Optimized heat recovery
Purify the kitchen exhaust air and recycle tens of thousands of euros every year!
Greasy and dirty exhaust air is associated with costs. If purified, it would be a valuable resource.
A restaurant with about 1 500 m3/h exhaust air loses up to 14 000 euros per year in heat energy depending on the operating conditions. The payback period for an air purification system and a heat recovery unit can be as short as a few years.
Kitchen ventilation is needed in order to create a good working environment in the kitchen, to dissipate heat as well as cooking odors and moisture and to supply the area with fresh air. However, in Sweden alone, an estimated 280 million euros disappears in the form of heat energy through the ventilation of our properties.
There are ongoing projects designed to make commercial kitchens more energy efficient. Energy savings can be achieved by selecting the right equipment, utilizing demand-controlled ventilation, correct service intervals of the equipment and training of staff. The (heat) energy in the exhaust air from a kitchen constitutes the largest part of the possible energy savings by far – probably as much as 40% of the total energy consumption in a kitchen.
An average sized kitchen can save tens of thousands of euros annually by taking measures that allow heat recovery from the exhaust air with a heat exchanger.
Start purifying the air and installing a heat exchanger. Already at moderate thermal efficiencies, the potential savings are significant.
In purely theoretical terms, how do you recover the greatest amount of energy?
Here are a few tips on how to recover the maximum amount of energy:
1. Buy a high-quality heat exchanger
Put time and energy into your choice of heat exchanger. Choose a reliable model with a high efficiency rating, and then make sure to keep it clean to prevent it from losing efficiency. It must be able to work under ideal conditions – at all times. Only then, will you be able to recover the maximum amount of energy year after year.
2. Remove as much grease as possible before the air reaches the heat exchanger
Make sure the air that reaches the pre-filter of the heat exchanger is as clean as possible at all times. This is important, since large amounts of grease have a number of negative effects. The grease may cause pressure drops in the exhaust duct and the efficiency of the heat exchanger is reduced. Heating costs increase, the pre-filter needs replacing more often and the heat exchanger has to be cleaned more frequently.
3. Understand the advantages and drawbacks of the various technical solutions – and make the right decision
The hot grease-laden air travels at 3–5 m/s on its way to the heat exchanger. Choose the method that most effectively at removes the billions of small grease particles and aerosols that rush through the air stream. Additionally, choose the solution that manages to keep the exhaust duct clean at all times!
Set high demands on the treatment solution
The purpose of the treatment solution is to minimize the amount of grease that reaches the heat exchanger. These are the requirements we think should be met by a really good solution:
- It must remove a high proportion of the grease particles and aerosols in the air stream
- Any reduction in treatment capacity over time must be no more than marginal
- The need for service, maintenance and other continuous handling must be minimal
- The treatment solution must not be the cause of operating outages, pressure drops or generally impact the ventilation as a whole
- The treatment must be efficient enough to make sure that the exhaust duct rarely requires manual cleaning
- It must be easy to reduce and increase the treatment capacity
Avoid active and moving parts in the exhaust duct and hood
We strongly recommend refraining from using any active or moving parts in the exhaust duct and hood. If equipment is positioned in the contaminated air flow, treatment capacity will be reduced quicker, and it will require more cleaning, maintenance and replacement of spare parts.
A highly energy efficient commercial kitchen requires that a combination of factors are properly incorporated.
Studies show that the majority of potential savings can be derived from the five aspects described below, and taking action on these give the highest profit:
- Technology in the kitchen – choose equipment and tools with low energy consumption and/or demand-controlled operation
- Ventilation - use demand-controlled ventilation, purify the exhaust air and recover heat from the purified air
- Cooling: refrigerators, freezer rooms etc. / Replace cooling where possible e.g. garbage rooms
- Maintenance – regular maintenance of equipment allows their energy efficiency to remain high and constant. This leads to lower energy consumption
- Staff – educate the staff! The efficiency and use of equipment by the kitchen staff have a large impact on the energy consumption
Read more in our broschure "The Grease must be removed" for more tips and measures to consider to optimize heat recovery.