HVAC design for supermarkets

HVAC and refrigeration costs make up a significant portion of supermarket and convenience store budgets. In fact, the energy usage of supermarkets per square is about 5 times more compared to any other commercial building. 

Here’s why! In essence, refrigeration creates cold, people create warmth while humidity creates wetness. Therefore, the HVAC design for supermarkets has to maintain the right humidity for people, products, and equipment. For that to happen, supermarket operators have to balance these factors as well as optimize refrigeration & HVAC systems to work in coordination with each other. More importantly, the HVAC system has to significantly reduce that consumption, while maintaining a comfortable and inviting store environment. 

Why supermarkets and grocery stores are complex applications for HVAC systems! 

The main reason that makes HVAC design for c-stores and supermarkets a bit challenging is that they house a unique mix of applications under one roof. At the same time, each application has specific HVAC requirements for cooking & heating the space and providing adequate ventilation air. 

For instance, one part of the supermarket contains refrigerated cases that produce a steady stream of cold air into the walkways. On the contrary, another part contains cooking equipment that emits heat that should be exhausted from the supermarket. The amount of exhaust air may determine the amount of outdoor air intake needed to maintain a positive pressure in the store. 

Also, if the indoor air conditions are too dry, the products shrink and if the conditions are too hot, some products tend to spoil. On the same note, if the conditions are too cold, most customers will complain. More notably, cooling loads and people in the store continuously fluctuate during operating hours. 

With that in mind, you should aim to have an HVAC design for grocery stores & supermarkets that cuts energy costs, while ensuring customer and food safety. Moreover, the system should provide an adequate amount of healthy, outdoor air at the precise humidity and temperature for the space. This will help the store lower operating costs, realize higher sales, and improve indoor air quality for occupants. 

Minimize latent loads in HVAC design for convenience stores & supermarkets to save energy 

Display cases in c-stores & supermarkets operate in a wet-bulb condition of less than 64 deg F. This results in humidity from ventilation, internal loads increase the display cases’ refrigeration loads, while frost forms on the evaporator coil. Continuous refrigeration is needed to defrost the coils, but it increases compressor run time and energy consumption. 

To sum up, most of the sensible cooling in c-stores and supermarkets comes from refrigerated cases. For that reason, the mechanical design must focus on the latent load in these cases. Specifically, the HVAC design should minimize the latent load. In return, this will reduce anti-sweat heating unit run times as well as the amount of defrost cycles. Moreover, reduced humidity within the c-store will lower energy costs and improve product shelf life. 

Things to consider when creating HVAC design for supermarkets 

  • Separate latent and sensible loads 

Latent and sensible loads for supermarkets are different from most commercial uses. This is because the effect of refrigerated cases affects both latent and sensible loads. Therefore, the HVAC designer has to account for both loads to avoid oversizing the heating, ventilation & air conditioning system. 

  • Take advantage of lower humidity to increase temperatures for occupant comfort 

Neglecting humidity control in c-stores negatively affects employees’ productivity. At the same time, this affects the customers’ comfort since the store will be too hot. However, employees will feel comfortable even at 75 deg F at 40% Relative Humidity. This is because lower humidity promotes natural perspiration which is a very effective cooling mechanism. 

  • Treat outdoor air before it enters the store 

In most cases, ventilation air is the major source of moisture in stores. Following ASHRAE Standard 62 guidelines, the HVAC designer has to consider exhaust hood activity and supply an adequate amount of outside air to balance exhaust air. 

Door opening and vestibules can also be used to introduce moisture to ensure a positive air pressure. As for energy, it’s less costly to condition outside air with the HVAC equipment than refrigerated cases. 

  • Reduce defrost cycles to maintain 40% RH

Most manufacturers of refrigerated cases recommend that the level of indoor humidity be maintained at 55% Relative Humidity or less. Moreover, reducing the RH level helps to improve the case operation. 

HVAC Design Services for Supermarkets, c-stores, and grocery stores 

At Innodez, we assist retail spaces and supermarkets with their HVAC system design, maintenance, audits, repairs, and inspections. Moreover, our licensed, certified, and experienced HVAC professionals ensure that your store has the best possible MEP system for your customers, staff, and budget. As many studies have established, a comfortable indoor environment will encourage customers to linger longer and improve your employees’ productivity. 

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