This article explores the double glazed vs single glazed windows cost debate, and how retrofit double glazing could be the smartest and most cost-effective option for Kiwi homes.
Understanding the Differences
What is Single Glazing?
Single glazed windows consist of a single pane of glass. While they’re still common in many older New Zealand homes, they are not energy-efficient and provide minimal insulation. As a result, single glazing contributes to higher energy bills, condensation problems, and year-round discomfort from drafts and heat loss.
What is Double Glazing?
Double glazing uses two panes of glass separated by a layer of air or gas that acts as insulation. This setup helps reduce heat transfer, prevents cold spots, and blocks out more noise.
Traditional double glazing involves removing and replacing your entire window unit. However, Magnetite’s retrofit system allows you to keep your existing windows, adding a secondary acrylic panel with a magnetic seal that creates a similar insulating effect.
Performance Factors to Consider
When comparing window glazing options, especially when looking at double glazed vs single glazed windows cost, consider:
- U-value: Measures heat loss. The lower the U-value, the better the insulation.
- Solar Heat Gain Coefficient (SHGC): Indicates how well the window blocks solar radiation.
- Acoustic rating: Important for homes near traffic, schools or industrial zones.
Magnetite’s retrofit system performs on par with many traditional double-glazed units and is tested to deliver up to 70% improvement in both thermal and acoustic performance.
Cost Factors Breakdown
Upfront Costs
- Single Glazing: Cheapest initially, as it involves no changes. However, this cost is often outweighed by higher heating bills over time.
- Double Glazing (New Install): Most expensive option. Full replacement involves removing the current frame, purchasing a new double-glazed unit, and completing joinery and finishing work.
- Retrofit Double Glazing: More cost-effective than replacement. Magnetite’s retrofit double glazing is customised to your home, allowing for installation without disrupting walls, sills, or heritage frames.
In fact, full replacement is typically 30–50% more expensive than retrofitting. The latter is quicker, cleaner and retains your existing window frames.
Running Costs
Double glazing significantly reduces the need for electric heating and cooling. With retrofit solutions, you retain those savings while avoiding full replacement costs. Over time, the energy savings can be substantial, particularly in colder regions like Wellington, Christchurch or inland Northland.
Most homeowners see a return on investment in 3 - 7 years depending on their energy use and climate, making retrofit a compelling financial case.
Maintenance and Lifespan
Double glazed units generally require little upkeep. Magnetite’s panels are made from high-quality acrylic, which is impact-resistant, UV-stabilised and long-lasting. With a 7-year warranty and proven durability, they’re a smart long-term investment.
Retrofit vs Full Replacement
Magnetite’s Retrofit System Explained
Rather than ripping out your existing windows, Magnetite’s system adds a discreet secondary glazing panel on the interior side. This forms an airtight pocket of still air, reducing heat loss and noise intrusion.
It’s also perfect for heritage and architecturally significant homes, as it preserves the original character without altering the window structure. The system is non-invasive and doesn't usually require building consent, making it easier and more accessible for many Kiwi homeowners.
Key Benefits
- No building consent required in most cases
- Preserves original character and framing (ideal for villas, bungalows, and heritage homes)
- Lower labour and installation costs
- Environmentally friendly with less construction waste
- Independently tested to reduce noise by up to 70%
Some councils and lenders also offer incentives or rebates for energy-efficiency upgrades, so it’s worth checking with your local authority or the Energy Efficiency and Conservation Authority (EECA) for eligibility.
Cost Comparison
Full replacement can cost between $15,000 - $20,000 for a standard 3-bedroom home. Retrofit double glazing typically falls between $8000 - $12,000 depending on the number of windows and their size. That’s a potential saving of up to 50%, with comparable performance benefits.
This makes the double glazed vs single glazed windows cost equation more favourable when retrofit is an option.
Long-term Value & Savings
Energy Efficiency
Improved thermal performance means you’ll rely less on heaters and air conditioning. Magnetite’s retrofit system can improve insulation by up to 70%, providing a more stable and comfortable indoor temperature all year round.
Noise Reduction
Whether you live near a motorway, busy road, or school, unwanted noise can disrupt sleep and concentration. Magnetite’s glazing reduces noise levels by up to 70%, creating a calmer, quieter home environment.
Property Value
Energy-efficient homes are more attractive to today’s buyers. Upgrading your glazing can help improve your property’s energy rating, reduce carbon emissions, and enhance resale potential.
Real-Life Cost Comparison: An Example
Let’s take the example of a 3-bedroom home with 10 windows:
- Single Glazing (leave as is): No upfront cost, but expect high heating bills - often exceeding $1500/year in colder areas.
- Full Replacement Double Glazing: $15,000 - $20,000
- Retrofit Double Glazing with Magnetite: $8000 - $12,000
With average energy savings of $400 - $700 annually, a retrofit installation could eventually pay for itself. Plus, you’ll gain the added benefits of comfort, noise control, and improved aesthetics.
When weighing double glazed vs single glazed windows cost, retrofit glazing provides a strong return on investment.
Why Choose Magnetite
Unique Benefits
- Custom-made for each window to ensure a perfect fit
- Delivers results similar to traditional double glazing at a lower cost
- Quick, clean installation process
- NZ-wide service with experienced local installers
- 7-year product warranty and 25+ years of industry experience in Australasia
With thousands of happy customers and proven results, Magnetite has become New Zealand’s trusted name in retrofit glazing.
Ready to Improve Your Windows?
If you’re looking for an affordable, energy-smart way to improve your home, retrofit double glazing could be the answer.
Book your free in-home measure and quote today. Our team will assess your windows and provide a tailored recommendation to suit your home, lifestyle, and budget.
Learn more about our residential retrofit glazing services or explore the full benefits of double glazing with Magnetite.
Looking to compare more solutions? Check out our blog: Windows for Better Home and Living
