16 Ways to Reduce HVAC Energy in Supermarkets and Retail
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Singh360, Inc. | Complete Facility Solutions Home About » Services Products » 360 Blog News Contact Home > 360 Blog > 16 Ways to Reduce HVAC Energy in Supermarkets and Retail September 5, 2012 By Singh360 Leave a Comment By Abtar Singh, President – Singh360 Inc. When it comes to reducing energy in supermarkets, we either focus on refrigeration (because it consumes 40-50% of the total energy) or lighting (which is pretty easy to understand). However, HVAC equipments (almost 20% of the store power) are often overlooked though they can significantly impact energy consumption, provide customer comfort for better shopping experience and reduce food product quality and shrinkage. So what are the ways HVAC energy consumption can be reduced in a retail environment? Here’s a roundup of the important ideas to consider in your store: 1) Store Pressure. Negative pressure encourages leakage of the unconditioned air from the outside. Maintaining the store under a positive pressure eliminates the introduction of outside air into the building. Moreover, besides causing thermal discomfort, air infiltration may also lead to the buildup of humidity that has a negative impact on refrigeration performance (longer defrost and higher door heater consumptions). 2) Optimum Make up Air. In order to reduce the need of heating or cooling, the fresh air intake in the building can be regulated. This is done via Demand Control Ventilation (DCV) strategy. DCV allows the regulation of ventilation based on the amount of CO 2 level in the building at a particular time. Energy is saved not only because air distribution is lessened but also because lesser air is heated or cooled. It should also be noted that some retailers have cleaning chemicals, plants and apparels that exhale CO 2 , and hence the CO 2 sensor can give false readings. Therefore, the location of a CO 2 sensor and alternative strategy becomes important. 3) Free Cooling. (Also called economizer strategy.) During cooler days, the air can be just brought in without any conditioning. Traditional enthalpy method may not be suitable for supermarkets due to cold air spillage from refrigeration units in the store. Depending on the type of cases (open, doors etc.) and air pattern, the free cooling (economizer) strategy will have to be fine-tuned for a supermarket. 4) Un-occupied Settings. If the store is not trading 24 x 7 or there are certain zones that are un-occupied during certain times of the day, the easiest way to save energy is to raise the cooling set point from 72F to 78F and lower the heating set-point from 70F to 66 F during an un-occupied period. 16 Ways to Reduce HVAC Energy in Supermarkets and Retail http://singh360.com/16-ways-to-reduce-hvac-energy-in-supermarkets-and-... 1 of 4 5/31/2014 11:15 AM
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Home > 360 Blog > 16 Ways to Reduce HVAC Energy in Supermarkets and RetailSeptember 5, 2012 By Singh360 Leave a Comment
By Abtar Singh, President – Singh360 Inc.
When it comes to reducing energy in supermarkets, we either focus on refrigeration (because itconsumes 40-50% of the total energy) or lighting (which is pretty easy to understand). However,HVAC equipments (almost 20% of the store power) are often overlooked though they can significantlyimpact energy consumption, provide customer comfort for better shopping experience and reduce foodproduct quality and shrinkage.
So what are the ways HVAC energy consumption can be reduced in a retail environment? Here’s aroundup of the important ideas to consider in your store:
1) Store Pressure. Negative pressure encourages leakage of the unconditioned air from the outside.Maintaining the store under a positive pressure eliminates the introduction of outside air into thebuilding. Moreover, besides causing thermal discomfort, air infiltration may also lead to the buildup ofhumidity that has a negative impact on refrigeration performance (longer defrost and higher door heaterconsumptions).
2) Optimum Make up Air. In order to reduce the need of heating or cooling, the fresh air intake inthe building can be regulated. This is done via Demand Control Ventilation (DCV) strategy. DCVallows the regulation of ventilation based on the amount of CO2 level in the building at a particulartime. Energy is saved not only because air distribution is lessened but also because lesser air is heatedor cooled. It should also be noted that some retailers have cleaning chemicals, plants and apparels thatexhale CO2, and hence the CO2 sensor can give false readings. Therefore, the location of a CO2 sensorand alternative strategy becomes important.
3) Free Cooling. (Also called economizer strategy.) During cooler days, the air can be just broughtin without any conditioning. Traditional enthalpy method may not be suitable for supermarkets due tocold air spillage from refrigeration units in the store. Depending on the type of cases (open, doors etc.)and air pattern, the free cooling (economizer) strategy will have to be fine-tuned for a supermarket.
4) Un-occupied Settings. If the store is not trading 24 x 7 or there are certain zones that areun-occupied during certain times of the day, the easiest way to save energy is to raise the cooling setpoint from 72F to 78F and lower the heating set-point from 70F to 66 F during an un-occupied period.
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If one does not have a building management system (BMS), then plan spending $200 on aprogrammable thermostat. This will definitely provide quicker payback.
5) Humidity Control. Humidity control is an important factor in controlling the energy consumptionin a supermarket. HVAC has an EER (Energy Efficiency Ratio) of 10 and refrigeration has an EER ofabout 4. Hence, it is more economical to de-humidify using a HVAC system rather than to create frostin the refrigeration coils & doors. However, one has to watch out for the reheat strategy whende-humidifying the store. Lower humidity is always not best for the produce and hence food qualityplays a role in deciding the optimum control strategy.
6) Zone Separation. Zoning reduces the area you need to heat & cool. Zoning allowsde-centralization of control and allows each zone to have a temperature independent of the other and atemperature which is required for that zone without affecting the other. Ensure that your conditionedzones (typically the sales floor) are physically separated from the un-conditioned zones (typically theback room).
7) Sensor Calibration. Humidity and temperature sensors that control the HVAC unit should becalibrated periodically. Even a small error in the percentage of calibration can cause the HVAC unit toprovide a less optimum environment for the store.
8) Variable Speed Drives (VSD): VFD or VSD on fan blowers is a useful energy saving strategy. One should regulate the motor speed according to the cooling demand requirement. Since power isequal to the cube of speed, when the speed is reduced the power consumption will also reduce, henceallowing a reduction in energy consumption.
9) Component Performance. Check performance of key components such as compressors,condensers, evaporators, TXV, furnace & filters. This should be a part of the planned preventativemaintenance schedule.
10) Digital Thermostat or EMS Retrofits. If the HVAC unit is on mechanical control, a computerbased controller can provide quick payback. Automatic control can be used for occupancy scheduleand remote diagnostics.
11) HVAC Test and Balance: Air testing and balancing is required to adjust the amount of airdistribution in a given HVAC zone. The amount of air that is required to be supplied to each conditionedzone is the amount required to balance the given gain (or loss) of heat in that particular area.
12) Replacing Older Units with Energy Efficient Units: Replacing older, inefficient heating andair-conditioning units with more modern and efficient units can save substantial money. Besides, newunits typically are much more reliable and can reduce maintenance cost as well. Specification of size,weight, energy costs should be kept in mind while choosing a new unit. The heat from the unitscondensers can also be reclaimed and utilised for re-heating (de-humidification).
13) Avoid Simultaneous Heat & Cool: Many a times, either controls are improperly set or the designof the HVAC system within a supermarket is such that while one RTU is in the cooling mode, the otherRTU within the same zone is in the heating mode. This can cause a huge wastage of energy. A properretro-commissioning of the store can unearth such flaws.
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14) Reheat using Refrigeration Condenser Load: A refrigeration system within a supermarket canhave a huge condenser heat available that can be used in the reheat stage during de-humidification. Typically, dehumidification is required during summer when significant refrigeration condenser heat isavailable. This will help in supplying fresh air at lower dew-point and higher dry-bulb temperature,which is important for better refrigeration equipment (defrost and door heater) performance.
15) Heat Reclaim Strategy: Refrigeration condenser heat within supermarkets can be reclaimed toheat the building in winter. This is not always the best strategy because it increases the refrigerantcharge and potential for refrigerant leaks. However, depending on the logistics, store size and zone, itmay be worth considering. However, one has to be careful that the heat reclaim strategy does requirecondensers to run at higher head pressure (increased compressor power); though it is usually cheaperthan heating using electric heaters or natural gas. However, in some states natural gas is cheaper thanelectric and hence it may not be cost effective to heat the building using condenser heat.
16) Retro-commissioning: It is well documented that retro-commissioning identifies maintenanceissues, improves equipment performance and saves 10-15% energy. Retro-commissioning is asystematic process of assuring that a building performs in accordance with the design intent and theowner’s operational needs. The goal is also to achieve energy savings by ensuring that all includedsystems are operating at an optimum level of performance.
What Energy Idea do you think matter most to you? Leave a comment and give us your take.
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“I have been working with Abtar for many years. He has a deep and impressive understanding of storeoperations, IT infrastructure, Control system and energy technologies. He persuaded us to implementa web-based facility solution that helped us reduced our energy cost by more than 10%.”
- Wally Lindeman, Director of Facilities, Lunds Food Holding
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