A small correction to what I had written below to avoid any appearance of contradiction:
In the second paragraph, "These are actually the heat flows..." refer to heat flows that have been "weighted" using Weighting Factors, i.e., they have been translated from heat flows to space loads.
in the last sentence, the "component heat flows" refer to the heat flows in EnergyPlus that have not been translated to space loads.
Joe
Joe Huang White Box Technologies, Inc. 346 Rheem Blvd., Suite 108D Moraga CA 94556 yjhuang@xxxxxxxxxxxxxxxxxxxxxxxx http://weather.whiteboxtechnologies.com for simulation-ready weather data (o) (925)388-0265 (c) (510)928-2683 "building energy simulations at your fingertips"
On 12/11/2013 1:12 PM, Joe Huang wrote:
Seeing as how there haven't been any responses to Rodrigo's question, I'll take a shot at it, but bear in mind that I haven't pondered this aspect of EnergyPlus for over ten years and might be outdated in my perceptions. If anyone has a better answer, please correct me.
There's not a quick answer, because DOE-2 (the engine behind eQUEST) and EnergyPlus work differently, so that you can't always get the same reports. For the benefit of those unfamiliar with DOE-2, the LS-B report gives the component loads breakdown (wall, roof, lights, etc.) for the days with the largest heating and cooling loads. These are actually the heat flows to the spaces calculated by DOE-2's LOADS module at fixed reference temperatures, and are approximate since the true indoor temperatures are not solved until the following SYSTEMS module.
EnergyPlus, however, does not distinguish between LOADS and SYSTEMS, but simulates both within each time step. Thus, if you ran EnergyPlus with just the building model, you will not get the reference loads (in the DOE-2 sense), but the floating building conditions with neither heating nor cooling. If you want to get something similar to the LS-B report, you will have to add a fictitious system (used to be called PurchasedAir) and then set the heating and cooling setpoints to the same reference temperature as you would have used in DOE-2 (preferably the annual average indoor temperature). You can then find the days with the largest heating and cooling loads. But if you have to go through all this effort, why not simply use the actual thermostat schedules, which should give you more accurate peak loads, particularly for commercial buildings with intermittent operations? Lastly, don't expect to get the component loads as in the LS-B report, because EnergyPlus doesn't work that way (for those who like to quibble, yes you can get the component heat flows, but that's not the same as the loads).
Joe
Joe Huang White Box Technologies, Inc. 346 Rheem Blvd., Suite 108D Moraga CA 94556 yjhuang@xxxxxxxxxxxxxxxxxxxxxxxx http://weather.whiteboxtechnologies.com for simulation-ready weather data (o) (925)388-0265 (c) (510)928-2683 "building energy simulations at your fingertips"
On 12/10/2013 1:01 PM, Rodrigo Cerqueira wrote:Hi,
I’m new in Energy Plus and I want start to use it to load calculations. I used to do that in eQuest. Can I have a report like LS-B (DOE2)? Normally in eQuest, I make just the shell model, with the zone internal loads and I run the simulation to get the peak heating and cooling loads. Can I do the same with Energy Plus? if so, which variable should I select to get the results?
Thank’s
Rodrigo
__._,_.___
Primary EnergyPlus support is found at:
http://energyplus.helpserve.com or send a message to energyplus-support@xxxxxxxx
The primary EnergyPlus web site is found at:
http://www.energyplus.gov
The group web site is:
http://groups.yahoo.com/group/EnergyPlus_Support/
Attachments are currently allowed but be mindful that not everyone has a high speed connection. Limit attachments to small files.
EnergyPlus Documentation is searchable. Open EPlusMainMenu.pdf under the Documentation link and press the "search" button.
Your email settings: Individual Email|Traditional
Change settings via the Web (Yahoo! ID required)
Change settings via email: Switch delivery to Daily Digest | Switch to Fully Featured
Visit Your Group | Yahoo! Groups Terms of Use | Unsubscribe
Change settings via the Web (Yahoo! ID required)
Change settings via email: Switch delivery to Daily Digest | Switch to Fully Featured
Visit Your Group | Yahoo! Groups Terms of Use | Unsubscribe
__,_._,___