Process of updating of air in rooms, necessary for maintenance of normal internal microclimate, is called ventilation. In fact, ventilation of the building is direct continuation of our breath as:
- provides intake of fresh air and fills up oxygen level;
- evacuates stagnant air outside, thereby deleting CO2, excess humidity and the substances contaminating air.
The supply and exhaust ventilation, therefore, represents itself bidirectional air flow and its functions consist in the following:
- to reduce concentration of polluting substances in internal space, to provide qualitative level by extraction of clean air from the outside;
- to reduce the excessive level of air humidity by extraction it from places where it is formed in high concentration: shower rooms, kitchens, etc.;
- to delete the dioxide of nitrogen (CO2) emitted at breath and to replace it clean, fresh, full of oxygen, with air;
- to delete unpleasant smells from cooking and some natural functions of organism.
Besides, the supply and exhaust ventilation performs also such functions as cooling of internal air by removal of surplus internal heat or airing of rooms where heating devices are installed.
Basic principles of the competent device of ventilation
When planning and mounting systems of supply and exhaust ventilation it is necessary to be guided by achievement of the correct balance meeting such requirements:
- Air exchange in the necessary volume is indoors necessary for achievement of the best results on air quality.
- Not to allow heatloss during heating season as external cold air quickly forces out warm internal air.
- Imperceptible change of air without drafts and sharp temperature drops is the key to thermal comfort.
- Capital expenditure for mounting, operating costs and service of vent systems have to be adequate and not burdensome.
- The ventilation system has to be simple in service and easy to control.
- Presence of the working vent systems and the equipment should not raise considerably internal noise background and not bring discomfort in premises.
- The extract from rooms with the increased humidity has to be carried out most intensively, but dispersal of humid air on the rest of the building has to be minimized. The intensity of extract, in this case, can be adjustable in the automatic or manual mode or continuous with recuperation of heat. Required speed has to be adjusted depending on type of the room and its functionality.
- The supply and exhaust ventilation of all house has to provide extreme situations when intensive removal of high concentrations of polluting substances or vapors of water can be required. For example, removal of smells during coloring, painting classes using oil paints or because of the accidental passage of hot water on big surface, burning of food in oven, etc. As a rule, we use for this purpose doors and windows.
- The incoming and exhaust flows have to be precisely calculated in order to avoid operation of the equipment empty.
Types of vent systems: their features, advantages and shortcomings
Most often, arguing on ventilation of the house, we mean installation of conditioners, table or floor fans, cleaners or humidifiers in living rooms. Perhaps, the lack of ideas of functional vent systems of other types is connected with the fact that in recent times all standard projects provided the device of natural forced-air and exhaust system. The ventilating channel which have become such usual in kitchens and bathrooms, not dense window and door openings fully provided compliance of internal air to sanitary standards.
Available facts of unauthorized re-planning of rooms as a result of which not seldom expansion of the areas is made due to destruction of air shafts, demonstrate absolute illiteracy of certain owners. Still nothing if such re-planning is made in one-storey buildings, but some inhabitants of high-rise buildings, destroying ventilating ducts, put at risk life of inhabitants of all strut, and occasionally and all entrance.
Today at construction more modern designs of windows, doors and other finishing materials are applied. Through skintight plastic windows and the isolated interroom doors air simply ceases to circulate therefore in houses of new construction it is necessary to provide full-function natural and forced supply and exhaust ventilation.
Natural ventilation is subdivided into unorganized and organized:
- Unorganized ventilation (infiltration) happens through the thinnesses which are available in designs (slots in windows, doors, walls and partitions). Infiltration is carried out at the expense of the difference of temperatures of outside and internal air, movement at the same time is created because of different consistency values of air masses. Infiltration can satisfy needs of the house with area no more than 140 sq.m at application conditions in it old wooden windows which air permeability can be from 10 to 20 kg / час∙м2. It is in addition possible to air rooms opening of windows, doors. Lack of airing, especially in cold season considerable heat waste is. In order that there was full change of indoor air it is necessary to air it 30 – 60 minutes. However for such time there is considerable cooling of designs, adjacent to window, that is fraught with formation of condensate. It is possible to make airing within 5 – 12 minutes, separation of window and door on opposite walls in an expedited manner. But it threatens with strong drafts which can be hazardous to health of people, pets and houseplants.
- Organized ventilation is carried out continuously without participation of the mechanized devices. Motivation of the movement of air happens at the expense of the difference of temperatures and specific weight of outside cold and warm internal air to participation of window leaves, transoms, ventilating ducts, flue. Organized ventilation, as a rule, provides kitchens, bathrooms, boiler houses, baths, cellars.
On accepted standards the movement of air flow in the house has to be carried out with the following speed:
- Kitchen with gas-fire — 70 m ³ / h
- Kitchen with the electric stove — 50 m ³ / h
- Bathtub or the combined bathroom — 50 m ³ / h
- toilet — 30 m ³ / h
- The living rooms separated from kitchens, bathrooms and toilets by not less than two doors — 30 m ³ / h
- The hall, the storeroom, the built-in niche — 15 m ³ / h
Considerable violation of these norms leads to formation of condensate, mold and emergence of potentially dangerous microorganisms, moth and other insects. Insufficient ventilation is dangerous not only to human health, but also to designs, the equipment, furniture, etc.
The first sign that in the house not sufficient ventilation can testify loss of condensate at windows, mirrors. It is possible to improve situation in this case installation of kitchen extracts, electro fans at the weekend channels. Fans work from current network and not economically to use them constantly especially as they rustle. They are used right after acceptance of shower or campaign in toilet. There are fans equipped with moisture sensors which join and switched off automatically. But they also rustle and demand power supply.
Can say that the exhaust ventilation is excessive that air in the house is overdried. Usually, the excessive extract provokes heat waste, drafts and becomes the discomfort reason. It is possible to eliminate these negative phenomena with installation method on extract of the automatic valve with moisture sensor. The valve to allow to reduce heatlosses in the house by 10 – 15%.
It is possible to increase quality of microclimate by means of humidifiers, dehumidifiers, air purifiers, conditioners.
Houseplants also affect purity and air humidity in rooms. Well purify air and such plants as chlorophytum, aloe, spathiphyllum, geranium, the English ivy, ficus, kalanchoe, bamboo palm tree and others emit oxygen.
The incoming valves began to enjoy wide popularity among owners of apartments of high-rise buildings and owner-occupied dwellings recently. When replacing windows models with adjustable ventilating slot (the window incoming valve) are most demanded now. Install also infiltration valves (wall incoming valves). Such devices are installed through external wall, they represent themselves the branch pipe on both sides closed by grids. The incoming valves are recommended to be installed near window openings, behind heating devices (radiators). At such installation outside air will get warm at once. Models, can be generally expected air flow from 50 to 100 m3/hour. They can be equipped with complementary filters, temperature and moist sensors.
Naturally organized ventilation has the advantages:
- it is simple in mounting, does not demand essential material inputs;
- it is reliable, it is mounted counting upon long time of use as does not fail;
- does not demand costs of service, it is necessary to examine and clean channels only from time to time;
- it is silent;
The main lack of natural ventilation is that control and regulation of intensity of airing cannot be carried out. Besides:
- through the slightly opened doors, windows, valves dust, pollen of plants, insects, noise gets into rooms;
- quite often too fast air flow forms drafts that is not comfortable and useful to health;
- atmospheric conditions resolutely affect efficiency of its work;
- limitation of adjustment of productivity of system: during the heating period can provoke considerable heat waste; for lack of temperature difference ventilation does not work;
- the air given to the room is not controlled, i.e. preparation is not carried out it.
The ventilation organized by means of micro airing of the incoming valves in external walls can solve problem of airing in small one-storey building. The house from two or more floors needs forced ventilation system.
Mechanical ventilation of owner-occupied dwelling – it arranged is centralized system with recuperation of heat, with possibility of complete control of condition of internal air. Are making the systems of the centralized forced supply and exhaust ventilation: fans, heat exchanger recuperator, filters, valves, grids, air ducts, air distributors, noise suppressors, control devices block.
It is necessary for effective aeration of rooms that air could pass freely from windows or the incoming valves in aspiration ducts. In new houses the device of ventilation is, as a rule, provided on house projecting phase. Ventilating ducts have in the building. When it is necessary to install the system of forced supply and exhaust ventilation in already built house, ventilating ducts construct in the form of added mines.
Air flow to the system of mechanical ventilation is carried out through the incoming air ducts. Air from the street by means of the air inlet goes to the block of ventilation and is distributed on all house.
In winter time in the recuperator (heat exchanger) two air flows meet (warm and cold from the street). The recuperator does not mix flows, but uses warm exhaust air for heating fresh, thus, heatlosses are excluded. The fresh, but warmed-up air comes to rooms. The system with the recuperator allows to reduce costs of heating of 25% in comparison with system without heat exchanger.
The contaminated air is evacuated from the house by means of the exhaust air duct and the deflector installed on the rooftop.
The centralized system provides process automation: operating mode and serviceability check of elements. Install different means of preparation of air in the block of ventilation: filters, heaters, humidifiers, ionizers, dehumidifiers, etc.
The soil heat exchanger – the most rational solution of problem of preparation of air as he is capable to lower costs of conditioning and heating of the house of 25%. The device represents itself pipe, the laid lower than frost depth of soil, approximately on 2 meters. One pipe end protected by filters is removed over the surface of soil, and another joins the airintaking block.
Shortcomings is that:
- Mounting of system, a priori, demands the financial investments. The most expensive element of forced supply and exhaust ventilation is the recuperator. The complex system, demands professional installation, costs of component parts.
- Functioning of system constantly requires the electric power, in lack of power supply it does not work.
- She demands the qualified technical maintenance: cleanings of channels, equipment, replacement of filters, repair.
- The equipment is rather noisy, demanding acceptances of antinoise measures.
Unconditional advantage of mechanical ventilation is that it is effective and at competent approach provides saving of energy costs. The payback of such system occurs quicker in more severe conditions of climate where heating season more long. Installation of forced supply and exhaust ventilation considerably increases comfort of accommodation in the house, improves internal microclimate as:
- normative air exchange happens in all rooms of the house constantly and does not depend on season and atmospheric conditions;
- it is easily regulated and can be ready under specific features of health living in the house.
The progressive aspiration of economy of resources is accompanied by need of operation of energy saving houses. But new houses remind more and more hermetic containers therefore the issue of ventilation of such housing needs to pay special attention.
For effective implementation of ventilation it is necessary to provide natural and forced supply and exhaust ventilation.
In the project of the house it is necessary to put air ducts, cable channels for electrical wiring and to choose optimal variant of installation of the central ventilating block. For this purpose calculations and consultation of the specialist are required.
It is impossible to save on it if finance does not allow to buy the expensive equipment at once, it is possible to establish cheap models without recuperator, to provide the soil heat exchanger.