Stewards of Nature

STEWARDS OF NATURE

Lighting designer Chiara Carucci’s experience in lighting the Collepardo Caves near Rome has taught her some important lessons on what is – and isn’t – ‘bat-friendly’ lighting

By Chiara Carucci

Back in 2021, I was privileged to have my project to light the Collepardo Caves near Rome featured in arc magazine [1]

The project, to recap, saw me design and supervise the installation of a new lighting scheme for the tourist-attraction caves. Working for Lazio region and LAZIOCrea, under the supervision of the Natural and Cultural Heritage department, it was a scheme that not only brought a sense of mystique but, even more importantly, contributes to raise awareness and protects its hugely delicate ecosystem.

The caves are classed as an SIC or ‘site of community importance’, since they are home to at least five species of bats – as well as showing archaeological findings and geological features. This cultural and natural heritage site is open to the public, especially for education purposes.

Among other issues, we had to ensure the new lighting limited the ecological problem of ‘lampenflora’. Beyond the aesthetical damage, lampenflora causes deterioration and structural changes, and therefore it represents a serious issue for the ecosystem of the caves.

Working closely with local managers, guides, the in-house chiropterlogist, and three researchers, I tested and specified

solutions (for example fixtures to be installed far from speleothems, mineral formations), relying on perception and storytelling (setting different scenes), than usual techniques.

‘PURPOSEFULLY’ DARK

To protect the caves, we worked to keep the lighting deliberately minimal, and purposefully dark, with low luminance and high-quality control systems.

While the original article covered the description of the project itself, here we share our lessons learned, also from ongoing research and feedback, with the hope of enriching and raising the bar for heritage and ‘bat-friendly’ lighting.

Giovanni Mastrobuoni, the in-house chiropterlogist, has continued visiting and counting the chiroptera population in the caves once a month. His regular feedback continues to be very positive, alongside those by one of the researchers, specialist for bats, Leonardo Ancillotto.

Giovanni enthusiastically illustrated the new lighting system to local and national TV, even after the grand opening, remarking how the lighting design improved bats’ living situation, compared to the past. In fact, chiroptera are inhabiting more areas of the cave as a result and, especially now, hibernating.

Professor Jo De Waele, of the Italian Institute of Speleology within the University of Bologna’s Department of Biological, Geological and Environmental Sciences, taught me how to identify the relevant formations and how to reduce the impact for installation.

His feedback was equally positive: ‘In general, people try to light up underground spaces like cathedrals… that is a mistake in my opinion. You allowed even the dark “to speak”, and highlighted peculiar features of this cave – like the lines and the detachment fault (the fault plane), not just the obvious speleothems – creating a good visiting experience and basis for people’s education,’ he told me.

Rosangela Addesso, PhD, specialising in lampenflora, discussed with me the use of specific wavelengths that could hypothetically reduce lampenflora. After careful evaluation, we agreed to work on three parameters for the lighting fixtures: distance, low intensity, and time of operation.

Visiting the site, she said: ‘Just six months from the installation of the new lighting system – also following a few months for the building site, when the lights were mostly off – we found a reduction of lampenflora of more than 80%, with few areas where biofilms are still visible, but now brownish in colour due to degradation.

‘These results are excellent and surprising: we hope to be very close to the solution (for lampenflora as an ecological problem). However, the solution may not be definitive: there is still much to understand about the physiology of these microbial communities, defined as “alien” in underground ecosystems.’

Liliana Mannocchi, on behalf of the client and local managers, said: ‘This project has contributed to increasing the number of visits, already growing thanks to the management of the Lazio Region, through its in-house company LAZIOcrea and their artistic-cultural programme (in addition to the permanent offer of guided tours). Visitors continue to appreciate the results of this project, which has reduced energy consumption and minimized the impact on biodiversity.’

PROJECT REFLECTIONS

My own reflections from this project come down to the following learning points:

• Explaining the concept of a project such as this to the client is usually very complex, almost impossible in this context, if not with a full-scale test lighting. Consequently, giving feedback on site, the stakeholders feel part of the decision process, start to feel ‘owners’ of the project. This helps for keeping the scheme on track, and well-maintained.

• Designing for a harsh environment (the cave’s environment is more corrosive than the ocean’s) is not only related to the choice of materials. For example, we used SAE 316L marinegrade stainless steel and ourselves designed installation accessories. Care should also be given to the methods for installation, for example, reducing the time of exposure for cables. In fact, allochthonous material can undergo harmful degradation processes and affect the longevity of the project.

• Care and appropriate time planning should be given to the construction process. Here, for example, the building site was planned in relation to chiroptera’s phenological phases, in other words starting after hibernation and concluding before the nursery.

• Building site management, naturally, is challenging in this sort of environment. So, aim to collaborate with the client in setting the requisites for contractors (previous experience, tasks and so on), not only for procurement.

• Communication is key for raising awareness and for education, not only for marketing purposes. For example, the valuable collaboration with professional photographers should be planned and discussed with the client in advance.

• Collaboration is the way to go. Consult experts and work in multidisciplinary teams, in order to learning for oneself and improving the project, besides avoiding mistakes from the start.

The new lighting scheme in the Collepardo Caves Caves, outside Rome. All images, including main image on the previous page, by Jansin & Hammarling

KEY CONSIDERATIONS

Therefore, I would like to share some takeways for other exterior projects.

First, as lighting professionals, we have both an opportunity and a responsibility to act as a protector of resources and of the environment. We should strive to be making or encouraging decisions that consider the effect of light on all living items, now and in the future.

Therefore, on this sort of project it is vital to collaborate with researchers, as well as identify stakeholders and ‘local heroes’. Building partnerships is as important as identifying goals for the project. Ultimately working with – and as part of – a multidisciplinary, genuinely collaborative team will actually make you save time.

Second, when or if clients say ‘there isn’t enough budget’ to consult experts that, simply, isn’t (or shouldn’t) be true. Sometimes it’s enough to call your local cultural heritage or conservation department or contact a local environmental association. Their advice is usually free of charge.

Otherwise, if you have the chance, ask for an offer to researchers: their fees will often be less expensive than you may think.

Ultimately, if you really do not have time to incorporate others’ suggestions in your design, you have probably set the timeline and budget wrong! As designers, we should also be able to admit a mistake, rather than delivering at all costs. Next time, you may want to consider involving a lighting designer (as an expert and/or project manager) who can deal with multidisciplinary projects.

Many heritage sites around the world (including, but not limited to, monuments) are nowadays exhibited almost like a movie set. It’s all about the tourism, with biodiversity often down the priority list.

I believe that limiting spill light is not enough. As lighting professionals, we have to be brave enough to argue the case for somewhere not to be lit, for silence or darkness to be a preferable choice (especially if the alternative will be of poor quality).

On that note, heritage sites, especially natural environments like touristic caves, cannot be lit like an amusement park, not even for seasonal or event lighting. The inevitable compromises between conservation and touristic needs should be found somewhere else.

As lighting designers, we can, however, create special settings for different times of the year, albeit avoiding coloured light or strong intensity variations, especially if there are nocturnal animals close to the site.

I realise this may be controversial with some ILP members, but I believe that it isn’t worth investing in red (monochromatic) lighting fixtures, sometimes seen as ‘bat friendly’.

Why? Well, we should not only consider the effect of light at night on mammals but, especially far from cities, on all living items. For example, vegetation can be severely damaged by the red part of the spectrum, as reported by several researchers.

Trees that are sensitive to day length, and those that require a long period of darkness

are negatively affected by the continuous lighting especially if the fixtures are mostly in the red (625 nm to 760 nm) or in the infrared range.

Bats perceive red, even if some species perceive it less than other parts of the spectrum. Several species of bats, nevertheless, are known to have functional long-wavelength-sensitive ‘opsins’. Opsins are proteins that bind to light-reactive chemicals to underlie vision, circadian rhythm, and other light-mediated responses of organisms.

Several species of bats fly close to lights as a result of the accumulation of insects that are first attracted to the light sources. Artificial light can also impair the defence mechanisms of moth species, so facilitating some bats’ foraging. However, not all insects are less sensitive to red, on the contrary mosquitoes are attracted, as several studies report.

Birds are only theoretically less sensitive to red light at night. Much long-distance bird migration happens at night. Many nocturnally migrating birds die or lose a large amount of their energy reserves during migration as a result of encountering artificial light.

Some studies have shown birds becoming disoriented and attracted by red and white light (containing visible long-wavelength radiation). Whereas they may be less disoriented by blue and green light. Therefore, in the context of bird migration it is arguable that red light should be avoided, at least during migratory season, especially with overcast sky.

Red lights cannot show properly the coat (or fur) of several mammals. This can mean drivers may not perceive them when they are crossing a road, especially since the verges will often be dark.

Generally speaking, especially where safety and security are at stake, I would avoid red.

Finally, studies on artificial lighting at night (ALAN) are not always consistent. As Annika K Jägerbrand of Halmstad University, Sweden, and others have highlighted, there can be a lack of a unified method to measure the effects of ALAN.

SUMMARY

Red ‘bat-friendly’ lighting sounds great in principle. But, to my mind, it can be limited as a ‘solution’ and certainly should not be seen as a panacea.

There are multiple other factors lighting professionals need to take into consideration when lighting ecologically sensitive exterior sites at night. Do not just copy and paste solutions; tailored projects are the most sutainable and valuable.

Consider light-motion sensors that automatically dim-down during the off-peak hours. This will of course have the added benefit that clients will save on energy bills, making the luminaires adjust their lumen output based on the presence of pedestrians, bicycles or cars. However, it also goes without saying that this choice must be integrated into the broader lighting design, for example including safety concerns and escape routes. Make guidelines and guidance your friend – but not your only friend. The ILP with its GN08 guidance proved to be at the forefront of best practice around bat-friendly lighting and spot on – and we await the updated version of this guidance with interest [2].

However, as GN08 says in chapter three: ‘Effective mitigation of lighting impacts on bats depends on close collaboration from the outset between multiple disciplines within a project.’

Therefore – and finally – with any project like this, before evaluating mitigating measures it is imperative to consult the experts – local stakeholders and researchers, environmental scientists or other specialists.

Study the context and get information on the local population of bats and their habits. Keep ’stewardship’ in mind. Suggest (quality) lighting only where and when really needed; and be brave enough to say no lighting is actually the answer here.

Chiara Carucci, IALD Associate, is an award-winning independent lighting designer based in Stockholm, Sweden and Salerno, Italy

[1] ‘Cave of wonders’, arc, [d]arc media, August-September 2021 (123) [2] GN08 ‘Bats and artificial lighting in the UK’, in association with the Bat Conservation Trust, is available by scanning the QR code https://theilp.org.uk/publication/guidance-note-8-bats-andartificial-lighting/