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Why internal blinds lose on a bifold
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A bifold is a large pane with a high g-value. Sunlight becomes heat once it is indoors, and a blind then has to cope with air that is already warm.
What the glass admits
The worked opening for Why internal blinds lose on a bifold is 4.2 m wide by 1.5 m high, 6.3 square metres of glass. This figure puts 595 watts per square metre on the pane and uses a g-value of 0.7, about 2624 watts into the room if the curtain is up. An opaque external shutter, taken as stopping 85 percent of that gain while it is fully down, leaves about 394 watts and keeps about 2230 watts out. That is a noon figure for comparison. An internal blind does not get the same reduction. For Why internal blinds lose on a bifold, use the noon figure to compare two openings on the same house, then let a measured survey replace the figure.
An internal blind does not get that reduction, because the energy has already crossed the glass.
The hot part of the day
An external curtain stops a large share of that energy before the glass. If the blind is the thing you already own, keep it for glare in the evening and stop asking it to cool July.
Dusk in January
Winter figure for Why internal blinds lose on a bifold: glass at 1.4 W/m2K, 6.3 square metres, a 12 degree inside-outside gap and eight night hours. The bare pane is about 0.85 kWh a night on that crude sum. A closed shutter cutting about 24 percent of the flow leaves 0.64 kWh and saves about 0.20 kWh a night, only while it is down. Open it when you want winter sun.
Leave it if
Stop Why internal blinds lose on a bifold if the solar panel would sit in a soffit with no sky, and the quote has no wired alternative. A photograph is not a manufacturing size.
Glasgow is only a setting for Why internal blinds lose on a bifold. The streets there are not the product.
How to use the figure
The 4.2 by 1.5 metre opening inside Why internal blinds lose on a bifold is there so a quote has something to disagree with. If the tape gives a different size, the tape wins.
The example drive is a wired motor, and the illustration is £4,636. A belt, a wired motor and a solar motor can share a curtain and still be different jobs. Compare those lines, not a single bold total.
What the survey still has to write down
For Why internal blinds lose on a bifold, ask where the box lands, what colour reference will be ordered, and how the curtain opens when the motor is dead. Those three answers move the job more than a rounded price.
Leave the lantern, the side light and the next elevation off the order unless they are drawn. Why internal blinds lose on a bifold covers one kind of opening. The house may have three.
When I would not order yet
Why internal blinds lose on a bifold should wait if the opening is an escape door with no way to raise a dead motor, or if the front is the elevation a conservation area was drawn to protect.
A photograph is not a manufacturing size. Two quotes for Why internal blinds lose on a bifold only compare when the slat, the box and the drive are the same kind of thing.
Questions worth asking the fitter
Is the price on this page a quote?
No. £4,636 illustrates Why internal blinds lose on a bifold for a 4.2 by 1.5 metre opening with a wired motor, at September 2026 rates. Your survey replaces it.
Does the shutter cover every pane?
It covers the opening it is built for. Here that example is 6.3 square metres. A roof lantern, a side light or the next elevation is another line.
What if planning is unclear?
Do not pay the factory for Why internal blinds lose on a bifold until a listed building, a conservation front, a flat or a shopfront has a written answer. Ordinary rear walls on houses are sometimes simpler.
What should two quotes share?
The same openings, the same slat type, and the same drive. Why internal blinds lose on a bifold uses a wired motor in the example so you can see how much the motor choice moves £4,636.