Sunlight governs the schedule of our activities and lives. It is an infinite source of energy and even influences our health and mood. So why not take it into account for the design of our homes?
The sun is the main source of heat and natural light. Using it correctly will allow us to save energy for heating and illumination, therefore polluting the planet less (and saving money!)
Buildings are our shelters. Sustainable architecture understands that we must protect ourselves, but for that, we must gain complete knowledge of our site: its temperatures, winds, and incidence of the sun. The idea is to adapt our homes as much as possible to the site where we are and to take advantage of its resources - without losing comfort.
The path of the sun
In order to design a passive solar house, the main thing is to know how the sun affects the land. The first thing to know is that the sun’s path varies based on the hemisphere. In the Northern hemisphere the sun rises in the east, moves southwards during the midday hours (this is the ideal orientation) and sets in the west. In the Southern hemisphere, on the contrary, its path is east-north-west.
On the other hand, the direction and position of the sun vary according to latitude and the time of year. The closer we are to the equator, the smaller its variations are. During the winter the route is shorter, therefore, less daylight hours. Depending on where we are, the sun is likely to rise in the east or southeast and go down in the west or southwest. It will also hang lower in the sky, generating longer shadows.
During the summer months, the sun takes a longer path, so your days are longer. It also rises higher in the sky, increasing the temperatures.
The sun and house design
In addition to the path of the sun, we must know how these solar rays affect our terrain. It is very important to know the surroundings of the construction site. Vegetation or other construction around our land might generate shade and limit us. As mentioned, an analysis must be done for winter and another one for summer, since the height of the sun and the natural environment vary. For example, if we have a deciduous tree nearby, it will shade us during the summer but not during the winter. On the other hand, if we are in the city, we probably have to make greater effort to get the sun's rays to enter our house.
At the same time, it is necessary to know what activities will be carried out in the building, as sunlight will greatly affect the function that can be defined for each space. If we can position the spaces according to their schedule of use, following the path of the sun, we can provide natural lighting for the entire building. For example, in a single-family house, we can situate the bedrooms as well as the kitchen and the breakfast nook to the southeast, to take advantage of the morning rays. The living and working spaces can be located at the south and the service facilities (bathrooms, laundry) to the north. The western orientation is the most cumbersome, since during the summer it will experience the hottest rays, which are difficult to control. In these cases, it is essential to design a good screen to be able to stop them from entering the house and properly isolate the façade to deter heat.
The sun is our main source of light and allows us to reduce our electricity consumption. If we design a good layout of the premises, all of the spaces can have natural light. It is not necessary for all the spaces to have an outside opening to receive light; it can be achieved using skylights, glazed ceilings or courtyards. Some rooms may still not receive direct sunlight, but the lighting can be indirect, although there is a risk that on cloudy days it will not be enough.
There are also devices to multiply those rays, such as the use of light colors in coatings, mirrors or solar trays that allow the illumination of spaces of great depths. On the other hand, the opposite can happen and sunlight can generate inconvenient glare. For these cases, it is important to design the appropriate apparatus to avoid discomfort.
The heat of the sun
Although the entrance of the solar rays allows natural illumination and eliminates mites and bacteria, during the summer it causes high temperatures in the home. That is why the sun's rays must be controlled in a home’s south and west orientation during the hottest months. It is important to know the solar angles to design the openings in a way to avoid them. There are also different elements that help mitigate this inconvenience such as eaves, blinds, sunshades, awnings and even vegetation.
On the other hand, that heat can be captured and used during the cold months. To meet this objective, we can utilize trees with deciduous leaves that protect in the summer and allow sunlight entry in winter, the correct design of the openings and eaves, Trombe walls (in very cold locations), and flooring and walls with thermal inertia (especially if we are in a place with thermal amplitude).
The sun is one of the main factors in designing green buildings, impossible not to take into account. If it is not researched well, it can generate much discomfort. But if we manage to employ the sunlight correctly, we can significantly reduce our bills and increase our quality of life!