Yes, roller shutters cut the heat coming through a window, and they do it by stopping the sun outside the glass. Once sunlight has hit the glass, most of that heat is already in your room and a blind or a curtain is only dealing with the leftovers.
Why the shade has to be on the outside
Internal blinds and curtains block light after the sun has already warmed the glass and the air behind the fabric. A roller shutter sits in front of the window, so the aluminium takes the heat and the glass never gets the chance.
On a west facing bedroom that is the difference between a room you can use at four in the afternoon in January and one you shut the door on. Same glass, same afternoon, very different room.
The air gap does more than the aluminium
Each slat is roll formed aluminium with a polyurethane foam core, so the slat itself has some insulating value on its own. The bigger effect is the pocket of still air trapped between the closed shutter and the window.
That is why a shutter fitted neatly to the opening, with the guide rails close in against the frame, performs better than one standing well off the wall with gaps down the sides. Air that can move freely carries the heat with it.
The same pocket works in reverse through winter. Closing the shutters at dusk slows the heat leaving through the glass overnight, which is most noticeable in a room with a lot of window and not much wall.
What it feels like through a Sydney summer
The rooms that change most are the ones facing west and north west, plus anything with a big run of glass and no eave over the top of it. Upstairs bedrooms under a tile roof are usually next on the list.
You will still feel the room warm up, because a shutter is not air conditioning. What it does is take the direct radiant load off the glass, so the air conditioner is not fighting a hot window all afternoon and a room without one stays usable.
Half closed is a setting people forget about. Dropping the shutter most of the way and leaving the bottom section open keeps the sun off the glass while you still get daylight and some breeze through an open window.
Motorised operation is what makes it happen
Every window roller shutter we fit is motorised, with a tubular motor inside the roller tube and a wall switch or a remote to run it. For heat control that matters more than it sounds.
Shutters only reduce heat if they are closed before the sun swings around to that side of the house. A timer or a sun sensor closes the western side at two in the afternoon whether anyone is home or not, then opens everything again in the evening.
Grouping shutters onto one channel is worth setting up while the installer is there. Closing the whole west side of the house becomes one press instead of a lap around four rooms with the afternoon already lost.
What changes how much difference you notice
- Which way the window faces, and whether an eave, a pergola or a tree is already shading part of it.
- How much of that wall is glass.
- How tight the install is, including guide rail clearance and how well the headbox sits back against the wall.
- Shutter colour, since a lighter finish reflects more of the sun than a dark one.
- Whether you actually close them in time, which is the real reason timers and sensors are worth having.
Fitting them to a Sydney house
Most installs anchor the guide rails and the headbox into brickwork, which is straightforward on solid brick or brick veneer as long as the fixings land in brick rather than mortar joints. Over the opening you are often into a timber lintel behind the render, and that needs the right fastener rather than a guess.
Guide rails need clearance either side of the opening, so a window hard up against a corner, a downpipe or a meter box has to be looked at before anything is ordered. That is a five minute check on site and a real problem if it gets missed.
If one room in your house is unusable on a hot afternoon, start there rather than doing the whole place at once. Have a look at motorised roller shutters, or outdoor shutters for exposed windows if the glass is very open to the weather.
The only way to know what a particular window needs is to stand in front of it. Book a free measure and quote and we will tell you which windows will make a difference and which ones are already shaded enough to leave alone.
Common questions
Do roller shutters work better than internal blinds for heat?
Yes, because they stop the sun before it reaches the glass. An internal blind only works on heat that is already inside the room, so it is always playing catch up on a west facing window in summer.
Do roller shutters help in winter as well?
They do. Closing them at dusk traps a pocket of still air against the glass, which slows the heat leaving the room overnight. Rooms with a lot of glass and little wall notice it most.
Do I have to close the shutters fully to keep heat out?
No. Dropping the shutter most of the way and leaving the bottom section open still keeps the sun off the majority of the glass, and you keep some daylight and airflow. Fully closed gives you the best result on the worst afternoons.