Blue & Yellow
While a low 'Uw' (whole window u value) offers better insulation it is also important to note that individual needs are dependant on climate zone. For example, in cooling climates (Cairns...) lower u values can offer diminishing returns by keeping the heat in at night when outside air may be cooler. In this case better selection of glass for solar heat gain and/or window shading is the most practical (cost effective) option.
I have to disagree... Double glazing seals the inside of the home from the outside temperatures (cold or warm), it is always more beneficial...it MAY be even more beneficial to have high performance glass to reflect the radiant heat or to reduce the emitted energy, but high performance glass never replaces what double glazing does, it only supplements it. So Double Glaze first. That said, the less energy you need to maintain your comfort level in your home, the less benefit that can come from increased insulation. If the inside and outside temperatures are the same without using any energy then insulating will have zero effect.
Blue & Yellow
While a low 'Uw' (whole window u value) offers better insulation it is also important to note that individual needs are dependant on climate zone.
You may or may not need high performance glazing (insulated glass units, low-e glass, thermally broken frames, uPVC etc.) and the best way to determine what will be most effective for you is to have a building thermal assessment conducted.
You may or may not need high performance glazing (insulated glass units, low-e glass, thermally broken frames, uPVC etc.) and the best way to determine what will be most effective for you is to have a building thermal assessment conducted.
Unless the home's inside temperature is the same as the outside temperature, you can only maintain your home's inside temperature by using energy (gas or electricity), and you can only reduce the amount of energy you use by insulating your home, and that means double glazing for conducted heat, Low-E for radiant and emitted heat. The amount that the insulation reduces energy usage depends upon the difference between inside and outside temperatures. And where high performance glass may be useful in some cases, double glazing is always useful.
Ed