Webinar on Building Services: External Lighting

Speakers: Geraldine O’Farrell, Caroline Cattini, Matt

Geraldine: Thank you, Matt. Good afternoon and welcome to Historic England’s webinar on external lighting for historic buildings and churches. Before we get started, I’d like to briefly introduce my co-presenter and myself. I’m Geraldine O’Farrell, Senior Building Services Engineer belonging to a small team of national advisors on building services and energy management. I personally advise and write guidance on a range of building services including external and internal lighting, emergency lighting and exit signage, fire alarms and lightning protection.

Caroline: Thanks, Geraldine. Hello, my name’s Caroline Cattini. I’m the Principle Building Services Engineer and the Building Services Engineering Team Leader. I also advice on building services and historic buildings and both Geraldine and I also look at historic building services systems, ones that exist, and how we can reuse and retain them. And I am also involved writing guidance on building services and renewables.

Geraldine: So, before we make a proper start, I’d just like to let you know a little bit about the Technical Conservation Team. We are group of technical specialists, including conservators, scientists and engineers and we undertake research and provide guidance and advice on technical conservation issues. The first link that Matt is posting in the chatroom for you takes you to the main Technical Advice page on our website where you can find all of our technical advice. All our research reports and PDF guidance documents are free to download from our website, and the second link takes you to the catalogue shown on the right where they are all listed. Also I thought you might like to know that we’re introducing a technical conservation newsletter which is planned for the last Tuesday of each month. This will let you know about new technical conservation guidance and publications or any forthcoming technical conservation training events. If you’d like to add your name to the mailing list and haven’t already done so at a previous webinar, just click “Yes” and we’ll send you the next edition of the newsletter. Just to be clear, this is for technical conservation guidance and events and not for all Historic England publications or training. Everybody wants to join the list, that’s great. I was about to say that if you’ve already signed up at a previous seminar, there’s no need to do so again, although don’t worry, we’ll check to make sure you only get one email.

So, here’s today’s topic we’re going to be discussing and hopefully helping you take the right approach to this sort of work. Our online guidance, which is available via our website, replaces the external lighting guidance document, published in 2007. The basic principles are still the name. It can found by just typing “external lighting” into our website’s search facility and you’ll find it very easily. The web pages reflect the changes to available technology in the intervening 13 years, the most obvious being the rapid rise and domination of the lighting industry of LED lamps. Just remember, lighting design is specialist work and should not be undertaken by anyone not suitably trained or qualified.

Caroline: So, the guidance is about making you an informed client, so that when you do decide or are advised to install or update your external lighting, you’ll know what to do and what not to do. The purpose of our guidance has always been to prevent bad and wasteful lighting installations and to understand the impact that poor lighting design can have on neighbours, animals and landscapes. Hopefully with this knowledge, you will be able to ensure that you achieve an energy efficient design that doesn’t waste light and also add to the already high levels of light pollution we suffer in this country and very much across the developed world.

Geraldine: So, let’s get started. On screen are the fundamental issues you need to consider before starting an external lighting project. The location of your building will determine how much background illumination your installation has to compete against. Your lighting installation does not have to illuminate every last square millimetre of all the elevations, especially if they can’t be seen by anyone from a normal public form of access. Neighbouring properties are also a key point. There’s nothing worse that light trespassing through windows at night from a badly lit adjacent structure. The fittings’ location has to be well disguised. It’s no good having a wonderful night-time view, only to have the daytime one ruined by visible light fittings fixed to the façade. There is a good example of what not to do coming up in about five slides time of what I mean.

Caroline: So, good lighting can enhance and heighten the night-time view of a building but done badly can completely the opposite effect. The three images here on the screen are examples of poor lighting design. So, let’s have a look at them. The one on the left shows accidental light spillage into a residential building whilst the historic church at right angles to it remains unlit. So, you’re not lighting the right thing there. So, if we then look at the image on the right, it shows an example of a high contrast and poor control and it creates quite an unwelcome ambience. And finally, if we look at that image in the middle, it’s a really good example of over-illuminating all the façade and this causes visual light pollution. Just before we move on, it would be good to ask, just through a little poll here. Who is in the process of designing an external lighting scheme? I think we’ve got a poll to bring up.

Matt: Well, it looks like we have a few already.

Caroline: Oh, that’s good.

Matt: Still voting. So, I’ll broadcast the results. There you go.

Caroline: That’s great.
Matt: So, a few of you are. That’s wonderful. Great. OK.

Caroline: I’ll move the slides on, Geraldine.

Geraldine: Sorry about missing the earlier slide out. Yes, so, before you start any new lighting project and compiling the brief for it, you should ask yourself or your client what the real need for lighting is for. Has the driving force behind the proposed works been established? And what is the real need? What is trying to be achieved? Do you know what you want to make your building? Do you want to make your building stand out from the background? Or are you celebrating a local/national event? Will you, by doing this, improve the local community’s enjoyment of this building’s heritage?

Caroline: So, if a genuine need for an external lighting scheme has been established, then it’s your lighting designer’s duty to limit the amount of light and luminaires to a minimum that delivers all their client requirements for the building needs. And it is really necessary to write all light, all elevations or features of a building or all the surrounding places. And if we look at this image to the left of the screen, this demonstrates the argument. This building has sections of heritage construction linked with more modern infill buildings. At night, you will note that only the heritage sections are illuminated. So, those important features there, they’ve lit. Now, if we look at the ones on the right, the night-time view is one of contrast and throwing the rest of the building into shadow, creating a negative effect. Unique night-time view. Remember that some building parts are often unsuitable or inaccessible for normal viewing and so it makes no sense to light them at all. And also, it’s best to concentrate on the best nearby and/or distant night-time viewpoints.

Geraldine: Rather than illuminating the whole building, as we’ve seen illustrated in the previous slide, it’s sometimes better to select features such as pediments or columns and niches to light. Cross lighting and uplighting and backlighting can all be considered, although uplighting should be limited and very well controlled to avoid unnecessary and wasteful upward light spillage and pollution. The images on the screen show examples of backlighting, which throws the columns on both buildings into shadow relief in different ways, each of which provides a unique night-time view of the building.

This slide shows what can happen if care is not taken locating floodlights as I mentioned earlier. These large floodlights are not only badly located but very likely to contribute to local light pollution by the way they are angled upwards. Plus, on the right-hand side of the image is another fitting acting as part of the street lighting, but not very discretely.

You can see them because I’ve highlighted them with little red arrows, hopefully it makes them easier to see. It is important that many external luminaires are inconspicuously positioned but still relatively easier to maintain. If that can’t be achieved, then you should think about positioning the lights remotely. This idea is shown in the images on the right-hand side of this slide, where the fittings have been hidden in or on street lighting columns. I realise that this is not always feasible but every possibility for a hidden location should be considered, even if that means approaching neighbouring properties and structures for permission.

So, as well as the existing ambient light levels coming from street lighting, shops and offices, the reflectivity of the heritage building service must be taken into account when designing an external lighting scheme. The reflectivity value is affected by the colour of the building materials and how clean they are. The lighter the colour or the cleaner the material, then more light will be reflected back into the space, and fewer or less powerful luminaries will be needed. The colour of the surfaces being lit will also assist in determining the colour temperature of the lamps used in any lighting scheme. The image on the right is a listed Victorian gas holder, which as a metal framework, has little structure to reflect back any light into the surrounding space, so, narrow beamed spotlights have been used to illuminate up the vertical sections of metal work to make the gas holder stand out from its background as a ghostly image. Compare this to the image on the left which has chosen to backlight the building. But you can also see that it has a pale colour which makes the areas illuminated pop brightly against the rest of the structure.

Caroline: The question on the screen is probably one of the most important of all the questions asked so far. One result of a badly designed lighting scheme is light pollution, not least of all light spillage into neighbouring properties and surrounding areas as shown in the middle image. This can not only disturb other residents and wildlife but can also wash out the starlight in the night sky, interfere with astronomical research and disrupt local ecosystems. And if you compare those two images of the sky on the left-hand side, you can quite clearly see the Milky Way there, which is just wonderful, but obviously on the other one before, you can’t because of all the light pollution. Another thing is that owls and bats are two such creatures that could be affected, firstly because of the light, if they are night-time hunters, and not all owls are, and secondly, because its food source such as nocturnal insects and rodents that might be impacted by the light. Poor lighting can also have an adverse impact on neighbours plus waste valuable energy as demonstrated in that middle image there. Overlighting can also decrease our ability to see anything in the immediate area, which ironically can decrease our sense of safety and the overall attractiveness of the space of the building.

Geraldine: Even in 2007, when the original guidance was written, the issue of light pollution was a hot topic. Representation was being regularly made to parliament on the subject. There are so many installations, large and small, that were being wasteful, i.e. sending light up into the sky to achieve nothing, or being intrusive, preventing neighbours from sleeping or appreciating the night sky, plus, coupled with badly designed street and amenity lighting that was just not directing the light where it was needed but just adding to sky glow, which is another name for the diffuse illumination of the night sky apart from that coming naturally from discreet light sources such as the moon and visible individual stars. It is the most commonly noticed aspect of light pollution.

The importance and relevance has not decreased in the intervening 13 years. If anything, it is more of a hot topic than ever. There is now a network of national and local astronomy and environmental organisations supporting the creation of more places where dark skies can be re-established. Also, more people have a realised level of awareness of the importance of treating light or any form of energy as a valuable, finite commodity rather than something that is easily expendable. We should all think of light in conjunction with dark. We can use darkness as well as we can use illumination. We should always use light sparingly, and as Caroline has already said, we should only use the amount of light and luminaires that delivers all their client’s requirements and building needs.

Caroline: And as previously mentioned, overlighting in rural areas can have a dramatic impact on wildlife. All of the creatures feature on this slide here can have their lives, breeding cycles and food sources negatively affected by too much light. And the satellite image in the centre clearly shows just how much light is escaping into the atmosphere. The areas of natural darkness are disappearing rapidly and with them the slow extinction of some small creatures that we may come to realise, and hopefully not too late, that we depend upon to pollenate certain plants or enable other ecosystems to function. Rural areas can often be places where buildings are frequently overlit. This is because the lack of competing light from shops, streets and advertising panels is not taken into account. And with a lower ambient alert level comes a lower light requirement for your building. It’s not competing with any background lighting as the same building would if it was to relocate to a town or a city centre.

Geraldine: Another aspect of an external lighting scheme is that it does not have to include just floodlights which are broad beam fittings that generally should be thought of as the type of luminaire that illuminates sports fields and play areas after dark or spotlights which are narrow beam light fittings aimed at a building façade from the ground. External lighting can include buried uplighters, concealed lighting, such as that showed in the picture illuminating the edge of the step, or bollard lighting. Or conventional lighting can be fitted with suitable control fitments such as baffles, snoots, soothers, glare hoods, barn doors, plus suitable controls to assist in unnecessary light spill. Fittings can also be fitted with asymmetric optics to ensure that the light only travels in one specific direction. They can also be designed so that light travelling upwards from the lamp is redirected internally and not wasted into the night sky. In other words, there are lots of ways and methods of controlling the lighting and where it goes in your design. There is no excuse for light pollution on the scale we still see in some designs. The most suitable light source has to be LEDs. The image in the bottom left shows a typical range of LED floodlight fittings. In the past, we would have employed a variety of different lamps, but with the EU directives from 2009, these older, inefficient light sources are being phased out. LEDs are now available in a range of lamps styles, sizes, shapes, colour temperatures and applications to suit most installations and fitting types. They are often capable of being retrofitted into existing fittings as well.

Caroline: So, after asking yourself all the questions previously discussed, you will have started the decision making process which you need to go through when writing the brief for your project. This document should include topics like your objectives, target audience, the extent of the scope and any background influences. It does not necessarily need to be technical in nature, just clear in your desired aims for the scheme.

Geraldine: So, this is the stage at which you decide what you are trying to achieve. This can be a free-for-all, so don’t discard any ideas. Just brainstorm with your designer and/or architect and consider everything that comes out of this process as potential ideas.

Next, you should consider who the proposed lighting is for. Who is your target audience? Is the lighting for security, appearance, to give the building a night-time presence or to celebrate a local or national anniversary or event? This last point could include like Remembrance Sunday, Christmas, Eid-Mubarak or Diwali. Then you need to consider if the installation is to be permanent or for short-term lighting celebrations such as the Durham Luminaire Festival which is held every November. This event is held to showcase Durham’s iconic places and buildings. Maybe it’s like the new external lighting scheme for Ironbridge. You can see two images of that on the far left-hand side of the slide. This involves using white light that varies its intensity over the course of an evening with colour used at the weekends to recall iron furnaces that used to light up the night sky nearly three centuries ago. In the centre, or maybe like Lincoln Cathedral shown there, you can show your support for the work of the NHS as it did during the COVID-19 pandemic.

Caroline: The scope of the document will likely cover which elevations and features are to be lit by your scheme and what your control requirements are necessary to achieve your aims. Now, at this point, you should be considering what level and type of control your scheme needs. Is it just a simple photocell or a timer which merely switches the lighting off and on at a pre-set level? Or, as previously mentioned by Geraldine, are you looking for more sophistication and finesse in the way that the installation can be adjusted?

The requirements will help you narrow down the type of luminaires to consider. Your lighting designer will help you with the final choices, but basic aspects such as lamp temperatures, your ingress protection rating and your IK rating and your CRI, which is the colour rendering index, need to be discussed at this point.

[They discuss an issue with the presentations]

Geraldine:  At this stage, we recommend that you start experimenting with ideas by mocking up different lighting schemes. The type of things to remember are, for example, what sort of lighting to have, subtle or dramatic. Keep remembering the environment that your building is in and keep using light sparingly and remember to treat it as a valuable and finite resource. Also remember that the more rural the setting, the less light your design will need to make an impact on its surroundings.
It can help when trying to finalise the overall style and look by experimenting, possibly by using computer software initially, and afterwards progressing to mock-up installations on site. Photographs of the latter can help when making planning applications and in the case of Grade I and Grade II* buildings when consulting with Historic England. It’s important to keep remembering that throughout the whole process that you should manage your use of light in a responsible and sustainable way.

Caroline: So, this is the bit where Geraldine and I are going to play Good Cop/Bad Cop. So, I’m going to do the “Dos” of lighting. So, with all the categories of listed buildings, reversibility is a key consideration. Fixing must and wherever possible made into sacrificial material such as your mortar joints and not into the brick or the stone. Now, where the fixings do not permit this, then the use of mounting using a pattress, and you can see that in the middle image, should be considered to help to avoid damaging the historic fabric. All pre-existing holes and slots should be reused rather than creating new ones and this holds true, even if doing so results in a slightly convoluted cable route. And finally, do not guess what any prototype light fitting will achieve. You must build in and test your theories out first.

Geraldine: Right. Bad Cop here. The images on the screen are just a few examples of what not to do. You saw back on slide 10 how not to locate large floodlights on your façade so that they stand out like a sore thumb when viewed in daylight. As mentioned in the previous slide, cabling is another issue. The cables in the middle and right-hand images show a mineral-insulated cable fixed into stonework rather than mortar joints. When this eventually is removed or replaced, there will be lovely set of holes left to try and disguise. Also, knocking out bricks to form fresh openings for cables, conduit trunking etc, should not be done unless there is absolutely no alternative. And then this type of work should only be done after discussions with your architect, local conservation department and/or Historic England, if the building Grade I or Grade II*.

Caroline: So, there are plenty of standards you can refer to if required and on-screen are just a few of the organisations that have publications available to view. Now, some of these not free, some of them you do have to pay for a paper copy or a downloadable PDF. These will give you a starting point, but remember that the British Standard documents and the like, they’re just advisory, they’re not a statutory requirement. If you are new to the process of designing external lighting, this could be one place to start your journey along, of course, with other guidance. These documents may quote light levels. These are a guide so don’t feel obliged to stick to them.

Geraldine: Also, just a quick reminder to ensure that you have consulted with Historic England before you start any work on a Grade I and Grade II* building. We are always happy to assist and advise you, so don’t be scared of approaching us. If you’re working on a listed church, however, remember that you have to involve your diocesan advisory committee as soon as you’re able. They also are there to give advice and ultimately the necessary faculty if appropriate. Finally, your local authority planning department and conservation officer are also there to help advise and guide you through the application process, so make use of these people before you make any firm commitments to one design or another.

Caroline: Yeah, good point. Another important point to remember is that the electrical contractor you appoint to carry out the installation work in conjunction with your lighting designer and architect should be a member of either or both of the trade organisations shown on the screen now. And I’ll just explain the meaning of these acronyms. The ECA stands for the Electrical Contractors Association and the NICEIC stands for the National Inspection Council for Electrical Installation Contracting and you can search on both of those websites for their members for their members. And in addition to these memberships, the electrical contractor carrying out the work should ideally be familiar and experienced with working on heritage building stock and the unique problems that these buildings can present.

We also need to not forget health and safety issues. Installing an external lighting scheme will often involve working at height and can involve dangerous locations as well. Health and safety legislation places a duty of care on contractors, consultants and their employees. This is for the benefit of the public and themselves. All other parties, including you, the client, and all others involved with the design and installation must comply with health and safety legislation and ensure both the access and working conditions are safe. Also shown on the screen you will see CDM mentioned, and this stands for the Construction, Design and Management regulations. These are the main set of regulations for managing the health and safety and welfare of construction work and includes new build, demolition, refurbishment, extensions, conversions, repair and maintenance. Now, to ascertain whether your project is what is referred to as “Notifiable for CDM”, this will depend on its duration and the number of people working on the site. So, for example, if you’ve got a project that is expected to exceed 500 person days or say, when you have 20 people on the project at any one time and the project lasts over 30 days, then it’s notifiable. And you can get further guidance on the links shown on the screen now where the main duties are listed.

Geraldine: Thank you, Caroline. Well, we’ve come to the end of this webinar. Caroline and I hope that you’ve found it informative. On screen are our respective email addresses should you wish to discuss any projects, specific or general issues with us. We are always happy to give you guidance. Please do get in touch. We don’t bite, honest! And finally, just a quick reminder of all the lovely free advice documents available to download from our website and again, thank you for listening and hopefully we’ll take some questions now. Thanks, Matt.

Matt: Thank you, Geraldine and Caroline, for a wonderful presentation. I’ve got a few questions already lined up here for you but I’m going to bring this Q&A window in. I’m sorry it goes over the top of your slide, I do apologise for that. There you go. So, people can actually type in at the bottom of that window there. You can type in any questions you have and we can read those out and Geraldine and Caroline can answer them as they come in. But, we have some question here. First one is quite a long one, so let’s see how we get on. “Using neighbouring buildings and structures for lighting your buildings…”, so this was near the beginning of your presentation when you were talking about using adjoining structures. “…what is an optimum distance to light a building from? Are there additional light pollution issues that may come up as a result of lighting a building from afar rather than from the building itself or immediate proximity? Presumably you will need an agreement with the other building owner? Are there key things that should be covered in that?”

Geraldine: Yeah, you’re obviously very right. There will have to be an agreement with adjacent buildings. It’s problematic; I think you would have to use very tightly controlled spotlights rather than anything that would have a bigger spread of light because, as you say, depending on how far away the adjacent building is that your using, you could add to light pollution rather than prevent it increasing. I know that the abbey in Bath has been floodlit by using adjacent buildings around the small square. If any of you know Bath Abbey, you know that it’s part of one side of a square in the middle of Bath. And they are using adjacent buildings to light the abbey quite successfully, the main elevation that is on to that square. I think it’s a case of trial and error. It’s a very difficult thing to do, but it is done. There were talks about also the British Museum being floodlit from adjacent buildings the other side of the road. You would have to have a very cooperative set of neighbours I think, and there would obviously have to be agreements about electricity, energy use and similar and also maintenance access. So, it’s not easy, but it’s one of a few alternatives that you have to keep fittings off the main building that you’re trying to light.

Matt: OK. Next question: “Do we agree that listed building consent is required to light a building? I’m thinking freestanding lights, not those on the building itself.”

Geraldine: I think it’s always best to err on the side of caution if you are dealing with a Grade I or Grade II* building especially, to just consult very briefly. It may not be necessary at all. You may be right. I’m not absolutely certain about whether or not anything that impacts on a listed building would have to be agreed. Obviously there’s no physical impact, but it’s worth just checking with us that we haven’t got any problems with what you’re proposing.

Matt: OK. Next question: “Is there an acceptable amount of light pollution? I notice most schemes illustrated have uplighters”.

Geraldine: Yeah, well, we all know that uplighting is the favoured and preferred way for a lot of people because one, it gets round the issue of fixing to a building. If you have tightly controlled optics, you can prevent a good amount of light pollution. Whether there’s an “acceptable” level of light pollution is an open-ended question I can’t answer. I don’t know. As little as possible I would probably suggest. As we said in the talk, it’s about measuring the amount of ambient light already existing and pairing your installation back to what will achieve what you’re trying to do, i.e. illuminate your building, make it stand out, make it look beautiful against trying to compete with other forms of lighting that vary depending on the location.

Caroline: And I think, Geraldine, if you don’t mind me adding, it’s like what you said about experimentations and running those tests beforehand because from what someone can calculate, or expect what it look like when you actually put it on the building with reflection and with heat. I mean, in your opinion, it does make a huge difference doesn’t it?

Geraldine: It certainly does and I’ve seen people who’ve gone the whole hog and got to the point of doing a mock-up and found, much to their chagrin, that it doesn’t work. So, physical trials, I think, are incredibly important. Please. I know software is incredibly good at giving you an idea, but there is nothing better than actually doing a physical trial on site, just to check that everything does what you think it does.

Matt: OK. So, here we go, next question: “There is a bit of a grey area between different diocese about what needs planning permission for work in the churchyard and lighting a church”. So, I think that’s asking for a comment from you, Geraldine.

Geraldine: Yes. I’ve got to be slightly diplomatic here. The problem is that the diocese do not all have an agreed set of criteria that they all stick to. With regards to building services, they often have a services advisor and that person will advise based on their knowledge, their preferences and their experiences. So, you will get different opinions being given from different diocese. It’s not ideal. It’s something I would like to see changed and as a member of the Church Building Council I would hope that I would be able to effect some alternation at the moment. But, it’s kind of low on their list of priorities given that COVID has kind of taken everybody’s attention away from other things. But, yes, you’re quite right. There is a grey area and it does need to be attended to. If the church is listed, you can always ask for advice from us as well and weigh one up against the other. I’m not saying that we are in direct competition, we aren’t, but sometimes we have more up-to-date information than the diocese secretaries do.

Matt: Oh, that’s interesting. An interesting comment here in the chatroom: “All the Dark Sky Areas are now working together.” I am assuming this is from someone who is part of the Dark Sky Areas group. “We are going to produce some comprehensive guidance with the ILP, CPRE, CFDS…” Sorry, I don’t know who those acronyms are. Maybe you guys do.

Geraldine: Well, ILP I recognise. Sorry, had you finished Matt?

Matt: Our colleague was just saying it would be great if HE could feed into this and they’ve posted an email address in there as well. So obviously, we’ll make a note of that and maybe we’ll be able to respond directly.

Geraldine: I’ve just seen it on the feed for chat. That would be fantastic. Personally, and I’m sure I speak for HE, yeah, we’d love to get involved with helping you with that. There’s also the Society of Light and Lighting you might like to get in contact with, who are part of CIBSE, the Chartered Institute of Building Services Engineers, but the Society of Light and Lighting are a similar group to the ILP and I’m sure that they would be interested in getting involved. But, yes, certainly, I would love to help.

Matt: Marvellous. We’ve made a connection! There you go. Fantastic. Our work here is done. That’s absolutely marvellous. I can see that the questions are beginning to dry up, so shall we call today’s session to a close? Geraldine and Caroline, thank you so much for your time today. Absolutely brilliant presentation as always. And I hope for our guests and attendees, I hope you found today’s presentation as equally interesting and informative. I will keep the room open just for a little while longer, in case anyone wishes to make a comment or ask a question, but at that point we will mute our microphones and close the session down in two or three minutes. It’s for me just to say, once again, thank you to Geraldine and Caroline and to all of you, our attendees and guests, thank you very much for taking the time to join us today and hoping you have a very good afternoon. Take care. All the best. Bye bye.

Caroline: Thank you.

Geraldine: Thank you.