Recuperation
What is recuperation?
The recuperator is a device whose main function is to provide air exchange in rooms by the method of heat recovery.
Ventilation with recuperation is also called ventilation with heat recovery for its repeated use, thus allowing to recover up to 90% of the outgoing heat energy.
The air recuperation mechanism uses the thermal energy of the air leaving the room to warm the fresh air entering the room from outside, or vice versa – it cools the incoming air using the outgoing air. The recuperator ensures uniform air exchange in the premises without losing
the existing heat energy.
Ventilation with heat recovery for a healthy microclimate and lower bills.
Building ventilation is one of the most important prerequisites for a favorable indoor microclimate. The main task of ventilation is to supply clean, fresh air, remove excess moisture and polluted indoor air caused by people, animals, fumes from various materials and indoor activities.
Good ventilation ensures that the building does not develop moisture damage in the form of mold and mildew or other adverse conditions such as condensation on windows. Fresh air from outside is almost always cleaner than air inside. Using a mechanical ventilation system, microscopic dust particles and other pollutants are filtered, thus reducing the risk of possible allergies.
Signs of poor ventilation:
- Condensation inside the window
- Fatigue and poor sleep
- Stifling feeling of air when entering the premises
- Feeling winded and losing energy
What fresh air means
One person emits 20-50 liters of carbonic acid gas or CO2 in an hour. This is the air quality indicator that is easiest to measure. The amount of CO2 outdoors is approximately 350 ppm (parts per million). Indoors, it should not exceed 1000 ppm, if it is exceeded, working capacity will decrease, general fatigue will be felt, poor quality sleep, the risk of infectious diseases will increase and other problems will arise.
Meters manufactured in Latvia, such as Aranet4, Maple CO2, are also available for displaying the level of CO2 pollution. To obtain accurate measurements, it is important to choose a CO2 meter with an NDIR sensor.
The human body is able to adapt to the surrounding conditions, and most often people do not even realize how bad the air is in unventilated rooms. This can only be understood after taking measurements. Not infrequently, there is also an understanding of why children cannot concentrate on their studies or cannot get enough sleep at night.
What fresh air means
One person emits 20-50 liters of carbonic acid gas or CO2 in an hour. This is the air quality indicator that is easiest to measure. The amount of CO2 outdoors is approximately 350 ppm (parts per million). Indoors, it should not exceed 1000 ppm, if it is exceeded, working capacity will decrease, general fatigue will be felt, poor quality sleep, the risk of infectious diseases will increase and other problems will arise.
Meters manufactured in Latvia, such as Aranet4, Maple CO2, are also available for displaying the level of CO2 pollution. To obtain accurate measurements, it is important to choose a CO2 meter with an NDIR sensor.
The human body is able to adapt to the surrounding conditions, and most often people do not even realize how bad the air is in unventilated rooms. This can only be understood after taking measurements. Not infrequently, there is also an understanding of why children cannot concentrate on their studies or cannot get enough sleep at night.
How much air is needed
When you familiarize yourself with the building regulations of Latvia, you may get the impression that the required amount of air is completely different. For example, LBN 231-15 “Heating and ventilation of residential and public buildings” states that the minimum amount of air is 15 m3/h per person if the only source of pollution in the room is people. Harmful fumes from furniture, paints, packaging, which are especially important for new buildings, are not taken into account.
Building standard LBN 211-15 “Residential buildings” determines the internal air temperature and the required amount of ventilation air exchange in various rooms, such as living rooms, bedrooms, bathrooms. The regulation does not take into account the number of people who will be in the premises. As a result, strange calculations arise, as a result of which, for example, an underpowered device is installed in a 50 m2 apartment with 4 residents. On the other hand, in a 250 m2 house with the same 4 residents, in accordance with the regulations, a high-power device must be installed, which is expensive and uneconomical to operate.
Latvian national standard EN 16798-1:2019 “Energy efficiency of buildings. Building ventilation” describes several methods for calculating ventilation air exchange. One of them is to take into account the permissible CO2 PPM level, which is achieved by applying fresh air intake and polluted air exhaust corresponding to the air quality category.
In the case of private houses and apartments, we can assume that the amount of fresh air required for one person is 30 – 50 m3/hour.
Centralized ventilation with recuperator
Ducted supply/exhaust ventilation is the most common type of ventilation in all new and renovation homes. It provides a good indoor climate in all rooms, in all seasons and is energy efficient.
For ventilation to work, air must be able to circulate even when the door is closed or the room has both fresh air supply and exhaust diffusers. Air flow between all rooms in the house can be ensured, for example, with a gap at the bottom of the door.
Balanced ventilation has two main functions – it removes polluted air from the building and simultaneously supplies clean, filtered air at the required temperature. This is done by using two separate air duct systems: one for exhaust air and one for air intake.
Exhaust pipes remove polluted air from bathrooms, kitchens, toilets, laundry rooms and other wet rooms. Supply air ducts supply clean and fresh air to living spaces, bedrooms, living rooms.
Centralized ventilation with recuperator
Ducted supply/exhaust ventilation is the most common type of ventilation in all new and renovation homes. It provides a good indoor climate in all rooms, in all seasons and is energy efficient.
For ventilation to work, air must be able to circulate even when the door is closed or the room has both fresh air supply and exhaust diffusers. Air flow between all rooms in the house can be ensured, for example, with a gap at the bottom of the door.
Balanced ventilation has two main functions – it removes polluted air from the building and simultaneously supplies clean, filtered air at the required temperature. This is done by using two separate air duct systems: one for exhaust air and one for air intake.
Exhaust pipes remove polluted air from bathrooms, kitchens, toilets, laundry rooms and other wet rooms. Supply air ducts supply clean and fresh air to living spaces, bedrooms, living rooms.
Various types of recuperators are used today
Various equipment are used to ensure recuperation, which differ in terms of capacity, construction, and additional equipment. Taking into account our climatic conditions, in Latvia it would be useful to choose a recuperator with a built-in small electric heater, which would ensure a sufficiently high temperature of the incoming air even on the coldest winter days. Therefore, it is necessary to make sure that the equipment is
also designed to work on a large island.
Recuperators can have built-in heat exchangers of various types, which differ in their structure and efficiency. The highest efficiency (at optimal conditions) is for counterflow plate type heat exchangers. They are installed in both domestic and commercial ventilation systems. Efficiency up to 99.9%.
Various types of recuperators are used today
Units are also available that use a rotary heat exchanger for heat recovery. In such equipment, a rotor is mounted on bearings, which is made up of flat and wavy aluminum strips that form air flow channels. Efficiency up to 85%.
The most popular of the types of heat recovery is the cross-flow plate type heat exchanger , because its costs are relatively small and it can be installed even in a simple ventilation system of individual components. Its efficiency is up to 70%, and heat exchangers of this type, like heat exchangers of the counterflow plate type, have a very high efficiency of separation of supply and exhaust air – up to 99.9%.
Text author: Raivis Jēčis
Various types of recuperators are used today
Units are also available that use a rotary heat exchanger for heat recovery. In such equipment, a rotor is mounted on bearings, which is made up of flat and wavy aluminum strips that form air flow channels. Efficiency up to 85%.
The most popular of the types of heat recovery is the cross-flow plate type heat exchanger , because its costs are relatively small and it can be installed even in a simple ventilation system of individual components. Its efficiency is up to 70%, and heat exchangers of this type, like heat exchangers of the counterflow plate type, have a very high efficiency of separation of supply and exhaust air – up to 99.9%.
Text author: Raivis Jēčis