energies Article Assessment of Outdoor Lighting: Methods for Capturing the Pedestrian Experience in the Field Johan Rahm * and Maria Johansson Environmental Psychology, Department of Architecture and Built Environment, Faculty of Engineering, Lund University, 221 00 Lund, Sweden; [email protected] * Correspondence: [email protected] Abstract: This study assessed whether methods for capturing the pedestrian experience of outdoor lighting, previously evaluated in a full-scale laboratory, were applicable in a real-world setting. It applied an approach capturing the human response to outdoor lighting in a systematic way, by assessing perception, evaluation and behaviour in the lit environment. The study involved 81 participants from two age groups (Young—n: 48, mean age: 26, 63% women; Elderly—n: 33, mean age: 69, 67% women) and was carried out on a pedestrian path in a park in the centre of Malmö, Sweden, in the evenings during wintertime. Two LED lighting applications, differing in light distribution, uniformity and horizontal illuminance, were presented, and the pedestrians’ perception (facial expression recognition and sign reading), evaluation (arousal, valence and perceived outdoor lighting quality) and behaviour (pedestrian flow) were assessed. The results from the perceptual tasks differed significantly between the lighting applications, in favour of the lighting application with greatest uniformity and horizontal illuminance. There was a significant difference in sign reading distance between the two age groups. The methods applied in this study are feasible to administer and could be used to assess lighting solutions in order to capture the needs of vulnerable groups. Citation: Rahm, J.; Johansson, M. Keywords: street lighting; outdoor lighting; pedestrian; perception; evaluation; behaviour Assessment of Outdoor Lighting: Methods for Capturing the Pedestrian Experience in the Field. Energies 2021, 14, 4005. https://doi.org/10.3390/ 1. Introduction en14134005 Today, the majority of the world’s population lives in cities, and further urbanisation Academic Editor: Fabio Bisegna is expected globally [1]. This trend accentuates the need to develop sustainable cities, with safe and healthy living environments, and energy-efficient transportation systems [2]. Received: 31 May 2021 The pedestrian is central in sustainable urban design, since nearly all journeys undertaken Accepted: 30 June 2021 in the urban environment incorporate walking in one way or the other. Walking is therefore Published: 2 July 2021 an essential component in sustainable intermodal transportation systems [3–6], and ben- efits public health, by reducing the risk of chronic diseases such as cancer, diabetes and Publisher’s Note: MDPI stays neutral heart disease [7]. with regard to jurisdictional claims in In the Nordic countries (and other countries at similar latitudes), daylight hours are published maps and institutional affil- very limited in winter and pedestrians depend on outdoor lighting to provide functional iations. levels of visual accessibility and perceived safety when getting to and from work. The social-ecological model of walking [8] suggests a hierarchical structure of pedes- trian needs consisting of five levels (ranging from feasibility via accessibility, safety and comfort to pleasurability) that people consider when deciding to walk. The existence of Copyright: © 2021 by the authors. artificial outdoor lighting impacts the evaluation of accessibility and safety needs [9–11], Licensee MDPI, Basel, Switzerland. and is fundamental for people’s decisions as to whether to walk or not after dark. The im- This article is an open access article portance of outdoor lighting for pedestrians was highlighted in a recent focus-group study distributed under the terms and in Malmö, Sweden, where the participants were encouraged to speak freely about the per- conditions of the Creative Commons ceived design qualities of neighbourhoods in relation to walking. In most cases, despite the Attribution (CC BY) license (https:// discussions taking place during daytime, outdoor lighting was mentioned spontaneously, creativecommons.org/licenses/by/ in relation to perceived safety and intention to walk after dark [12]. This is in line with the 4.0/). Energies 2021, 14, 4005. https://doi.org/10.3390/en14134005 https://www.mdpi.com/journal/energies Energies 2021, 14, 4005 2 of 15 previous research indicating that the presence of outdoor lighting improves the perceived neighbourhood quality [13] and increases the amount of walking after dark among all age groups: adolescents [14], adults [15–17] and elderly [18–20]. Unfortunately, the benefits of outdoor lighting are associated with adverse ecological consequences [21], as well as considerable energy use, generating financial and environ- mental costs [22]. One way of reducing energy use is to replace or retrofit existing outdoor lighting applications with light sources with greater energy efficiency [22–24]. In Sweden, many municipalities are actively promoting walking as a means of trans- portation and have developed pedestrian plans [25]. In these plans, improved outdoor lighting for pedestrians is stressed as a key factor. Municipalities on the verge of upgrading the lighting infrastructure are looking to LEDs to reduce energy use. However, LED light- ing may have different photometric properties (e.g., spectral power distribution) than previous lighting technologies, such as high-pressure sodium and ceramic metal halides, and vary greatly depending on the quality and design [26]. Before committing to a costly, long-term investment, the needs of the users should be considered. Both technical aspects of lighting and the pedestrians’ experience should be taken into consideration, in order to find lighting solutions adapted to user needs while minimising energy use. Moreover, the needs of users from vulnerable groups, such as the elderly and the visually impaired, must be considered [9,27,28]. Most components of the visual system deteriorate with age, which affects visual performance negatively. Elderly therefore are more sensitive to glare and may have difficulties performing certain visual tasks important for pedestrians (such as detecting obstacles [29,30] and recognising facial expressions [30]) at low illuminance levels [31]. For people with low vision, it has been deemed difficult to provide general illuminance recommendations, due to large individual differences [31]. Therefore, in order to design lit environments more suitable for people of all ages, with varying levels of vision, it is important to identify which parameters are central for the pedestrian experience, and to develop tools that can be used to assess them. In many municipalities, for economic reasons, it is likely that only the luminaire will be exchanged, while the old lampposts are retained. This might bring about an unsatisfactory lighting solution and indicates the need to assess the pedestrian lighting experience in the field before initiating large-scale retrofits. 1.1. Previous Research The pedestrian response to outdoor lighting has previously been researched both in laboratory and field settings. A systematic review suggests that the research to date may be characterised by the overarching themes of perception, evaluation and behaviour in the lit environment [32]. Prominent areas of research within perception have been perceived brightness [33–39], facial recognition [36,40–46] and obstacle detection [29,47–51]. Within the evaluation theme, focus has been placed on perceived safety [36,52–58] and perceived lighting quality [10,24,59,60], whereas the behaviour domain has focused on pedestrian flow [52,61], walking speed [62–64] and visual fixation [65–69]. To identify and evaluate the methods that assess pedestrians’ experience of the lit environment, Rahm and Johansson [30] conducted a full-scale laboratory study, with three different lighting applications. The identified methods for perception (obstacle detection, facial expression recognition distance and sign reading distance) and evaluation (level of arousal [70,71] and Perceived Outdoor Lighting Quality scale (POLQ) [10]) differentiated between the different lighting applications. The lighting application with the greatest mean horizontal illuminance (EH) (32 lx, compared to 28 and 18 lx), the widest light distribution, and highest correlated colour temperature (CCT) (3810 K, compared to 2912 and 2890 K) achieved the best results on the perception tasks and was perceived as significantly dif- ferent on the Perceived Comfort Quality (PCQ) and the Perceived Strength Quality (PSQ) dimensions of the POLQ scale, as well as on the composite arousal measure. No significant difference in the behaviour measure, walking speed, was found between the different light- ing applications. However, other studies indicate that differences in illuminance level may Energies 2021, 14, 4005 3 of 15 result in changes in walking speed (0.05–0.11 m/s for differences in horizontal illuminance ranging from 14 to 290 lx [62–64]) and in pedestrian flow when improving the lighting conditions [52,61]. 1.2. Aim and Hypotheses The aim of this study was to assess whether the methods for capturing the pedestrian experience of outdoor lighting, previously evaluated in a full-scale laboratory, are ap- plicable in a real-world setting. A second aim was to investigate whether the group of elderly (60–75 yrs.) experienced the lit environment differently than the group of younger participants (20–35 yrs.),