Philadelphia installed white roofs on seniors' homes: temperatures dropped and electricity consumption decreased by 560 kWh per year
The initiative managed to reduce roof temperatures by between 4 and 5 degrees Fahrenheit
A solution as simple as painting roofs white . That was the basis of an initiative that demonstrated more than two decades ago that advanced technologies are not always necessary to combat high temperatures . Between 2001 and 2003, the Philadelphia Energy Coordinating Agency (ECA) carried out a pilot project that made it possible to improve the thermal conditions of about 340 homes occupied by low-income older adults.
The selected buildings were located mainly in the northern and western neighborhoods of Philadelphia, where the so-called ‘row houses’, the city’s characteristic terraced homes, received a very basic treatment: the roofs were painted white .
Less heat and lower energy consumption
The project's results were especially striking as well as functional. Measurements taken afterward showed that the temperature of the roofs decreased by approximately between 4 and 5 degrees Fahrenheit, which is equivalent to between 2.2 and 2.8 degrees Celsius .
The improvement was especially significant in the bedrooms located on the upper floors that did not have air conditioning. By receiving less direct solar radiation, the white roofs absorbed less heat and helped prevent temperatures inside the rooms from rising.
The effect also carried over to energy consumption . According to the data provided by the project, the homes whose roofs were painted recorded an approximate reduction of 560 kilowatt-hours per year in the electricity used for air conditioning.
The Philadelphia experience is striking for the simplicity of the intervention. No solar panels, smart climate control systems, or sophisticated technological devices were installed. The action consisted solely of applying white paint to the roofs .
The project exposed the potential of reflective roofs as a simple and effective tool to reduce the impact of solar radiation and heat, especially in vulnerable homes and in urban areas where high temperatures can become a problem during the warmest months.
