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ENERGY EFFICIENCY & U-VALUE PERFORMANCE
At Best Deal Windows, we proudly supply and install window and door systems manufactured with the highest industry standards. Partnering with Selecta Systems, we offer Eurolook70 profiles combined with Thermaglas sealed units to deliver exceptional thermal efficiency and compliance with current UK Building Regulations.
Our multi-chambered window and door profiles, in combination with 40mm triple glazing (TGU) or 28mm double glazing (DGU), can achieve U-values as low as 0.8 W/(m²K). These performance levels help homeowners reduce energy bills, improve comfort, and meet sustainability targets.
DOCUMENT L — Future Homes Standard Compliance
Our products fully comply with Document L, ensuring energy efficiency standards are met for both new and existing homes.
New homes now require:
✓ Windows: U-value ≤ 1.2 W/(m²K)
✓ Doors: U-value ≤ 1.2 W/(m²K)
For existing homes:
✓ Replacement windows must meet at least 1.4 W/(m²K)
✓ Replacement doors (with >60% glass) must also meet at least 1.4 W/(m²K)
DOCUMENT F — Ventilation Requirements
As of June 2022, homes must have background ventilators with trickle vents unless other adequate systems exist.
✓ Kitchens/Living Rooms: 8000mm² (2 EA)
✓ Bathrooms/Toilets: 4000mm² (1 EA)
Stricter requirements may apply where natural ventilation is limited.
2022 BUILDING REGULATION CHANGES
As of 15 June 2022, updates to Part L and F require:
-
Lower U-value limits for both new and existing homes
-
Mandatory background ventilation
-
Full compliance with carbon efficiency targets
SUPPORTING THE NET ZERO 2050 GOAL
Best Deal Windows is committed to the UK government's goal of achieving net zero carbon emissions by 2050. By offering energy-efficient windows and doors, we help reduce overall carbon impact, support sustainable building practices, and future-proof properties against tightening regulations.
WHY CHOOSE US?
✓ A-rated systems with U-values as low as 0.8
✓ Fully compliant with Document L & F
✓ Expert installation with technical support
✓ Ideal for new builds and renovations
✓ Environmentally responsible solutions
📞 Contact us today to discuss your project requirements or request technical documentation.
At Best Deal Windows, we proudly supply and install window and door systems manufactured with the highest industry standards. Partnering with Selecta Systems, we offer Eurolook70 profiles combined with Thermaglas sealed units to deliver exceptional thermal efficiency and compliance with current UK Building Regulations. Our multi-chambered window and door profiles, in combination with 40mm triple glazing (TGU) or 28mm double glazing (DGU), can achieve U-values as low as 0.8 W/(m²K). These performance levels help homeowners reduce energy bills, improve comfort, and meet sustainability targets. [...]DOCUMENT L — Future Homes Standard ComplianceOur products fully comply with Document L, ensuring energy efficiency standards are met for both new and existing homes.New homes now require:
Windows: U-value ≤ 1.2 W/(m²K)
Doors: U-value ≤ 1.2 W/(m²K)
For existing homes:
Replacement windows must meet at least 1.4 W/(m²K)
Replacement doors (with >60% glass) must also meet at least 1.4 W/(m²K)
DOCUMENT F — Ventilation RequirementsAll replacement and new-build installations follow Document F, which requires background ventilation to ensure healthy air flow:
Trickle vents must be fitted regardless of whether existing windows had vents
Minimum vent sizes per room type:
Kitchens/Living Rooms: 8000mm² (2 EA)
Bathrooms (with or without toilet): 4000mm² (2 EA)
For new homes with natural ventilation, stricter requirements apply based on layout and air tightness.--- 2022 BUILDING REGULATION CHANGES As of 15 June 2022, updates to Part L and F require: - Lower U-value limits for both new and existing homes - Mandatory background ventilation - Full compliance with carbon efficiency targets Our windows and doors are manufactured in line with these updated standards, helping customers stay compliant while reducing energy use. --- SUPPORTING THE NET ZERO 2050 GOAL Best Deal Windows is committed to the UK government’s goal of achieving net zero carbon emissions by 2050. By offering energy-efficient windows and doors, we help reduce overall carbon impact, support sustainable building practices, and future-proof properties against tightening regulations. --- WHY CHOOSE US? ✔ A-rated systems with U-values as low as 0.8 ✔ Fully compliant with Document L & F ✔ Expert installation with technical support ✔ Ideal for new builds and renovations ✔ Environmentally responsible solutions Contact us today to discuss your project requirements or request technical documentation.
DOUBLE SASH OPENING WINDOWS




They are used in double sash or no-mullion profile windows and doors. A sash adaptor profile called moving-mullion profile has been connected to one of the vertical parts of the sashes that open to right or left where the two sashes are joined. This sash is called the passive sash and it is initially closed during closing and is opened after the opening. The passive sashes operate like single opening windows. The active sash may operate as single opening window, double opening window or lockable door depending on the customer's request.
It is possible to implement three types of double opening sash window depending on the mechanism of the passive sash.
1. Shoot Bolt Fitted System: Two sliding locking systems are connected on top and in the bottom in the vertical profile of the passive sash fitted with an adaptor profile. In this application which is generally used in doors, the handle is single and is located on the active sash. While opening the window, the active sash is initially opened by means of the handle. Then, the lower and upper slides are retracted to ensure that the passive sash is opened. The shoot bolt locking system is controlled with the opening-closing handle or traction latches in different models. In the closing action, initially the passive sash is suppressed by being manually pushed towards the frame. The handle of one of the lower or upper slides is turned to the closed position while the suppression is on the passive sash to ensure that the sliding prowl is secured on its rest Then, the other shoot bolt sliding handle is turned to the closed position and it is ensured that the passive sash is closed.
As for the closing of the active sash, it is closed in a way as similar to the single opening window, double opening window or lockable doors due to its internal espagnolette. Make sure that the sliding pawls are fully secured in their slots on the rests while the passive sash is being closed. Trying to close the active sash before the slides are fully closed will cause the locking action not to take place. The sashes may seem like they have been closed by turning the handle. However, it can be seen that the two sashes are easily opened from the middle later on or in frame of coercion from outside. Please do not turn the slide handles to the closed position while the sashes are open. If it is forgotten in this position and is attempted to be closed, the slides or their rests may be damaged. Shoot bolt-fitted system is a system with low isolation and high risk for double sash opening windows since it is not possible to ensure locking in the horizontal parts of sashes.
2. Double-Levered System: These are systems that are operated via control with the handle after installation of an espagnolette also in the passive sash. The handle on the passive sash activates the espagnolette and the passive sash is locked on its lower and upper horizontal parts. Therefore, it is slightly more advantageous in terms of isolation as compared to shoot bolt systems. Passive sashes are hinged and they are used entirely in the same way as the single opening windows. While the sashes are closed, it is not certain which one is active and should be opened beforehand. However, it is identified via method of trial and error. It is possible that the equipment will be harmed during this operation. Do not attempt to open double-handle, double-sash windows without know which one is the active sash, do not open or close the handles at the same time. The handles on sashes being close to one another may potentially cause fingers to be compressed. First, hold the passive sash by the arm, push it to make it rest against the frame and turn the handle. The handle is in the closed position while it is in vertical mode. As for the closing of the active sash, it is closed in a way as similar to the single opening window, double opening window or lockable doors due to its internal espagnolette.3. Adaptor-Fitted Espagnolette System: These are the most appropriate espagnolette systems designed and developed for double sash opening systems. The handle Is on the active sash. The upper and lower horizontal parts of passive sash and the vertical part to which the sash adaptor profile is connected is completely surrounded by an espagnolette assembly. They have their own proprietary hinges. Since the passive sash equipment looks just like the double opening window equipment when the sashes are closed, namely, it is seen as if it is a double opening system upon looking inside through the window in the closed position -if the active sash is double opening-, it constitutes a fully symmetrical image. To make sure that the passive sash is closed, it is necessary to push the sash towards the frame manually, to exert pressure on the gasket, then to push forward the lever or switch in open position close to the lower corner on the sash adaptor profile in order to switch it to closed position. This switch on the passive sash will pass above and under the sash adaptor profile conveying the movement to horizontal parts, thus ensure perfect locking in place. The number of locking actions will increase depending on the size of sash dimensions. As for the closing of the active sash, it is closed in a way as similar to the single opening window, double opening window or lockable doors due to its internal espagnolette. While opening the double sashed and adaptor-fitted espagnolette system, the active sash is initially opened by turning the handle on which it is located from the vertical-closed position to the horizontal position that is parallel to ground. The lever or adaptor switch that remains hidden between the two sashes in closed position will be exposed on the passive sash. The passive sash is opened by pulling the switch towards oneself. Do not turn the passive sash switch to closed position while the sashes are In open position. Do not attempt to close your window if it was turned to the close position in any particular way. Make sure that the switch remains in the closed position after closing the passive sash.When double sash opening windows are opened, they become ideal windows for situations where wide ventilation areas are required. To be able to meet adequate and necessary isolation values as required by the system, it may be perceived as if the sashes are being strained since the pressure on gaskets of double sash opening windows is a bit too high. This situation is normal for such types of windows and doors. Prevent the sash connected to the vertical part of the passive sash as well as the covers located on the upper and lower parts of the adaptor profile from during cleaning or due to any other reasons. Otherwise, the isolation will be disrupted, incursion of water and wind may occur from beneath the sashes. More dangerously, the support plate inside the sash adaptor file will be corroded more rapidly since it will contact air and rain. Please contact your window manufacturer if the small covers are not in place.