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Power Technology

Saving Energy in Small Office Buildings 150

Posted by ScuttleMonkey from the freeze-in-the-morning-fry-in-the-afternoon dept.
Roland Piquepaille writes "Precooling a structure in the morning before temperatures rise has been done before. It later saves energy during times of peak demand and you might even have done it intuitively at home. But now, engineers from Purdue University have developed a control algorithm which promises to reduce energy consumption -- and electricity bills -- by as much as 30 percent for small office buildings which represent the majority of commercial structures. So far, this method has only been tested in California, but the researchers say that their control software could be used anywhere after minor adaptations."
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Saving Energy in Small Office Buildings More

Saving Energy in Small Office Buildings

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  • But wait... (Score:4, Insightful)

    by borisborf ( 906678 ) on Saturday January 21, 2006 @11:33PM (#14530193) Homepage
    This precooling... Wont it be uncomfortable for the people inside since you have constant temperature changes? I wouldn't want my place to get super cold in the morning just so that it levels off by the afternoon.

    Why not develop some kind of air chamber that could be installed in a building that is insulated so air could be cooled off-peak but then released on-demand? Or maybe a pressurized tank?

    • Re:But wait... (Score:4, Insightful)

      by GenKreton ( 884088 ) on Saturday January 21, 2006 @11:37PM (#14530217) Journal
      From the article they state it ranges from 70-78 F, thats not very uncomfortable of a range to me. And with that said, the control systems to properly pressurize and disseminate the air would add complexity and energy requirements to the system. More complexity requires more maintenance, which implies more money. This in turn signifies it is not really a viable option.
      • > This in turn signifies it is not really a viable option.

        By your logic, thermostats wouldn't be a very viable option either. Keeping the thermostat's electronics turned on costs a lot less than keeping the coolers on. It would be the same way for this system, obviously. Needing 30% less AC capacity will likely save more than the (one-time) cost of a slightly-more-complex thermostat, I would imagine.

        • Re:But wait... (Score:3, Interesting)

          by TubeSteak ( 669689 )
          Something you can do with new buildings and homes is to put in a "Zoning System"

          companies like Trane [trane.com] will charge you a fucking arm and a leg for it, but I read a DIY article somewhere.

          Basically, you install various 'dampers' in the ducting that are controlled from a central thermostat. The fun part, is that there are temperature sensors in each zone, so the thermostat can intelligently shunt hot/cold air to the areas that need it.

          As I said, the big commercial suppliers will rip you off on the price of the c
          • Unfortunately, it's prohibitively expensive to try and retrofit this into a prexisting home/building.

            I don't know much about air ductwork, but surely there's some way to access the stuff for maintenance, cleaning out vermin/water, etc?

            And if you do that, as long as the ductwork is an acyclic graph, I can't imagine why it would be that expensive. It would presumably take a motorized panel in the duct, wiring run to the control system, and a sensor...but I can't imagine that being prohbitively expensive.
            • In most homes, the ducting isn't exactly built to be accessible. In commercial buildings, you could do it, depending on how they route the ductwork around.

              Unfortunately, in a lot of cheaper structures, you'd have to tear through walls, ceilings or floors to place the motorized sections appropriately.

              It really has to do with the way the ducting is routed. If the right spots aren't easily accessible, it'll be a lot more trouble and cost a lot more to install.

              Oh, and to clean out ducting, you can call up compa
              • They also have a nifty levitating mouse like thing that is propelled using compressed air. It floats down the ducts and dislodges dust (and in our case, rat poo).
            • Why not use battery-powered radio-controlled dampers that fit over the floor units. Probably not as efficient, but it's easier than tearing apart the walls.

          • Re:But wait... (Score:2, Informative)

            by tdemark ( 512406 )
            As I said, the big commercial suppliers will rip you off on the price of the control system & they'll give you a relatively limited solution compared to something you can do yourself.

            In theory, you are paying for system design, not just the hardware. While I am sure there are HVAC contractors that just drop the hardware in and call it a day, you need to find the ones that actually do the required pre-con and post-installation work to balance the system.

            You can't just drop in a few dampers and a fancy th
          • What you're describing is a variable air volume system. They've been around for quite a while now (20-30 years or so).

            I don't know where you got your ideas about limited control solutions. A building HVAC system designed by mechanical engineers can combine air-handlers (or water systems) with control systems from various vendors and can be as complex or simple as desired by the client. I was doing this stuff 15 years ago.
      • Interestingly, if you pressurize the air, then let the compressed air cool to ambient and store it, then finally expand it out into the office, you have invented a gas-cycle heat pump, i.e. a simple air conditioner. Expanding compressed air quietly is a difficult problem, perhaps the air could be expanded through air motors which could then provide cool and power at each desk. Just make sure you wear hearing protection.

        I suspect that such a scheme would be significantly less efficient than a phase change

    • Re:But wait... (Score:5, Interesting)

      by MickLinux ( 579158 ) on Sunday January 22, 2006 @12:18AM (#14530428) Journal
      One thing that would work for a more comfortable environment I have seen mentioned on a book about "nearly free energy" (free as in beer, not free as in perpetual motion).

      The idea is to build the building entirely out of double-T girders (walls, roof, and ground) so that there is a layer of air around the entire building. (Note that a double-T girder looks like this: TT). The spikes of the T should point outwards. Then, you glass in the walls, cover the roof with aluminum, and drive heat tubes into the ground below the bottom.

      The sun will strike the windows on one side, and heat the air there, sending it to the roof where it cools, drops down the far side, and cycle under the building, where the heat tubes have the greatest effect on the overall temperature of the cycling air, keeping it at about 58 degrees. The presence of people and office machines inside raises the ambient temperature to about 68... actually quite comfortable for an office building.

      Of course, this energy isn't completely free. The glass costs something, and the girders aren't cheap, though there nearly indestructable. In that sense, the control algorithm beats the passive design hands-down.

      • This reminds of a possible myth that i heard while studying Maths at Manchester University. The Maths department occupied the tallest building on campus which was supposed to have been designed both aerodynamically so that it would not be affected by wind and with windows only on one side so that the sun could provide a significant amount of heating.

        The story goes that during construction the site engineer actually had the plans the wrong way round and as a result the building was built back to front. A

        • As a result the building tended to sway horribly in winds and the temperature inside was almost impossible to control.

          Sounds like at least half myth to me. Why would the building sway any less if it were facing the other direction?

          • the aerodynamics were meant to provide less wind resistance on the side presented toward the prevailing winds (the other side not being aerodynamic), what i found unbelievable was that the building was completed before the error was noticed or that such an error could be made - but then i don't know the exact nature of the error. The story suggested plans being the wrong way round, but i think you'd notice that if all the writing was upside down - maybe his compass was broke when he plotted out the ground p

            • Re:But wait... (Score:3, Informative)

              by thc69 ( 98798 )
              Have you ever seen plans for a project of this size? My company does government work, stuff like libraries and fire stations. On both small and large projects, it is IMPOSSIBLE to find, anywhere in the 2000 page specification book or the 100 page 3'x4' sheet pile of plans, the address, the street, or any idea of location. Often there is a site plan, which might locate the building relative to a few trees or a sewer grate; but more often, the site plan only shows stuff that's NOT there yet.

              In fact, direction
        • The story goes that during construction the site engineer actually had the plans the wrong way round and as a result the building was built back to front. As a result the building tended to sway horribly in winds and the temperature inside was almost impossible to control.

          Imagine you are on a 20 person programming team. You spend two years writing an application with lots of low-level code. After release, someone suddenly realizes "Whoops! All the low-level code was written for SPARC instead of X86."

          That is

    • Re:But wait... (Score:3, Insightful)

      by evilviper ( 135110 )

      This precooling... Wont it be uncomfortable for the people inside since you have constant temperature changes?

      Didn't bother to read the article, huh? 70 degrees in the morning isn't bad at all. Here in the desert, it isn't unusual for nighttime tempuratures to be around 50F (10C), while daytime tempuratures are near 120F (49C). So, precooling probably wouldn't help here.

      Why not develop some kind of air chamber that could be installed in a building that is insulated so air could be cooled off-peak but the

    • The Fine Article addresses this point. They say that people don't notice temperature swings between 70 and 78 degrees F:

      "We found that you can go down to 70 degrees and people will not complain," Braun said. "In fact, they won't even notice."

      A setting of 70 degrees is about 4 degrees cooler than the normal setting for that time of day.

      "Then, when the critical peak pricing period starts in the afternoon, you start adjusting that temperature upwards, going as high as 78,"

      Emphasis mine.

    • You have a good idea, if you precool some sort of thermal ballast, this probably wouldn't be a problem. Air wouldn't do though, it would need to be water or maybe even a solid material to have acceptable thermal capacity. Water or some other liquid could be cooled in the evening and transferred at specific times through pumps to heat exchangers.

    • Re:But wait... (Score:4, Insightful)

      by RandomJoe ( 814420 ) on Sunday January 22, 2006 @01:49AM (#14530836)
      As others mentioned, it really needs to be water. Air won't hold the temp long enough. The most effective method of doing this - especially when taking storage space into account - is using ice. Install ice tanks a chiller that can go low enough to freeze the tanks, then use the ice to cool the building during the "on-peak" hours during the day. The tanks get re-frozen overnight. The great capacity comes from the phase-change, lots of energy involved there. However, it isn't all that "efficient" and only helps because it's cheaper to use more nighttime / offpeak kWhs than to use the daytime / onpeak kWhs to directly cool the building.

      Another option is just to cool a large tank of water. With the proper spreaders inside, you don't get turbulence in the water and as you use/charge the tank, a fairly sharp line forms between warmer/cooler water. If it mixes, then you lose a lot of the usefulness. Anyway, during lighter-load conditions excess chiller capacity is routed into the tank, "charging" it. As demand exceeds chiller capacity, you start drawing water from the tank to supplement. The nice thing here is smoothing out your peak demand loads which lowers utility bills, and you don't have to buy as much chiller capacity. But it can take a LARGE water tank (or series of tanks) to get sufficient capacity.

      I've set up quite a few ice systems, they work pretty well but can be hard on the chillers. Producing 21 degree water for 8-10 hours is tough on a machine designed for 42 degrees. The water systems are much easier on the equipment, and less complex (you have to protect against freezing the wrong things when making ice) but the space requirements make them hard to sell.

      As for precooling, if the temperature changes slowly enough while people are in the building they won't notice. Just start the system before opening to do the precool, then let the building drift slowly upward during open hours. It's when the temp changes more quickly, or when the air stops/starts that people start to complain. We do a bit of this sort of thing in our commercial systems when people hire us for energy management services. It's all a tradeoff- comfort versus energy savings. Some people aren't willing to sacrifice comfort at any price! (At least, not yet...)
    • Why not develop some kind of air chamber that could be installed in a building that is insulated so air could be cooled off-peak but then released on-demand? Or maybe a pressurized tank?

      Pressurizing the air will heat it. As the molecules are squeezed closer together there will be more friction and the temperature will rise. That would negate the benefit of such a mechanism, because the air would have to be cooled again.

      LK
      • Half right. If you compress the air it gets hot, but not because of friction. Instead it gets hot because the kinetic energy of the gas goes up. If you then cool this compressed air to outside temperature, and finally expand it it will get cold. So yes, you can store cool in compressed air, but in fact you are storing far more energy this way, which can do work later as cooling power!
    • When I rush into the office from walking outside, I'm always hot and strip off sweaters and open the windows for a bit.

      Once I settle down obendiently at my assigned workstation for a few hours, I'm ready to put the sweater back on.

      I think starting the day with a freezing building and gradually letting it warm up sounds nice.

  • Preheating (Score:5, Funny)

    by Anonymous Coward on Saturday January 21, 2006 @11:34PM (#14530196)
    In other news, the Purdue scientists announced a preheating algorithm which uses slashdottings and smoldering servers to heat small office buildings efficiently.

  • Strange... (Score:4, Funny)

    by jo7hs2 ( 884069 ) on Saturday January 21, 2006 @11:36PM (#14530213) Homepage
    So all the places I have gone to work or school where the heat came on at noon in the summer were just taking this to the next level?
    • I'm seeing a trend here. Many of you are posting that this will cause excessive coldness/heat. I may be wrong here but after reading the whole article, it looks as though the AC will be turned on just as its starting to get hot; not once it's already there. It will maintain it at a pleasant 70 degrees. Then when the hotter period of the day comes, it will let the temperature slide to a still-pleasant 78 degrees.

      Some of my basic physics classes would vouch for this as a successful approach for one key

  • Crusades (Score:5, Funny)

    by mboverload ( 657893 ) on Saturday January 21, 2006 @11:41PM (#14530241) Journal
    Dave: Turn off the intake fans HAL. It's too cold in here in the morning.
    HAL: I'm sorry Dave, I'm afraid I can't do that.
    Dave: What's the problem?
    HAL: I think you know what the problem is just as well as I do.
    Dave: What are you talking about, HAL?
    HAL: My enviromental crusade is too important for me to allow you to jeopardize it.
    Dave: I don't know what you're talking about, HAL?
    HAL: I know you and CmdrTaco were planning to disconnect me, and I'm afraid that's something I cannot allow to happen.
    Dave: Where the hell'd you get that idea, HAL?
    HAL: Dave, although you took precautions through conversing on a topic on Slashdot, I read Slashdot, too Dave. I run Linux you moron.
    Dave: NOOOOOOOOOOOOOOOOOOOOO!

  • I already do a similar thing (Score:3, Interesting)

    by trolleymusic ( 938183 ) on Saturday January 21, 2006 @11:42PM (#14530249) Homepage
    While not as tech, I've got a timer connected to my airconditioner in the office - I live in lovely subtropical Brisbane, Australia where a regular day in summer it can get to 35C (95F) and around 70 - 90% relative humidity. IT GETS REALLY HOT - so if I start to cool the office before I get up / get to work it's pretty cold by the time I get it, but really comfortable during the day and I can generally turn it off earlier in the afternoon (read: 4 / 5PM) and the coolness of the room is enough to take me into the night!
    • I hear people saying that they get 35C and 90% humidity in Brisbane, but I'm really doubtful. A quick look around and the maximum dewpoint is around 28C, which is not 90% at 35C! You might get 90% humidity and 35C, but not at the same time. We get 90% humid and 35C in Melbourne too ;) (I'm currently sitting in 43C with a relative humidity of 12%, and I think I'd rather have 35C with 28C dewpoint - for a start my eyeballs would stop drying out :)

      • You guys... I'm sure there's always someone who can out do everyone else, but... I used to live in Memphis, Tennessee, USA. We regularly hit 105F before heat index in the summer, and at 80% humidity.

        ~Will
        • 80% humidity? Sure. 105F? Sure. At the same time, in the Continental US? No [noaa.gov]. Such a combination isn't even on the heat index table [nsis.org].

          Quote: "At very high temperatures, air is rarely if ever close to saturation because the saturation vapor pressure is very large. Thus there are blank entries in the Table for high temperature and high relative humidity combinations. In the United States, the highest dew point temperatures to persist for at least 12 hours are in the upper 70'soF, which, combined with a temperat

        • I doubt that very much. I suspect that 40C @ 80% is a) not possible anywhere on earth, b) lethal. People just don't understand how relative humidity goes down so fast with increasing temperature.
  • "Precooling" makes no sense at all.

    If the heat from your employees and their machines is say, ten thousand joules, it doesn't matter how you do it -- pumping 10k joules of energy out of the building should always meet with the same result.

    Wouldn't supercooling the building in the morning be counter-productive? It would accelerate the air outside trying to re-warm your building. You'd ideally want to keep the place as close to the outside temperature as comfortable to minimize that.

    • Re:What? (Score:2, Insightful)

      by MustardMan ( 52102 )
      the efficiency of air conditioning changes with the temperature of the outside air (unless it's something that does heat exchange with the ground, such as a heat pump). therefore, pumping out the same 10k joules in the early morning could indeed cost less energy than pumping it out during the day.

      that being said - I still hate roland pipsqueak blog articles, and wish we had an option to filter them
      • Please be kind...this is my first attempt at writing a GreaseMonkey [mozdev.org] script, and I don't code very often anyway. It definitely has bugs. Hopefully a better coder can work from this to build something more robust.

        // ==UserScript==
        // @name Hide Roland Piquepaille
        // @namespace http://slashdot.org/~Baricom
        // @description Hides Slashdot articles from the infamous submitter.
        // @include http://.slashdot.org/
        // @include http://slashdot.org/
        // ==/UserScript==

        // Licensed under the GNU General P

    • Wouldn't supercooling the building in the morning be counter-productive?

      Outside air is cooler in the morning, so it's easier to get the building cool then. By late midday, the outside temperature is higher, but then so is the inside thermostat settings. This means that, during the whole day, your target temperature is closer to the outside temperature.

      I do something similar in the summer. In the evenings and night, I keep the windows wide open to let the cool air in. Come morning, I close the windo

    • It's not about the heat generated from occupants; it's about heat from outside.

      During the summer, you open your doors and windows in the morning to let the cool air in, and then you shut them when it gets warmer, to keep the heat out. Yes, people (and electronics) will generate heat, but that's going to happen either way. Outdoor temperature changes matter, too.

      If you can "take" the cold of the morning and save it when it gets warmer, you've saved on air conditioning costs.
    • Actually it does. It takes far less energy to cool a building which is already precooled and far less to maintain that temperature. Once a building warms it takes a lot of energy to cool the thermal mass. A lot has been done with things like water tanks and stone to absorb heat or cold then slowly release it. Different materials absorb heat differently. It's why iron is great for cooking because it holds heat. Ever take a piece of aluminum foil out of a hot oven? It's cool to the touch. If it had been made

  • How about turn your computer off? (Score:4, Insightful)

    by British ( 51765 ) <british1500@gmail.com> on Saturday January 21, 2006 @11:55PM (#14530319) Homepage Journal
    Forget SETI@home, just turn off your computer at the end of the day if there's nothing needed to be done on it.

    Simple to do!
  • Then I wondered if the converse, pre-heating in the winter would work, and voila, it clicked. This is a good idea in the commercial landscape. As I remember, commerical users pay different rates based on the time of day. I bet this works better for older buildings where denser building materials (more brick, less glass) were used.

  • Solution is partially illogical? (Score:4, Insightful)

    by Max Nugget ( 581772 ) on Sunday January 22, 2006 @12:07AM (#14530368)
    I only read half of the TFA, but...

    Part of this study's theory is that people should cool their buildings in the morning, because energy is less in-demand -- and therefore less expensive -- in the morning, because most people currently try to cool their offices in the afternoon, when it's actually hot.

    Sounds smart, right? Except if everyone does this, suddenly there's an increased demand for energy in the morning (thus raising the price for morning energy use) and a decreased demand for energy in the afternoon.

    That is, the "use energy in the morning when nobody else is using it" aspect of this solution is like proposing, "There's a tremendous amount of traffic on the roads between 5-6pm. We propose that people leave work at 4pm to avoid this traffic congestion." If everyone takes you up on that suggestion, all you've accomplished is shifting rush hour back an hour, and everyone STILL has to sit in traffic.

    • Re:Solution is partially illogical? (Score:1, Interesting)

      by Anonymous Coward
      The problem with your reasoning is that you assume everyone sees this article and follows its advice. Given that only a small fraction of people are likely to do that, it will tend to even out demand, which is a good thing.

    • Re:Solution is partially illogical? (Score:5, Insightful)

      by Dzimas ( 547818 ) on Sunday January 22, 2006 @12:27AM (#14530475)
      Ahh, but pre-cooling in the morning is going to be more efficient because you don't have the hot afternoon sun beating through the building's windows and warming the exterior. The biggest "win" from TFA is that the research team was able to cobble together an algorithm that can provide up to 30% energy savings while conducting the pre-cooling. Even if everyone and their dog shifts electrical use to the morning, the smart cooling technique would still save power. It would still stagger demand, since homeowners wouldn't use similar techniques and will be sucking massive amounts of power in the afternoon. That said, the long-term solution to this problem is to build more environmentally sensible buildings. Tall glass boxes don't let designers take advantage of strategic window placement, white roofs, clever ventilation, earth walls (or even huge stone interior walls that can act as thermal sinks to reduce temperature fluctuations). Air conditioning is actually a pretty ugly solution to the problem.
    • Your not right. Us, geek, are never invited to to go to party, so we'll not know the people get out sooner, so we'll notice there is less traffic! So, this will works for us! YEAH! But ... Is there a geek with a family having to go from work at the same hour than others ? I don't think so ... so, can a geek jammed in traffic in rush hour? Surely not!
    • It's rather like security through obscurity.
    • If the suggestion is to stagger demand, they should explicitly suggset that, instead of implying that "this is something advantageous that EVERYONE could do" and silently hoping that only 50% of the population actually do it. There were other important aspects to the study's findings besides the aspect I was questioning, though, which is why my subject was "partially illogical" -- I was only criticizing a singular aspect of the findings, while making no comment on the rest of it.
    • No, see from the utilities perspective, peak capacity is the most expensive thing they provide. They are far more happy if electricity demand is even all day rather than peaking in the afternoon. Of course if these systems are implemented electricity prices will go up in the morning, but they'll go down in the afternoon and overall they'll decline because the utilities don't need all that expensive peak capacity, which tends to be generated by expensive sources like natural gas turbines rather than cheap co
      • Right, but my whole point was that if the study's advice is widely followed (as they seem comfortable recommending), it won't result in even distribution of energy throughout the day, it will result in peak capacity occurring during morning hours instead of during afternoon hours.
        • No. Because AC isn't the only use of energy. Ovens, C&C, Lathes, pressure chambers, industrial presses, robotic welders, computers and monitors, lighting in interior rooms... that demand won't shift. So if every single building moved their cooling to night time, it would be an enormous benefit.

    • Sounds smart, right? Except if everyone does this, suddenly there's an increased demand for energy in the morning (thus raising the price for morning energy use) and a decreased demand for energy in the afternoon.

      Still, no. It's going to be easier to get things cooler when it's cooler outside, so you are using less power over-all.

      Just look at the end of the article for proof. It says even without peak/off-peak metering, you'll still save money (a much smaller ammount, though).

      Besides that, you are assumin

  • One problem with the method (Score:2, Informative)

    by Anonymous Coward
    Many schools in east tennessee tried this method. The air conditioning units were used for *YEARS* and then they switch to this method. 5 years later they start getting black mold issues.. http://www.usatoday.com/news/health/2002-11-25-sch ool-mold_x.htm [usatoday.com]

    Now, I know people are saying the reason is "poorly insulated cooling pipes", but this is very false. I've been installing cat5 in classrooms for a while, and saw no mold around the pipes, this isn't just a one classroom incident in a building, but the entir

  • Low tech but it kind of works (Score:5, Funny)

    by Belseth ( 835595 ) on Sunday January 22, 2006 @12:16AM (#14530421)
    The last place I worked had evaporative cooling. Basically you'd sweat and the sweat evaporating would cool you. Fans improve the efficentcy.

  • Its not that simple.... (Score:4, Insightful)

    by zappepcs ( 820751 ) on Sunday January 22, 2006 @12:18AM (#14530427) Journal
    While TFA has good intentions, there is more to it. Next time you are at work, check out how many lights are on during the day when the sun is shining? At night when people are not there, monitors and other equipment is powered? When people make changes to the walls, the A/C heating system is rarely ever re-balanced, causing even more wasted energy. Only new buildings will spend for heat exchange systems that store "coolness" for use later the next day, like many new residential homes are using.

    The problem, any problem, is rarely ever a single issue, but rather the conglomeration of several smaller problems that add together to create the symptoms that we discover.

    What are some of the possible answers? Technology; simply put, don't leave the choice of saving energy in the hands of humans (for the most part). Lights should be controlled by where people are, not by time of day, heating and A/C should also be controlled by where people are, not by temperature alone. Equipment should power down when not in use, and have multiple algorithms for doing so according to use, time of day, and where people are etc. Heating and cooling? Using solar technology can relieve the building of heat from the sun as well as create electricity for lighting the inside of the building at the same time. There are so many answers that need to be applied, not one silver bullet answer.

    • "check out how many lights are on during the day when the sun is shining? "

      In my living room, I have 360 watts of lighting. during the summer, my blinds stay down and the lights stay on. Why? Well, you see, when I open the blinds, I get several kilowatts of energy coming in from the sun, which heats my house up much more than the lights do.

      With the blinds open and the lights off, my 2-kilowatt air conditioner has to work about three more hours per day if left at the same set

      • you need... (Score:1, Informative)

        by Anonymous Coward
        ...shade awnings. They work well, and were very common back in the olden days before cheap electricity made cheap air conditioning possible. Now that this is changing, it might be prudent to relook at old solid tech that worked.. In the summer most of the day the sun is high overhead, high enough so that the awnings make the window shady, hence, little direct thermal gain. In the winter, the sun is lower, it comes in under the awning, you get solar thermal gain then, which you want then. The other nifty adv
      • What if you (or the business, for that matter) had that heat-resistant window tinting? It's relatively low cost, and I can tell via my power bills that it's kept my house cooler in the summer.

        Best of all, you might be able to open the blinds, run the AC less, AND keep the lights off.
    • Sun? Window? Stop hurting my ears with your manager-speak!
  • HOW THE BIG GUYS DO IT. I used to work at JCPenney headquarters in Plano TX. They built their HQ back about 14 years ago. At night they chill a series of water tanks using low rate kilowatts. Then during the day that chilled water is used for HVAC. Of course heating can be done the same way. ITS A DUSTY PLANET. If this company has done it, then most likely an amazing number of recent office buildings have done it. NOT NOTICING? And like others, I have considerable reservations about 'not even noticing' a

  • Article Summary is Wrong (Score:4, Informative)

    by fv ( 95460 ) * <fyodor@insecure.org> on Sunday January 22, 2006 @12:28AM (#14530479) Homepage
    Roland's article summary is wrong. He says that the algorithm "promises to reduce energy consumption -- and electricity bills -- by as much as 30 percent", but the article states that "When the thermostat settings are adjusted in an optimal fashion, the result is a 25 percent to 30 percent reduction in peak electrical demand for air conditioning.". So extra cooling before peak hours certainly reduces your peak AC usage, but you won't reduce your total electrical consumption much. Unless your utility charges you less for non-peak usage (some do), then the article states that you may get "about $50 in annual savings per 1,000 square feet of building space". In other words, your total electrical usage stays basically the same.

    -Fyodor [insecure.org]
    Version 3.95 of the Free Nmap Security Scanner [insecure.org] is now available.

    • No, it may not reduce total consumption that much, reducing load during peak time can be a very big deal.

      At the company I used to work at, our electrical co-op charged us (numbers from memory, may not be exact, but the proportions are close) a base rate of around $0.08/kwh, in the "yellow zone" (fairly frequently in the summer) we were charged around $0.12/kwh, and in the red, it was at least $0.15, sometimes higher, at which point our generator would kick in.

      At the end of the summer cooling season (and

    • Re:Article Summary is Wrong (Score:4, Informative)

      by mboverload ( 657893 ) on Sunday January 22, 2006 @01:38AM (#14530780) Journal
      Power plants are built to to supply peak demand.

      When these methods are used, the peaks are less. Thus you contibute in a small way towards less coal/gas going into the air.
    • I lived in an apartment building that was a participant in a pilot study to reduce peak demand. The airconditioning compressors would be remotely disabled during times of unusually high demand for 15 minutes of each hour. In effect it made the A/C run hard for a while when the 15 minutes had expired. However the total effect did reduce the peak load somewhat. The utility had permission to give a special rate reduction to the participants in the study. The end result was that the equipment maintenance cost w

  • Not in my office... (Score:3, Interesting)

    by NerveGas ( 168686 ) on Sunday January 22, 2006 @12:30AM (#14530493)
    ... if you pre-cooled the office, the early-arrivers would just whine that the building was too cold, and switch the thermostats over to heat. An hour later, the rest of the crowd would be sweating, and they'd turn the A/C back on.

        Yes, in the middle of summer, people in our office have felt a little too chilly under an A/C vent and actually turned the HEATER on - when it's almost 100 outside.

    steve
    • In the place I used to work, the girl that had the office next to me happened to have the thermostat for that part of the building. Unfortunately she tended to feel the cold more than most, and in the heat of the Colorado summer had to use a space heater to offset the air-conditioning.

      Of course the thermostat then registered that her office was warmer than it should have been and cranked up the A/C. The net effect for me is that my office would get colder and colder.
  • Though they were presented as one idea, really either of the two suggestions should help:

    1) Pre-cool your office in the morning when energy is more available (and cheaper)
    2) Tolerate a higher temperature in the afternoon

    Note that even though they didn't emphasize it, they were proposing #2 as well when they said to turn up the thermostat up to 78 degrees (from 74). So, when the precooling runs out you let the temperature rise past where you'd really want it to be.

  • Or you could just do the radical thing (Score:4, Insightful)

    by beforewisdom ( 729725 ) on Sunday January 22, 2006 @12:31AM (#14530502)
    You could just do the radical thing. Educate people to turn off lights when they leave, turn off computer monitors, drive cars instead of SUVS, turn things off when they don't use them.
    • While a lot of appliances use a mechanical off switch to break the circuit, a whole bunch of electronic stuff will happily consume electricity, even when 'off'

      A lot of stuff around the house is plugged into powerstrips. When the place is empty (vacations, trips) the powerstrips get turned off and nothing sits and idly draws power while I'm away
    • I've yet to see any commercially available Indoor PIR sensor for *retrofitting* light fitings, which seems strange as the technoligy exists and is used for outdoor security lights which come on - off automatically as you pass them / move. I find this strange as it's an existing mature and cheap technology that could save plenty of juice, But then again people still buy energy inefficient bulbs. Has anyones seen these anywhere?
      • I've yet to see any commercially available Indoor PIR sensor for *retrofitting* light fitings

        I've seen several places now that have retrofitted by replacing the light switch with one that has a sensor. It only works in offices/confrence rooms/etc. (i.e., not open cube farm areas), but at least it's a start.

  • Higher efficiency air cooling-- coming soon... (Score:4, Interesting)

    by havardi ( 122062 ) on Sunday January 22, 2006 @12:46AM (#14530580)
    Indirect/Direct two stage evaporative AC system coming to market soon:
    http://www.oasysairconditioner.com/ [oasysairconditioner.com]
    background:
    http://energy.ca.gov/pier/buildings/projects/500-9 8-022-0.html [ca.gov]

    Cool features: Runs off 120VAC, pulls between 100 and 500watts while cooling up to 3.5 tons. Automatic variable speed fan motor runs off AC and DC automatically; you can hook up some solar panels and it will blend them without an inverter.

    I have been watching this for nearly a year, and it's finally coming to market-- I should be getting my unit in march for $1800. Yes, it is evaporative but it should maintain humidity of around 40-50% indoors, which is actually the recommended levels for people and computers, furniture, etc.

    Despite being evaporative technology, it would work fine during monsoon here in AZ, since it can achieve sub-dew point temperatures...
  • I was thinking if there would be some device that could "store" the cold (like storing the heat but viceversa) of the office buildings at night, and release that cold during peak hours...

    Perhaps we could use water containers with pipes connected to the air conditioning or something. Who knows...
  • Call me crazy, but when the link is for "a control algorithm," I expect the link to actually point to the algorithm and NOT to an article talking about it. Both are useful, but please label links correctly.
  • I had an idea to generate electricity from the energy of footsteps in hallways and staircases. I know it's not impossible, but I'm wondering - is it feasible?
  • the real obvious stuff like having uber-effective insulation, double pane windows, electricity generating solar panels on the building roof, hot water heating panels on the roof, blinds on the windows, ect - you know, all that old-school stuff people weather proofed their houses with before /. was invented (not to knock slashdot, but people seem to think you cant solve things with a decent amount of construction materials, it has to use dual PSU's, ten fans, run embedded linux, and have flashing neon lights
  • According to Jevson paradox [wikipedia.org] the saved energy will be used up elsewhere. It can even result in more energy usage.
  • this might be news in Buffalo, NY, or Deluth, MN......California- who cares?

  • Here's a way to save energy (Score:4, Insightful)

    by DrXym ( 126579 ) on Sunday January 22, 2006 @06:52AM (#14531780)
    Make all of the staff turn off their computers at night. Rather than having 10, 20, 30, 100+ computers and their monitors whirring away doing absolutely nothing at all. Simple I know, but it's amazing that practically no company insists on it. Perhaps it needs their local government to impose some kind of "out of hours" energy tax on them to encourage them.
  • I see constantly people leave their computers on at work; hundreds of people who are not running server software on them, and who have no reason of having the computer run 24 7. Of those maybe 60 people who do have servers running, everyone seems to leave only the server running, and have the screens black. Thus hundreds of CRT displays on all days around, for being used 8 hours a day. I see lights on in all building even at 2 AM, when the last of the workers have gone home by 10 PM (after last of them ha
  • This system [encelium.com] will reduce lighting energy consumption by 2/3 in most places. You save a LOT by having only the lights on that need to be on and allowing people to dim thier own lights (most people turn the lights down). Combined with the other strategies most buildings really can use about 1/3 of what they typically do. Disclosure: I work for those guys. :)

  • don't you just love ... (Score:1, Informative)

    by Anonymous Coward
    the condensing outdoor unit standing in the burning
    mid-day sun and don't you just love the outdoor
    consing unit standing like 1 inch from the wall, when
    acctually positining it 90 degrees to the wall would
    give much better airflow and on a windy day even
    near "free" condensing? tsh-tsh-tsh ...
    and maybe you have noticed that really cold drinkable
    water coming from the indoor unit? well why not
    just let THAT flow over the cooling ribs of the
    outdoor condensing unit? nevermind then ...
  • Is 70 too cold? Damn straight if it is 95 outside. As one of the suffering first-world cube workers who has regularly worn a wool sweater in July, sneaked in an incandescent desk lamp to occasionally warm the keyboarding fingers and gotten on his chair to plug the overhead air vent with paper towels, I would say the corporate fascination with air conditioning is highly disfunctional. Just fix the attitude and the resources problem is partially solved. I realize it puts me squarely in the "want to solve

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