Ventilation and air conditioning

Ventilation is adjustable air exchange in a room with the aim of creating a desired microclimate, that is, removing polluted air from the room and introducing fresh, treated air.

It is necessary to ventilate not only industrial objects or large buildings, but also private houses and apartments. By installing artificial ventilation equipment, air quality improves significantly.

The most common reason for installing ventilation is poor-quality air that enters every home from the polluted urban environment through an open window, bringing dust, pollen, etc. The ventilation system can solve this problem.

Another reason is poor ventilation of the premises – in many premises ventilation is not possible at all, for example in bathrooms and toilets, where there are often no windows. In such rooms, moisture and stuffy air accumulate, causing mould. In this case, too, ventilation helps to cope with the problem.

Ventilation is installed so that people feel more comfortable at home. In many cases, ventilation systems make it possible to maintain the required temperature even without an air conditioner and other special equipment.

There is supply and exhaust ventilation. The first ensures the inflow of purified air into the room, while the second ensures the removal of polluted air from the room. It is best if both of these processes take place at the same time, then the ventilation of the room is full-fledged.

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Indoor air quality

Today, people spend most of their lives indoors, so it is very important to take care of the microclimate of the housing. Air quality requirements for rooms with different needs may vary. In addition, every person may also have a different comfort temperature, but it should preferably be maintained between 18 °C and 22 °C.

The recommended relative humidity of air is between 40% and 60%. Low relative humidity can cause adverse effects on the skin, respiratory tract, nasal mucosa and eyes, causing irritation, and dry air increases the ability of viruses and bacteria to spread. On the other hand, high relative humidity increases the likelihood of dust mites and water drops that cause moulding may condense on cold surfaces, such as window frames.

The concentration of carbon dioxide (CO₂) in the room is a very important indicator of the microclimate. It is measured in parts per million or “ppm”. The CO₂ level in the room should not exceed 800 ppm above the outdoor CO₂ reading of 350–400 ppm. A CO₂ concentration of up to 1000 ppm is considered acceptable air quality. Beyond this value, oxygen is reduced in the room causing people to feel tiredness, drowsiness and even headaches.

According to the Latvian construction standard, the quantity of fresh air supply in a room where one person is present and there are no other sources of air pollution should be 15 m³/h. However, to maintain an optimal level of comfort and to remove all possible pollutants and humidity from the room, an air exchange of 20 to 30 m³/h should be ensured.

Types of mechanical ventilation

Types of decentralised ventilation

In the case of a decentralised ventilation system, separate installations ensure air exchange in specific rooms or groups of rooms.
There are solutions in which air supply and air extraction are performed by separate devices or simple fans.
Such solutions are suitable for multi-apartment buildings, where all the dwellers of the building do not want or cannot install a joint ventilation unit.

Types of centralised ventilation

Centralised ventilation systems are intended for both private houses and multi-apartment houses.
In this case, one installation takes care of air exchange with the air circulation through separate air channels.
It is recommended to install fresh air supply channels in the rooms where fresh air is needed primarily, such as the bedroom and the living room.
It is recommended to install air exhaust ducts in the kitchen, bathroom and toilet.
It is not desirable to install the fresh air supply ducts and the indoor air exhaust ducts located outside the building close to each other, so that the ventilation equipment won’t suck the air that has just escaped from the house back into the building.

Measures to reduce the electricity consumption of ventilation equipment

Ventilation equipment can be divided into two groups according to their energy consumption: equipment that changes the thermal properties of air (heating, cooling humidification and dehumidification) and equipment that moves air through ventilation channels.

The ventilation system has the following energy-consuming components:

Heating surfaces. The energy source is usually hot water from the boiler room or central heating system. Electric heaters are also found, but in most cases they are in less powerful ventilation equipment.
Cooling surfaces. The primary energy source is the electricity supplied to the compressor.
Humidifiers. The energy source can be both electricity and heat. Steam humidifiers use electricity directly. Water humidifiers use hot water to reheat the air.
Dehumidifiers are always powered by electricity, either in the form of a refrigeration compressor or by regenerating hygroscopic material in absorption dehumidifiers.
Fans. The energy source for fans is always electricity.

To reduce energy consumption during the operation of ventilation equipment, the following energy-saving measures can be taken:

Reduction of operating time

Changing the operating time can be done manually or automatically.
Manual regulation can be implemented by installing an automatic on/off mode in the room. This type of regulation is usually installed in rooms that are not used regularly, such as conference rooms.
Timers can be used when rooms are used at predetermined intervals, for example in office spaces or classrooms in schools.
When the operation of the ventilation system is stopped, the local circulation pumps must also be stopped.

Reduction of fresh air flow

The amount of air flow should be as small as possible to ensure a comfortable indoor climate and protect the premises from moisture damage.
The fresh air flow should be adjusted according to the actual demand.

Reducing or turning off humidification

Air humidification requires a lot of energy, so it is recommended to reduce it as much as possible.

Reduction of supply air temperature

Lowering the supply air temperature will require less energy to heat the air.

Implementation of heat recovery

The heat recuperator or heat exchanger will reduce the electricity consumption of the ventilation system for air heating by approximately 90%.
The operation of the recuperator is based on the recovery of heat from the exhaust air, thus significantly reducing heat loss.
The system also works effectively in the summer, when cool air is kept indoors.

Maintenance of ventilation equipment

If the equipment is not regularly maintained, the energy consumption is affected by dirt on the heat exchange surfaces (heaters, heat exchangers, etc.) and dirt on the filters, as well as wear and tear of movable mechanical parts and damage to the duct system.

Installation of demand regulating ventilation

Generally, demand-controlled ventilation is used in public places where the controlling parameter is CO₂.

Air conditioning

Air conditioning is the process of air treatment, or the creation and automatic maintenance of humidity, temperature and air movement speed in closed spaces. In a broader sense, this term refers to ventilation.

The main purpose of conditioning is to create pleasant and comfortable indoor climate conditions. Air conditioning equipment is capable of both cooling and heating the air in the room, as well as maintaining air cleanliness and ventilation.

Equipment such as air conditioners are used for conditioning purposes. During the summer they cool the air in the room, but during the winter they can heat the air.

Air conditioning

Is air conditioning healthy?

In low-quality air conditioners and improperly installed ventilation shafts, there is a possibility of bacteria and infection foci, which can adversely affect human health. One such dangerous infection is legionella.
New generation conditioners have special filters and self-cleaning functions that prevent such risks. On the other hand, air conditioning is very desirable in cases of asthma and other respiratory diseases and has a positive effect on human health in the long term, providing room air with a sufficient amount of oxygen, as well as making heart patients feel better during the hottest period of the year.

Why do you need air conditioning?

By installing high-quality ventilation and conditioning the climate of the room, you will get a convincing sense of well-being at any time of the year. Of course, there is a possibility to ventilate the rooms also by opening the windows. But in this case, let's forget about energy efficiency – in winter there will be large heat losses, up to 50%, while in summer you will not be able to avoid street smells and dust, not to mention noise.
The ventilation system will prevent the occurrence of mould inside the premises, as well as the spread of various infections and bacteria.
By choosing a quality ventilation and air conditioning system, you will make a sustainable investment in improving the quality of your life.

What types of conditioners are there?

There are several types of conditioners:

Split system conditioner

Multi-split system conditioner

cassette conditioner

duct conditioner

window conditioner

mobile conditioner

Technical, functional characteristics of air conditioners

One of the main and most important components of an air conditioner is the compressor. The scroll compressor is one of the best. It is characterised by long service life, low noise, low vibration and economical use of electricity.
When choosing this household climate control device, special attention should be paid to noise level indicators. Most of the time, the air conditioner emits noise between 38 dB and 54 dB from the outside, and between 26 dB and 36 dB from the inside (for reference, people in a room usually talk, making noise between 35 dB and 45 dB). Therefore, special attention should be paid to the installation of air conditioners in the room where the family rests at night – the bedroom. When the windows are closed, the noise level of the outdoor unit of the air conditioner is not audible.
Amongthe main components of the air conditioner are automatic diagnostic systems. Sometimes, after the long years of operation of this climatic household appliance, Freon (refrigerant) flows from it. The device should deal with the problem by itself and block the compressor from starting. If the air conditioner does not have this function and will work with an empty circuit, the unit will quickly break down.
High-quality air conditioners are protected against power surges. With this protection, all settings are preserved during power fluctuations, as an automatic restart is included. When the mains voltage is restored, they work in the same mode as before, without interference.

What should be considered when buying a conditioner?

There are several factors to consider when choosing an air conditioner.

Power – It is important to choose this parameter according to the area of the room. If you choose a device with low power, it will not be able to cool a large room. If you are not sure how powerful a device to choose for your home, be sure to ask a professional for advice. A specialist will recommend the best option that will be suitable for your home.
Energy efficiency – When choosing a specific conditioner, you must pay attention to its energy efficiency. If you want to pay the lowest possible electricity bill, the energy efficiency class of the device should be as high as possible.
Functions – Nowadays air conditioners are equipped with several functions such as air cooling, ventilation, as well as air heating. It should be noted that each function increases the cost of the device. To avoid overpaying, choose a device that only has the features you need.
Installation – Not all air conditioners are easy to install. In order not to damage the device during installation, it is better to entrust this work to professionals.

What is air recovery and who needs it?

Air recovery is the recovery of warm air, which makes the building energy-efficient, using modern ventilation and air conditioning systems.

This technology makes it possible to recover up to 90% of the thermal energy that is conveyed through the ventilation shafts together with the used air.

The fresh incoming air is respectively either warmed (in winter) or cooled (in summer) with the help of the temperature of the outgoing air, without the air flows mixing. This allows you to save on heating costs.

Types of recuperators

Plate recuperator

The plate recuperator consists of cross-shaped plates, between which isolated supply and exhaust air flows are flowing across and in parallel and their temperature equalises.
The advantage of the plate heat exchanger recuperator is very high efficiency of separation of exhaust and supply air – up to 99.9%.
Thus, it can be used to recover heat even from the warm air flowing out of the kitchen exhaust channel without worrying that unwanted smells will spread in other areas of housing.
This type of recuperator does not recover the humidity in the room.
In cases where the outdoor air is very dry, humidity levels in the room will also decrease.
The disadvantage of a plate recuperator is the possible formation of condensate in the heat exchanger itself. This may occur during the winter period, when the outdoor air temperature drops below –2 °C.

There are two solutions that are used to prevent condensate formation:

reduce the intensity of the supply air and increase the intensity of the exhaust air, thereby reducing the efficiency of the recuperator and reducing the temperature of the supply air;
install an electric heater in the outdoor air supply duct and heat the outside air above –2 °C, but this will cause additional electricity consumption.

Rotary recuperator

An aluminium plate rotor containing air flow channels is installed on bearings in the ventilation unit with a rotary heat exchanger. The exhaust air heats up the rotor and this heat is used to heat the supply air.
In this type of equipment, supply and exhaust air are slightly mixed, from 2% to 5%.
Thus, there is a small possibility of transmitting odours from exhaust air to supply air.
The rotary heat exchanger partially recovers humidity from exhaust air, which is important during the winter period when the relative humidity of the outdoor air is low.
There is no possibility of condensate formation in the rotary heat exchanger, which eliminates the risk that the equipment may freeze.
It should be noted that the efficiency of this type of recuperator decreases in cases of very low outdoor air temperature.

Enthalpy recuperator

An enthalpy heat exchanger has been created to combine the good properties of a plate heat exchanger and a rotary heat exchanger.
The enthalpy heat exchanger basically is a plastic plate heat exchanger.
Its plates are made of a special nanomembrane, the main property of which is the recovery of humidity.
The membrane structure is designed so that only compounds that are the size of water vapour molecules can move from one side of the membrane to the other.
The enthalpy heat exchanger has high energy recovery efficiency.
Due to the property of moisture recovery, the risk of the heat exchanger freezing is significantly reduced.
Such a recuperator allows you to maintain the air humidity level in the premises and at the same time guarantee that the exhaust and supply air flows are separated from each other.

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