Thermal Windows and Doors

Thermal windows and doors, characterised by their enhanced insulation properties, are becoming increasingly prevalent as key elements in modern architectural designs. They are recognised for their ability to maintain indoor temperature levels, thereby contributing significantly to the energy efficiency of buildings. At JL Windows and Doors, we specialise in the customisation, installation, and replacement of thermal windows, offering tailored solutions that align with this emerging trend towards enhanced energy efficiency and sustainability in building design.

What are thermal windows or thermally broken windows?

Thermally broken windows are an advanced type of window frame construction designed to significantly reduce heat transfer across the window frames, improving thermal insulation properties and energy efficiency in buildings. The “thermal break” refers to the inclusion of a non-conductive material between the inside and outside aluminium profiles of the window frame, effectively interrupting the thermal pathway.

How thermal windows work?


Thermal windows are constructed with an aluminium frame that is divided into two separate interior and exterior pieces. Between these two aluminium components, a non-metallic insulator or thermal break is inserted. This material is typically made from polyamide or reinforced polyurethane, known for its low thermal conductivity.

Thermal Break

The thermal break acts as a barrier that prevents the transfer of thermal energy (heat or cold) through the aluminium frame. Aluminium, while strong and durable, is a highly conductive material that can easily transfer outdoor temperatures to the interior of a building. The thermal break stops this process, helping to maintain consistent indoor temperatures.

Energy Efficiency

By interrupting the heat transfer, thermal windows reduce the demand on heating and cooling systems within a building, leading to lower energy consumption and costs. They contribute to a building’s overall energy efficiency and comfort.

Our thermal windows and doors

Thermal Windows

Thermal Doors

Thermal Hardware

Benefits of Thermal Windows

Improved Insulation

Thermal windows offer better insulation against heat and cold, making them ideal for areas with extreme weather conditions.

Energy Savings

With improved thermal efficiency, they can significantly reduce energy bills by minimising the need for heating and cooling.

Condensation Reduction

They help to reduce the risk of condensation forming on the inside of the window frames, which can lead to mold and mildew problems.

Sound Insulation

The thermal break can also improve sound insulation, reducing the level of outside noise that enters the building.


Aluminium frames are known for their durability and resistance to corrosion, making them a long-lasting window option.

Thermally broken windows represent a blend of technology and design to improve living and working environments by offering superior thermal insulation without sacrificing the strength and durability that aluminium frames provide. They are particularly suited for modern constructions that require high energy efficiency standards and aesthetic flexibility.


When selecting thermal windows for a building, several factors should be considered to ensure optimal performance and efficiency. These include the window’s U-factor, which measures how well it insulates against heat loss; the solar heat gain coefficient (SHGC), which indicates how much solar heat the window allows into the building; the window’s air leakage rate, which affects energy efficiency and comfort; and the framing material, which can impact durability, maintenance requirements, and overall energy performance. Additionally, factors such as orientation, shading, and local climate conditions, should also be taken into account to maximize the benefits of thermal windows.

If you live in a climate with extreme temperature fluctuations or high energy costs, thermal windows can be a worthwhile investment. if your existing windows are old, single-pane, or drafty, upgrading to thermal windows can significantly improve your home’s energy efficiency and comfort. Consult with a professional window installer or energy efficiency expert to assess your home’s specific needs and determine whether thermal windows are a suitable solution.

While the initial cost of thermal windows may be higher than traditional windows, they often provide long-term cost savings through reduced energy bills. Furthermore, many utility companies offer rebates or incentives for installing energy-efficient windows, which can help offset the upfront cost. When considering the investment in thermal windows, it’s essential to factor in the potential energy savings over the lifespan of the windows, as well as the added comfort and value they bring to your home.

Regular maintenance is crucial to ensure the continued efficiency and functionality of thermal windows. Keep the window frames and tracks clean and free of debris, and inspect for any signs of damage or deterioration, such as cracked seals or fogging between the panes. Seal any gaps or cracks around the window frames to prevent air leaks, and consider adding weather-stripping or caulking if necessary. In addition, avoid using abrasive cleaners or harsh chemicals on the glass or frames, as these can damage the window’s coatings and seals. Finally, if you notice any issues with your thermal windows, such as drafts or condensation, contact a professional window installer for repairs or replacement.

JL’s Thermal Windows are engineered with cutting-edge technology to provide superior insulation against heat transfer, ensuring optimal energy efficiency for your space. Unlike traditional windows, which can contribute to heat loss or gain, JL’s Thermal Windows feature advanced materials and construction techniques that minimize thermal conductivity. This means they help maintain consistent indoor temperatures year-round, reducing the need for heating and cooling and ultimately lowering energy costs. These windows offer exceptional durability and longevity, making them a smart investment for both residential and commercial applications.