Are Plantation Shutters Good Insulation? What Window Coverings Do in a Hunter Winter

A window in winter gets 5 hours or fewer of solar heat gain but 19 or more hours of night-time heat loss. The NSW Government's advice is to close windows, curtains and blinds at night, and open them during the day to let the sun in. Put those together and the long winter night is when a window covering has the most to do.

So the real winter question about a plantation shutter is not how it looks open in the sun. It is what it does closed, through the long night, over glass that can account for up to 40% of a home's heating energy. Here is how Maitland Shutters reads the evidence, including what the figures say and what they don't.

Why the long winter night is when shutters matter

Source: YourHome, NSW Government

Windows usually have the lowest R value of any construction element in a house. In plain terms, glass is the thinnest part of your home's winter coat. The same YourHome page says heat loss is further minimised by appropriate windows and curtains or blinds.

The routine is simple, and it costs nothing. Open the louvres on sunny windows in the morning so the sun can do some heating. Close them at dusk, before the room starts giving that warmth back to the night.

The NSW tips go further than the windows. They suggest you set the heater or air conditioner to 18 to 21°C, noting that every degree lower can save about 10% on the heating bill. They also suggest you block draughts with a door snake or rolled towel.

If you want timing for your own street, the Window Shading Association of Australia (WSAA) offers a postcode-based Schedule of Operation for when to open and close shading.

Are plantation shutters good insulation?

As a layer over existing windows, they are part of the answer the government itself gives. YourHome says window furnishings (for example, louvres, blinds, curtains) can be used to improve the thermal performance of your windows, and that they are especially useful on windows you already have.

WSAA says that even with modern glazing, blinds and shutters can improve insulation by lowering the U value, and that closed shutters and blinds retain warmth on cooler nights. Its list of energy features includes timber or composite internal shutters.

One figure gets misread often. The "up to 40% lost through windows" figure is the heat that escapes through the glazing, not what a shutter or curtain saves.

A shutter adds a layer between cold glass and a warm room. How much that layer holds back depends on the window behind it, how well it fits, and whether it is actually closed when the sun goes down.

What a U value tells you about your windows

A U value measures how easily heat passes through a window. YourHome says heat loss through glass depends on the U value, and lower means better insulation. The same page has a table with figures for common windows.

Whole-window U value (Uw), lower is better

Source: YourHome

YourHome also gives the rule behind the numbers, with a worked example. 70 m² of aluminium-framed clear glass (U 6.2) on a night 15°C colder outside loses 6.2 × 15 × 70 = 6,510 W. Halve the U value and you halve the loss, to 3,255 W.

That example is a whole house of glass. A single window is far smaller. Take a 2 m² single-glazed aluminium window at Uw 6.9 on a night 15°C colder outside: it loses about 207 W (6.9 × 15 × 2).

The calculator shows the window itself. A closed shutter, blind or curtain sits on top of that figure, adding its layer to the glass and frame.

Do plantation shutters provide insulation on their own?

They work best as part of a tidy window, not as a cover for a leaky one. The NSW Government advises using blinds, shades and curtains to add insulation, and separately advises sealing gaps with weather stripping on movable frames and sealant on fixed ones.

Fit matters too. WSAA lists cassette-mounted or pelmet-enclosed systems and well-fitted external shutters among its energy-saving features, and advises that window shadings be recessed or paired with pelmets for insulation.

Source: Window Shading Association of Australia, NSW Government

For most living rooms and bedrooms, that means internal shutters set neatly within the window reveal. Our interior plantation shutters page shows the options. If you are weighing inside against outside, our guide to interior or exterior aluminium shutters walks through the trade-offs.

Shutters vs curtains: what the published figures cover

The most quoted number in this debate belongs to curtains and roller blinds. WSAA says reflective roller blinds and curtains have been shown in studies to cut heat loss through single-glazed windows by as much as 40%. That figure is for roller blinds and curtains on single glazing, so it doesn't carry over to shutters.

For shutters, WSAA's claim is the U value one: closed, they retain warmth on cooler nights.

Both can be opened in the morning to let the sun in and closed at dusk. Our comparison of shutters vs blockout blinds covers the light and glare side.

Shutters, double glazing, secondary glazing or film?

Double glazing changes the window itself. YourHome's table puts double-glazed timber or uPVC at Uw 3.0, against 6.9 for single-glazed aluminium. It also corrects a common belief: insulated glazing is "sometimes wrongly assumed" to be only for cold climates, when double glazing can deliver better energy performance in all climates, especially in heated and air-conditioned homes.

It is also the biggest step. The NSW Government describes double glazing as a significant home improvement project, with the price depending on window size and frame material.

The same page says "There's currently no Australian Government incentive or rebate available for double glazed windows." It does list NSW Home Energy Saver zero-interest loans for double glazing, for NSW homeowners or landlords who meet an income test.

The in-between options have limits. Secondary glazing, a sheet fitted inside the existing frame, does not perform as well as a factory-made double-glazed unit, because the edges can't be fully sealed. Window film can roughly halve a window's SHGC, the share of the sun's heat that gets through, so it mainly helps hot east and west windows in summer. Film can also reduce light, and YourHome advises an accredited installer.

For existing windows, coverings are the step YourHome names, and they sit alongside these options rather than competing with them. For how shutter pricing is put together, see what shutters cost in Maitland.

What the same windows do in summer

The glass that leaks heat in July lets it pour in come January. YourHome says windows can account for up to 87% of heat gained, against up to 40% of heating energy lost.

Windows: the weak point both ways

Source: YourHome

The direction a window faces matters most here. For east and west windows, YourHome calls adjustable vertical shading such as external blinds the optimum solution, because the sun comes in low from those sides. Adjustable shading suits these windows because it can block low sun and open up when you want the view.

Our guide to the west-facing room covers afternoon sun in detail. The 5pm Test is a quick way to see which of your rooms cop it worst.

Winter windows: the figures at a glance

Source: YourHome, NSW Government

Windows are the weak point in both seasons. The government guidance comes down to three habits: open to the sun by day, close up at night, and keep air from slipping around the edges.

Start with your coldest room

If one room never quite warms up, start there. Note which way its windows face, whether they are single-glazed, and whether you can feel a draught at the frame on a cold night. Then book a measure and quote with Maitland Shutters, and we can talk through which shutters suit that window, how they would sit in the reveal, and how they fit with any draught-proofing or glazing plans you have. Our service areas page shows where we visit.

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