon Reduction Institute has certified ecolour as completely carbon neutral – a first in the paint industry. Ecolour paint is also a GECA approved environmental choice product. In an industry dominated by multi-national chemical companies, ecolour is wholly Australian owned, a member of the Australian Paint approval scheme and ISO 9001 certified.