Low E glass - are you using it, pros and cons

Hi amsaini15,
We have not made the decision yet on what to do.
[b]If we were building new I think we would definitely strongly [b]consider double glazing.[/b][/b]

IMO
Go for standard double glazing, low-E has a limited value and only in solar heat gain. The film I presume is to emulate low-E so rule that out too. If you have a solar heat gain problem, then double glazing will not help, and the best way to deal with this is to shade that window externally, if you cannot do that due to aesthetics then, and only then add low-e to the double glazing for that window only.

Don't waste your money.

Hello,

I haven't been here for a while as we finished our house and been in it for few years now.
I thought I share the outcome here.

We have around 35 PVC windows all double glazed Low-E, sizes from huge to small. German profiles and hardware (Kommerling) and local glass Viridian modules, about 20mm gap. We also used that for the laundry door. Builder had originally laundry door as a metal-framed single glazed door - we asked to put it in garage where it is almost a fit-for-purpose (rough quality). We do not have any sliding doors or windows to avoid extra energy leaking, we only have several french sets. We have used a 3rd party to build, supply and install the windows as the builder wasn't keen and we did not like their supplier came across.

The house is 2 storeys, was on paper given almost 8 stars and without garage is about 300m2.
We heat using hydronics on Bosch gas boiler - all panels are undersized at our request about 40% from original, "default leaky house" design - at our request. That gave us a small boiler under 20KW. This works like a charm, we keep 20-21C from late May to early Oct.

Aircons are all split, either single or mutihead instead of builder's default "central" aircon (which is energy, duct dust and external jumbo noise lunacy). We use Daikin. Again we recalibrated original sizing down by about 30%. For example we use 1KW in 10m2 or similar rooms and studies. The huge open kitchen area has 6KW unit. All works as a charm - some units we do never turn on. We keep 23-24C for a number of reasons, beyond this discussion.

Have family of 4 with teenage kids and dog, in Melbourne. Our electricity use is typically under 10KWh per day and using no frills retailer we pay around $90 per month. We have space on flat roofs for more than 30KW solar with all cabling in place but could not see any economical reason to install this - our electricity bill is around $1,100 per year.

When we were getting windows build the supplier presented us with an offer Viridian had at the time - low E glass at normal glass price. Se we saved a bit and have Low E everywhere even in shower and WC windows.

The house is also fully insulated (at least on paper, we took max option we paid the builder for but could see installers doing a poor job). We used Proctor, gray membrane to wrap the house which allows moisture control - not the default blue or, whatever compliance plastic/solid wraps, used commonly to save costs and trap moisture inside. Cladding is all Hebel, roofs are flat steel with extra blanket and layer of Proctor.

Apart from everything else, the house feels like living in Europe - it keeps temperature stable, its not getting cold when it rains or sun goes behind the cloud and all towels get dry in few hours without heating - its nice an dry inside. Temperature changes a little and slowly. On hot days we can go without air cons for 3 days after our next door turns their jumbo noise unit on, on their new house. Partially the reason is we can open all windows (tilt and turn) and ventilate the house in 10 minutes flat, in the evening.

Good luck folks with your projects

I believe there are different types of Low E coatings? Some are passive, e.g. focusing on keeping heat in and not preventing solar heat gains (e.g. good choice for north facing windows?) while others block solar energy completely and reduce cooling costs (e.g. good choice for western facing windows?)

Check out this article:

https://brennancorp.com/blog/low-e-glas ... explained/

Several different metals are used to create the micro-thin layer on the surface of low-e glass. Tin, silver and zinc are some of the most common, and many types of low-e glass utilize a combination of different metal layers. Still, with all the possible combinations, there are two basic types of low-e glass coatings: passive low-e coatings, and solar control low-e coatings.

There's a crucial difference between the two. 

• Passive low-e coatings are designed with the purpose of maximizing solar heat that passes into a building. This creates what's known as a “passive” heating effect, which reduces the amount you have to rely on artificial heating. Windows with passive low-e coatings are ideal for colder climates, as they can significantly reduce the cost of heating your home.
  
• Solar control low-e coatings limit the amount of solar gain into a building. The purpose of of solar control low-e windows is to keep buildings cooler, and to reduce the amount of energy used by air conditioning. They are ideal for hot climates, and for homes and buildings that receive a lot of direct sunlight.