Thermal break aluminium windows: what it is and when it pays
"Con RPT" or "sin RPT" is one of the first things you will see on a Spanish quote for aluminium windows, and it explains a big part of the difference in price and comfort. Here is what it means, how you notice it in a home on the Alicante or Murcia coast and when it is worth paying for.
Updated 19/10/2026
What a thermal break is
Aluminium conducts heat and cold very well. In a standard aluminium window the profile is one metal piece running from outside to inside, so in winter the inner frame is almost as cold as the street and in summer almost as hot. That is a thermal bridge: a direct path for heat.
A thermal break (in Spanish rotura de puente térmico, RPT) cuts that path. The profile is made in two parts, outer and inner, joined by polyamide strips, a material that hardly conducts heat. It is still aluminium on both faces, but there is no continuous metal path between the street and your living room.
What changes at home
- A warmer frame in winter: the inner profile stays close to room temperature, so far less condensation forms on the frame and less mould in the corners.
- Less heat in summer: a standard aluminium frame in the sun can be too hot to touch from inside; with a thermal break you feel the difference with your hand and on the air-conditioning bill.
- Better sound insulation: thermal break profiles are usually deeper and take thicker or acoustic laminated glass.
- A tighter seal: thermal break ranges usually have better gaskets and hardware, so less air gets through.
As a rough guide: a standard aluminium frame has a thermal transmittance of about 5.5–7 W/m²K, a thermal break usually brings it down to 2–3.5 W/m²K, and a good multi-chamber PVC frame is below 1.6 W/m²K. The lower, the better. Glass matters even more: double glazing with low-e glass insulates far better than single glazing, and a thermal break makes sense precisely with good glass.
Thermal break aluminium, standard aluminium or PVC
- Standard aluminium (no thermal break): the cheapest. It makes sense in storerooms, garages, terrace enclosures that are not heated or cooled, and summer-only holiday homes.
- Thermal break aluminium: the aluminium choice for a home you live in. Slim profiles, any powder-coated colour and large sliding patio doors with 3 or 4 panels.
- PVC: the best insulation for the money, and it does not corrode in salty air. Ideal for bedrooms, bathrooms and sunny façades. More in PVC or aluminium?
Is it worth it on the Alicante and Murcia coast?
The coast has mild but damp winters and long, hot summers, so you notice a thermal break more in summer and in humidity than in heating. From our experience:
- Yes for a home you live in, for living rooms with big sliding doors facing south or west, and for homes with air conditioning.
- Yes if you already get water on the frames and black spots every winter.
- Maybe not for a terrace or balcony enclosure that is not heated or cooled: standard aluminium or a glass curtain is usually enough there.
Also, Spain's building code sets minimum insulation values for new builds and for renovations that change the façade, and tax deductions and grants for new windows usually require a proven energy improvement, which is hard to achieve with standard aluminium.
What to ask for in the quote
- A clear "con RPT" (thermal break) and the polyamide strip width or the frame transmittance (Uf).
- The exact glass: cavity, low-e or solar control, laminated on the ground floor or with children at home.
- Whether it includes measuring, removal of the old window, fitting, sealing and VAT (IVA).
- The colour inside and outside: with a thermal break each face can have a different colour.
- Lead time and guarantee.
How we can help
- We make thermal break aluminium and PVC windows and sliding doors in our San Fulgencio workshop and fit them with our own team. We speak English.
- See the indicative prices and compare materials in the price calculator in a minute.
- We work in Torrevieja, Orihuela Costa, Elche, Alicante and the whole Vega Baja, with free measuring within 30 km of the workshop.
Frequently asked questions
How do I know if my windows have a thermal break?
Look at the edge of the profile with the window open: if a strip of dark plastic separates the outer and inner aluminium, it has a thermal break. If it is solid metal from side to side, it does not. Another clue: in winter a frame without a thermal break is icy and wet.
How much more does a thermal break window cost?
It depends on the range, size and glass, but thermal break aluminium usually costs noticeably more than standard aluminium and somewhat more than equivalent PVC. The calculator shows indicative prices for PVC and aluminium for your size.
Does a thermal break sliding door insulate as well as a casement window?
Less than a tilt-and-turn window of the same material, because the panels slide and seal with brushes. Even so, a good thermal break sliding door with double glazing is far better than an old one with no thermal break and single glass.
Can I just put double glazing in my old aluminium window?
Sometimes, if the profile takes the thickness, but the frame will stay cold and wet. You improve the glass, not the window. If the window is old or closes badly, replacing it usually pays.
Is building work needed to switch to thermal break windows?
Usually not. We remove the old window, fit the new one in the same opening and seal it. A standard window is replaced in a few hours.
Thermal break, standard aluminium or PVC?
Send us a photo and the sizes of your windows on WhatsApp and we will tell you what makes sense for your home, with an indicative price.