Public street lighting has a major influence on safety, perception of safety and atmosphere perception. The municipality of Rotterdam has the obligation to provide the city with public street lighting. Also, they have the desire to create a pleasant atmosphere in the city during both day and night. A user study performed for this project has helped determine what a pleasant atmosphere means; clean streets (no litter), knowing your neighbors, enough urban nature and seeing in the dark. This thesis focuses on the last two points, because they seemed to be conflicting each other. A hypothesis was formulated, suggesting that urban nature and street lighting conflict each other above and underground. Above ground, trees reduce the light output of the street lighting when they grow close to a lighting point. Below ground, the roots of the trees get strangled between the power cables. This conflict seemed to be enhanced by the fact that space is limited in the urban environment, especially in residential areas. A certain distance is needed between lampposts and trees, because of street lay-outs (side streets, parking spots, cables under ground) the options for are limited for placing a satisfying amount of trees in between the lighting points. However, the living quality of residential areas benefits from more urban nature. The hypothesis was researched with observation and nine interviews. It was revealed that trees blocking light is solved easily by placing trees and lighting point correct. Correctly distancing trees and lighting points, both in height and horizontal spacing. Trees can be allowed to block the light a little bit, because it creates a dynamic shadow on the road. For high speed roads (from 50 km/h) these shadows would become a problem for safety reasons. However, in residential streets it is not. The underground conflict between tree roots and power cables can be solved in two different ways: find other ways to create residential green or redesign public street lighting. Within the first direction many solutions were found, however within the second direction there were not. Since 1800 the lamppost has looked the same: a light source on a pole. Other forms such as hanging street lighting and facade lighting solve some problems above ground (space consumption) but not underground. And these forms of public street lighting bring new problems with them (convincing building owners to allow this way of mounting). With this analysis the assignment for this thesis was formulated: "Solve the conflict between urban nature and public street lighting by designing a new street lighting system." Rotterdam has the goal to reduce CO2 emission with 50% in 2020 (compared to 1990). To help reach this goal the CO2 emission of the solution should be lower then the CO2 emission of the current public street lighting. In order to do this the environmental aspects of public street lighting were researched for every step in the life cycle. This was done together with the (financial) value for every life cycle step. Together this results in an Eco-costs Value Ratio (EVR). The manufacturing and energy consumption turned out to be the most harmful steps for the environment. Maintenance and administration and energy consumption are the most expensive steps. Reducing the energy consumption is beneficial in both environmental and financial terms. Reducing eco-costs in the manufacturing phase, together with reducing costs for maintenance and administration would make the design more valuable for the municipality. This results in a list of requirements: - create a better atmosphere - create a safer feeling - create more space for urban nature - reduce CO2 emission of Rotterdam - reduce energy costs - reduce maintenance costs - reduce administration costs - reduce eco-costs of the manufacturing phase The assignment and list of requirements resulted in a new design for public street lighting, mounted on top of the roof of a house, the system is connected to the grid of the house. During night the light uses energy from the house. During the day one or two solar panels generates energy to compensate this use. The solar panel generates more then only what the light is using. This overcapacity is delivered free of charge to the resident. He or she gets a discount on the energy bill (up to 50 euro per year per resident). The resident is not the building owner in many situation. A housing cooperation can be owner as well. Their benefit is the increasing value of a building with solar panels. For the municipality the new concept means no energy costs, no digging, no separate grid and it is easier to convince the resident and building owner to cooperate. Because of these benefits the new design is cheaper then the current system, even with addition of the relatively expensive solar panels. The initial investment is a little bit higher, but the running costs (maintenance, administration and electricity) are much lower. With one solar panel the payback time is 9 years, with two solar panels the payback time is 36 years. The lifetime is at least 40 years. Because of the energy production of the solar panels the new design has reduced the eco-costs and CO2 emission to negative values. This means the environmental burden, caused by manufacturing and energy consumption, is largely compensated. The environmental benefits can get up to 2300 kg CO2 equivalent per street per year.