Windows decision

We have finally decided on the windows.  Went with Creative Windows (http://www.creativewindows.com.au/) in Braeside who are fabricating the Schuco (http://www.schueco.com/web/au) frames.  After a number of discussions with other suppliers, and nearly placing the order with Qualital (http://www.qualital.com.au/) we went with a locally made product.  Qualital pricing was very good and the quality of the windows was also very good but they do not provide local installation and since all windows are imported, any glass breakages mean that you either have to wait for replacement glass from Europe or use a locally sourced product which inevitably will have a different appearance.

Initially, Creative offered a double glazed window with Low E glass but were only able to achieve a U-value of 1.61 and a SHGC of 0.59 (Qualital were offering U-value of 1.2 and a SHGC of 0.59). In addition, the Shuco frames (not their passive house version) performed worse than the Qualital composite frames.

Working with Creative to find alternatives they offered a locally double glazed product with a U-value of 1.34 which was approaching the Qualital numbers but the SHGC was only 0.27 which meant that was not enough solar gain and had a significant impact on the Space Heating Demand when modelled in PHPP (Passive House Planning Package) with numbers exceeding 30kWh/m2a.

Clearly, this was not acceptable, so I asked Creative to explore the cost impact of going to triple glazed, we had quotes from other suppliers and they indicated that the jump to triple glazed would only add 5% to the cost, but they were European windows so I was keen to see how Australian made units compare.  The first pass saw an increase of >8% but the suppliers of the glazing and Creative began to tweak the specification and ended up with a 5mm/8 argon/4mm Energytech / 8 argon / 5mm Energytech glass option with a U-value of 1.0 but still retaining a SHGC of 0.59.

To further keep the costs down but keep as much performance as possible, we downgraded a number of very small windows (eg.450x450mm) where the frames had a significant impact on the overall window U-value back to double glazed.  This left all of the North facing windows (90% of the total glazed area) as triple glazed.  It saved a few thousand dollars and had little impact on the SHD.

The new Space Heating Demand is 15.99kWh/m2a and a Heating Load of 9.9 W/m2 - so border line within the PH requirements but the model is not complete - so watch this space...

Other window suppliers worth consideration;

• Dopfner from Laros Technologies - (http://www.laros.com.au/windows--doors.html)
• Binq (http://www.binq.com.au/)
• Reynaers from MSF (http://www.msfaustralia.com.au/)