QUDT Unit Extensions for HVAC quantities

BrickSchema / Brick

Uniform metadata schema for buildings

http://brickschema.org/

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QUDT Unit Extensions for HVAC quantities #187

Open gtfierro opened 4 years ago

gtfierro commented 4 years ago

In the process of using QUDT for units in Brick, a few gaps have emerged for HVAC specific units:

Cooling Tower ton (15k BTU instead of 12k BTU for a refrigeration ton) one source
kW/ton (e.g. for chiller efficiency)
Boiler horsepower (33475.36 BTU/hr)
MBTU/hr, kBTU/hr, MBH, MMBTU/hr
this list may grow as the conversation continues

Another issue is how to handle temperature differentials. A 5 degF temp difference is 2.8 degC, not -15 degC. How do we express this in QUDT?

praftery commented 4 years ago

Re: MBTU/hr, kBTU/hr, MBH, MMBTU/hr: these are commonly used for heating systems in the US - boilers etc. I'm guessing (?) that the 'M' prefix here comes from the Roman meaning (1000) instead of the SI 'M' prefix for mega (1000000).

MMBTU/hr = 1,000,000 BTU/hr
MBTU/hr = 1,000 BTU/hr
MBH = 1,000 BTU/hr (the above, but common abbreviation)
kBTU/hr = 1,000 BTU/hr

Note that for each of the above the '/hr' is often omitted (e.g. a '1.5 MMBTU' nominal capacity for a boiler boiler).

gtfierro commented 4 years ago

I talked to Steve from QUDT and he pointed me to this page which describes how to handle the differential values. What it boils down to for us is we need to associate the qudt:isDeltaQuantity property with the Brick quantities that are deltas; this annotation wil ltell us which formula we would need for the unit conversion