Your cooling plant keeps emitting after the day it is commissioned. Refrigerant leaks from it every year, its efficiency depends on how it runs at part load, and it will be replaced two or three times before the building is. This tool works through those three things for the plant you are proposing in Assignment 2, using Australian registers and data. It starts on a worked example: replace it with your own plant on tab 1.
Numbers on screen: the worked example (two 450 kWr air-cooled chillers in Sydney).
Everything on the later tabs is worked out from these few numbers. The plant size comes from your scaled Assignment 1 loads and the way you have split that capacity across machines. Where you are building sets the grid emission factor that turns electricity into carbon. The tool estimates the plant's annual cooling electricity from its size, its location and the efficiency of registered chillers; if you have a better figure of your own, use that instead.
Duty machines only; a standby machine holds refrigerant too, so count it if you have one.
Scaled to the Assignment 2 building.
Every refrigerating system leaks a little each year, through joints, valves and servicing, and loses more when it is decommissioned. A refrigerant's global warming potential (GWP) says how many kilograms of CO2 one kilogram of it is equivalent to. So the same leak can be trivial or larger than a year of a small building's electricity, depending only on which refrigerant is in the machine. Low-GWP refrigerants bring their own constraints, which is why the safety class matters as much as the GWP.
The first group lists refrigerants actually used in the plant type you chose on tab 1.
Annual leakage (t CO2-e) = number of units × charge (kg) × leak rate × GWP ÷ 1000.
End-of-life loss = total charge × share of charge still in the machine at end of life × (1 − recovery rate) × GWP ÷ 1000. The share left at end of life is 85% for chillers and 80% for VRF.
Over one plant life = annual leakage × plant life + end-of-life loss. The electricity comparison uses today's scope 2 factor for every year. Australia's grid is getting cleaner, so over 20 to 25 years the electricity figure is an overestimate and refrigerant's share will grow. That is an argument for low GWP, not against it.
GWP values are the 100-year values that Australian law uses, taken from the IPCC’s fourth assessment report (AR4). Refrigerants listed only as “less than 5” are calculated at 5, an upper bound; CO2 is 1 by definition.
What this leaves out: a refrigerant change usually changes the efficiency and the charge too. A low-GWP choice that costs a few per cent of efficiency adds electricity emissions every year, so check the manufacturer's data before claiming the whole saving.
A chiller's COP is measured at its full rated load, which it almost never runs at. The IPLV weights four part-load points by how many hours a typical plant spends at each (1% of hours at 100% load, 42% at 75%, 45% at 50%, 12% at 25%), so it is the better guide to annual energy. Every chiller sold in Australia is registered with both numbers under the GEMS Act. Each dot below is one of them.
Hover over or tap a dot to see the product. Its registration number finds the full record on the register, and the model name finds the manufacturer’s data sheet.
IPLV = 1 ÷ (0.01÷A + 0.42÷B + 0.45÷C + 0.12÷D), where A to D are the efficiencies at 100, 75, 50 and 25% load (the AHRI 550/590 weights).
For the same cooling delivered, compressor electricity scales with 1 ÷ efficiency, so the ratio of two medians gives the rough size of the gap. The ratings are not like for like on heat rejection. An air-cooled rating includes its condenser fans. A water-cooled rating stops at the chiller, so the cooling tower fans and condenser water pumps come on top, and so does the water the tower evaporates.
The chart holds the 199 chillers registered as sold in Australia when the register was exported on 30 September 2026. A few are marked as no longer available. Nothing on the register is below about 350 kWr.
Cooling plant usually lasts 20 to 25 years and a building lasts 50 or more, so the plant you propose will be replaced at least once. Each replacement brings a new refrigerant charge, new embodied carbon and a crane lift, which is why a replacement route belongs in the plant-room layout. Different plant also brings different maintenance duties, and some of them are set by law.
Two sources, read together. The Australian lifespan is what the national refrigerant inventory assumes for this plant class. The ASHRAE figures are field records from about 345 US buildings: the age at which units were actually replaced, and the current age of units still running. Where few units have been replaced, the second number is the more useful one, and it is a lower bound.
A summary of your numbers to paste into your notes. The figures are indicative. In the report, state which values are your own (from DesignBuilder or manufacturer data) and which are typical values from this tool.