Blog · Advice

Double or triple glazing: what to choose, and what it costs

10 September 2026 · 4 min read

When you come to choose the glass, the surcharge for one more pane looks like a simple decision. Before you accept it or set it aside, though, it helps to know exactly what you are comparing. The number of panes is the start of the specification, and the decision also depends on how you use the room. A double-glazed unit has two panes of glass and one cavity; a triple-glazed unit has three panes and two cavities. Coatings, the gas fill, and the spacers also affect the thermal performance — so two “triple” units do not have to have the same values.

Be clear about the problem you want to solve

Before the question of how many panes, describe the room. Do you sit beside a large window while you work? Is the living room uncomfortably sunny in the afternoon? In the bedroom, is traffic the main thing that disturbs you?

Those are different requirements. In the quote, thermal insulation, the solar energy that passes through the glass, and the acoustic performance should therefore be considered separately. The sentence “I want the best glass” leaves too much room for different interpretations.

Ug and Uw: two marks worth understanding

Ug describes heat transfer through the glass, while Uw covers the complete window, including the frame and the effect of the joint between glass and frame. For both marks, a lower value means less heat transfer. The same Ug value therefore does not mean that two different windows will have the same Uw. GEALAN explains how the figures for the glass and for the whole window differ.

Ask for both marks to be written clearly when they are available for the configuration offered. Do not compare the Ug of one product with the Uw of another.

When to include triple glazing in the quote

Triple glazing is worth considering when you set more demanding targets for thermal insulation. Its extra cavity and suitable coatings can contribute to lower heat loss; the actual result depends on how it is made. The development and use of triple-glazed units is described by the Department of Energy.

For the decision, ask for parallel quotes: the same opening and the same functions, with the differences in glass, performance, and price stated clearly. Ask in particular whether changing the unit requires a different sash or hardware configuration.

Look at the benefit together with the state of the walls, the roof, and the rest of the building. A concrete saving on the bills cannot be worked out from the number of panes alone.

What triple glazing costs per square metre

With us, a triple-glazed unit is a surcharge of 26 € per m² of glass on VEKA 70 and GEALAN LINEAR 74MD. On VEKA 82MD, triple glazing is standard — there is no surcharge, because it is already in the price of the position.

One detail is often calculated wrongly: the surcharge applies to the area of the glass, not of the opening. The glass is always smaller than the opening, and how much smaller depends on the number of sashes and the width of the profile. The amounts in the table are therefore an upper limit — the real surcharge is a little lower, and the quote states it exactly.

All prices include VAT and exclude installation, for white. The exact price depends on the opening style, the hardware, the glazing, and the quantity — we send an itemised quote within 48 hours of a free measuring visit.

VEKA 70 with triple glazing, or VEKA 82MD straight away

On a 140×140 cm opening, VEKA 70 with triple glazing comes to 316 € at most, and VEKA 82MD is 355 €. The difference is small enough that the question asks itself — and the answer is not in the glass.

VEKA 82MD has seven chambers instead of five, and a greater installation depth, so it also performs better in the profile, not only in the glazed unit. If you are choosing for insulation as a whole, compare Uw for the whole window, not Ug for the glass — otherwise you pay for a better glazed unit in a weaker frame.

A comparison of the systems by chambers, depth, and hardware: VEKA 70, GEALAN 74MD, or VEKA 82MD.

When to consider double glazing

Include a double-glazed unit in the comparison when you want to check whether it meets the requirements of the room at a lower total investment. That should be a check of a concrete quote, not an assumption that all double glazing is the same.

If, for example, you are renovating several rooms, ask for the requirements and the recommended configuration to be stated clearly for each one. You can then spread the budget according to priority, instead of automatically accepting the same unit everywhere.

Noise and sun need a separate check

If noise is the main problem, ask for the tested acoustic performance of the window offered. The thickness of the panes, how they are arranged, acoustic laminated glass, and the construction of the whole element affect the result. The number of panes matters least here: three identical panes often perform worse than two of different thickness, because a symmetrical unit resonates.

For a room in strong sun, ask for the solar energy transmittance and a proposal for shading. Solar gains are a separate characteristic from heat transfer, as the guide to energy-efficient windows explains.

What to send with the enquiry

State the sizes, what the room is used for, the compass direction if you know it, and the problem you want to solve. Add whether you are changing only the windows or renovating the whole building.

Common questions

How much does triple glazing cost per m²?

The surcharge is 26 € per m² of glass on VEKA 70 and GEALAN LINEAR 74MD, including VAT and excluding installation. On VEKA 82MD, triple glazing is standard and is not charged extra.

How much does triple glazing add to the whole window?

On a 140×140 cm window the surcharge is 51 € at most, so a position of 265 € goes to 316 € at most. It is calculated on the area of the glass, which is smaller than the opening, so the amount in the quote is usually a little lower.

Is triple glazing filled with argon?

The gas fill, the type of coating, and the spacers are stated in the specification of the quote, together with the Ug value. Ask for them to be written down — two units with the same number of panes can have different values.

Does triple glazing stop noise better?

Not necessarily. For noise, the arrangement and the different thickness of the panes, and acoustic laminated glass, matter more than the number of panes itself. Ask for the sound-insulation figure for the exact configuration offered.

Does triple glazing pay in a flat?

It depends how exposed the position is. Large openings and a north-facing side gain the most. On small windows the surcharge is small in money, but the effect is also smaller than people expect — so look at Uw for the whole window, not only Ug for the glass.

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