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Fresh air, less power

Opti­mised venti­lation systems in houses can save up to 75 per cent energy

Cooking, washing and even just living are constant sources of mois­ture and CO2 in the home. The atmos­phere and well-being of the resi­dents can be improved by the use of a controlled mechan­ical venti­lation system to ensure fresh air circu­la­tion around the clock. Such an instal­la­tion extracts odours and mois­ture which could other­wise promote the forma­tion of mould, and damage the struc­ture of the building.

Since 1969, hundreds of thou­sands of type R2E190 and R2E140 fans have been fitted in this sort of system in France. For a 4-room house, these systems have a power consump­tion of around 35 WTh-C (WTh-C = Average consump­tion for one hour at high speed and 23 hours at low speed). The total throughput is between 200 and 250 m³/h. This type of system is extremely effi­cient, but the power consump­tion cannot be disre­garded in view of rising elec­tricity prices.

Exhaust air box by Aldes

Exhaust air box by Aldes. The centrifugal fan used in this product is driven by an energy-saving motor

There are two possible ways of cutting the power consump­tion Reducing the power consump­tion of the actual fan and regu­lating the fan throughput on the basis of how the room is used. By employing EC fans and in partic­ular motors of the ESM (R1G160) type, a consid­er­ably lower power consump­tion can be achieved. Energy consump­tion can also be reduced by the use of throughput control based on room util­i­sa­tion. When­ever rooms are not in use and the impact level is low, there is little need to extract air. With conven­tional systems, users can regu­late the air throughput as required by means of a switch. In modern systems, the air throughput is adapted as a func­tion of the mois­ture content of the air with­drawn by grad­u­ally opening the extractor vents (reduc­tion of pres­sure loss by inte­grated sensor).

The use of EC fans and throughput control based on room util­i­sa­tion makes it possible to achieve a power consump­tion of roughly eight WTh-C. In other words, consump­tion can be reduced by nearly 75 per cent as compared to a stan­dard system. This also has a bene­fi­cial effect on heating costs, as the system helps to improve the energy perfor­mance of a building. Heating costs can be cut by 10 to 15 per cent in this way.
Even more advanced systems have the capacity to recover the heat contained in the extracted air to warm up the air on the supply side. The use of a heat exchanger does however result in greater pres­sure losses. A fan of type R3G140 is there­fore employed. This prin­ciple fully satis­fies Direc­tive 2009/125/EC of the Euro­pean parlia­ment, which aims to both increase energy effi­ciency and reduce green­house effects by 20 per cent. 

The priciple

EntlueftungsprinzipAn encased fan, usually installed on the top floor, is connected by way of a duct system to extractor vents fitted in the rooms affected, i.e. with damp condi­tions, such as the bath­room, toilet and kitchen. The pres­sure in these rooms is then a few Pa lower than outside. The fresh air flowing in from outside is conveyed via air inlets into the “unaf­fected” rooms, such as bedrooms, living room and dining room.

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