Hello,
I send few days ago a query concerning a model of a building with DDS and VAV system.
I am sorry to insist but it is crucial for the LEED certification process of this building to manage good results of the Proposed building.
I didn't have so much problem to model the Baseline building model. But concerning the Proposeb building model, it gives me a heating consumption so low that it is impossible that my model is right.
So, I send you the files and I hope someone will find what happen. I check in the Bldg-sim]archives but DDS is not an usual system (because of its price) and I could'nt find any answer.
I really need you help...
Thank you
Regards
Amandine Gal
De : Gal, Amandine
Envoy? : 24 septembre 2009 14:41
? : bldg-sim at lists.onebuilding.org
Objet : [Bldg-sim] DDS too low gas consumption in Equest
Hi,
I am modelling a new building with a DDS system for the peripheric zones and a VAV for the internal zones and I have a too low gas consumption for heating.
I tried almost everything but I didn't find what happen.
I send you the file.
Thank you for your help.
Regards
Amandine Gal
I just ran it and got the following outputs.
1250 therms in January seems about right for a 70,000 square foot building with a 59 degree setback temperature and a boiler heating input ratio of 1.0 and wall/roof U-values approaching 0.03.
By the way, your delta T on your hot water loop is only 10 degrees, which seems low unless you're doing this for a reason.
James Hansen, PE, LEED AP
I have a delta T of 10?C only, because condensing boiler will be installed.
I forgot to tell you that the building is located in Montreal. So, do you still think that the heating consumption is not too low?
Thank you very much for your time.
regards
Amandine Gal
De : James Hansen [mailto:JHANSEN at ghtltd.com]
Envoy? : 1 octobre 2009 12:20
? : Gal, Amandine; bldg-sim at lists.onebuilding.org
Objet : RE: [Bldg-sim] Low heating consumption in Equest
I just ran it and got the following outputs.
1250 therms in January seems about right for a 70,000 square foot building with a 59 degree setback temperature and a boiler heating input ratio of 1.0 and wall/roof U-values approaching 0.03.
By the way, your delta T on your hot water loop is only 10 degrees, which seems low unless you're doing this for a reason.
James Hansen, PE, LEED AP
Please check your zoning. Unless the model did not load correctly on my machine, I am getting a variety
of small intersecting zones on levels 2 & 3. And check interior wall types (std vs air vs adiabatic).
Also, looks like you are using a heat recovery loop on your chiller. Maybe that helps?
Amandine,
I haven't ran the file and looked into possible issues so I'm afraid I can't offer any concrete solutions, but something seemed a little odd with the results. Based on the screenshot of the end use breakdown it appears that heating represents approx. 10% of the total energy use, which I think is too low for a building in Montreal. My experience with buildings in a "comparable" Toronto climate is that heating typically represents between 40-60% of the total energy, depending on the efficiency measures. Are you getting significant unmet heating loads?
Also, when simulating buildings with VAV systems I've often seen reheat energy show up in the shoulder seasons and even in the summer, depending on the controls. However it may be that due to the details of your system and controls, you don't have this issue.
Cheers,
Luka Matutinovic, B.A.Sc., LEED? AP
Hi, I transfer the discussion to the Equest mailing list as asked.
I know that my zoning is not usual but I had to do this because I have exterior floor and I only find this solution.
I will check my interior wall types.
I know that I have a heat recovery loop on my chiller. I try to delete it to see the influence that it has on the energy consumption but as it has to be, the influence is not so important.
Amandine Gal
De : Umesh Atre, LEED [mailto:umesh at innovativedesign.net]
Envoy? : 1 octobre 2009 13:59
? : Gal, Amandine; bldg-sim at lists.onebuilding.org
Objet : RE: [Bldg-sim] Low heating consumption in Equest
Please check your zoning. Unless the model did not load correctly on my machine, I am getting a variety
of small intersecting zones on levels 2 & 3. And check interior wall types (std vs air vs adiabatic).
Also, looks like you are using a heat recovery loop on your chiller. Maybe that helps?