All I was pointing out was that the current "Cloud" is simply a name change to make money.
All the Apps on the iPhone, etc. Are they better than what you can do on a PC? In this world, nothing is free. The cost of running PC on Internet has not come down. It seems to be coming down because the usage limit has increased. The basic rate is still increasing. The search engines are now showing more ads. to shield the real information, so that a user will see the ads.. The time needed to find what I want has increased. This is the real cost. ===================================== I do not carry out annual simulation on EPlus. Therefore I do not need distributed computation. I used the four season four day DesignDay simulation for most of my work. If a building does not use much energy for those four days and is comfortabale, it will be comfortable for the whole year. ================================= Large shopping centre, hospital, Hotel, airport, railway stations have special need in HVAC. The designer for these have sufficient resources and do not need to use the public Cloud. They will have their private Cloud with distributed processing, but not free for public users. =============================== I am really worried for our next generation. Thay may be deaf (iPod) and dumb (iPad) and communicate with one another by finger pointing throgh a Cloud (Face book, etc.). ttyl. Dr. Li To: EnergyPlus_Support@xxxxxxxxxxxxxxx From: yizhang@xxxxxxxxx Date: Fri, 23 Dec 2011 11:08:35 +0000 Subject: RE: [EnergyPlus_Support] Running E+ on the "cloud" Or to rewrite the E+ core and all component models, using OpenMP ;-)
This is not impossible. I bet there are tools that help you identify parallelizable code blocks. But, how many people out there thinking a single run of E+ is too long, if they are not trying to repeatedly run the same model? My guess at the moment is, a GUI that can adapt a parallel workflow to a 'slow' engine is more practical than to speed up the engine...
Yi
Dr Yi Zhang
IESD, De Montfort University, United Kingdom From: EnergyPlus_Support@xxxxxxxxxxxxxxx on behalf of Marcus Sent: Fri 23/12/2011 10:11 To: EnergyPlus_Support@xxxxxxxxxxxxxxx Subject: Re: [EnergyPlus_Support] Running E+ on the "cloud"
Lot's of great discussion points about one of my favorite topics, here are my two cents,
Dr. Li; I have to take a contrary opinion here and bet that internet capacity in the aggregate will fall in price and both bandwidth, processing, and storage will become more accessible in the near and long term future. But even if we are headed to a change in the market, I am still willing to pay good money for a cloud based simulation service, if it means, such as in Jim's case, that we can reduce from 16 hours (2 hours per run over ~8 ASHRAE 90.1 runs) for multi-use LEED certified facility, to something around a lunch or coffee break. I believe this is possible with the hardware sitting 95% idle in most consultancy offices, or with fee based cloud computing like EC2. One challenge is how to parallelize the problem. We can already parallelize the discrete simulation runs. I've heard this called "embarrassingly parallel". This is done by the "multiple simulation" tab in EnergyPlus, and also done independently many times over for building simulation and other engineering domains. This would break up Jim's 16 hour problem down to 2 hours if you had 8 cores. And this works great for global search meta heuristics like evolutionary algorithms if your runs are small and population size can be large. But to get below 2 the two hours barrier requires significantly more effort. I see three strategies; 1. Underlying simulation kernel can run naturally in parallel (domain decomposition?) - This would be true parallelization, where the solution of the underlying equations and algorithms is distributable, i.e. Matlab parallel for loop. - Or individual EnergyPlus simulation modules are running in parallel? - Is this really possible for a building simulation? 2a. Break up individual run, functional decomposition - Jim has proposed breaking the building apart into sub-geometry/systems. - I see this as fine for some cases, but generally speaking it has two challenges; one is simply knowing how to break it apart (time cost of expert user intervention), and two is that a building is inherently tightly coupled leading to high bandwidth between sub problems or loss of accuracy (paraphrasing Building Sim. Augenbroe 2001) 2b. Break up individual run, temporal decomposition - For an annual simulation, break up into i.e. 12 months over 12 processors, and stitch them back together at the end, as in (Garg 2011) that Yi Zhang kindly pointed out. 3. Other problem decomposition approaches? Sounds like a project for 2012! Cheers and happy holidays, Marcus -- Marcus Jones, M.Sc., LEED®AP BD+C http://www.optimalenergetics.com/ Freelance energy consultant Vienna, Austria On Thu, Dec 22, 2011 at 11:03 PM, YuanLu Li <yli006@xxxxxxxxxxx> wrote:
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