www . refrigerationandaircon . co . za RACA Journal I September 2023 15
Events and Exhibitions
GLOBAL WARMING AND CHANGING HGAV AND BUILDINGS
The fifth SAIRAC Tech Talk of the year was presented online on 20 July by Arshad Ali Khan , managing director of EHVAC , on the subject Global Warming and Changing HGAV & Buildings . Edited by Eamonn Ryan .
Change is inevitable . Climate change due to global warming has pushed the HVAC industry to new developments , adopting new equipment to minimise power consumption .
During the talk , Khan discussed how new technological and ideological changes are going to be the main drivers for the HVAC industry in the future . He touched on how global warming is affecting the building industry . He also touched on new , modular means of construction which will not be covered in this article .
Today my focus is on what we can do to make our HVAC projects more energy efficient , and what we can use as a natural resource – particularly ground water to make our water-cooled chillers more efficient .
An example of ways of reducing the global warming potential ( GWP ) is to use refrigerant ammonia , which gives a COP of more than four compared to a COP of three for standard air-cooled chillers in South Africa .
There are other options such as the geothermal HVAC which we don ’ t see employed much in South Africa . Another option is the absorption chiller technology for generator-based projects where we use gas engines to generate electricity , whereby the generator has an efficiency of 40 % with the other 60 % going into the air as thermal heat . If we can tap that using the absorption chillers , whereby we can use the jacket water as well as the exhaust from the generator to provide chilled water for a particular building or even a district - that is a future option for improving energy for HVAC .
Geothermal involves putting the coil beneath the ground and running the refrigerant through that to disperse the heat generated or collected from the building into groundwater . Geothermal heating is more efficient and cheaper than the alternatives , and consequently needs to be encouraged in larger projects .
Ammonia is extensively used in the refrigeration sector where entire rooms are cooled using this technology . However , the old technology pumps ammonia from the condenser outside to the building up to the evaporator . This means that the ammonia has to be run into pipes that are made of stainless steel since ammonia is not copper-friendly . This makes the project
All images by © Eamonn Ryan / RACA Journal
1 to 3 : Attendees at earlier in-person SAIRAC Tech Talks .
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www . refrigerationandaircon . co . za RACA Journal I September 2023 15