Designing, Installing and Maintaining an Internal Lighting Scheme

The design brief

The lighting design brief will need to include:

• The objectives of the new scheme
• The areas/rooms included in the design
• Historic furnishings and decorations
• Retention and re-commissioning of historic fittings
• New light fitting design and fixings
• Listed building consent (if required) or other permissions

The place to start with any brief is to decide what you want the lighting to achieve in each room or area of the building. To do this you need to decide what each room or area is going to be used for and if the space is to have multiple uses over the course of a day/week/month.

Having worked up ideas, the brief needs to set out the desired overall look including details such as colour renderings and lamp colour temperatures, and lighting controls required.

The brief should also include the requirement to carry out tests, trials and calculations as necessary to ensure the proposed design performs as required. It may be necessary to build some prototypes to test the design's efficacy and performance.

Historic furnishings and decorations

When dealing with historic buildings' rooms there may well be special finishes such as wallpapers and silks, painted or decorated surfaces, paintings, objects d’art, carpets and wood panelling amongst other furnishings that have to be considered, along with the period light fittings.

Some materials and fabrics such as textiles, paper, leather, book covers and so on, are adversely susceptible to excessive heat and light which can cause fading and embrittlement. Take special care to assess the amount of ultraviolet (UV) radiation given out by your chosen light source as this can have an adverse impact on both synthetic polymers such as plastics and naturally occurring polymer materials such as wood.

Light emitting diodes (LEDs) only create small amounts of UV because they contain phosphors that convert UV light into white light. Although some manufacturers have stated in the past that LEDs emit no UV, this is technically not true so take care and seek expert advice as necessary.

The choice of the colour of light used can impact of the accuracy on the colours as rendered to the eye. This could be an important issue in the presentation of rooms and objects.

Areas and rooms included in the design

The brief must contain precise details of which areas of the building are part of the internal lighting design. A room by room schedule will ensure that no part of the project is missed and that no area is included by mistake. List out the name and/or number of the room, the existing services contained within it, especially if there are heritage fitments, the parts required to be removed and/or protected, plus outline details of the new installation.

If there are special surfaces, decorations and floor finishes in each room or area, include those in your list along with details of suitable protection.

New light fittings and fixings

As with other new work in historic buildings, the Historic England approach is that new light fittings should be well designed and harmonise with the rooms, fittings and furnishings. This neither implies nor precludes traditional, replica or contemporary design.

Pay attention to how you can achieve a good installation with the minimum damage to the historic fabric.

Fittings can be:

• Decorative – pendants, chandeliers, table lamps and wall lighting
• Architectural – uplighters, step lights, artwork lighting and recessed down-lights, or
• Central features – chandeliers and pendants

Fittings like chandeliers are both decorative and central features. They are often the central feature in a room, very decorative, eye-catching and make a strong visual statement.

Architectural light fittings are discreet, and you really should not notice them. These are the functional fittings that illuminate steps or pictures and provide accent lighting often in combination with the decorative fittings. It is possible to integrate architectural accent lighting such as small directional spotlights into central features like chandeliers, so they are not visible.

All fixings should be carefully located in sacrificial material such as mortar. Reuse any pre-existing holes and openings wherever possible and avoid making any new openings. Only use recessed light fittings in a historic building where there is no surviving historic fabric, for example where the original ceiling has been replaced. The same caution applies to the use of wall lights. Unless there is an extremely good reason for chasing walls, this sort of fitting should not be used. The exception would be re-plastered walls.

Advice on cabling and controls is provided below.

Codes of practice and internal lighting guidance

For advice on suitable light levels refer to:

• British Standards
• The Chartered Institution of Building Services Engineers (CIBSE) / Society of Light and Lighting (SLL) 

There is also guidance on selecting the right low energy lighting which is accessible from the Energy Saving Trust and the Health and Safety Executive.

Planning permissions, building regulations and other consents

Although internal lighting schemes are not subject to planning control, you may still need to comply with buildings regulations and permission and consents may be required for listed buildings and making changes to Places of Worship.

You should involve the local planning authority and other stakeholders early on in developing the lighting scheme(s) for listed or scheduled buildings and structures. ChurchCare offers advice about designing lighting schemes.

Installing an internal lighting scheme

This section provides advice on:

• Contractors
• Health and safety
• Cabling
• Controls
• Daylight harvesting

Contractors

Only employ suitably qualified and registered electrical contractors, with extensive experience of working in heritage buildings, to carry out you lighting installation.

They should also be registered with either the

• ECA (Electrical Contractors’ Association) or
• NICEIC (National Inspection Council for Electrical Installation Contracting)

They should be able to follow safety procedures and all the necessary care when working within a listed and potentially vulnerable environment.

Cabling

Reuse all pre-existing cabling routes and ducts, where feasible, and install as many services as possible along a shared common route around the room(s). Any additional holes and chasing should either be installed in new fabric or avoided altogether if possible. A desktop survey of the areas involved is a useful tool in locating promising routes through a historic building.

Where the space offers up features that lend themselves to providing discreet cabling routes such as skirting boards, mouldings, cornices and capitals, then surface mounted cabling may be the better solution. The use of mineral insulated cable (MICC) is one method that's often used. The cabling is mechanically protected and resistant to fire and dresses neatly around building features. Any cabling type you use should have low smoke and fume (LSF) outer sheaths

The use of mounting pattresses allows fixings to be secured into sacrificial material. Items like lighting switches and wall lights can use this technique.

Use any existing conduit systems that are in a good enough condition to rewire the installation as the design requires. In this case use single core (6491X/7) cables.

Wherever possible, consider using wireless systems to replace cabling, such as in the case of light switches.

Internal lighting controls

A lighting scheme must be suitable for the use(s) of the rooms. If there are to be multiple applications for the space, then controllability and adjustability are important considerations. For example a room used for work during the day will need suitable lighting for using a PC. Later in the day the room might be used for handicrafts or reading calling for a higher level of task lighting. Later still the room could become an area to relax and watch television in for which you would want a lower light level.

Room lighting can be controlled in a variety of ways. Examples include:

• A simple conventional single on/off switch for all the lighting, or multiples in a bank controlling parts of the room’s installation
• A suitable dimmer for all the lighting
• A multiple switched/dimmed layout, dividing the lighting into controlled zones
• A remotely controlled lighting installation, with any of the above features, operated via an app on a smart phone or tablet
• A daylight-controlled system which switches out all or part of the installation when daylight sensors reach a predetermined light level
• An occupancy-controlled system which switches off all or part of the lighting in the room if there is no movement in the space for a set period, (often used in areas where long term occupancy is unlikely such as WCs), or
• In larger buildings, via a Building Management System (BMS)

A good lighting scheme should always have the best and most flexible control system that can be incorporated within the design.

A lighting control system does not have to be complicated just appropriate for the scheme and achieves what is needed.

The more flexibility that is required the greater the level of lighting management will probably be required. It is also one of the best methods to enable energy savings to be made.

Internal lighting control components:

• Plate switches
  These can be recessed or surface, single or multiple gangs, single way or two-way, in the room or remote.
  
  They are now available as wireless units. Inside the switch there is a magnetic coil and when the switch rocker is pressed it creates enough energy to send a radio signal to the receiver. The built-in receiver is wired to the light and stored in the light fixture.

• Dimmer switches
  Like plate switches these can be recessed or surface, single or multiple gangs, in the room or remote. Dimming a lighting installation can change the whole look and feel of a space by shifting the emphasis and drawing the eye to different aspects of the room.
  
  With LED lighting becoming the norm it's important that the dimmer is compatible with the LED lamp used. There are some LEDs that are designed for use with standard dimmers and there are others that are not, so compatibility is key.

• Zoning with multiple switches
  If dealing with a large space, such as you would find in a church, zoning simply means splitting the space into areas you wish to light together. Zones allow you to control more than one light or lighting area at the same time. A control zone is defined as one or more light sources controlled simultaneously by a single control input or switch.
  
  
• Smart controls via phone or tablet
  Remote control over lighting is becoming ever more readily available and popular.
  This can be achieved by a manner of differing technologies. Some systems work wirelessly through a mobile operating system and use purpose designed lighting protocols to communicate. This means you can control the lighting via your mobile phone or tablet, (other systems use area networks [WPAN and LAN], Bluetooth and Wi-Fi).
  
  Such control systems lend themselves to what is referred to as ‘scene setting’ where pre-set controls can be established for a series of different lighting modes such as ‘morning’, ‘evening’ and ‘night’ as one example.

• Daylight controls
  This is often known as daylight harvesting, or daylight response. It is an automatic lighting control strategy in which interior lighting adjusts to maintain a target lux level, therefore reducing energy costs.
  
  It's most effective in areas that consistently receive ample daylight, such as lighting close to windows or near skylights. See separate section on daylight harvesting below.

• Occupancy controls
  An occupancy sensor is an indoor motion detecting device used to detect the presence of a person or persons. This automatically controls the lighting system by either switching it on or off as appropriate.
  
  The sensors use infrared, ultrasonic, microwave, or other technologies.
  
  A slight variation on this is called a vacancy sensor. These assume that a person will turn the lights on manually, typically via a wall switch. The sensor will then monitor the space and turn the lights off if the space is then vacant for a specified length of time.

• Building Management System (BMS)
  Larger buildings tend to have a building management system (BMS) as a central control system. It can be used to monitor and manage the mechanical, electrical and electromechanical services in a facility. Such services can include power, heating, ventilation, air-conditioning, physical access control, pumping stations, elevators and lighting.
  
  
• Auxiliary lighting
  In a domestic style environment low level lighting from standard and table lamps are often used for auxiliary lighting. Usually 13 amp socket outlets are used to plug in table lamps and there is no ability to control these fittings other than at the lamp. If 6 amp circuits and lighting outlets are installed then a more convenient and easier form of control over this lighting can be provided and other power outlets freed up for other uses.

Daylight harvesting systems

A daylight harvesting system controls a room’s lighting by registering the level of sunlight coming into a space via light sensors which are usually installed within the luminaires, but sometimes installed externally. As the amount of daylight increases or decreases the system automatically adjusts the level of artificial electric lighting that is switched on or off to achieve a pre-set lighting level in the room. This saves electricity which in turn saves carbon emissions and energy costs for the end user.

The amount of energy that can be saved depends on the illuminance level from daylight alone for hours occupied over a year. The carbon savings are calculated based upon the types of lamp and their typical energy use in watts per square metre.

Although there are health benefits in using more natural daylight such as reductions in vitamin D deficiency and tiredness, and improvements in productivity, we must also consider thermal comfort and the impact of overheating for occupants, especially in summer months. With climate change, the risk of overheating in some types of buildings will only increase and so this must be considered when carrying out feasibility studies into the use of daylight harvesting in your own building.

Bessie Surtees House and The Engine House daylight harvesting case studies

Historic England commissioned daylight harvesting studies for two of its’ offices. We wanted to investigate the viability of using such a system in historic buildings with unusual floor plans, unique window layouts and different wall finishes to those found in modern buildings.

The first was the Grade I listed Bessie Surtees House in Newcastle. This building is a combination of two merchants houses, one from the 16th and the other from the 17th century. The second was in a Grade II listed building called The Engine House, which is our office in Swindon and home of the National Archive. This much larger building dates from the 19th century.

For these case studies, we used typical energy figures for lamps:

• LED lamps 3 watts/m²
• Fluorescent lamps 9 watts/m²

Our key findings were:

• Historic window design, such as the Swindon office’s large sash windows on different elevations, can both help and hinder. The windows allow a lot of light in but at certain times of the year produce problems of glare at some current desk positions.
• Electrochromatic or smart glazing is unlikely to be an appropriate option in historic buildings especially where original glass remains or where there would be a visual impact. However, this form of shading however might be suitable for skylights.
• Blinds may help address specific problems. For example, at the Swindon office we experimented with blinds that only covered the lower part of the window to allow light in but prevent glare and reduce overheating for a colleague. The individual could adjust the blinds to suit their needs.
• The internal layout of the room influences the plentifulness of natural light and issues such as glare. Re-arranging desks and furniture can help improve daylight harvesting.
• Where just a few people are adversely affected then it might be worthwhile considering measures that allow them to override the daylight sensor controls for a limited period.

For a more detailed overview on these case studies see the recording of our Technical Tuesday webinar on Climate Change Adaptation: Saving Energy Through Daylight Harvesting and the Lighting Journal article.

Maintenance

Maintenance is important and if neglected makes itself felt very quickly through the loss of available light. Even something as simple as cleaning, if forgotten, will eventually impact on the available light for the occupants.

Maintenance must be carried out on a regular basis along with any routine statutory inspections and tests to ensure compliance with BS7671:2018 IET Wiring Regulations. Check and clean the fittings thoroughly and rectify any faults.

This work is less likely to be carried out if the lighting design has made access difficult and expensive through the need for specialised equipment such as a cherry picker or mobile scaffolding.