Energy efficient supermarkets - Indoor Climate

Measurements have been made in two grocery stores to investigate how the choice of ventilation filter affects the use of electrical energy, the air quality in exhaust air and the indoor environment in the store. The results show the large cost savings can be made both in terms of operation and maintenance (costs for electricity to the fans and costs for filters). The electricity use for fan operation depends on what the system design etc. looks like. For the stores studied, this means a total saving of approximately 6 000 SEK/year respectively 12 000 SEK/year.  

A store retrofitted doors on all its refrigerated counters. The cooling capacity demand in the cooling counters decreased by about 40 % during the day, after doors were installed. The electricity requirement in the cooling system decreased by about 15 % after the door installation. By making changes in the cooling system, you can also reduce the electricity demand by about 40 %.

Measurements has been performed in order to verify the energy saving potential for comfort heating and comfort cooling when using recirculated air, compared to ventilation with outdoor air, while a good indoor environment is achieved regarding, among other things, air quality. The results from the measurements showed a large saving potential by using recirculated air, while good air quality was achieved both with and without recirculated air.

The aim of the feasibility study has been to produce a prioritized compilation of the most important measures for energy efficiency in food premises. The results show that energy efficiency does not have to be expensive - much can be done quickly and at a low cost. Usually no major investment is required in components or equipment.

The purpose of this study is to compare and define new plug-in solutions for in-store cold with central cooling. The decommissioning of refrigerant such as R404A are a driving force to look at plug-in solutions. There is a risk that the phasing out of R404A will result in investment in coolers with inferior energy performance. Here, the work with eco-design requirements and energy labeling has an important role to play.

This study has investigated the question of how the choice of filter classes in the ventilation system affects airborne particle levels in the supermarket. As far as air quality in terms of particulate concentrations in the supermarket air is concerned, the performance of ventilation units is more important than the choice of filter class. A lower filter class reduces the electrical energy use. Over the whole country, in Sweden, this represents a potential saving of about 45 GWh of electricity.

The purpose of the project has been to compile knowledge on how an existing grocery store can be renovated to reduce its energy use so that it approaches zero. Proposals for energy efficiency measures were developed in the categories of refidgeration, ventilation, heating and lighting. If all proposals were implemented, the theoretical savings potential was 60-65 percent.

Read more about: The concept supermarket approaching zero

Dehumidification of air in supermarkets has been identified as one way to reduce the energy use in supermarkets. The result shows that many larger supermarkets in Sweden include comfort cooling in their ventilation systems. This, in combination with that more display cabinets are equipped with doors and the use of ventilation with recirculated air contributes to that dehumidification of air is not considered to be a problem.

Energy for refrigerators and freezers account for a significant proportion of grocery stores total energy use. This prestudy shows, among other things, that the conditions differ, depending on the size of the store. Large grocery stores often have the air supply temperature chilled during summer while there is no air conditioning at all in the smaller stores. This means that several operating conditions should be investigated. 

There is a great potential for energy savings in using ventilation systems with recirculated air in stores. The pre-study shows an energy saving of 66 % for heating, 36 % for comfort cooling and 2 % for a vertical cooling counter when using recirculated air compared to outdoor air alone.