Beside from being an ecological and low cost housing project, Sacred Groves is a place worth living. During the design and the construction of the houses a lot of attention is given on the health and well being of its future inhabitants. Physical health is being taken care of by considering the indoor climate. Mental health through creating an inspiring environment. This blog is about the indoor air quality, this is one of the aspects essential for a healthy life.
The passive ventilation system, powered by the sun and wind, make sure that there will be sufficient fresh air entering all spaces. The roofs of the houses are designed in such a way that they become solar chimneys. These solar chimneys heat up the air in the top area of the house, mainly in the space between the outer roof and a false ceiling. Hot air rises and will be pulled out of the houses by means of motor less, roof ventilators, aided by the wind. This will create an under pressure in the houses. Air is being forced to enter from the lower parts of the buildings. Preferably from the site of the garden, where the plants and water bodies take care of the cooling of the air. This takes partly care of the temperature control of the indoor climate.
There are two ways to controlling the temperature, convection (controlling the air temperature) and radiation (controlling the amount of infrared radiation emitted by the building materials). Ideally it would be if we could keep our head cool and our feet warm. Unfortunately the most common way of temperature control (convection) does the opposite.
The walls of the Sacred Groves houses will have a large body mass, this makes them capable of creating a temperature control based on radiation. They keep the temperature equal between the lower parts and the upper parts of the spaces. The mass of these walls have a large heat capacity. In simple words it means that these walls are able to level out the temperature. So it will feel cool in summer and warm in winter. All this without the need of using additional energy for cooling or heating. The fact that these walls are made out of cob with a lime plaster, makes them diffuse and hygroscopic, they are breathing walls. Breathing walls have the capacity of absorbing the air humidity when the relative humidity is high and releasing this humidity when the air is dry.
The climate in which Auroville is located has a high relative humidity. Reducing this humidity when ever possible is more important for feeling comfortable then only taking care of the temperature. Dryer air makes it easier to evaporate our sweat, in this process we experience more coolness. Another importance is the cleaning of our body through the air we breathe. The air we breathe has a relative humidity of almost 100%. Our out-breath is the most important way of removing toxins from our body. The amount of water (including the body waste products) that leaves our body depends on the difference between the surrounding humidity and the humidity of our out-breath. The higher this difference the more we clean our body. To low air humidity should also be avoided, since this may lead to irritation of the respiratory tract. Due to the formation of micro dust, and unwanted air-ionization. These high density walls, build from locally abundantly available material, earth, are the perfect means of regulating the indoor air humidity and temperature.
A good ventilation, and an optimal temperature and humidity control gives biological pollutants like bacteria and fungus less chance to grow. With lime as finishing plaster fungus is less likely to find the required conditions to grow, because of the alkaline properties of lime.
Many modern building materials contain chemicals, they might be beneficial for cheap and fast construction practices, but they are certainly not good for our health. Conventional paints and glues contain solvents that lead to irritations, allergies, and other chronically ailments, as well as mental degeneration, and they are often carcinogenic. Pesticides are also commonly used to control termites and fungus, these are less volatile and will remain for many years in our indoor climate. Notorious is formaldehyde, used in adhesives for fiber board, plywood and synthetic carpet flooring’s. Fiber materials, of which asbestos is the most notorious, are also commonly used in construction. Many people are conscious about the use of chemicals in their food, but are unaware of its presence in the air we breathe. By choosing natural building materials, also on a finishing level, makes Sacred Groves not only a very sustainable project, but it makes it also a healthy place to live.
René