Air purification and heat recovery in commercial kitchens

One of Sweden’s largest cities has opted to build a brand new kitchen and canteen in of their primary schools since the old one did not meet all requirements. The objective is to reduce energy use by 50 percent compared to the old kitchen. Measurements in the project “Energy Efficient Commercial Kitchens”, co-funded by Belok and the Swedish Energy Agency, indicate that Sweden’s municipalities could save almost  €60.000 daily if they improved the energy efficiency of their commercial kitchens.

One of the toughest environmental and energy requirements in the country

This large, Swedish city has set high objectives regarding its environmental efforts. Energy use (primary energy) must be reduced by 14 per cent in residential and commercial buildings, and 90 % of the carbon dioxide emissions must be eliminated by 2020 compared to 2009.

“We have one of the toughest energy and environmental requirements with regard to buildings – 45 kWh/m2, anually including building services”, says the energy expert and project manager in charge. “And we also calculate energy use more strictly than required in the Building Regulations of the Swedish National Board of Housing, Building and Planning (BBR). An extremely tough goal!”

“Buildings are able to comply with the requirements, but we see a potential for improvements in commercial energy use.” To reach these goals, the city builds structures that are as energy-efficient as possible while optimizing heating and ventilation on its properties. But energy-efficient construction is not enough. In addition to having Sweden’s toughest energy requirements for buildings, the city is under way with the development of Sweden’s best system for ensuring that all energy targets are met. It is a package of measures that includes, among other things, early operational optimisation and a completely new energy follow-up system.

“We are working on this at the moment and aim to have it ready midway through 2017.” “To be sure we are on the right track, we need to implement a number of actions including, for example, a way of making continuous measurements. We have great energy demands!”

Ventilation stands for a large portion of each commercial kitchen’s energy use, a figure that can be reduced by recovering heat from the extract air. This is also something the Swedish Energy Agency’s network for energy efficient buildings, Belok, recommends in its commercial kitchen guidebook.

Cooking fumes contain grease and odors that accompany the extract air into the extract duct. Without air treatment, the grease is collected in the ducts and on the thin blades of the heat exchanger. The grease creates other problems too. Grease deposits burn intensely and are hard to put out.

Saving energy in the new kitchen

“Our goal with the new kitchen is to generate as much energy savings as possible based on our very tough energy requirements,” says the responsible energy expert and project manager. “If we achieve this the way we intend to, we can create a new standard based on the energy use in the school. This is why we are going all in here.”

“At the same time, it is of vital importance that the kitchen staff be completely on board and that they experience that the kitchen works to their satisfaction. We will not reach this objective without their assistance.”

Compliance with the tough energy requirements requires, among other things, a well-functioning ventilation system as well as a functioning heat recovery from the kitchen exhaust air.