Bounties attract serious brainpower to the challenge.
The background: In northern countries lack of sunshine during winter months negatively affects people's mood. Some people might develop an SAD. One of the things that help to ease the melancholic mood is seeing more bright colors around you. If buildings and other elements of urban architecture are colorfully painted or people are dressed in colorful clothes, this makes the atmosphere more joyful even if the sky is grey. However, lack of sunshine makes even brightly painted objects look somewhat greyish and dull. Also, frequent precipitation and wind contribute to this by eroding and dirtying the surfaces.
The solution: What would really make a difference, is implementing colors that glow into urban landscapes. In this case, not only the colors themselves but also the light emitted by luminescent materials might contribute to the mood boost. Although luminescent light is off the UV spectrum, it is likely that any bright light reaching the eyes positively influences our mood by suppressing melatonin production in the pineal gland. A gentle luminescent glow is also more soft and natural to the eyes than artificial lighting. On top of that - colorful, luminescent decorations are one of the most visually beautiful things there are:
Luminescent elements are not new to urban architecture, but they are very rare. What I'm proposing is to use them abundantly, but elegantly in places with long and cloudy winter season with the main purpose of increasing emotional well-being of local inhabitants.
This could start, for example, as a local initiative of a town or a city to make a luminescent sculpture in the town square or a glowing facade of a famous downtown building and spread like a seasonal fashion little by little implementing more and more luminescent elements into the urban environment. In addition to public initiatives, people could decorate exteriors of their houses, just like they decorate them during the Christmas season, but leave them be over the entire winter season.
There are many types of luminescence, but in this particular context, I'm not considering luminescence that is produced by electrical energy and used for artificial lighting. Colorful neon signs that glow at night in big cities are not what I'm talking about. Two main types of luminescence that are relevant to this context are photoluminescence and chemoluminescence. Photoluminescence is further divided into fluorescence and phosphorescence. I'll discuss these three types and their suitability for such application.
Fluorescence:Fluorescent materials absorb UV light and emit lower frequency electromagnetic waves - visible light. There is no noticeable delay between absorption and emission, therefore fluorescent pigments glow as long as they are exposed to UV light. UV lamps (a.k.a. black light) are hence necessary to make the pigments glow in the dark or in low-light conditions.
Pros: Fluorescent pigments are most often used for making "glow in the dark" decorations. They are superior to other types of luminescent pigments because they exhibit rich color variety. Fluorescent materials of various colors seem to be abundant in contrast to phosphorescent or chemoluminescent materials. Also, the use of UV lamps makes the glow very intense. The glow could be turned on and off by removing the UV source.
Cons: Additional energy to power UV lamps is required. They could possibly be powered by locally installed solar cells and batteries. UV light is harmful to the eyes, therefore if used abundantly to light fluorescent decorations, the lamps should be covered in a way that the light would be projected towards the decoration only. This is possible by, for example, placing elongated lamps to form the frame of the decoration and then covering their sides facing the observer with black material. Decorations themselves would absorb the UV light and emit only visible spectrum. Their intense glow is at the same time a con because it might become tiring to the eyes, but if used in low-light conditions (not in total darkness) it might be just right, it could also be adjusted by regulating the intensity of the UV light.
Phosphorescence: In contrast to fluorescence, phosphorescent materials might glow for hours after high-frequency light source is removed. They may be charged like batteries in sunlight or daylight and then glow in the dark or low-light conditions by themselves.
Pros: Phosphorescent pigments could, theoretically, be used in a most energy-efficient way - if there's one sunny day, they would "charge" during that time and then glow in the evening and possibly even through the whole next day (given that the next day is very cloudy and gloomy). Even a gloomy day might be enough to charge phosphorescent materials, the issue here is whether they would glow bright enough for the glow to be at least partly visible on a gloomy day. I imagine if they were charged by sunlight first then this could work. Maybe varying intensities of natural light defined by varying weather conditions could be sufficient for the required contrast.
Cons: It's difficult to obtain phosphorescent pigments of various colors - they usually glow green or greenish-blue. Also, in contrast to fluorescence, once charged, you can't just turn the glow off by removing the energy source, therefore the decorations would need to be covered up or otherwise hidden for this purpose if they, for example, were too bright and disturbing at night.
Chemoluminescence: Materials with chemoluminescent properties don't need to be exposed to light for them to glow. The light they emit is a result of chemical reactions.
Pros: No need for UV lamps or "charging" in sunlight/daylight. Chemoluminescence is present in many living organisms (a.k.a. bioluminescence), therefore some bioluminescent microorganisms could theoretically be kept in liquid-filled transparent vessels - tubes of various shapes that would form decorative patterns and glow. They could be fed through automatized system regularly providing nutrients. The idea of harnessing bioluminescent bacteria for light-producing purpose is explored in this session.
Cons: Just like with phosphorescence, chemoluminescent materials usually glow green or greenish-blue. This is especially true for bioluminescence. Some deep-sea animals emit a red and yellow glow, but this is rare. If chemiluminescent materials were used, the chemical reaction emitting the light would sooner or later run out and there would be a need to add new chemicals to support it.
Each of the three types has its own advantages and disadvantages, therefore it would be best to combine all of them and use phosphorescent materials for specific locations/conditions, fluorescent for others, etc. It's important to stress that a very intense luminescent glow might be tiring to the eyes especially if the decorations are abundant. Therefore it's necessary to make the intensity of such light balanced for it to be gentle, but at the same time intense enough to be joyful.
To make the decorations long-lasting, when using luminescent paint it's important to envelope luminescent surfaces with transparent materials (plexiglass or others) to protect the paint from eroding atmospheric impact - rain, precipitation, etc. Automatic, dynamic shields could also be installed to cover phosphorescent or chemoluminescent elements in times when the glow is not desired. For fluorescent ones it's enough to turn the UV lamps off, on top of that, some fluorescent pigments are invisible in daylight, therefore they would blend with the color of the background.
Luminescence can also serve a practical purpose:
If used abundantly, luminescent decorations could supplement or in some places even replace artificial lighting. During the winter season, especially in far-north regions, the day is very short, so public lighting is anyway required most of the day. Such decorations would not only light the streets but would be beautiful to look at. During cloudy days, when natural light is present, the intensity of the glow could be boosted up to make them visible enough.
Luminescence can also be used to mark objects in the dark, guide the way, etc. This award-winning landscaping project shows how can it be both beautiful and practical:
A post scriptum notion to ponder: The most colorfully decorated cities are arguably in the southern and not the northern countries. Having in mind the issue that is expressed here, this is paradoxical, because northern cities (or rather their inhabitants) need colors the most. It seems that the look of the surroundings reflects the average mental state of the inhabitants, which is heavily affected by the weather. This is also reflected in other cultural artifacts - songs, literature, paintings. Northern people also seem to emphasize the practical aspect of things more, e.g. it's not practical to wear bright clothes in winter, because they will quickly appear dirty, therefore it's better to "blend" with the greyish environment. The emotional value this brings is not emphasized.
Bringing more colors to the surroundings is a way to tackle this vicious circle.
During the northern winter period, people are more or less confined to the indoor "habitats". Sure, we can go out for a quick "spacewalk" in our protective suits but majority of the time is spent indoors. In a way, this is a very mild version of what awaits people on Mars. It's is why I started thinking about an indoor plant wall which eventually resulted in this:
A way to add color during winter time. I constantly find myself being drawn to look at the plants rather than anything else in the room.
Street jungle booths
To extend this into the streets, such plant walls could be positioned in street-facing exhibition windows. The plant care can be made fully automatic and require maintainance check-ups once in a while.
This effectively extends the convenience of using "spacesuits" to the plants as well. That way we can co-exist in all seasons:)
Town square jungles during winter time
I can imagine a 360 degrees glass cylinder booth (similar to revolving doors) where the plants are positioned in the center and facing outwards into every direction. Something like this could be placed in the center of town squares during winter time and removed in the spring.
Jungle bus stop
I can imagine a glass bus stop design where the entire street facing wall is made of tripple insulated glass that separates the outdoor air from the heated compartment sheltering the plants. The plants are illuminated with full spectrum light that resembles the sunshine.
Something like this, but enclosed in glass and more colorful plants used: