More Information on Thermal Lining
Thermal curtains are specially designed curtains that help regulate the temperature of a room by reducing heat loss in winter and blocking out excess heat in summer. If you're a buyer considering purchasing thermal curtains, here's what you need to know:
GTOT (G-value) and Solar Gain:
When purchasing thermal curtains, it's important to look for curtains with a low GTOT (G-value). GTOT or solar gain is the amount of heat that passes through a window into a room. The lower the GTOT, the less heat will enter the room, resulting in cooler temperatures in the summer. In winter, you want curtains with a high GTOT value to allow more heat to enter the room, which helps keep the room warm.
Thermal Insulation of Direct Fabrics Curtain Lining:
Direct Fabrics Curtain Lining is a 3 pass blackout lining that provides a 320 per cent reduction in heat loss through windows. This means that the lining helps to retain heat in the room, reducing the amount of energy needed to heat the room. This lining is especially useful in colder climates, where it can significantly reduce energy bills and help keep homes warm.
In summary, when purchasing thermal curtains, pay attention to the GTOT (G-value) and choose curtains with a low GTOT for summer and a high GTOT for winter. Additionally, consider Direct Fabrics Curtain Lining to provide extra thermal insulation and help reduce heat loss through windows. With these factors in mind, you can choose the perfect thermal curtains to keep your home comfortable all year round while saving on energy costs.
Why Choose Direct Fabrics Thermal Lining
Direct Fabrics 3 Pass Lining is designed to provide both thermal insulation and light-blocking capabilities to curtains. The ivory colour of the lining gives it a low GTOT, making it effective at reflecting sunlight and preventing excess heat from entering the room during the summer months. Meanwhile, the thickness of the lining helps to retain heat in the room during the winter, reducing heat loss through the windows and keeping the room warm.
To keep a room cool in summer with thermal curtains, it's important to close the curtains during the hottest part of the day, typically midday to late afternoon. This will prevent excess heat from entering the room and keep the room cooler. Choosing curtains with a low GTOT, such as those with Direct Fabrics 3 Pass Lining, will also help to reflect sunlight and prevent heat from entering the room.
To keep a room warm in winter with thermal curtains, close the curtains at night to prevent heat from escaping through the windows. Choosing curtains with a high GTOT, such as those without a lining or with a thin lining, will also help to allow more heat to enter the room through the windows.
Thermal curtains are designed to stop heat energy entering a space and the heat/cold escaping from a space. If you are using them in your home they complement your windows to create a further barrier to the outside.
Why Use thermal Curtains
Thermal curtains add a level of insulation to the space and work to keep your space:
● Warm and comfortable in the winter
● Cooler in the summer
Understanding Thermal Acronyms and information
When talking about thermal properties there are a variety of words used and these combine to provide the thermal information of the fabrics used.
U-value is a measure of thermal transmittance which is the ability of a material to transfer heat. All elements of a building have U-values for example walls, windows and other insulation materials such as plasterboard. The lower the U-value, the lower the heat loss through that particular material. Therefore a material with a low U-value is a good insulator. The U-value of glazing is always improved by installing blinds.
Understand Gtot
Total solar energy transmittance (gtot) relates to the performance of solar protection devices such as blinds or curtains and is the percentage of solar energy incident on the fabric of a blind or curtains that are transmitted to the interior of the building, including both the transmittance of the solar protection device itself and of the window glazing.
The lower the g-value (or gtot), the lower the heat gain. The value of gtot is between 0 and 1, where 0 equates to no radiation being transmitted into the room and 1 means all radiation (100%) is transmitted. So a gtot of 0.25 (25% heat gain, 75% heat rejection) reduces heat gain three times more effectively than a gtot of 0.75 (25% heat rejection). External shading helps to significantly reduce gtot values and has a much more significant impact on gtot than internal shading.
Although the levels of Reflectance (Rs), Transmittance (Ts) and Absorbance (As) can vary depending on the type of material, its colour, thickness, etc., their total will always add up to 1
What is the goal of thermal curtains
The goal when using thermal curtains is to reduce the solar transmittance into the space and as such reduce the amount of solar energy passing into the building and in turn keep the room cooler in the summer.
The opposite is also the case when trying to keep heat inside a room. We want to stop the transmittance of energy passing back out of the window. So again putting a fabric between the room and the window will reduce heat loss through the window.
To maximise the thermal benefits within your space your should do the following
Summer
● Close the blinds at night on the east-south elevations to protect from early morning heat gains
● Open the blinds at night on the west and north-west elevations to assist night-time cooling
Winter
● Close the blinds after the sun goes down to retain heat
●On Sunny days open the blinds during the daytime to maximise heat gain from the winter sun and close the blinds at night.
Winter Blinds in unoccupied rooms should always be closed.
Heat Loss Through Windows
● Conduction – direct loss of heat through the window to the outside
● Convection - where the warm air in the room hits the cold surface of the glass and cools the air inside the room
● Radiation and Re-radiation - this is where the cold surface of the glass absorbs the heat from inside the room
● Air leakage – heat lost through cracks in the frame or from around poorly fitted glazing
Improvements in Blinds When Using A Blind:
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Clear Single Glazing
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Double Clear Glazing
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Double Glazing with Low emissivity
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Glass Alone
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U=5.8 W/m2K
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U=2.9 W/m2K
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U=1.1 W/m2K
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High Air Permeability
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4
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2.4
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1
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Average Air Permeability
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3.5
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2.2
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1
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Low Air Permeability
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3.2
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2.1
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1
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Percentage Improvement
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Glass Alone
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5.8
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2.9
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1.1
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High Air Permeability
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31%
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17%
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9%
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Average Air Permeability
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42%
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24%
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9%
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Low Air Permeability
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45%
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28%
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9%
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Credits and BBSA website for this information:
https://www.shadeit.org.uk/wp-content/uploads/2016/09/BBSA-Guide-to-low-energy-shading.pdf
