Why Your Windows Are the Key to Energy Savings
Windows are the weakest point in any home's insulation. According to Spain's Institute for Energy Diversification and Saving (IDAE), between 25% and 30% of a home's energy losses occur through windows. This means that on an annual energy bill of €1,500, between €375 and €450 literally escapes through the windows.
In the climate of Granada and Malaga, where summers exceed 40 degrees and Granada winters drop below zero, efficient windows are not a luxury but a necessity. A home with old aluminium windows without thermal break can spend up to 60% more on climate control than one with modern windows.
At Tecnisun C.B., we have been manufacturing and installing high energy efficiency windows throughout Granada and Malaga provinces for over 30 years. As official STRUGAL manufacturers, we work with the most advanced aluminium RPT and PVC series on the market.
What Is the Uw Value and Why It Matters
The Uw value (thermal transmittance of the complete window) measures how much heat passes through the window. The lower the Uw value, the better the window insulates. It is measured in W/m²K (watts per square metre per degree Kelvin).
This value includes three components: the profile (Uf), the glass (Ug), and the perimeter spacer effect (Ψg). That is why improving only the glass or only the profile is not enough — the whole system must be optimised.
Window Classification by Uw Value
| Uw Value | Window Type | Performance |
|---|---|---|
| Above 3.0 W/m²K | Old aluminium without RPT | Very poor — Frequent condensation |
| 1.8 - 3.0 W/m²K | Basic improved windows | Insufficient for current CTE |
| 1.2 - 1.8 W/m²K | Quality aluminium RPT (STRUGAL S74RP/S88RP) | Good — Meets regulations |
| 0.8 - 1.2 W/m²K | High-end STRUGAL PVC | Excellent — Maximum savings |
| Below 0.8 W/m²K | PVC + triple glazing | Premium — Passivhaus standard |
Glass Types and Their Impact on Savings
Not all glass is equal. The right glazing choice can make up to a 30% difference in the window's energy performance:
| Glass Type | Approximate Ug | Features | Recommended For |
|---|---|---|---|
| Single (4 mm) | 5.7 W/m²K | No air chamber. Obsolete. | Nothing (fails CTE) |
| Double (4/16/4) | 2.7 W/m²K | 16 mm air chamber | Minimum required |
| Double low-e + argon | 1.0-1.1 W/m²K | Metallic coating + argon gas | Recommended standard |
| Double solar control + argon | 1.0-1.1 W/m²K | Reflects solar heat. Solar factor 0.3-0.5 | South and west-facing |
| Triple low-e + argon | 0.5-0.7 W/m²K | Maximum insulation | Cold zones, Passivhaus |
How Much Can You Really Save?
Real savings depend on several factors: the type of window being replaced, home orientation, climate zone, and your consumption habits. However, we can offer reliable estimates based on hundreds of projects completed in Granada and Malaga:
Savings by Zone and Scenario
| Scenario | Zone | Old windows (Uw ~5.7) | New PVC (Uw ~0.9) | Annual savings |
|---|---|---|---|---|
| 80 m² flat (6 windows) | Granada city | €1,800/year | €1,050/year | €750 |
| 150 m² house (12 windows) | Granada Vega | €2,800/year | €1,550/year | €1,250 |
| 90 m² flat (8 windows) | Malaga city | €1,600/year | €1,050/year | €550 |
| 200 m² villa (15 windows) | Costa del Sol | €3,200/year | €1,800/year | €1,400 |
Overall Estimated Savings
A typical 100 m² home with 8 windows can save between 500 and 1,050 euros annually on energy after replacing the windows. This means the investment pays for itself in 6 to 10 years, and from then on, it is pure savings for the remaining 40+ years of the windows' lifespan.
Return on Investment (ROI)
Investment
8 STRUGAL PVC windows with double low-e glazing: €5,500-7,000
Annual Savings
€700 (heating + cooling combined)
Payback Period
8-10 years without subsidy / 5-6 years with Plan Renove (40%)
Property Value
Energy rating jump: +5-15% increase in property sale value
Energy Certificate Impact
The energy performance certificate is mandatory for selling or renting property in Spain. Windows are one of the factors with the greatest impact on the rating. Upgrading from old aluminium to modern PVC can jump your rating by 3-4 letters (e.g., from F to B), increasing your property's valuation by 8% to 15%.
Granada and Malaga Climate: Why Efficiency Matters Even More Here
Andalusia has one of the widest thermal ranges in Spain. Granada city belongs to climate zone C3 (cold winters and very hot summers). Malaga, in zone A3, has mild winters but extremely hot summers with high humidity.
This duality makes investing in efficient windows especially profitable in our area, as you save on both heating and air conditioning. With over 2,800 hours of sunshine per year in Malaga, solar control glass is essential on south and west-facing facades.
Zone-Specific Recommendations
Granada City and Vega (C3)
Priority: winter thermal insulation. PVC with Uw ≤ 1.0. Double low-e glazing with argon. Solar control on south facade.
Malaga Coast (A3)
Priority: summer solar control. Solar control glass mandatory. Solar factor ≤ 0.40 on south/west. Ideal: aluminium RPT + solar control.
Sierra Nevada / Mountain (E1)
Priority: maximum insulation. PVC with triple glazing. Uw ≤ 0.8. Anti-corrosion hardware for altitude.
Malaga Interior (B4/C3)
Heat/cold balance. PVC or aluminium RPT per budget. Double low-e + argon minimum. SAXUN screen blinds for exposed facades.
Available Subsidies in Andalusia
Plan Renove
Up to 40% of cost, maximum €3,000 per home. 65% for low-income households.
Next Generation EU Funds
Up to 80% for complete building energy rehabilitation
Income Tax Deductions
20% to 60% depending on savings achieved. Compatible with Plan Renove.
At Tecnisun C.B. we help with all paperwork. We arrange the before and after energy certificates, prepare the necessary documentation, and advise you on the best combination of subsidies for your case.
Complementary Solar Protection
Efficient windows are the foundation, but to maximise energy savings, combine them with solar protection systems:
- SAXUN screen blinds: reduce solar gain by an additional 60-85%. External ZIP systems are 40% more efficient than interior ones.
- Motorised awnings: block direct radiation before it reaches the glass. Ideal for terraces and south-facing facades.
- SAXUN bioclimatic pergolas: adjustable louvres that regulate sun and ventilation. Reduce temperature by up to 10°C under the pergola.
Want to Reduce Your Energy Bills?
At Tecnisun C.B. we offer free energy audits of your current windows. We tell you exactly how much you can save with high-efficiency windows. Official STRUGAL manufacturers with over 30 years of experience. Request your free energy audit or call 627 84 14 04. Check prices on our online calculator.
See energy-efficient windows →Frequently Asked Questions
Is it worth replacing windows in a rental property?
If you are the landlord, yes: efficient windows allow higher rent (better energy certification) and prevent complaints about condensation or noise. If you are a tenant, talk to your landlord about available subsidies.
Can I replace just the glass without changing the frame?
Technically yes, but we do not recommend it for aluminium frames without thermal break. The old frame remains a thermal bridge causing condensation. The ideal approach is to replace the complete window.
How long until the investment pays for itself?
Between 5 and 10 years depending on the windows being replaced and subsidies applied. With Plan Renove (40% subsidy), payback can drop to 4-6 years. After that, it is pure savings for the remaining 40+ years of the windows' lifespan.
Energy Certificate: How Windows Affect Your Rating
The energy performance certificate is mandatory for selling or renting property in Spain. Windows are one of the most impactful factors. Upgrading from old aluminium without thermal break to modern PVC with low-e glazing typically jumps the rating by 3-4 letters (e.g., from F to B). According to property portal data for Granada and Malaga, this can increase your property's valuation by 8% to 15% — a significant financial benefit beyond energy savings alone.
The Importance of Professional Installation for Energy Performance
A window's rated Uw value is only achieved with correct installation. Poor installation can degrade thermal performance by 30-50%, negating much of the investment. Common errors include insufficient foam sealing around the frame (creating thermal bridges), incorrect shimming causing hardware misalignment and air gaps, and missing or damaged vapour barriers at the frame-wall junction.
At Tecnisun, our installation teams follow STRUGAL's official protocol with laser-level precision. Every installation is tested for airtightness before sign-off, and we provide a 10-year warranty on profiles and 5 years on hardware and installation.
Combining Windows with Solar Protection for Maximum Savings
Windows alone provide the foundation, but maximum energy savings come from a holistic approach. Our most successful projects combine efficient windows with complementary systems:
- Exterior screen blinds (ZIP): installed on south and west facades, these reduce solar heat gain by 60-85% before it reaches the glass — far more effective than interior blinds or curtains
- Bioclimatic pergolas: adjustable louvres provide shade in summer and allow solar gain in winter, adapting to seasonal needs automatically
- Upgraded shutter boxes: the shutter box above the window is often the weakest insulation point. Modern insulated boxes can improve the window zone's overall Uw by 15-25%
The combined effect of efficient windows + exterior solar protection + insulated shutter boxes can reduce energy consumption by up to 55-65%, compared to 25-40% for windows alone.
Want to Know How Much You Can Save?
Replacing your windows in Granada or Malaga is not an expense — it is an investment that pays for itself. We offer a free energy assessment and no-obligation quote. Use our online calculator for an initial estimate.
Request free energy assessment →