Wednesday Aug 15, 2007

Energy curtailment day

Today is another "curtailment day" here in San Diego. When SDG&E forecasts that peak demand will come too close to available electricity supply, they notify commercial customers who participate in their voluntary curtailment program. At Sun that means that more lights are turned off, and the air conditioning is turned down especially as we approach the peak energy usage time of day in mid-afternoon. Cal-ISO publishes near real-time charts of current and forecast energy demand.

For employees, and email notice of impending curtailment means it's a good time to come to work in shorts and sandals, aka "San Diego business casual." (It reminds me when I lived in Houston, Texas, there was a campaign to persuade businessmen downtown to stop wearing neckties. Open collar, higher temps, lower A/C, big energy savings.)

Another thing a San Diego curtailment day does is persuade more people than usual to work from home. That certainly saves energy for Sun, with more computers and lights powered off, and less human heat load on the A/C.  For the city as a whole it could save electrical energy, not to mention the gasoline saved by the car trips avoided. For instance when I go home to work I don't need air conditioning (I don't even have an air conditioner) because I can just open windows to get a comfortable cooling breeze, whereas this office building has the usual sealed windows and needs air conditioning even on the most pleasant days. The Sun office and my home are both located near enough to the coast to get shore breezes.

But in certain cases might telecommuting cost energy city-wide? Consider a person who usually works in his Sun office cooled by a high efficiency air conditioner using a 4W Sunray. What if he works from home in the East county where temperatures are much higher, using a lower efficiency home air conditioner and using a 300W home PC? Sunray at home looks better and better.

Friday Aug 10, 2007

energy efficiency and virtualization

There's an interesting posting on ZDnet from LinuxWorld about workload consolidation and virtualilzation to reduce power consumption, with some pros and cons. Then looking at other postings by George Ou I saw this idea for secure anonymous Wifi hotspot access. Maybe we'd all better read Ou's blog before our usernames and passwords end up posted on Defcon's wall of sheep.


Tuesday Jul 31, 2007

Power measurements of home computers

I measure power of my home PC's. The one I expected to be worst is best. Sometimes suspending saves a lot, sometimes not. Even turned off some use a lot of power. A Nokia palmtop is good. How about Sun Ray?

[Read More]

Wednesday Dec 07, 2005

Before Eco-Responsibility was Cool

Hey Scott, I was eco-responsible before before eco-responsibility was cool. Not like a friend who endeavored to live so that everything required for life, from food to energy to clothing, could be produced on a single plot of land a few meters square. No, I'm the type of "green" who doesn't want to give up anything, but hears his mother's voice: don't waste, leave some for the next person (or the next generation).

Power from Sun - the real sun

The electricity crisis and rolling blackouts of 2000-2001 hit us here in San Diego before the rest of the west. Day after day while working I kept a window open on the CalISO system status page to anticipate blackouts. It was obvious then, well before the Enron revelations, from the way generating capacity went offline when demand neared capacity that somebody was gaming the system.

We bought a rooftop photo-voltaic generating system sized to meet our household needs over the course of a year. Economically it was about a break-even proposition amortized over the life time of the solar panels verus the current price of electricity per kW-hour. We didn't give up anything, like cutting off appliances to stay within a power budget on a cloudy day. We stayed connected to the grid, spinning the meter backwards to sell electricity back to SDG&E during the day when they need it most, and buying it back at night when they have idle generating capacity. Win-win. Mostly it was insurance, that even if the Electric Robber Barons continued their looting, our price was fixed. We could leave our lights on and thumb our noses at Ken Lay. In the worst case, if the grid did become too unreliable we could always buy batteries and cut ourselves off the grid.

Driving Hybrid

We weren't interested in the Toyota Prius in 2003 - too small and too slow. But in 2004 it got really interesting, with as much interior room, as much acceleration, and better carrying capacity than my full size V6 sedan. Since a few hundred thousand people figured this out before I did, there was quite a waiting list, and I ended up with a 2005 model.

Power Efficient Computing

Sorry, I don't mean Sun UltraSPARC T1. What would I do with over 50,000 transactions per second in my home? Go over to Rich McDougal's cross reference if you want to read about CMT. This is about how I picked a PC from my buddies at HP. My goal really wasn't power efficiency; it was quiet. Power makes heat, heat needs fans, fans make noise, noise doesn't belong in my home. I already had an old Sony PC that did everything fine, except it sounds too much like a lawnmower when it runs. It has an Intel Pentium III chip; you know, back before they started really pushing the clock rate and the power.

So I started by looking at chip power consumption and SPECint2000 ratings. I picked an AMD Athlon processor which had good performance per watt, and nice power management features These features were supported by SuSE Linux, upon which my desktop JDS operating system was based. Several PC vendors used that chip, but colleagues recommended a Compaq Presario and they were right. That PC is so quiet that often if the screen is blacked out you can only tell it's running by spotting the green pilot light.

Little Green Data Center

Thorsten writes about running a Sun Fire T1000 powered by the solar panels on his house. His PV system looks about the same size as mine, but I generate a lot more electricity (3 kW DC, about 2.2 kW AC on a sunny day) - just an advantage of living in San Diego California instead of Hamburg Germany I suppose.

If he only cared about staying within a 1 kW power budget, Thorsten could build a home data center populated with Motorola 68040 processors: 6 watts at 40 MHz. Remember when an 040 was a fast machine? Remember when Macs didn't have fans? No wonder power consumption of data centers has grown so dramatically. But maybe he doesn't want to give up anything either, like thousands of transactions per second.


I am a software engineer in San Diego, president of the Standard Performance Evaluation Corporation (, formerly a mathematician and a violist.


« June 2016