HVAC in schools T


here are discussions about fi ltering air, and increasingly


the need for air exchange in classrooms by an appropriate school ventilation system. A healthy indoor climate is about more than just


ensuring virus-free air: the CO2 concentration and the air humidity also need to be controlled.


Plug and go solution with one-touch operation button


When retrofi tting ventilation technology in existing buildings, a quick installation is required that does not interfere with school operation, or only for a short time. The WZA from the brand manufacturer Kampmann is a device that has been developed precisely for this purpose. It is a decentralised ventilation unit: one WZA is installed per room. The installation eff ort is low. Two core drillings are required for access to the outside air, otherwise the unit is ready to plug in. Electrical work is not required, nor a connection to a waste water system, which is necessary with many units. Once in operation, the unit can be controlled simply and intuitively with just one button, with which the user switches through the four operating modes. The unit delivers large air volumes of up to over 280 l/s at low operating noise levels, e.g. of 35 dB(A) in anticipated regular operation around 225 l/s.


CO2 removal for better learning


One of the great advantages of ventilation systems over air fi lters is that they not only break down viruses and other pollutants, but also remove


carbon dioxide. Carbon dioxide, or CO2, is a colourless, odourless gas that humans exhale.


When CO2 levels are high, learners and teachers can no longer concentrate well and become tired. Something can be done about this. With the WZA, the air quality is constantly monitored, exactly in line with BB 101 (CIBSE Guide B2, Building Bulletin 101, Guidelines on ventilation, thermal comfort and indoor air quality in schools).


Healthy air humidity thanks to enthalpic heat exchanger


In addition to the elimination of viruses and CO2, healthy room humidity is important. The enthalpic heat exchanger fi tted in the school ventilation unit ensures that a large part of the room air humidity and heat or cold can be recovered from the extract air/exhaust air. This prevents energy losses and reduced air humidity, with ensuing environmental and economic benefi ts. The health aspect for the people working in the room is also very important. Especially in winter, rooms are often insuffi ciently humid because of dry heating air. This can lead to dry mucous membranes, which have been shown to encourage infections. These quality features distinguish the Kampmann unit quite signifi cantly


12 April 2022


The decentralised ventilation unit for existing schools from Kampmann can be positioned variably in the front or rear area of the classroom


www.heatingandventilating.net


Ventilation in existing schools


As a result of the coronavirus pandemic, a host of measures have been put in place to reduce the risk of infection. The spotlight in society has fallen on the risk of infection is schools, particularly in full classrooms. Thorsten Niehoff of ventilation specialist Kampmann off ers some insight into some innovative solutions


from other decentralised ventilation units on the market.


Mixed ventilation for minimising draft risks


The decentralised school ventilation unit WZA works on the principle of mixed ventilation to feed the supply air into a room. The WZA supplies air into the room through an outlet on the top of the unit. It fl ows at a high induction level along the ceiling of the room, above the occupied zone. The Coanda eff ect produced ensures that the fresh, clean air penetrates deeply into the classroom, and does so without creating draughts. Mixed ventilation is therefore ideal for quickly mixing large volumes of air with the room air.


Left: With just one button, the user switches through the four operating levels: automatic ventilation, shock ventilation, continuous ventilation and quiet ventilation


Above: Simulated room air humidity curve in a typical classroom. Blue: room air humidity line when an enthalpic heat exchanger is used Red: room air humidity line when a standard heat recovery system is used, without humidity recovery


With displacement ventilation, the air fed in


spreads slowly across the fl oor of the room and then rises upwards. Displacement ventilation only works if the supply air is colder than the room air. This technology therefore tends to be more suitable for offi ce rooms in which 4 to 6 people work, rather than for a fully occupied classroom where a high number of people in a relatively small space generate high thermals in the room. At the same time, with such high numbers of people, it cannot be ensured that the entire room is fl ushed through and aerosol concentrations etc. safely diluted.


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