E36: Variable Speed Hoods with Automated Fan Controls – Above Green

Requirement Summary

This measure can be claimed if the exhaust fans in the kitchen hoods have Variable Speed Drives (VSD) installed.

Intention

By specifying VSD on the fans of exhaust hoods in kitchens, energy consumption and related utility cost are reduced. Also, the lifetime of the system components is increased and less maintenance is needed.

Approach/Methodologies

Standard exhaust hoods in commercial kitchens typically operate at a fixed speed designed for maximum (peak) load. However, that peak ventilation is not always required. Smart controlled hoods have VSDs installed on the fans, which are controlled by a temperature sensor, therefore reducing energy consumption between 20% and 50% (see Figure 19 below), because the VSDs control and regulate the fan speeds depending on the temperature of the cooking surface. Lowering fan speed reduces noise levels as well as maintenance costs, while the life of kitchen equipment could be extended.

To claim this measure, the design team must demonstrate that VSDs with temperature control are installed within the exhaust hoods of the kitchen.

Potential Technologies/Strategies

According to the US Environmental Protection Agency (EPA), kitchens in commercial premises consume 2.5 times more energy than any other commercial space, of which only 40% is used in food preparation and storage; much of the wasted energy is dispersed into the kitchen. Kitchens in hotels mostly have grills, ovens and fryers, which require high levels of ventilation and therefore consume large amounts of electricity. In many cases, this high consumption is due to the fans in the kitchen hoods running constantly at maximum speed regardless of the requirements. Lowering the speed of fans and controlling the time of use with sensors (air temperature) will result in energy reduction.

The fans can be electronically controlled with the Variable Speed Drivers (VSD), a piece of equipment that regulates the speed of the fan according to air temperature, which is detected by a sensor installed inside the exhaust hood. It can determine if the cooking surface temperature rises, therefore the fan speed increases to compensate, but if the air is cooler, then, the fan runs more slowly. VSD offer an improved system reliability and process control, as well as result in energy savings.

Relationship to Other Measures Energy

reduction due to kitchen equipment is expected by automated control hoods which will be reflected in the 'Catering Energy' portion of the energy chart, and its contribution is purely related to energy.

Assumptions

The base case assumes conventional exhaust hoods in kitchens, while the improved case assumes that all the exhaust hoods are provided with VSDs that control the fan speed according to the temperature at the cooking surface.

Compliance Guidance

To demonstrate compliance, the design team must provide documentation to support the claims.

Design Stage

Post-Construction Stage

At the design stage, the following must be used to demonstrate compliance:

Electric drawings/specifications of automated control hood including make and model of the VSD control; and
Manufacturer’s specification of the automated control hood; and/or
For systems including more than one exhaust hood, the design team must ensure that all fans are provided with VSDs.

At the post-construction stage, the following must be used to demonstrate compliance:

As-built electrical drawings detailing the automated control hood installed; and
Purchase receipt for the automated control hood; or
Photographs of installed VSDs in the exhaust hoods of the kitchen.