Have you seen “CLASSE+ windows” in an advert or a quote? It is a label that shows, with letters, the energy performance of a window. Here we explain what it is, in plain words, what it does not say, and what you should check with the official source before you decide.
Note: this text sums up what we know in general terms. Rules, classes and support schemes can change. Before deciding, always check the website of ADENE (the Portuguese energy agency). We deliberately give no classes, figures or dates here.
What the label is
CLASSE+ is a label linked to ADENE. It is meant to compare windows by how much energy they let escape. It works like the label on home appliances: a letter tells you how the window performs, and the buyer does not need to understand technical numbers.
In principle, the label looks at the whole window: glass, frame and seals. Not just the glass. Check with ADENE how it is calculated.
Why it can be useful
Imagine you are comparing two quotes for the same window, from two companies. One shows the label for each model and the other only says “quality window”. The first gives you something concrete to compare. The second asks you to take it on trust.
The label also helps when you talk to the installer. Instead of “it is good”, it becomes “what class is it, and why?”.
What the letter means
In general, a better letter means less heat lost in winter. It is a simple way to compare two windows without having to understand technical values such as Uw (the number that measures the heat passing through the whole window; the lower, the better).
To compare, always use windows with a label on the same scale. If one has a label and another does not, or if the scales differ, the comparison is not fair. Ask the installer to show the label of each model in the quote. If you want to know more about Uw, see Window energy efficiency.
What the label does not say
- It does not guarantee the installation was done well. A window with a good letter, badly installed, lets in air. See PVC window installation.
- It does not say how much you will save on the bill. That depends on the home, the ventilation and the use.
- It says nothing about noise, security or durability. It is an energy label.
- It does not replace the installer’s visit, or a written warranty.
- It does not say the rest of the home is well insulated. Excellent windows in a home with uninsulated walls and roof have a limited effect.
The label and support schemes
State support schemes have existed that asked for windows with a minimum class. But schemes change: they open, close and alter their conditions. We deliberately give no figures or dates here.
Before buying with a grant in mind:
- Check whether a scheme is open right now.
- See which class it asks for, and whether your case (house, building, rented home) qualifies.
- Ask whether the application comes before or after the purchase. This matters: in some schemes, buying before approval can lose you the right.
- Keep the invoices and the label of each window.
- Ask the installer to make sure the model name on the invoice matches the label.
An everyday example
Mr António wants to replace four windows and has heard there is a grant. Before asking for quotes, he goes to the ADENE website and checks what the scheme requires. Then he writes to each company: “The windows must have a label with the required class. Can you state the class of each model?” One company replies with the list and the sheet for each model. The other replies “they are all very good”. The choice gets easier.
The most important point: he asked before buying. Whoever asks afterwards may no longer have a way back.
How to check it yourself
- Look in the quote for the word “CLASSE+” or the class letter. If it does not appear, ask.
- Ask for a copy of the label or the model sheet.
- On the ADENE website, check whether the manufacturer and model are in what ADENE publishes.
- Compare only models on the same scale.
The most common mistakes
- Thinking the label solves everything. It is one number among many.
- Buying with a grant in mind without reading the conditions.
- Comparing windows with different labels as if they were equal.
- Forgetting the installation, which weighs as much as the product.
- Accepting “it is CLASSE+” on word alone, with no paper.
Mini-glossary
- ADENE: the Portuguese energy agency. It handles energy labels and certificates in Portugal.
- Uw: heat passing through the whole window. The lower, the better.
- Class: the letter that sums up the window’s performance.
- Energy certificate (SCE): a document about a building’s energy. It is not the same as a window label.
- Sealing: what closes the gaps so no air or water gets through.
What to check with ADENE
- Whether the label is voluntary or mandatory (as far as we know it is voluntary, but check).
- Which classes exist today and what each one means.
- Which manufacturers and models are registered.
- Which support schemes ask for this label.
In short: CLASSE+ helps compare windows, but it is not everything. Check the facts with ADENE and find an installer who explains the label and takes care over the installation.
What to do next
- See what moves the price in How much do PVC windows cost.
- Learn which papers to ask for when buying: Warranties and certificates.
- Already have quotes? Read How to read a window quote and use the calculator.