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How to Replace Windows? A Complete Guide to Choosing and Installing Energy-Efficient Joinery

In many older buildings, windows no longer meet modern energy efficiency or security standards. Technological advancements in window design now offer significantly better performance, but to benefit, homeowners must consider a full window replacement. This guide explains what to focus on when replacing windows and how to choose the best window solutions for your home.

Why Replace Your Old Windows?

Windows installed in homes built several decades ago often lack proper insulation, durability, and noise reduction. Replacing outdated window joinery improves thermal comfort, reduces energy bills, and enhances the visual appeal and security of your property.

1. Choose the Right Glazing

Since glazing can account for up to 85% of a window’s surface, it’s the most crucial factor in determining performance. Here’s what to pay attention to:

• Thermal insulation (Ug value): This indicates how much heat escapes through 1 m² of glass. The lower the value, the better the insulation.
• Noise reduction: High-performance glazing helps block out external noise—a vital feature for urban areas or noisy neighborhoods.
• Light transmission (Lt value): A higher value means more natural light inside, positively affecting mood and reducing the need for artificial lighting.
• Safety glazing: Choose glass with increased resistance to break-ins. While no glass is entirely burglar-proof, stronger glass significantly slows down intruders.

For enhanced security, integrated alarm sensors can be installed directly during production, allowing seamless integration with your home security system.

2. Window Frame Material: Aluminium vs. PVC vs. Timber

When selecting new windows, materials matter:

• PVC Windows: Known for excellent insulation and cost-efficiency, ideal for residential homes.
• Aluminium Windows: Preferred for large-format glazing and modern architectural designs due to their strength and sleek look.
• Timber Windows: Though aesthetically pleasing, they are more expensive and require more maintenance, which is why they’re less commonly chosen.

Each material has different thermal and structural properties, so select according to your design preferences, budget, and energy goals.

3. Security Features: Burglar-Resistant Windows

Anti-burglary windows combine several elements:

• Laminated or reinforced glass.
• Special security hardware with multiple locking points and reinforced hinges.
• Professional installation ensuring there are no gaps or weak points.

Always verify the burglary resistance class of both glazing and fittings. Windows equipped with additional sensors and certified hardware provide higher protection and peace of mind.

4. Energy Efficiency: Go Green with Eco Windows

Energy-efficient windows help reduce heat loss and lower heating bills. Here’s what defines an eco-friendly window:

• Triple glazing with low-emissivity coatings.
• Gas-filled chambers (argon or krypton) between panes.
• Low Uw value (below 0.9 W/m²K, preferably even 0.75).
• Deep and wide profiles to accommodate larger glazing packages and improve thermal resistance.
• High solar energy transmittance (g-value) to utilize passive solar heat gain in colder months.

Proper window orientation also plays a role—southern-facing windows offer better natural light and solar heat, while windows on the northern side are less energy-efficient.

5. Professional Installation Matters

Even the most advanced window won’t perform well if it’s poorly installed. Thermal bridges, air leaks, or misalignments can undermine insulation performance.

• Use experienced installers familiar with the product.
• Ensure airtight fitting and correct use of sealing materials.
• Follow manufacturer guidelines for optimal results.

6. Costs and Timeline for Window Replacement

The cost of replacing windows depends on:

• Number and size of windows
• Type of glazing and profile materials
• Window style (e.g., balcony, roof, fixed, sliding)
• Custom features like anti-burglary or thermal glass

On average, replacing all the windows in a home is a major investment—but one that increases energy efficiency, comfort, and property value. Replacing a few windows can often be done in a single day, depending on project scope.

7. Choose a Trusted Window Manufacturer

Always work with a reliable supplier. A good manufacturer will:

• Offer tailored advice and technical support
• Ensure product compatibility across your entire joinery system
• Provide warranties and certifications for energy and safety standards

For best results, purchase all windows and doors from the same supplier to ensure design consistency and installation efficiency.

Conclusion

Window replacement is a smart investment with long-term benefits. From energy savings to enhanced security and comfort, new windows can transform your living space. Make sure to evaluate glazing performance, materials, installation quality, and supplier reputation to make the best decision for your home.

https://www.thisoldhouse.com/windows/21016627/how-to-install-replacement-windows

A Step-by-Step Window Replacement Guide | Glass Doctor