Night time LVIA

Night time assessments are increasingly being prepared in support of planning applications for new development.  Whether introducing new development in what is otherwise a dark landscape, or proposing schemes that may increase light levels in already lit environments, night time LVIA helps applicants to design schemes that can be accommodated within the receiving environment and gives planning authorities the confidence to reach a robust planning decision.

Landscape and Visual Impact Assessments (LVIAs) are used to determine the effect of development proposals on the immediate and surrounding landscape and visual receptors, and identify what, if any, mitigation measures are required. Night-time assessments are increasingly recognised and requested by planning authorities as a useful instrument to support LVIAs.

But surely ‘under the cover of darkness’ such impacts are limited …?  Yes, its true that much of the detail of development will not be appreciable at night but the importance of Dark Landscapes is also increasingly recognised by Planning Authorities in terms of the effects of lighting on the character of an area and views. Night time assessments are usually included either due to the high level of lighting proposed as part of a development, or the sensitive nature of the site that may, for example be within a Dark Sky Reserve or an Area of Outstanding Natural Beauty (AONB).

Night time LVIAs have inherent cross overs with Lighting Assessments carried out by lighting engineers, however, whereas Lighting Assessments will establish lux levels and consider light spill within specified limits; night-time LVIAs will further consider the ‘sight of light’ and the effects of light on the character of an area, views and a general quality of life.

Undertaking this type of assessment requires specific expertise, particularly in relation to the night-time photography and fieldwork assessment.  Photographs must record the baseline views in low light levels, preferably when other artificial lighting (such as street lights and lights on buildings) are on, in order to record the existing light levels and apparent brightness of artificial lights.  Scottish Natural Heritage 2017 guidance (1) recommends that ‘approximately 30 minutes after sunset provides a reasonable balance between visibility of the landform and the apparent brightness of artificial lights’ – this can be a tricky balancing act!

The period of time that photographs can be recorded can be relatively short depending on the time of year.  As well suitable timing, the assessor must also consider the phase of the moon to get accurate sky darkness; and the suitability of weather conditions, noting that as temperatures cool in the evening, mist or rain may form (2).  Wind movement in photographs can create another challenge as longer exposure times are used to record the night-time photographs and any movement in the landscape can create distortion.

Notwithstanding the technical challenges of this work, night-time assessment is one of the more unusual tasks undertaken as a landscape architect which creates a refreshing new challenge.  Our night time assessments have taken us to beautiful parts of the country, experiencing landscapes in a different way; we also often encounter a range of nocturnal wildlife.

Our in-house ecologists must often also consider light levels in their assessment work, and in particular, effects of new sources of artificial lighting on ecology such as bats.  Holistic solutions that serve to respond to both disciplines are often possible and contribute to wider objectives of visual mitigation and biodiversity gain.

A forthcoming Landscape Institute-supported publication called Landscape and Visual Assessment: Artificial Light and Lighting will shed some light on exposure and ISO settings for night time photography, expected to be released soon.

In the meantime, if you are considering a project within a sensitive area such as Green Belt, AONB or near protected wildlife sites then please do contact us to discuss any potential assessment requirements (lucy.foley@thelandmarkpractice.com).

1 Scottish Natural Heritage Guidance: Visual Representation of Wind Farms v2.2 February 2017 (SNH 2017)

2 Landscape Institute Technical Guidance Note 06/19: Visual Representation of Development Proposals (17 September 2019)