Start with the real need
Low-emissivity coatings are mainly used to reduce heat transfer through the glazing, while solar-control glass limits part of the incoming solar energy. Some products combine both functions, so the choice depends on climate and orientation.
Use Uw and Ug to understand thermal transmission, but also review solar factor and visible light transmission when solar gains matter.
The correct decision depends on the complete opening: frame, sash, glazing, gaskets, hardware, shutters where present and the joint with the wall. A single feature rarely explains the final comfort.
Compare the complete window, not one component
A south- or west-facing large glazed area may need a different balance from a shaded north-facing bedroom.
Compare alternatives with equivalent dimensions, opening type and glazing. Useful data can include Uw for the complete window, air permeability, water tightness, wind resistance and acoustic information when these are relevant to the project.
- Uw / Ug
- Air / water / wind
- Glazing and hardware
- Perimeter installation
Check use, installation and maintenance
Compare the complete glazing build-up, coating position, cavities, gas, spacer and safety or acoustic requirements.
Installation is part of the result. The frame must be properly supported, fixed, level and sealed, with the perimeter joint designed to control air and rain. Finishing trims do not replace a correct installation joint.
There is no universal configuration for every home. Orientation, climate, room use, noise, exposure, dimensions and maintenance change the most suitable solution. A final technical survey should confirm the specification before manufacture.
What to request in the quotation
Ask the quotation to identify every opening, dimensions, system, opening configuration, full glazing composition, hardware, shutters or boxes, removal of the old window, fixing, sealing and finishing work. This makes competing quotations genuinely comparable.
- Use Uw and Ug to understand thermal transmission, but also review solar factor and visible light transmission when solar gains matter.
- A south- or west-facing large glazed area may need a different balance from a shaded north-facing bedroom.
- Compare the complete glazing build-up, coating position, cavities, gas, spacer and safety or acoustic requirements.
Practical conclusion
There is no universal configuration for every home. Orientation, climate, room use, noise, exposure, dimensions and maintenance change the most suitable solution. A final technical survey should confirm the specification before manufacture.
The correct decision depends on the complete opening: frame, sash, glazing, gaskets, hardware, shutters where present and the joint with the wall. A single feature rarely explains the final comfort.
Frequently asked questions
What should I compare first?
Start with the problem you want to solve and compare complete windows with the same dimensions, opening and glazing.
Does the glass matter as much as the frame?
Yes. Glazing, frame, gaskets, hardware and installation work together, so one component should not be assessed in isolation.
Why is installation important?
Because air or water leaks and weak perimeter joints can reduce the benefit of an otherwise high-performance window.