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In recent decades, the amount of food and fat odor from the commercial kitchenware increasing because of the developing increase rate in the number of restaurants, and concurrently resulting in significant amounts of energy loss from these commercial kitchens. Hence, it is essential to initiate the thinking of an efficient ventilation system in a commercial kitchen perspective, with the feasible solution of heat recovery, whereby the vast amount of heat in commercial kitchens could be secured or re-used with efficient technology.

The biggest issue relative to commercial kitchens is the amount of heat energy loss used during cooking. To overcome this problem, the installation of suitable devices can contribute to reducing energy demand. Also, issues related to grease and odor that comes out from the kitchens’ exhaust duct needs resolving. With the consideration that there are possibilities of reducing the heating or cooling demands, based on different available technologies utilized in heating, ventilation, and air conditioning (HVAC) systems. This study explores the problem briefly and clarifies each situation with solutions in detail.

The studied project is a shopping center which is located in the center of Stockholm and named Ringen. It is a three-floor shopping center with two levels of parking lots. In 2016, there was an upgrade by adding the food court (Matteatern) in the center of the ground floor. The main purpose of the project upgrade was the increasing number of visitors to this shopping center, for them to get entertained with refreshments and have nice different kinds of foods in a cozy place. This master thesis, a study on the efficiency of the ventilation system in the food-court, has been undertaken, by considering the project’s energy consumption. The kitchens’ ventilation duct ventilates air from the kitchens to the garage in the underground (-1) floor, whereas the outlet air comes in for usage in the kitchen and garage. Since there is a prohibition against having the ventilation duct on the façade or attached to the roof, the outlet air quality in the garage is, therefore, required to be cleaned from fat and food odor. The current plan works with battery heat recovery ventilation to re-heated up the outlet air and use it in the kitchen. However, ozone injection and polishing filters are two cleaner technologies in use for the prevention of odor and smell.

The purpose of this study is to investigate if there are significant energy saving system for the undertaken project with an adjustment technology, as well as an assumption of cases by adding heat recovery and air purification to the ventilation system. The importance of energy has set the tone for finding the best solution to avoid unnecessary loss of energy demand from the ventilation of the kitchen in the case study. Besides, it is crucial to find the proper system with the view of energy and cost; meaning that expansive the system should have high quality in energy savings, and with a prospect that it could also save money for the project. If the system is efficient in energy consumption and could save a vast amount of energy loss, in-turn it could as well be used in subsidizing a substantial cost for the project. An ideal solution could be the system with less amount of energy usage, or even if, with a particular gap in energy usage, could be recouped by a vast amount of energy savings.

The thesis also investigates, through studies on two more optional alternatives to have a comparison of energy consumption and find a good solution for the kitchens’ ventilation, as well as see the amount of efficiency of each system. In the alternatives, one considers separated ventilation for garage and kitchen. The garage’s airflow rate calculated and there is a rotary heat exchanger in the garage ventilation. While as the current plan there is a battery heat exchanger via constant airflow rate in the kitchen. Ozone injection in hence of fat and odor in considering in kitchens ventilation. The second alternative, however, sees the project in a case where there is no ozone injection nor polishing filter and separated ventilation in the garage and kitchen. Also, the kitchens’ ventilation comes up to the roof directly.

This master thesis project, therefore, presents an energy consumption comparison in different alternatives. It has a view on the current situation, even though there is kitchen outlet air in the garage with a battery heat recovery system and added a polishing filter to optimize the smell from fat. In the case- study comparison, there is separated ventilation and duct for the garage. Also, the rotary heat exchanger in the garage has been considered via the special airflow rate for the garage. it has been taken when there is ozone filtering in the ventilation in place. However, instead of the polishing filters, a rotary heat exchanger has been designed with two different airflow rates. In one other case, there is an estimated airflow rate as the garage air flow rate, and in the kitchen, there is another one. There is no ozone, nor polishing filter in the ventilation system while there is outlet ventilation from the kitchen directly to the roof.

The current alternative project provides a solution when the outdoor air is heated up by battery in the heat recovery system, then transferred it to the shops and garage. There is ozone injection technology in the commercial hood to break the large parts of fat from the kitchen. Also, there is a polishing filter in the garage to reduce the food and fat odor, and in-turn provides clean air in the parking lots as the outlet air has been for usage in the parking where there is car-wash, and also in shopping floor.

Meanwhile, calculations from the study demonstrate energy demand and cost- efficiency. The calculations are based on some available data and some assumptions according to real figures. The different temperatures in outdoor and indoor air, the set temperature, and hourly Stockholm datasheet temperature are the base material been used to evaluate heat energy usage. The pressure drop and fan power are parameters been used to calculate the amount of electricity the project. Thus, according to the result, which provides a solution to investigate efficient technology for ventilation systems in commercial kitchens. The major focus of the study stands in a system which has ozone technology and polishing filter in the heat recovery of the commercial kitchen’s ventilation systems, and together in comparison with other cases when there is not.

Given the result, it has proven that the current alternative in the project has the acceptable amount of energy demand while first consideration alternative(alternative 1) via a rotary heat exchanger in the garage and separated ventilation and airflow rate for kitchen and garage has the best result in energy demand and saving. In contrast, the second alternative with separated rotary ventilation for the garage is neither without ozone nor polishing filter for the cleaning and kitchens ventilation up to the roof has the highest level of energy demand. Hence, with the cost of efficiency, the first alternative meets the lowest amount of cost while the second alternative, which has the highest amount of energy demand has the highest cost. There are also more advantages like an extended lifespan of the air handling unit, lower duct cleaning cost.

Additionally, the result proves that the first comparison plan has the lowest energy demand, whereas the second alternative has the highest one. With the high amount of energy demand, the energy cost will be increased. Thus, the second alternative has the biggest amount of energy cost, and it's not working. Moreover, there are some other positive points in the current plan, such as the extended lifespan of the air handling unit because of ozone injection in the path and being cleaned. Also, it causes a lower cost for duct cleaning costs as well. The mentioned options can be affected by the result and conclusion. It’s because they are important parameters which can be seen in projects result.