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With any plant replacement that is considered nowadays , there is never simply a “ like-for-like replacement ”. From the start , VMG would redo the heat load . In this , VMG has often discovered that older plants are considerably oversized .
Historically with old plants such as this one , the heat load calculations were cautiously concluded at best because energy and water were very cheap – quite the opposite in today ’ s environment . In those days with the information and technology available , a water-cooled plant was perceived to be more energy efficient , because it uses water to cool itself rather than the air and adding to that was the fact that being in Africa already involves higher average temperatures .
With that said , VMG notes that this could still also be a misconception because being in Africa , energy production and water scarcity are real issues that must be on the table . Having previously made use of water-cooled plants , over the last fifteen years they have moved away from this technology . Even though there are several new technologies , and old and new systems up and running with water cooling , their view is that because water has become such a scarce commodity , to waste it on something like air conditioning contributes to depriving someone , somewhere , access to water as a life preserving resource , and further where responsibility and moral boundaries have come into question .
Carrying on , supermarkets are very different to an office for example . In an office , there are a certain number of people , each requiring 7.5 litres of fresh air per second , so your calculations and setup tends to be quite simple . Supermarkets on the other hand have a continuously changing occupancy . Sometimes there are fewer than ten people shopping and sometimes you may have hundreds of shoppers simultaneously , so always accommodating for maximum occupancy is a complete waste of energy . Accommodating for often high infiltration rates through public entrances and receiving doors need to be considered , as well as the numerous extraction systems and extraction canopies which need to be included too .
New technology accommodates for things like CO₂ sensing , advanced controllers , computer software and loggers to create and maintain optimal conditions . However , old plants and buildings don ’ t usually have these functions , and it may not be cost-effective to retrofit to existing systems .
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The new coils that were installed . |
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Another angle of the coil installation . |
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The electronic expansion valve ( EEV ) controllers . |
RACA Journal I August 2021
THE NEW SYSTEM AND INSTALLATION The primary brief of this project was that the landlord essentially wanted to ensure that the whole store including the refrigerated area was air conditioned for as much of the summer as possible . As the supermarket had not had air conditioning for some time , and summer was fast approaching , the landlord was faced with a tough decision
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