Late last year, we wrote an in-depth article comparing energy efficient window options for new home builds. You can read this article here.
Today, we are comparing the costs, benefits and drawbacks of retrofitting double glazing into an existing Perth home versus installing new 3M Thinsulate Window film to your existing windows.
For the purposes of this case study, by retrofitting, we refer to the entire removal of an existing single pane window system, including the glass and frame, and replacing with a new double-glazed unit. There are some double-glazing systems which are designed to fit existing windows, using a subframe, acrylic panel and a magnetic seal, to create an air space between your existing window and the acrylic panel to mimic a double-glazing effect. This form of retrofitting is not covered in this article.
Benefits of New Double-Glazed Units
The benefits of retrofitting existing windows with new double-glazed units include:
- Reduction of neighbourhood, traffic or other external noise
- Reduced heat loss through the glass in winter
- Reduced heat transmission through the glass in summer
- Improved energy efficiency
- Updated and improved aesthetics from brand new window frames and glass installed
- 10-year warranty
Drawbacks of New Double-Glazed Units
The drawbacks of retrofitting existing windows with new double-glazed units include:
- High cost – see our case study below for more detail
- Disruption to the home owner by removal and replacement of windows
- Dirt and dust created from installation process
- Potential damage to the home from removal of existing windows/ install of new windows
- Very high replacement cost should a DGU be broken or damaged
Benefits of 3M Thinsulate
The benefits of installing 3M Thinsulate low-e insulating window film to existing glass include:
- Much cheaper to install than retrofitting double glazing or glass replacement with low e glass.
- Obtain similar benefits to double glazing for winter performance
- Minimal disruption to the home owner and no mess, as the film is installed to your existing windows and the installation process is clean
- Maintain the existing aesthetic of your home, as the original window frames and glass is maintained.
- 3M Thinsulate, in both the 40% VLT and 75% VLT (visible light transmission), outperforms double glazing for rejection of heat in summer, with a Solar Heat Gain Coefficient (SHGC) of between 0.40 and 0.53. Double glazed units achieve a SHGC of 0.60 (for low-e double glazed units) to 0.72 (for clear double glazing). As a memory refresher, SHGC is a measure of how much heat is gained through your windows from the sun. The lower the number, the better it performs at heat rejection.
- Enjoy significant reductions in your power bills and improved energy efficiency
- Low long-term maintenance costs – if a window fitted with Thinsulate film is damaged or broken, cost of replacing with standard glass and new film is much lower then replacement of a DGU or low e glass
- Lifetime manufacturer’s warranty from 3M for Thinsulate window film installed by a 3M Licensed Installer (for residential homes, 15 year warranty for commercial properties).
Drawbacks of 3M Thinsulate
The drawbacks of installing 3M Thinsulate Window film to existing windows include:
- Will not improve the aesthetics where existing window frames are in poor or unsightly condition
- Offers limited benefits for reduction of noise
- Additional care during cleaning is required when 3M Thinsulate is installed to ensure the long life of your film.
Let’s look at the costs in a little more detail with a case study.
Maria and Stephen have a 3-bedroom, 2 bathroom, 3 living area home in Booragoon with existing windows, consisting of a total of 34 individual panels within 13 window sets for the following rooms:
Lounge, Family, Playroom, Study, Kitchen, Master Bed, Beds 2 and 3, Bathroom, Ensuite, and WC.
3 quotes were obtained from double glazing companies in Perth, involving the removal of their existing windows and replacement with new double-glazed units.
The quotes received were as follows:
|Company||Details / Inclusions||Total Project Price (including GST)|
|A||4-5mm thickness glass, 18-20mm argon space, 4-5mm low-e glass, custom colour frames (Anthracite) including retractable flyscreens and installation/ removal of old frames||$24, 141.99|
|B||4mm clear glass, 20mm argon space, 4mm Energy Soltech low e glass, custom colour frames (Anthracite), including flyscreens and installation/ removal of old frames||$27, 091.69|
|C||4-5mm clear glass, 18-20mm thermal spacer, 4-5 mm clear glass, custom colour frames (Anthracite), includes installation/ removal of old frames. Does not include screens.||$25, 083.23|
|AVERAGE of ALL THREE QUOTES||$25,438.97|
Next, the same measurements for all 34 panels were used to calculate a quote for supply and installation of 3M Thinsulate low-e insulating window film.
The final quote came to: $7,349.76 including GST. This is less than ONE THIRD of the cost of retrofitting double glazing.
Outcome: 3m Thinsulate Most Cost-Effective Solution
3m Thinsulate is the clear winner, in terms of benefits and cost effectiveness. Before making the decision on whether to go for retrofitting double glazing or installing 3M Thinsulate window film, consider the following:
|Benefits of 3M Thinsulate Window Film|
|1. 3M Thinsulate Window Film is ONE THIRD of the cost of retrofitting double glazing|
|2. Double Glazing offers a 10-year warranty, versus a LIFETIME warranty for 3M Thinsulate|
|3. 3M Thinsulate OUTPERFORMS Double Glazing for Summer Heat Rejection – an important consideration in Perth’s Hot Summers|