An attic is an attic-type living space located under a roof. Attic ventilation is necessary for the full use of the attic space, it protects the roof from premature wear and tear. Warm and humid air masses from all over the house rise into the attic. The lack of proper ventilation in a residential attic leads to the formation of condensation on the ceiling. The roof insulation gets wet, which causes its thermal insulation characteristics to fall, the house loses heat, and heating costs increase in winter.
Excess moisture creates a risk of corrosion of the metal elements of the roof. Favorable conditions are created for the growth of mold and fungi. You can prevent this if you properly ventilate the attic.
Ventilation rates in a residential attic
Attic ventilation standards and requirements for indoor microclimate are set in SNiP 2.04.05-91 and 2.08.01-89. Ventilation in a residential attic should maintain a temperature of at least 20º C during the cold season at a relative humidity of 55%. The air exchange rate is 30 cubic meters per hour for each adult.
To properly ventilate the attic, you need to take into account its area, wall and roof materials, and geometry. The more complex the shape of the attic, the more calculations require the natural ventilation of the attic. For every 100m2, 0.2m2 of exhaust and supply openings are required.
Forced or natural attic ventilation?
There are two main types of ventilation: natural and forced. The work of natural attic ventilation is based on the movement of air due to the difference in temperature and pressure inside and outside the building. Air masses enter the attic through ventilation ducts, natural gaps and crevices, and exhaust air is removed through ventilation openings. The air exchange rate depends on the cross-sectional area of the mines, their angle of inclination, wind speed and direction, and weather conditions. The work of natural ventilation is heterogeneous; it is impossible to establish strict humidity indicators of the air with its help. To compensate for existing shortcomings, natural ventilation is supplemented with forced air circulation devices.
Mechanical ventilation in a residential attic is created using equipment: supply and exhaust valves, fans, split systems, solar collectors. They force air into the attic and divert stagnant air masses. Some systems pre-prepare the air: clean it of dust, remove excess moisture, increase the temperature. With the help of mechanical ventilation, it is easy to regulate the temperature and humidity indicators in the attic and establish a favorable microclimate.
The disadvantages of forced air circulation equipment include their dependence on external energy sources, a sharp increase in the load on the power grid, expensive installation and repair. These disadvantages can be partially compensated for by installing solar-powered devices.
Use of solar energy in ventilation systems
Solar-powered equipment has proven its effectiveness in the USA, Canada, European countries and is increasingly being used in Russia and the CIS.
Advantages of solar ventilation:
- independence from traditional energy sources – electricity, coal, diesel, gasoline;
- widespread availability and free use of solar energy;
- simple installation that does not require the development of project documentation;
- environmental friendliness of the solution and the possibility of its implementation in remote, non-electrified settlements.
Attic ventilation with the help of solar energy optimizes the amount of electricity consumed, helps to reduce the amount in the bills from energy sales companies. Therefore, solar energy is used in the housing and communal services sector for the needs of hot water supply, heating, and ventilation of premises.