Window film’s WERS ratings: every film rated 50 per cent or more for cooling on a single-glazed aluminium window lets in under a third of the light

What the register is

WERS is owned and managed by the Australian Glass and Window Association, an industry body. Its About page says the scheme rates the energy performance of windows, glazed doors, skylights, applied window films and screening products. The ratings sit in a public search on WERSLink, which has a Films tab with Residential and Commercial tables. On 8 October 2026 the Residential table held 841 records and the Commercial table 171. This story reads the Residential table, the one for houses.

We told readers in July that window film has a working energy rating. We did not show what those ratings say. This is that reading, done row by row.

Most films appear several times, because WERS rates them as applied to standard windows named in the register as WERS Standard Industry Typical windows: aluminium or timber and uPVC, single or double glazed. Three ratings are for doors.

One row, read in full

This is the first row of the Residential table as it opens, sorted by Window ID, exactly as displayed on 8 October 2026.

In plain terms, using AGWA’s own definitions from its FAQ and the key to its rating tables on About WERS:

• Cooling 44, Heating 0. The key defines the cooling column as Percentage improvement for cooling compared with the base case Generic Window 1 (3mm clear glass in a standard aluminium frame), and the heating column the same way. AGWA also describes this level of WERS information as an Indicative % reduction in heating and cooling needs. The film table carries no definition of its own; we are applying AGWA’s.
• SHGCw 0.29. The solar heat gain coefficient of the whole window: the fraction of the sun’s heat that gets in, as a number between 0 and 1. The lower a window’s SHGC, the less solar heat it transmits. Roughly 29 per cent here.
• Tvw 0.20. Visible transmittance of the whole window, also between 0 and 1. The higher the number, the more light is transmitted. This film-and-window combination lets through about a fifth of the light.
• Uw 7.1. The whole-window U-value, in W/m²K. The lower the U-value, the greater a window’s resistance to heat flow and the better its insulating value. It is the number that matters in winter.
• ai 5.00. Air infiltration, in litres per second per square metre at a set test pressure. It reads 5.00 on all 841 rows, so it does not separate one film from another.

Summer: the biggest cooling figures come with the least light

To see what a film itself does, the fairest window to look at is the single-glazed aluminium one, because it is the closest of the four to the base case the percentages are measured against. That is our reading of AGWA’s key, not a statement in the register. The register itself points the same way: on that window, a plain clear film rates 3 per cent for cooling, close to no change at all.

On that window, 209 films are rated. Their cooling figures run from 3 to 57 per cent, with a median of 40, and 110 of them reach 40 or more. Their SHGCw runs from 0.16 to 0.76. The trade is plain when each film is plotted by how much light it lets through:

• The 39 films rated 50 per cent or more come from six of the seven manufacturers. Their Tvw runs from 0.05 to 0.31, so the brightest of them lets through less than a third of the light.
• The 36 films that let through half the light or more (Tvw 0.5 or higher) top out at 43 per cent for cooling. Four of them combine a Tvw of 0.6 or more with a cooling figure of 40 or more: Saint-Gobain Solar Gard’s Ecolux 70 and MEP Films’ Signals Defenses Film at 43, and MEP Films’ VEP70 and LEP70SRCDF at 41.
• Eleven Saint-Gobain Solar Gard films named Clear or Graffitigard rate 3 to 6 per cent for cooling, with a Tvw of 0.76 to 0.79. On these figures they do very little about sun heat. The register does not say what they are sold for, so read that as a fact about heat, not a verdict on the film.

Winter: most films show nothing

Film is a summer product on this window, by the register’s own numbers. Of the 209 films on the single-glazed aluminium window, 186 show 0 for heating. The other 23 show between 1 and 23 per cent.

The seven films at 10 per cent or more all have a Uw of 6.3 or lower, against a median of 7.1 for the 209. By AGWA’s definition, those windows resist heat flow better than most in the set. A low Uw is not enough by itself. Avery Dennison’s R Silver 20i Low E has a Uw of 6.1 and still shows 0 for heating; it also has an SHGCw of 0.20 and rates 55 per cent for cooling. AGWA’s FAQ explains why that happens:

“Lower SHGCs lead to increased comfort in the summer at the expense of less winter solar warmth.”

One more thing about the zeros. The register works out its Cooling % and Heating % columns in the browser from each row’s Uw and SHGCw, and its search script shows any result below zero as 0. So a heating 0 means no improvement on the base window. It does not tell you whether a film makes winter heating need worse; the table cannot show that.

Why the same film scores higher on a better window

The four standard windows give very different numbers for the same set of films, and the reason is the base case. On AGWA’s key, every percentage is measured against 3mm clear glass in a standard aluminium frame, so a rating on a double-glazed timber window includes what the double glazing and the frame already do.

So compare a film’s figure only with other films on the same standard window. A quote that sets a 58 per cent figure from a double-glazed timber row beside a 40 from a single-glazed aluminium row is comparing windows, not films.

What to ask before you tint

• Ask for the WERS Window ID of the film on the window type closest to yours, such as AVY-001-01. Look it up on the Films tab yourself and check the manufacturer and frame match what you are being quoted.
• Ask what you lose in light. The Tvw is on the same row. On the single-glazed aluminium window, nothing rated 50 per cent or more for cooling lets through more than 0.31.
• If winter matters, read the Heating % and the Uw, not only the cooling figure. On the single-glazed aluminium window, 186 of 209 films show 0.
• Ask whether the applicator holds a WERS License. AGWA says that is a condition of certifying a rating:

“To be able to certify WERS energy ratings the film applicator must have a WERS License.”

The film table shows no date for any rating, so it cannot tell you when a rating was issued or whether the film is still sold. Ask.

Our read

This section is opinion, built on the figures above.

The film register is more useful than its plain table suggests. Every row gives the three numbers a buyer needs, side by side, for a named product on a named window type, and the pattern across 209 films on single glazing is consistent enough to act on: the deep cooling figures come with films that let in little light, and most of them show nothing for winter.

That makes film a good answer to one problem, a single-glazed window that cooks a room in summer, and a weak answer to a cold room. If you can live with a darker room, the register shows films that cut solar heat gain a long way. If you want the light kept, the register shows a handful of films that keep most of it and still rate around 40 per cent for cooling, and they are worth asking about by name.

The one trap is the percentage itself. It is measured against a bare aluminium window with 3mm clear glass, so it is only fair between films on the same window type, and the register’s own floor at zero would hide any film that made winter worse.

Sources

1. WERSLink, WERS Search, Films tab, Residential table (read in a browser 8 October 2026, all five pages): 841 records; Window ID, Manufacturer, Frame, Glazing, Cooling %, Heating %, Uw, SHGCw, Tvw and ai for every row, as displayed.
2. WERSLink, residential film data file (read 8 October 2026): the 841 rows behind the Residential table, with each film’s full glazing description; Uw, SHGCw and Tvw match the displayed values to the displayed rounding.
3. WERSLink, commercial film data file (read 8 October 2026): 171 rows, the Commercial film table.
4. WERSLink, search page script (read 8 October 2026): the film tables compute Cooling % and Heating % from Uw and SHGCw and show any result below zero as 0.
5. Australian Glass and Window Association, About the Window Energy Rating Scheme (read in a browser 8 October 2026): what WERS rates, and AGWA’s ownership and management of the scheme.
6. Australian Glass and Window Association, About WERS (read in a browser 8 October 2026): the three levels of WERS information and the key to the rating tables, including the base case Generic Window 1.
7. Australian Glass and Window Association, WERS FAQ (read in a browser with every answer open, 8 October 2026): the definitions of U-value, SHGC and visible transmittance, and the summer and winter trade-off of a lower SHGC.
8. Australian Glass and Window Association, Energy Efficient Windows (read in a browser 8 October 2026): “WERS for Film Ratings” and the WERS License requirement for film applicators.

How we did this. The WERSLink search page is a JavaScript application. We opened its Films tab in a browser, paged through all 841 Residential rows and saved the values exactly as displayed, then downloaded the data file the page loads and checked the two against each other: every Window ID matches, and every Uw, SHGCw and Tvw agrees to the rounding the page displays. Cooling % and Heating % are taken from the page, because the data file does not carry them. Counts of manufacturers were taken twice, from the Manufacturer column and from the Window ID prefixes. Medians, ranges and counts are ours, computed from the displayed values. “Single-glazed aluminium window” means the frame the register calls Applied Film on WERS Standard Industry Typical Aluminium Window, Single Glazed. AGWA’s pages were read in a browser, with the FAQ answers opened. We have no commercial relationship with AGWA, WERS or any manufacturer named here, and we have not contacted them.

Apply film, or read a WERS film row differently? Tell us and we will check it at the source and log the outcome here.