Natural ventilation in a private house: rules for arranging a gravity air exchange system

In the design of country houses, gravity ventilation is often chosen more often than the more efficient and independent mechanical ventilation. Time-tested natural ventilation in a private home is easier to implement and much more practical. It does not require special care, does not require maintenance or power supply.

We will talk about how to organize air exchange that occurs naturally. The article we have presented describes in detail the principle of operation of gravity ventilation. Let us introduce you to the devices that are used in the construction of systems that operate without third-party coercion.

How does the air exchange process work?

The main purpose of the gravity version of the air exchange device is to maintain the required microclimate. In addition to saturating the space with fresh air, it also removes exhaust air, gas combustion products, and various odors.

The efficiency of a natural ventilation system installed in a country house or country house is determined by the difference in atmospheric pressure inside and outside the house, which also depends on temperature, air humidity and wind strength.

Natural ventilation should ensure uniform supply, movement inside and removal of air flows, regardless of the number of floors of the house

Natural air exchange works as follows:

• Air from the street enters the house through open transoms and elements of window and door structures that are loosely adjacent to each other. Air flows rush inward during ventilation through slightly open plastic windows or through ventilation supply valves.
• The movement of air from one room to another and within it occurs spontaneously. To ensure that there are no obstacles to the flow, gaps are left between the floor and the doors. Their function is successfully performed transfer gratings installed in walls.
• Exhaust air leaves the house through exhaust ventilation ducts. They are located in rooms with unstable humidity/temperature - in kitchens, separate and combined bathrooms.

All city residents are very familiar with exhaust components. These are ducts connected to a public ventilation shaft. They are covered with grates that need to be cleaned periodically.

In the arrangement of a private house organization of natural exhaust may vary significantly. For example, this could be an vent at the top of the wall, an exhaust pipe or a hole in the ceiling with access to the ventilation duct into the attic, and from there to the street.

Components of gravitational air exchange

One of the common problems with natural ventilation in a private home is the lack of fresh air entering the room. Gravity ventilation works flawlessly only when the density of the air mass outside the window is significantly higher than inside the premises. In the summer, when their density is equalized, air from the street does not flow.

In addition, serious obstacles are now being placed in the path of naturally moving air flows. The seals of windows and doors offered to consumers these days perfectly resist heat leakage, but they also do not let air in from the outside.

In order to ensure natural air flow in houses with sealed windows, it is worth installing supply valves in the wall and providing exhaust ventilation pipes with deflectors

The issue of fresh air entering rooms with practically sealed windows and doors is solved by installing ventilation supply valves. If you don’t want to install valves, you will have to purchase supply units for plastic windows or buy window packages with supply units initially built into them.

Window inlet valve

This device is also called windowing ventilator. Refers to the most common options for solving the air exchange problem. The design of such a valve is mounted directly into the window profile.

The flow of incoming air through the window ventilator is directed upward so that the cold supply air mixes more effectively with the already heated air inside the room and does not cause discomfort to residents

Some valves are equipped with automatic air flow control. It is worth noting that manufacturers do not equip all models with mechanical adjustment. ventilators. This can create certain problems with sudden temperature changes.

The main disadvantage window supply valve is relatively low productivity. Its throughput is limited by the size of the profile.

Wall exhaust or supply device

For installation of wall ventilator you need to make a through hole in the wall. The performance of such a valve is usually higher than that of a window valve. As in the case of window inflow, the incoming volume of fresh air is controlled both manually and automatically.

Wall exhaust valves usually located at the top of the wall, where exhaust air naturally rises. Supply valves in the wall they are most often mounted between the window and the radiator. They do this so that the incoming cold air also heats up.

If a wall ventilation valve is installed directly above the radiator, the flow of fresh air will spontaneously heat up before being delivered into the room

Advantages of installing a supply valve over conventional ventilation:

• Ability to regulate the flow of fresh air;
• The ability to transmit significantly less street noise;
• Availability of filters of varying degrees of air purification.

The design of the wall supply and exhaust valve does not allow moisture to penetrate into the room. Many models of these local ventilation devices often include filters for air purification.

Interior transfer gratings

In order for fresh air to freely penetrate into all parts of the house, transfer components are needed. They allow air flows to flow freely from the inlet to the exhaust, taking with them dust, animal hair, carbon dioxide, unpleasant odors, household fumes and similar inclusions suspended in the air mass.

The flow occurs through open doorways. However, it should not stop even if the interior doors are closed. To do this, leave a gap of 1.5-2.0 cm between the floor and the interior door leaf.

In order for fresh air to move freely to the hood and wash all rooms, transfer grilles are installed in the door leaves. If they are not there, then a gap of up to 2 cm is left between the floor plane and the canvas.

Also used for these purposes transfer grilles mounted on a door or wall. The design of such grilles consists of two frames with blinds. They are made of plastic, metal or wood.

Specifics of duct hood

Exhaust air leaves the house through vents, ventilation shafts or air ducts. Ventilation ducts are usually led into the attic or connected to a ventilation shaft located in the center of the house.

Ventilation ducts in the installation and organization of natural ventilation in a private house are used mainly when installing the exhaust part of the system. Natural flow through air ducts is most often impossible or ineffective. In order for it to work at least somehow, a duct fan would have to be installed.

In natural ventilation schemes, ducts provide the exhaust part of the system. Exhaust air ducts in private homes are often combined into shafts

Air masses are pushed towards the exhaust of gravity ventilation by fresh portions of air drawn in through a window, a PVC window inlet or an open entrance door. The cross-section of air ducts is selected taking into account air exchange standards for certain types of premises, which are given in the collection of SNiP 41-01-2003.

In addition to residential and utility rooms in a private house, it is necessary to provide ventilation systems for a basement and storage built in it, a foundation without a basement, a cold attic or a furnished attic. In natural schemes they are provided with vents, gable and dormer windows.

Types of ventilation ducts

By location they are distinguished:

• Built-in. Constructed from hollow concrete or ceramic blocks and bricks. Such exhaust ducts are usually erected during the construction stage.
• Hanging. Made from galvanized steel or reinforced plastic. It is quite easy to install hanging channels, even after the house has already been built.

Air ducts are divided into round and rectangular cross-sections. Each type has its own advantages:

• Round duct. Easy installation, better air exchange, less weight;
• Rectangular duct. It takes up less space, is easier to disguise with boxes, false ceilings and walls.

In turn, pipes for a round air duct are rigid and flexible, i.e. corrugated.

Corrugated ventilation pipes are easier to install, but their installation is only possible on horizontal surfaces and on small areas of vertical walls

Rigid pipes allow air to move without any obstruction, so they provide the least resistance and minimal noise. However, with the help corrugated pipes faster and easier installation.

What is a deflector?

A deflector is a special cap that is installed at the mouth of the exhaust pipe of the ventilation system. It cuts the wind flow, due to which a low pressure zone is formed, while the traction force can increase up to 20%.

Also ventilation deflector prevents atmospheric water from entering the ventilation system and prevents wind from blowing into the ventilation duct.

The deflector is installed at the mouth of the exhaust pipe. This device performs two important functions: enhances traction + protects against precipitation

The following types of deflectors exist:

• Cylindrical or umbrella Volpera. It is a curved cylinder covered with a plate. It has average efficiency, protects ventilation ducts well from wind blowing;
• H-shaped deflector. The body is made of pipes in the shape of the letter H. It features increased protection against wind blowing, moisture entering the channel and reverse draft, but due to the design features it has low performance;
• Deflector type TsAGI. The design includes a glass with an extension at the end, an umbrella lid and a cylindrical shell. Recognized as one of the most effective. It protects well from wind, snowfall, rain, and has the lowest resistance coefficient;
• Turbo deflector. It is a rotating ball with blades, it is characterized by increased efficiency, but usually costs a little more;
• Vane. Reminds me of a wing. The operating principle is similar to turbo deflector.

The choice of deflector model depends on local conditions. In regions with high wind loads, ordinary fungi are preferred. In areas with low wind activity, it is better to install a deflector with a turbine; it will provide traction even with a light breeze.

Basic rules and recommendations

Standard data on the volume of air exchange are given in SP 44.13330.2011, SP 66.13330.2012 and the above-mentioned SNiP 41-01-2003.

The natural ventilation system should provide:

• In main rooms, such as the living room, bedrooms, children's rooms, the amount of air exchange for each person should be at least 30 m³/h;
• For the kitchen, constant air exchange according to the rules is 100 m³/h. Of this, 60 m is for servicing the electric stove.³/h, for 1 burner of a gas hob - 80 m³/h;
• In the shower and bathroom, the constant air exchange should be less than 75 m³/h;
• In toilets with one toilet 50 m³/h, if a bidet is installed, then it must be increased by 25 m³/h. In combined bathrooms, the standards for each plumbing fixture are summed up;
• In the pantry and dressing room, the constant air exchange is 10 m³/h, the same figure in maintenance mode.

If the natural system cannot cope with the standard air exchange, fans are installed on the supply or exhaust.

Standard data on air exchange are needed to calculate the performance of inlets and the diameter of exhaust ducts

It is advisable to select pipes for the installation of ventilation ducts of the same diameter. All elements of the air duct must be fixed evenly and securely. The fewer turns of the ventilation ducts, the higher the efficiency of the ventilation system.

The inlet openings of the natural system should be located no higher than 1.5 m from the ground level so that they can be cleaned and maintained.

The longer and wider the duct, the stronger the draft. You can calculate the required dimensions of the air duct using one of the online calculators.

Advantages and disadvantages of natural air exchange

Like any engineering system, the natural variety is not without its drawbacks, but also has significant advantages. To definitely decide whether to arrange it or not, it is worth comparing the list of pros with the list of cons.

Positive sides:

• Easy and inexpensive installation. This is the cheapest option for organizing stable air exchange.
• Low maintenance costs. If the system does not have mechanical devices, then it only needs periodic cleaning.
• Energy independence. Does not consume electricity, except for the installation of additional electrical appliances.
• Extremely quiet operation. Features reduced noise.
• Engineering flexibility. Ventilation can be modernized and equipped with various devices. It is possible to adjust the system performance.

Negative sides:

• Instability of traction. Its dependence on atmospheric pressure and specific weather conditions. The effectiveness of natural ventilation in summer may be insufficient.
• Formation of drafts. In winter, strong drafts can not only cause discomfort to residents of the house due to drafts, but also significantly increase heat loss. This results in increased costs for heating the premises. It is worth noting that there are different ways to solve this problem.

Anyone can organize a natural ventilation system in a private home. Its imperfections are compensated by the simplicity of its design and minimal maintenance costs.

Conclusions and useful video on the topic

The following video will introduce you to the specifics of the design of an air exchange system according to a natural scheme:

Normal air exchange has a beneficial effect on human health, increases brain performance, counteracts the onset of symptoms of lethargy, weakness and sleepiness, and also prevents the appearance of dampness, fungus and mold in the house.

Would you like to talk about how you installed the ventilation system for your own home or cottage? Do you want to share useful information on the topic of the article? Please leave comments in the block form below, post photos and ask questions.