Best Time to Buy and Install Windows: A UK Homeowner’s Guide

Best Time to Buy Windows

Winter Deals & Off-Season Discounts

• Winter is typically the slowest season for window companies, which can mean better pricing and promotions.
• Vendors are looking to fill their schedules, so you may have more room for negotiation.
• Downside: Installation in extreme cold can make sealing more challenging.

Spring & Autumn: The Installation Sweet Spot

• Milder temperatures make for ideal conditions for window installation.
• Less strain on your heating system while installers work.
• Less likelihood of weather-related delays compared to winter.
• Downside: Demand starts rising in these months, so prices may not be as flexible as in winter.

Summer: High Demand, Faster Installations

• Many homeowners schedule renovations during summer, meaning window companies are busier.
• Warm weather allows for quick and efficient installation.
• Downside: Higher demand can mean longer wait times and fewer discounts.

Best Time to Install Windows

• Ideal Temperature Ranges: Spring and autumn, when temperatures are typically between 10°C and 20°C, offer optimal conditions for installation.
• Plan for Delays: Many window manufacturers have lead times of 7–12 weeks before the windows are ready. Ordering in late autumn for an early spring install is a solid strategy.
• Avoid Extreme Weather: Installation can technically happen in any season, but extreme temperatures can affect the materials used.

Key Aspects of Installation:

• Proper Flashing: Ensures water is directed away from the window opening, preventing leaks.
• Sealing: High-quality expanding foam tape, EPDM membranes, and low-expansion foam insulation create an airtight fit to prevent draughts.
• Insulation: Insulated frames and correctly installed glazing improve energy efficiency and reduce heat loss.

Check U-Value and Energy Efficiency

Understanding U-Value

• The U-value measures how well a window prevents heat from escaping. The lower the U-value, the better the insulation.
• Windows with a Uw-value of 1.4 W/m²K or lower meet current building regulations, but for maximum energy savings and reduced bills, aim for windows with a U-value below 1.0 W/m²K.

Quantifying Savings

• A-rated windows can reduce heat loss by up to 75% compared to single glazing.
• This could translate to savings of £900 to £1200 per year on your heating bills, depending on home size and energy prices.

Why Lower U-Values Matter

Lower U-values mean less heat can escape through the window, reducing the workload on your heating system and therefore lowering your energy bills.

Window Energy Rating (WER) Explained

The WER system grades windows from A++ (most efficient) to G (least efficient). A++ rated windows offer the highest level of energy efficiency, significantly reducing heat loss and improving home comfort. G-rated windows, on the other hand, provide minimal insulation, leading to higher energy bills. Aim for A-rated windows or higher to maximise savings.

Other Energy Efficiency Metrics:

• Solar Heat Gain Coefficient (SHGC): Measures how much solar radiation a window allows through. An SHGC of 0.5 or lower is recommended for UK climates.
• Air Leakage (ACH - Air Changes per Hour): New windows should have an ACH of less than 0.3 to ensure minimal draughts and improved energy efficiency.

Planning and Budgeting for Window Replacement

• Set a Realistic Budget: Consider the cost of materials, labour, and necessary upgrades.
• Prioritise Needs vs. Wants: Replace windows that are damaged or impacting energy efficiency before cosmetic upgrades.
• Long-Term Value: Investing in higher-quality, energy-efficient windows can lead to greater savings over time.
• Get Quotes for Different Window Types: Comparing options like uPVC, timber, aluminium, and composite windows can help balance cost, performance, and durability.

Window Maintenance Tips

• Clean Regularly: Use mild soap and water to clean the glass and frames, avoiding harsh chemicals.
• Lubricate Hinges & Locks: Apply a silicone-based lubricant to moving parts to ensure smooth operation.
• Check Seals & Weather Stripping: Inspect for cracks or gaps and replace as needed.
• Inspect for Damage: Look for any cracks, warping, or condensation between panes.
• Check for Condensation Between Panes: This indicates insulation failure and requires glass replacement.
• Professional Servicing: Consider an annual professional check-up for hidden issues.

Final Thoughts

The best time to buy and install windows depends on your priorities. If you want the best deal, winter may be your best bet. If you want the smoothest installation process, spring and autumn offer optimal conditions. Whatever you decide, planning ahead and vetting your installer carefully will ensure you get the best results for your investment.