Local Shutter InstallersMyths · Ruling
The myth of a guaranteed temperature drop
Updated
No serious fitter can promise your kitchen will be 8 degrees cooler. They can promise a solid external curtain will stop most of the solar energy while it is down, on glass that would otherwise let it in.
What is being claimed
The thermometer then depends on how hot the room already was, how long you shaded it, and whether you ventilated.
The illustration beside the claim
The worked opening for The myth of a guaranteed temperature drop is 1.8 m wide by 1.5 m high, 2.7 square metres of glass. This figure puts 520 watts per square metre on the pane and uses a g-value of 0.63, about 885 watts into the room if the curtain is up. An opaque external shutter, taken as stopping 80 percent of that gain while it is fully down, leaves about 177 watts and keeps about 708 watts out. That is a noon figure for comparison. An internal blind does not get the same reduction. For The myth of a guaranteed temperature drop, 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.
A night cover is not a consent
Winter figure for The myth of a guaranteed temperature drop: glass at 1.2 W/m2K, 2.7 square metres, a 12 degree inside-outside gap and eight night hours. The bare pane is about 0.31 kWh a night on that crude sum. A closed shutter cutting about 18 percent of the flow leaves 0.26 kWh and saves about 0.06 kWh a night, only while it is down. Open it when you want winter sun.
Paper before manufacture
Stop The myth of a guaranteed temperature drop if the frame cannot take a guide and the wall beside it is crumbling. A photograph is not a manufacturing size.
Newcastle is only a setting for The myth of a guaranteed temperature drop. The streets there are not the product.
How to use the figure
The 1.8 by 1.5 metre opening inside The myth of a guaranteed temperature drop 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 belt, and the illustration is £1,799. 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 The myth of a guaranteed temperature drop, 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. The myth of a guaranteed temperature drop covers one kind of opening. The house may have three.
When I would not order yet
The myth of a guaranteed temperature drop 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 The myth of a guaranteed temperature drop 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. £1,799 illustrates The myth of a guaranteed temperature drop for a 1.8 by 1.5 metre opening with a belt, 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 2.7 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 The myth of a guaranteed temperature drop 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. The myth of a guaranteed temperature drop uses a belt in the example so you can see how much the motor choice moves £1,799.