Steam hoods: high energy savings possible

Significant potential exists in kitchen ventilation to save energy. This is the result of a comprehensive, new study. Both the appliances themselves and their controls and the return air and ventilation routing can be optimized.

As an industrial partner of no fewer than three research institutes, Naber once again demonstrated its competence and innovative strength in the topic of "Kitchen ventilation" with the study. The study examined all factors that influence the efficiency of a cooker hood system and its components: first and foremost, the degree of detection with which the cooker hood draws in damp cooking vapor laden with odors and pollutants and expels it from the living area. And further: possibilities of using sensors to adjust the air output of the appliance and therefore the energy consumption to the actual need. The energy loss through the exhaust air damper was also investigated, as were various variants of the afterflow of air in exhaust air systems. Last but not least, the researchers focused on the influence of size and aging behavior in ventilation filters.

Significant performance differences

Investigated was the detection rate of five overhead range hoods and three inclined range hoods, all in exhaust air mode. This showed clear differences in the detection of water vapor, in the air power required to do so, and in power consumption. A highly efficient hood transported 90 percent of the cooking vapor out of the room at only about 200 cubic meters per hour (m³/h). Other models require about 500 m³/h for the same detection rate or achieve significantly lower cleaning power. This also impacts the power consumption of the appliance and the heating requirements of the home, because with less air output, less room air also needs to be heated. Very good range hoods cause only 80 kilowatt hours of heating demand per year (kWh/a) in the chosen reference house (passive house, 156 m² heated area, use for 0.5 hours per day). Poor appliances cause more than double the heating demand. Very high is this value in cooktop extractors, whose values come from a previous study: due to the high air volume required for the precipitation of rising water vapor, the heating requirement in exhaust air mode is more than three times higher than for the best overhead range hood.

In practice, performance also depends to a large extent on the air duct used. Here, Naber offers with COMPAIR PRIME flow® an aerodynamically optimal system that can be installed extremely easily and flexibly in both flat and circular ducting.

Sensors reduce power consumption

The range hood does not always have to operate at maximum power. In the cooking phase or at low cooking plate temperatures, less air power is sufficient for proper cleaning. "Here, sensors can detect the air quality, for example with respect to moisture or odors and pollutants (VOC), and control the range hood directly accordingly. Or one uses indirect control devices, for example via the number and temperature of the active cooking zones," says Dr. Bing. Alfred Bruns who supervised the study for the company Naber GmbH. Against constant operation, both variants reduced power consumption. "However, either the moisture when cooking pasta or the odor load due to VOC when baking was not properly dissipated. A combination of both variants with each other is therefore probably the best way to achieve low energy consumption and good cleaning performance," says Alfred Bruns who heads the development department at Naber.

Outstanding results for wall penetration units from Naber

In newly built or rehabilitated efficiency and passive houses, comfort suffers from leaks in the exterior cladding. Numerous wall penetration units, return air dampers and supply air passages are therefore unsuitable. The study showed that efficient and extremely hygienic exhaust air technology for extractor hoods is possible in many cases. This was demonstrated by the flow Star GTS (mechanical), BIXO (motorized) and magnetic-mechanical THERMOBOX wall box units from Naber. Thanks to their sophisticated technology, the additional heating requirement for room air heating is minimal even in smaller homes. Compared to devices in do-it-yourself stores or a simple check valve on the range hood, there is a clear energy saving.

The study "Investigation of extractor hood systems in residential kitchens with regard to energetic, flow-technical and hygienic aspects" was commissioned by the German Federal Institute for Building, Urban and Space Research (BBSR) and subsidized by the German Federal Ministry of Public Works on the basis of funds from the "Future Building" innovation program. Involved were the Passive House Institute in Darmstadt, the ITG Institute for Technical Building Equipment and the Institute for Wood Technology, both in Dresden, as well as the company Naber from Nordhorn.