Actual weather data may give you a good utility cost match. If you do not have HVAC, there is no cost calibration requirement.
When natural ventilation is used in a tropical country, there is no cost element either. Therefore, TMY is a good data source to provide a good estimation of solar radiation on the building.
The use of air-conditioning has increased the urban day time temperature by as much as 5°C in Singapore. The weather station for Singapore is at the Changi airport which is not at the city centre. Therefore, the local real time data may still not the same as that at the City.
For Toronto, due to the lake effect, the downtown temperature is 2°C lower than that measured at the Peason Airport.
The above is for the reasons against using actual weather data instead of TMY.
Cost saving may not be energy saving. Simulation is done for comfort.
Once the high rise urban style is created, it does not matter what data or simulation tool one use, the result will not result in energy saving, because the building occupier will pay for all the air-conditioning comfort.
Most of the simulation work I have seen in this group gave me the impression that the users are more interested in comfort and cost saving, and not in energy saving.
I know the above is not what you would like to talk about at the ASHRAE conference. ASHRAE has done a good job in improving the building insulation standard. They have started to recognize that the 1955 comfort standard is too tight for energy saving. There is no real purpose in matching the actual utility cost with the simulated result. LEED certificate should address energy saving and not on cost saving.
Dr. Li
To: abakshi@xxxxxxxxxx; jim@xxxxxxxxxxxxxxxxxxxxxxxxxxx
CC: bldg-sim@xxxxxxxxxxxxxxxxxxxxx; EnergyPlus_Support@xxxxxxxxxxxxxxx
From: ncaton@xxxxxxxxxxxxxxxx
Date: Thu, 28 Jun 2012 16:51:05 +0000
Subject: [EnergyPlus_Support] RE: [Bldg-sim] Food for thought....
Hi Jim,
Using actual local weather data (AMY vs. TMY) corresponding to the utility bills being calibrated against is standard practice in my experience. I started out using TMY weather and quickly ran into pitfalls as you?re alluding to.
~Nick
NICK CATON, P.E.
SENIOR ENGINEER
Smith & Boucher Engineers
25501 west valley parkway, suite 200
olathe, ks 66061
direct 913.344.0036
fax 913.345.0617
From: bldg-sim-bounces@xxxxxxxxxxxxxxxxxxxxx [mailto:bldg-sim-bounces@xxxxxxxxxxxxxxxxxxxxx]
On Behalf Of Arpan Bakshi
Sent: Thursday, June 28, 2012 11:44 AM
To: Jim Dirkes
Cc: bldg-sim@xxxxxxxxxxxxxxxxxxxxx; EnergyPlus_Support@xxxxxxxxxxxxxxx
Subject: Re: [Bldg-sim] Food for thought....
I would contact Zheng O'Neill. She was commissioned to do a similar study for the Dept. of Defense as part of her work at United Technologies, which she presented at IBPSA New York.
_________________________________________
Arpan Bakshi Sustainability Manager
LEED AP BD+C, ESTIDAMA PQP
YR&G
sustainability consulting, education and analysis
217 Grand Street No. 802 New York NY 10013
D 646.704.2880
On Thu, Jun 28, 2012 at 11:49 AM, Jim Dirkes <jim@xxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
Dear Forums,
I am busy preparing a short talk for the Fall ASHRAE Energy Modeling Conference. The topic is ?An Approach for Calibrating Existing Building Energy Models to their Utility Consumption?.
As part of the preparation, I will address the issue of how much difference might result in energy conservation measure savings predictions if you use actual weather data for the billing period versus TMY data.
To get a rough idea how much variation there might be, I looked at Degree Days for a span of years. What a variation! (for the city I?m studying at least)
I am not yet sure how that affects total energy consumption ? you?ll have to attend my presentation in Atlanta to find out J.
In the meantime, I am starting to think that existing building energy models should use actual weather, not TMY data. Have any of you run similar comparisons for existing building models?
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