4 ms·

Temp delta to cool in the south may be lower than to warm in the north, but not convinced it's a net energy savings. Not an AC guy, but the figure bandied abou

Temp delta to cool in the south may be lower than to warm in the north, but not convinced it's a net energy savings. Not an AC guy, but the figure bandied about in the data center was that it takes 2W of power to remove 1W of heat. Anyone have a less hand-wavy figure?

titanomachy 7y ago
Modern data centres are a lot more efficient than that. Google currently uses 0.11 watts of overhead per 1 watt of compute, and that overhead includes voltage conversions. [0] As for residential systems, typical AC unit efficiency ranges from ~15 to ~25 SEER, which is essentially BTUs of cooling per watt•hour under "typical" conditions. Stripping away the weird units, that's 5-7x efficiency. So 5-7 watts of heat removed per watt spent, under whatever the EPA's definition is for "typical" conditions. [0] https://www.google.com/about/datacenters/efficiency/internal https://www.google.com/about/datacenters/efficiency/internal
- jstewartmobile 7y ago
  Good on Megan then! I'm in the south. We have a lot of Germans down here who bitch about how we do everything--AC included. I'll have to send her a thank you card.
  - titanomachy 7y ago
    I think it's in bad taste to voluntarily move somewhere and then complain about everything. Keep in mind that heating efficiency can also be better than 1:1. Pulling heat from the outdoors (heat pump) and putting it inside is more efficient than making new heat (radiator, furnace).
    - jstewartmobile 7y ago
      Just had a chance to read this--thanks. From the average, the data center guys I'm talking to aren't wrong in a heuristic sense--just inefficient: "According to the Uptime Institute's 2014 Data Center Survey, the global average (PUE) of respondents' largest data centers is around 1.7." From what I recall, Google does AC-to-DC outside of the cooled area, and has their own custom approach to UPS. The article adds that they leave the cool aisle at a toasty 80F+, and make use of free cooling techniques. Most non-FAANG data centers are using stock Dell/HP/Cisco servers with redundant internal AC adapters, attached to an APC UPS (with its own internal AC adapter)--all actively cooled to 70-something F in some poorly-insulated re-purposed downtown building. I think Google made many of those improvements a very long time ago. I'd have expected their practices to be ubiquitous by now, but they're not...
      - titanomachy 7y ago
        Yikes. I expected the average to be worse, but not by that much. No wonder FAANG is eating the world. As far as the environment is concerned, we'd better get our butts in gear and move to the cloud :)

titanomachy 7y ago

Modern data centres are a lot more efficient than that. Google currently uses 0.11 watts of overhead per 1 watt of compute, and that overhead includes voltage conversions. [0] As for residential systems, typical AC unit efficiency ranges from ~15 to ~25 SEER, which is essentially BTUs of cooling per watt•hour under "typical" conditions. Stripping away the weird units, that's 5-7x efficiency. So 5-7 watts of heat removed per watt spent, under whatever the EPA's definition is for "typical" conditions. [0] https://www.google.com/about/datacenters/efficiency/internal https://www.google.com/about/datacenters/efficiency/internal

jstewartmobile 7y ago
Good on Megan then! I'm in the south. We have a lot of Germans down here who bitch about how we do everything--AC included. I'll have to send her a thank you card.
- titanomachy 7y ago
  I think it's in bad taste to voluntarily move somewhere and then complain about everything. Keep in mind that heating efficiency can also be better than 1:1. Pulling heat from the outdoors (heat pump) and putting it inside is more efficient than making new heat (radiator, furnace).
  - jstewartmobile 7y ago
    Just had a chance to read this--thanks. From the average, the data center guys I'm talking to aren't wrong in a heuristic sense--just inefficient: "According to the Uptime Institute's 2014 Data Center Survey, the global average (PUE) of respondents' largest data centers is around 1.7." From what I recall, Google does AC-to-DC outside of the cooled area, and has their own custom approach to UPS. The article adds that they leave the cool aisle at a toasty 80F+, and make use of free cooling techniques. Most non-FAANG data centers are using stock Dell/HP/Cisco servers with redundant internal AC adapters, attached to an APC UPS (with its own internal AC adapter)--all actively cooled to 70-something F in some poorly-insulated re-purposed downtown building. I think Google made many of those improvements a very long time ago. I'd have expected their practices to be ubiquitous by now, but they're not...
    - titanomachy 7y ago
      Yikes. I expected the average to be worse, but not by that much. No wonder FAANG is eating the world. As far as the environment is concerned, we'd better get our butts in gear and move to the cloud :)