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A large part of the energy used in commercial kitchens is devoted to ventilation. Kitchen ventilation systems have to remove heat, moisture, and aerosols emitted during cooking and cleaning from the indoor air to ensure tolerable working conditions for staff. The 47th Working Group on Affordable Passive Houses allowed the Passive House Institute (PHI) to take a closer look at energy consumption for ventilation units used in commercial kitchens in order to find out how energy can be saved without reducing indoor air quality. The following aspects with potential for saving energy were identified pertaining to kitchen ventilation:
Reduction of pressure losses: Kitchen ventilation systems have to move relatively large amounts of air, so reductions in pressure losses have a significant impact on the system's power demand. Some components of kitchen ventilators, such as aerosol separators, cause tremendous pressure losses; [AkkP-47] compared different systems to see what the impact was on a ventilation system's power consumption.
Reduction in demand for extract air and the resulting reduction in the volume flow of fresh air: Reducing the volume flow probably has the most significant effect on energy-saving potential because it reduces not only the ventilator's power consumption, but also the amount of energy needed to heat fresh air. This paper therefore focuses on ways of reducing volume flow that nonetheless fulfill comfort requirements.
Heat recovery: Unfortunately, there is still a lot of reluctance to use heat recovery in kitchen ventilation systems. The concerns about hygiene and fire hazards are simply too great. Indeed, kitchens do have a few conditions that at least make it hard to use heat recovery. [AkkP-47] presents some of the special requirements for heat recovery systems in kitchens.
In the end, the ways of saving energy presented only represent individual solutions. A complete, energy-efficient system will, however, only come about when all of the ways to conserve energy interact and kitchen ventilation systems are optimally adjusted for actual usage during planning.
This in-depth article is available exclusively to iPHA-members.
The various steps taken to reduce volume flow – and the resulting reduction in ventilation heat losses and ventilation drive energy – probably reduce energy consumption the most. The proper selection of special kitchen appliances with reduced need for extract air is especially important. In other words, these appliances reduce thermal and material loads themselves rather than passing them on to the ventilation system.
In general, the ventilation system also has to be optimally calibrated for kitchen usage and workflows. Everyone (architects, building services planners, kitchen planners, and users) has to be involved from the beginning of the planning phase to prevent the selection of an oversized ventilation unit that would lead to excessively high operating costs.
These findings were compiled by the working group on affordable passive houses (with funding from DBU, HMUELV, ProKlima, and FAAG GmbH) as part of its focus on "energy-efficient cafeterias and commercial kitchens" (only available in German).
[AkkP-47] Energieeffiziente Kantinen und Gewerbeküchen; Protokollband Nr. 47 des Arbeitskreises kostengünstige Passivhäuser Phase V (only available in German); Passivhaus Institut; Darmstadt 2012
[VDI2052] VEREIN DEUTSCHER INGENIEURE: VDI 2052: Raumlufttechnische Anlagen für Küchen; Düsseldorf 2006
[FST2000] Swierczyna,R. at all, Commercial Kitchen Ventilation Performance Report Halton Capture JetTM Backshelf Hood, Food Service Technology Center, 2000
[FST2006] Karas, A., Fisher, D. Demand Ventilation in Commercial Kitchens An Emerging Technology Case Study, Food Service Technology Center, 2006
Overview of all articles on Passipedia about non-residential Passive House buildings
Overview of all articles on Passipedia about cafeterias and commercial kitchens
List of all released conference proceedings of the 17th International Passive House Conference 2013 in Frankfurt
Conference Proceedings of the 17th International Passive House Conference 2013 in Frankfurt