Skylights vs Sun Tunnels: Choosing the Right Daylighting Solution

March 2026

Natural daylight can transform interior spaces, improving comfort, reducing reliance on artificial lighting, and helping to create healthier living and working environments. Roof glazing systems such as skylights and sun tunnels are widely used to introduce daylight into areas where traditional vertical windows cannot provide enough light. 

While skylights are often associated with loft conversions and open living spaces, sun tunnels provide a highly versatile alternative, capable of delivering daylight into areas that would otherwise remain dark. These systems can transport natural light through roof spaces, ceilings, and even internal floors where direct glazing is not possible. 

For suppliers like Sterlingbuild.co.uk, sun tunnels offer solutions for a wide range of applications including pitched roofs, flat roofs, and even side-wall installations, making them suitable for both residential and commercial projects.

What Are Skylights? 

A skylight, often referred to as a roof window, is a glazed unit installed directly into the roof structure to bring daylight into a room below. Skylights are commonly used in pitched roof applications where the interior ceiling follows the roof line, such as loft conversions or vaulted ceilings. 

Common Applications 

• Loft conversions 

• Attic bedrooms 

• Kitchens and living areas 

• Home offices 

• Stairwells and landings 

Key Features 

• Large glazed surface providing wide daylight distribution 

• Available as fixed or opening units for ventilation 

• Typically installed using manufacturer flashing kits matched to roof coverings 

• Provides external views and natural airflow 

Skylights are ideal when there is direct access between the roof and the room below, allowing the window to sit directly within the roof structure.

What Are Sun Tunnels?

A sun tunnel, also known as a light tube or tubular daylighting system, is designed to transport sunlight from the roof through a highly reflective tube into interior spaces. 

Instead of a large roof window, the system uses: 

1. A roof-mounted light collector or dome 

2. A reflective tube (rigid or flexible) 

3. A ceiling diffuser that spreads daylight into the room 

This design allows natural daylight to travel through loft spaces, floors, and internal building structures where traditional windows or skylights cannot be installed. 

Key Advantages 

• Requires minimal roof space 

• Works with pitched roofs, flat roofs, and side-wall installations 

• Can deliver daylight to rooms far from the roofline 

• Minimal structural alterations required 

• Quick installation compared to roof windows 

Sun tunnels are particularly useful when daylight needs to be shafted through the building structure, delivering light to areas where a conventional window cannot be used. 

Pitched Roof Applications 

Most residential sun tunnels are installed on pitched roofs, where the roof-mounted collector captures daylight and transfers it through the loft space into the room below. 

Typical applications include: 

• Hallways and corridors 

• Bathrooms without external windows 

• Walk-in wardrobes 

• Utility rooms 

• Stairwells and landings 

In many homes, these areas rely entirely on artificial lighting during the day. A sun tunnel can introduce significant natural daylight, reducing electricity use and improving the feel of the space. 

For pitched roofs, installers can choose between rigid or flexible tube systems depending on the roof layout and available space. 

Rigid Tubes 

Rigid tubes provide the maximum light transmission because their internal reflective surface allows light to travel efficiently over longer distances. 

Flexible Tubes 

Flexible tubes are easier to install around obstacles such as rafters, pipes, or ductwork, making them suitable for more complex installations.

Flat Roof Windows vs Sun Tunnels 

Flat roof structures often use rooflights or flat roof windows to introduce daylight into extensions and modern buildings. 

These glazed units provide strong daylight and an open sky view, making them ideal for spaces such as: 

• Kitchen extensions 

• Open-plan living areas 

• Commercial offices 

• Modern residential designs

However, flat roof windows require clear space directly below the roof opening, which is not always possible. 

Sun tunnels provide a practical alternative when: 

• Structural elements block the direct path for a rooflight 

• The room is located further away from the roof surface 

• Only a small ceiling opening is available 

In these situations, a sun tunnel can deliver daylight through a light shaft that passes through the roof void or upper floors, making it an effective solution where traditional glazing cannot be installed.

Delivering Daylight to Difficult Spaces 

One of the major advantages of sun tunnels is their ability to bring daylight to areas where normal windows are impossible. 

Internal Rooms 

Many modern homes have internal rooms with no external walls, including: 

• Bathrooms 

• Storage areas 

• Internal corridors 

Sun tunnels can channel daylight through the roof space to illuminate these rooms naturally. 

Basements 

Basements often struggle to achieve natural light because they sit below ground level. In certain building designs, sun tunnels can be used to transport daylight from the roof level down through vertical shafts, improving natural lighting in basement areas. 

Multi-Floor Buildings 

In larger residential or commercial properties, sun tunnels can pass through multiple floors or ceiling voids, distributing daylight deep within the building. 

Commercial Applications 

Sun tunnels are widely used in commercial and industrial buildings where large internal spaces require daytime lighting. 

Typical commercial applications include: 

• Warehouses 

• Retail units 

• Offices 

• Schools 

• Healthcare buildings 

These buildings often rely heavily on artificial lighting. Installing sun tunnels helps reduce daytime electricity consumption while improving occupant comfort.

Reducing Artificial Lighting 

Both skylights and sun tunnels help reduce the reliance on artificial lighting during daylight hours. 

Benefits include: 

• Lower energy consumption 

• Reduced electricity costs 

• Improved indoor comfort 

• Enhanced wellbeing through exposure to natural daylight 

• Even small daylight openings can significantly improve the brightness of interior spaces.

Choosing Between Skylights and Sun Tunnels 

In many buildings, the best approach is to combine both systems, using skylights in larger rooms while installing sun tunnels in smaller interior spaces.

Expert Tip from Sterlingbuild 

When selecting a sun tunnel, consider the distance between the roof and the ceiling and the number of obstacles within the roof space. Rigid tubes provide the strongest daylight performance, while flexible tubes offer easier installation where roof structures are more complex. 

Sterlingbuild supplies sun tunnel systems suitable for pitched roofs, flat roofs, and even side-wall applications, allowing natural daylight to be introduced into almost any part of a building.

Frequently Asked Questions 

Conclusion 

Skylights and sun tunnels are both highly effective daylighting solutions, but they serve different roles within a building. Skylights work best in open living spaces where direct roof access is available, while sun tunnels excel at delivering light to internal rooms, basements, and areas where traditional windows cannot be installed. 

With options available for pitched roofs, flat roofs, and side-wall installations, sun tunnels offer one of the most versatile ways to introduce natural daylight into buildings. Whether used in homes or commercial environments, they help create brighter interiors while reducing reliance on artificial lighting.