Re: [EnergyPlus_Support] Problem with low heting values from e+

Jeremiah D. Crossett

CleanTech Analytics

503-688-8951

www.cleantechanalytics.com

This document may contain valuable information proprietary to CleanTech Analytics which is private and confidential. It may not be shared, copied, stored or transmitted in any form without the prior written consent of CleanTech Analytics

On Mon, Jul 30, 2012 at 11:11 AM, YuanLu Li <yli006@xxxxxxxxxxx> wrote:

Your modifications and comments are good.

However, it took 13 minutes to run on my PC. My DesignDay object version only took 6 seconds to complete.   with a 31 mega byte .csv file, I have no idea how to extract what I wanted to see from an annual simulation. The report is complete, but they are mostly averaged values.

Long PC running time is also energy wasting. No wonder so many users wanted to go to the "Cloud" and let the computor find the optimization.

Dr. Li

To: EnergyPlus_Support@xxxxxxxxxxxxxxx
CC: kontante@xxxxxxxxxxx
From: jeremiah@xxxxxxxxxxxxxxxxxxxxxx
Date: Sun, 29 Jul 2012 17:46:18 -0700

Subject: Re: [EnergyPlus_Support] Problem with low heting values from e+

Antonis,
Just for the fun of it I modified your model with Fanger thermal comfort thermostats, weather file extreme day, changed the HVAC to the non-template ideal loads system, added a phase change material and some output variables..

I like to run all simulations at 60 timesteps for increased accuracy so changed that as well.

The HVAC energy is much more, but that is how it goes with comfort control thermostats as they are based on the operative temperature, air velocity, zone averaged surface temperatures and amount of occupants rather then the normal well mixed air temperatures.

The specific heat of your materials looks fine- and I tried a run with normal design days but that had no real effect.

If the same building had greatly different results in V6 to V7.1 you may wish to submit a ticket to the energy plus help desk as they would know best and could provide the most definitive answers.

I like the fanger thermostats because I feel it more accurately reflects what will make for a comfortable environment- but it does increase energy consumption quite a bit so I am not sure if it is more or less accurate than choosing thermostat setpoints arbitrarily with the assumption that people will not change them.

Other items I can think of that might cause such low energy (other then a very good design) use could be ground temps and infiltration objects.

Not sure how helpful my modifications where but I figure it might get you thinking--- All the best-

Jeremiah D. Crossett
CleanTech Analytics

503-688-8951
www.cleantechanalytics.com

This document may contain valuable information proprietary to CleanTech Analytics which is private and confidential. It may not be shared, copied, stored or transmitted in any form without the prior written consent of CleanTech Analytics

On Sun, Jul 29, 2012 at 9:16 AM, kostas ordoumpozanis <ordoumpozanis@xxxxxxxxx> wrote:

Dear E+ users

    I am having problem to understand why e+ gives very low heating values to the attached model.
It's a simple 2floor domestic house with an ideal system and some classic internal load (people, lights, equipment) and an infiltration.
The results give a value of 0.07 kWh/m2 witch is not realistic. I have checked the internal load, I have changed a climate files but still cannot get realistic values.
The only thing that I can imagine is the thermal mass but I have checked the material properties as well could you suggest any other parameter that I might have not check, or if you had a similar problem to propose me a solution

Thank you in regards

K.O.