The Chartered Institution of Building Services Engineers (CIBSE) hosted a seminar this week on how to achieve emission reductions and improve energy efficiency in office buildings, hospitals and supermarkets with Co2 refrigeration plants.
The CIBSE Victorian chapter chair, Manus Freeman, said the seminar featured a presentation by Klaas Visser.
"If you thought ammonia had potential, Klaas explained how there is even greater potential in carbon dioxide," Freeman said.
Visser outlined the international refrigerant landscape pointing out that the United States and China reached in-principle agreement last year to use the Montreal Protocol to phase down the use of HFC refrigerants by 2030.
Moreover, the G20 group of leading economies, which includes Australia and represents 85 per cent of global economic activity, signed an agreement in September last year to phase down the use of HFC refrigerants by two thirds below present levels by 2030.
The EU parliament voted overwhelmingly in favour of legislation to meet the G20 target in March this year.
"2030 is not too far away so our industry is faced with some major decisions on which direction to take in a retrofit scenario as well as in new buildings," Visser said.
"The new HFOs are appearing on the market but have already met fierce resistance by Mercedes Benz, BMW, the Volkswagen Group and Toyota on the grounds of the production of fatally poisonous gases when burning in a car accident.
"Furthermore, Refrigerants Naturally whose members include Unilever, Coca Cola, Pepsi Co and Red Bull, will not use HFOs in any of their cooling equipment, instead choosing to use Co2 or hydrocarbons."
Using published data, Visser said it has been clearly proven that Co2 refrigeration, when used for both cooling and heating, can reduce specific HVAC energy consumption in office buildings and hospitals by 30 to 40 per cent.
"If the refrigeration, and AC cooling and heating functions in supermarkets are integrated into one central Co2 plant, even greater energy savings will accrue," he said.
"It isn’t difficult or expensive to convert existing CO2/HFC cascade systems to full CO2 operations.
"The link between Co2 supermarket refrigeration and AC is that the AC compressors enhance the efficiency of the refrigeration compressors. A world first Co2 plant of the type needed for supermarkets after a slight modification has been operating at Exquisite in Melbourne for more than three years now."
Visser explained how a retrofit for a building AC chilled water plant and a boiler for heating would consist of replacing the chiller and boiler with a Co2 refrigerated chilled water and water heating system and replacing the cooling tower with an evaporative condenser.
He said the boiler would be removed and in new buildings Co2 and hot water can be pumped around the building.
"The Co2 can also act as a zonal fire extinguishing system using the air distribution for Co2 distribution," he said.
Visser also explained how energy efficient building cooling design should not be based on matching the highest COP compressor to a restricted high resistance air distribution system where the fans often use as much energy as, if not more than, the compressors.
"It is clearly shown that any extra floor space gained with small ducts penalises the HVAC energy consumption of buildings for their entire life.
"The real message is that we need to put the ‘R’ back into ‘HVAC’, and go back to the future and make it HVAC&R."
A 10-page feature on refrigerants appears in the June edition of Climate Control News magazine.