Guide to Conversion of Traditional Buildings

6.5 Artificial and display lighting

Mandatory Standard

Standard 6.5

Every building must be designed and constructed in such a way that the

artificial or display lighting installed is energy efficient and is capable of being controlled to achieve optimum energy efficiency.

Limitation:

This standard does not apply to:

a) process and emergency lighting components in a building, or

b) alterations in dwellings or a building ancillary to a dwelling.

6.5.1 Application of standard to conversions

In the case of conversions, as specified in regulation 4, the building as converted shall meet the requirements of this standard in so far as is reasonably practicable, and in no case be worse than before the conversion (regulation 12, schedule 6).

6.5.2 Commentary

Artificial lighting can account for a substantial proportion of the electricity used within a building. Appropriate lighting design can reduce energy demand and running costs.

A limit for energy use arising from fixed lighting is included in the notional building specification for new buildings under standard 6.1. This does not apply to conversions, but while it may be challenging to comply fully in many other areas of the Technical Standards, this is one area in which compliance is relatively simple to achieve, particularly given the significant improvement in efficiency of modern LED lamps over all previous bulb types available. Given the overarching imperative to demonstrate savings where possible, it is expected that energy savings and broad compliance with section 6.5 should be manageable in most cases.

All technical guidance associated with section 6.5 is now provided through a link to the Domestic Building Services Compliance Guide for Scotland. In this guide, section 6.5 is largely represented by section 13: Lighting. Similar guidance also exists for non-domestic buildings.

Beyond energy efficiency, a well-considered lighting scheme, which might include the use of natural light, can benefit user comfort and the legibility of spaces. It can also improve safety and enhance appreciation of parts of a building (such as an elegant roof structure) that might otherwise be missed.

Electric lighting became gradually widespread within the UK during the 1930s and so nearly all traditional buildings (mainly constructed before 1919) would have originally been built without electric lighting. It is useful to bear this in mind when considering potential justifications for retaining inefficient incandescent or other lighting equipment.

Lighting levels and controls to enable the safe use of lighting in common areas such as corridors, stairs and other circulation areas, are separately identified in clause 4.6.2 within section 4.

6.5.3 Issues to be considered

Typical risks in the conversion of historic/traditional buildings

1. Compliance is easier to achieve

Whilst conversions do not need to comply with the standards, it is easier to comply with section 6.5 than it is with other sections and practitioners are obligated to demonstrate compliance as far as they can. Table 6.1 within Clause 6.1 sets out the requirements for new building:

• Fixed lighting capacity (lumen) = 185 x total floor area
• Efficacy of all fixed lighting = 80 lumen/Watt

Beyond simple written confirmation of compliance, supported by specifications etc., it is also possible to model spaces and light levels using specialist lighting tools. This may also be helpful when lighting larger spaces or those with particular functional or aesthetic requirements.

2. Impacts on historic fabric

Installation of fittings and associated wiring routes to suit new uses can be disruptive to historic fabric or impact on the character of key internal spaces. Routes need to be carefully planned.

3. Controls are important

While a strategic and inherently efficient lighting scheme is important, the contribution of a well-considered control strategy should not be underestimated.

6.5.4 Recommendations to meet the standard

Compliance (or near compliance) can be demonstrated in written or numerical form or modelled using commonly available modelling tools. These can also be useful where specific lighting requirements need to be met, for example for display purposes.

It is useful to consider lighting to be provided in three distinct ways. The first is ‘amenity’ or ‘background’ lighting. This is the light that is required to generally use a space safely, and in many domestic cases is achieved by the central ceiling pendant or similar. The second is ‘task’ lighting which allows for the provision of higher levels of lighting only where required, for example to undertake a specific task. A desk lamp is a common example.

The value of considering both together is that background lighting might reasonably be reduced (reducing energy consumption and cost) where it is effectively supplemented by task lighting. Lastly, display’ or ‘accent’ lighting can be used for largely aesthetic reasons, such as highlighting artwork or a particularly significant feature of a historically important building. Isolating this light strategically means that equivalent lighting is not required in all areas.

The above strategy can be used to ensure that beyond ensuring that all spaces are safe, accessible and functionally acceptable, that the architectural or historic characteristics of each building can be considered and optimised.

LED bulbs are now commonplace and have no toxicity, startup times, bluish colour and flicker disadvantages of fluorescent lights. They are also around seven times more efficient than old fashioned incandescent bulbs. They are dimmable and come in a range of types and light colours providing considerable flexibility, coupled with improved efficiency.

There are four types of control for lighting. The first is manual (a simple on-off switch), along with three types of automated control: daylight or ambient light-related, occupancy-related and timer-based. Each of these may be better suited to different functions and requirements throughout a building and should be considered as part of the overall lighting strategy.

The following may be worth considering:

• Natural light can help reduce artificial lighting as long as switching and controls are suitably set up. For example, if luminaires near the windows are separately switched, these can be turned off manually or via sensor, while lights away from natural light can be kept on.
• Lighter colours of internal surfaces can reduce the need for artificial lighting.
• Care may be required to consider wiring routes in areas of architectural or historic interest.
• There are maintenance (and sometimes health and safety) implications of different lighting designs, and it is important to ensure that future burdens and risks are not designed into systems at the outset.