The standards for energy-efficient and passive buildings rest on design principles that can be summed up in two points:
- minimising energy loss within the building
- and harnessing solar energy
In practice, this means that windows and doors become one of the key elements of a building's energy balance — alongside the insulation of the building envelope and airtightness. In the passive standard, the energy demand for heating or cooling the building should be very low, set at a level of < 15 kWh/m2 per year, which is why the quality of windows and doors, and the way they are installed, have a direct impact on running costs and occupant comfort.
The key parameters
When choosing windows for an energy-efficient or passive home, it pays to look beyond the price and focus above all on the technical parameters of the complete window.
Thermal transmittance Uw
The lower the Uw value, the smaller the heat loss. For energy-efficient buildings, it is worth choosing windows with excellent parameters of Uw≤0,9 W/m²K, while for passive buildings you should aim for solutions that meet the passive standard, namely Uw≤0,8 W/m²K. This is the fundamental criterion when deciding which windows to choose for a passive home.
Solar energy transmittance g
In a passive building, solar gains are of considerable importance. Well-chosen glazing can support the heating of the building during the heating season, which is why the g value should be considered together with the orientation of the windows relative to the points of the compass.
Airtightness
Passive buildings require very good airtightness, which means limiting uncontrolled airflow. Leaky windows or faulty installation can significantly worsen the energy balance and everyday comfort. Proper installation with attention to every detail means peace of mind and lasting comfort, free from mould and mildew.
Warm-edge spacer and triple glazing
Modern energy-efficient windows most often use triple glazing units together with warm-edge spacers, which reduce thermal bridging at the edge of the glass. This choice helps eliminate energy loss — directly improving the thermal transmittance of the complete window (bringing Uw down to current standards) — and also prevents water vapour from condensing on the glass inside the building.
Which windows should you choose for a passive home?
In a passive home, the focus is on the complete solution: the profile (the window frame), the glazing, the warm-edge spacers and the installation itself. Recommended windows for a passive home should offer:
- a very low Uw value — for a passive home even Uw≤0,8 W/m²K;
- triple glazing, or a double-cavity unit (both terms describe the same type of sealed glazing unit);
- high airtightness;
- reduced thermal bridging;
- the option of installation within the insulation layer.
Installation matters just as much as the window itself
Even the finest passive window will not perform as intended if it is fitted with thermal bridges or without proper sealing. In practice, this calls for warm installation, sealing tapes and positioning the window correctly within the insulation layer.
Which windows should you choose for an energy-efficient home?
In an energy-efficient building the requirements may be slightly less stringent than in a passive home, yet it is still worth opting for solutions with high thermal insulation. Recommended windows for an energy-efficient home likewise feature triple glazing (or a double-cavity unit), a warm-edge spacer and a profile — that is, a frame and sash — designed to minimise heat loss.
This solution is particularly attractive for homeowners seeking a balance between the cost of the investment and low heating bills.
PVC or aluminium joinery? A comparison for passive and energy-efficient homes
| Feature | PVC joinery passive / energy-efficient home | Aluminium joinery passive / energy-efficient home |
|---|---|---|
| Thermal insulation | Very good | Very good in systems with a thermal break |
| Structural rigidity | Good | Very good |
| Large glazed areas | More limited than aluminium | Extensive possibilities |
| Contemporary design | Wide choice | Minimalist, premium |
| Price | Usually lower | Usually higher |
In practice, PVC windows for a passive building are often chosen for their attractive value-for-money ratio of performance to price. Aluminium windows for a passive building, on the other hand, come into their own in contemporary architecture with large glazed areas and minimalist profiles.
Entrance doors in a passive building
In a building with very low energy demand, the entrance door should also offer excellent thermal insulation and airtightness. It is worth paying attention to:
- the door’s Ud value;
- an insulated threshold together with a warm sill;
- airtightness;
- the elimination of thermal bridges in the frame;
- professional installation.
What to look out for before you buy
- Check the Uw value of the complete window, not just the glass.
- Choose triple glazing and warm-edge spacers.
- Pay attention to airtightness and the air permeability class.
- Match the system to your design: PVC or aluminium.
- Ensure professional, correct installation.
- Make sure the architectural design takes into account the orientation of the windows relative to the points of the compass.
- For large south-facing glazed areas, plan for solar shading to limit overheating in summer.
Recommended windows for a contemporary home
Today's designs increasingly combine high energy efficiency with large glazed areas and minimalist aesthetics. That is why recommended windows for a contemporary home should deliver, all at once:
- excellent thermal insulation;
- slim profiles;
- large glazed surfaces;
- durability and resistance to the weather;
- the ability to integrate with smart home systems;
- a consistent look across windows, doors, roller shutters and blinds — ideally from a single manufacturer.
It is precisely this combination of energy efficiency, airtightness and aesthetics that today defines the concept of joinery for the contemporary home.
What to choose in practice
If your priority is maximum energy efficiency and a lower investment cost, PVC windows for an energy-efficient building or PVC windows for a passive building are often a sound choice. If your design calls for large glazed areas and minimalist architecture, it is worth considering aluminium windows for an energy-efficient building or aluminium windows for a passive building. In both cases, the Uw value, airtightness and professional installation remain decisive — they are what determine real energy savings and lasting comfort over the years.