Light pipes

Description
Large diameter (230mm or more) pipes with a highly reflective internal surface designed to reflect light from outside a building to internal areas with little or no natural daylight. The pipes are terminated outside with a transparent dome and internally with a diffuser. Versions are available which incorporate ventilation provision.

Unit cost of installation
The cost of a light pipe varies according to the complexity of each installations and the cross-sectional area of the light pipe. Costs for basic kits range from around £170 + VAT for a 230mm diameter model suitable for flat roof installation to £680 + VAT for a basic 530mm diameter version suitable for pitched roof. Fitting costs are extra.

Bulk cost of installation
Data not available.

Indicative energy cost and carbon emissions

The energy saving from a light pipe will vary according to the location and size. Assuming each pipe replaces a single 100w tungsten filament bulb used for 3 hours a day the savings will be:

However, these savings will be offset by a slight additional heat loss due to the light pipe penetrating the insulation layer. The heat loss in these situations has not been fully quantified, however it would seem reasonable to insulate the duct as it passes through the roof void, to reduce the risk of condensation occurring.

Maintenance
None normally required.

Lifetime
Life of the units should be >25 yrs.

Technical suitability
Suitable for use on any wall, and can easily achieve U-values which would comply with the new-build requirements of Building Regulations. Systems are available that have been certified by BBA and BRE Certification.

Suitable for most dwellings except flats and apartments not on the top floor. Light pipes can also provide ventilation ducts within the same casing, thus reducing the number of penetrations required through the roof.

Non-technical constraints
May require permission in some situations (e.g. on listed buildings).

Potential concerns with fuel poor
No specific issues.

Ancillary benefits
Light pipes provide natural light and can be an attractive design feature.

Trigger points for work
Repairs to roof, addition of ventilation to bathrooms etc.

Performance Limitations
Only operate during daylight hours, and operate most effectively in bright sunlight.

Technical Guidance Available
None.