[Equest-users] FW: Temperature in weather data-Energy Data for Retrofits
Barry Howard
barry at jeces1.com
Sat Jul 28 23:41:26 PDT 2012
From: Barry Howard [mailto:barry at jeces1.com]
Sent: Saturday, July 28, 2012 9:40 PM
To: 'Ralph Muehleisen'; 'Joe Huang'
Cc: 'equest-users at lists.onebuilding.org'
Subject: RE: [Equest-users] Temperature in weather data-Energy Data for Retrofits
Everyone,
After spending over 25 years on the Real Estate Finance and new development I transitioned into Energy use analysis and Sustainability. You are dead on with the importance of Retrofits. Big Value and Big Environmental impacts. There is starting to be some real movement within the DOE, ASTM( Std. 2797) and others for accepted protocols and standards. Within the next 1-2 years extensive data on actual operating data by space type with utilities expressed typically in Kbtuh/Square Foot per year will be available on several websites. Most Finance and Investment Professionals account for risk and uncertainty through required Equity as part of Project (Debt and Equity) Financing. Absent that, it is not difficult to obtain actual operating data from highly comparable space types in the same Climate zones and often within the same submarket in the city. Income streams are analyzed from comparable rents, utilities, Vacancy and Credit Loss, maintenance, taxes. The lender/investor recognizes a Debt Coverage ratio to account for risk. Many borrowers are required to buy “Caps”, financial instruments (derivative) that hedge against a rise in the loan interest rate. That may seem simplistic method than compared to using Stochistic Calculus (derivatives) but these ratios usually account for recessions, but not to the extent of the October 2008 meltdown.
The real problem within the Capital Markets that is still present is the minor focus and little value accorded to reduced operating costs and increased value from retrofits. There is now some context (before and after) case studies and Utility Rebate data that the “Green Premium” is finally being recognized. Once the tipping point is reached that should a big growth area in the Building industry.
In retrofits I have found doing an “Energy Pro Forma” which looks at the Water and Energy savings as the “Income” and then allocate the costs to maintain the savings, market vacancies, and a contingency to allocate risk is easier for Finance professionals to recognize. Importantly, there is some realization that design or renovation which reduces or eliminates an annual cost is just as important to Asset value as income, and has lower risk. The Energy Savings stream is Capitalized, worth multiples of the annual Energy savings.
I have attached a DOE FAQ on their Commercial Bldg website. The second relates to “Building Energy Performance Assessment” on valuing Energy efficiency. The BEPA ASTM 2797 Std. is designed to work with ASHRAE Energy Audits level 1-3. I have several larger files (2 mb and larger) which deal with quanitative methodology and more details on Energy Analysis valuation. E-Star’s has recently improved Portfolio manager and announced this week a 3,200 building Energy efficiency competition. They are also adding an Automatic Benchmarking Feature Software. The 2 should integrate in 2013. https://www.energystar.gov/istar/has/
USGBC is working on a forthcoming release “Green Building Information Gateway”on the R&D portion of the USGBC website. The information portal will begin LEED Centric then interface with other sites to provide asset data, operations, and case studies in multiple climate zones. The Beta site is operational and those interested should sign up for the site.
Thanks,
Barry Howard, Leed AP
Principal
JEC Lumen Solutions
www.jeclumen.com
214-870-5946
1400 S Sherman, 114
Richardson, Texas
From: equest-users-bounces at lists.onebuilding.org [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Ralph Muehleisen
Sent: Saturday, July 28, 2012 12:53 PM
To: Joe Huang
Cc: equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] Temperature in weather data
Great conversation everyone.
I guess I should have started my discussion by differentiating building design from analysis. I definitely see a place where actual energy predictions and characterization of uncertainty is of prime importance - retrofits.
While designing low energy new buildings is great, if we want to really impact the building energy and carbon footprint we need to retrofit the existing building stock as much as possible.
Since most owners look at this as an investment, we really need to given them information like other investments and provide risk analysis. That means probabilistic energy savings predictions and, when coupled with probabilistic cost and future energy costs, a true probabilistic return on investment and value added to the building. Then owners and financiers can look at a retrofit just like any other investment, and (I hope) pull the trigger on more retrofits than they are currently doing.
I'm not sure of a way to generate real ROI probability without stochastic analysis. The underlying model doesn't necessarily have to reflect the true physics (or even full systems of the building) as long as it captures the monthly energy use right and enough of the physics that when we make changes to the building, the model correctly reflects the energy savings and uncertainty in that savings.
Ralph T Muehleisen
PhD, PE, LEED AP, INCE Board Certified, FASA
Principal Building Scientist
Argonne National Lab
9700 S. Cass Ave, Bldg 221
630-252-2547, rmuehleisen at anl.gov
On Fri, Jul 27, 2012 at 8:50 PM, Joe Huang <yjhuang at whiteboxtechnologies.com> wrote:
Ralph, others,
I think it all depends on the purpose of the simulation. Leaving aside the issue of design sizing for the moment, use of energy simulations to predict, or more often, match observed energy usage is typically concerned with annual or long-term energy usage. In that case, stochastic variations around a mean doesn't provide much useful information, because the concern is not variability, but bias, in the results. It reminds me of when I saw that the uncertainty given for the modeled solar illuminance in the TMY2 weather files was less than 3%. That seemed wrong to me, since I know that for any particular hour the differences between modeled and measured solar could be quite large. However, when I read the documentation, it made sense because the uncertainty indicates not the stochastic variability, but the "mean bias error", i.e., systematic variations, between the modeled and measured solar.
How does that relate to the value of stochastic modeling? If we're only concerned in getting the annual totals to match, then whether or not we capture the stochastic variations from hour to hour seems to be minor importance. I'm also having difficulties in understand what
additional information is output from "stochastic modeling", except having error bars on each hour, which undoubtedly will be large.
My last comment is that although weather patterns are stochastic, the data on the weather files is quite deterministic, if we allow that the weather stations are doing a reasonably good job in measuring temperatures, wind speeds, etc. The question of adding precision to the DOE-2 weather files is not an issue of stochastic behavior, but simply that of round-off errors.
Joe
Joe Huang
White Box Technologies, Inc.
346 Rheem Blvd., Suite 108D
Moraga CA 94556
yjhuang at whiteboxtechnologies.com
www.whiteboxtechnologies.com
(o) (925)388-0265 <tel:%28925%29388-0265>
(c) (510)928-2683 <tel:%28510%29928-2683>
"building energy simulations at your fingertips"
On 7/27/2012 1:42 PM, Ralph Muehleisen wrote:
Chris, Joe, others,
The dramatic effects of simply rounding off/ceiling the temperature data in weather files is a perfect example of why we need to, as an industry, move from deterministic energy predictions to stochastic energy predictions.
Weather and occupancy are inherently stochastic and when we couple that stochasticity with our uncertainty in so many of the actual building parameters (at least uncertainty as to their what their values will be when installed), it seems to me that far more meaningful energy predictions could be made using stochastic methods.
While you wouldn't necessarily want to use stochastic methods during much of the design iteration, stochastic estimation should be a standard procedure for comparing major iterations and for final energy predictions.
For all us researchers, there is plenty of work to be done in properly quantifying the stochasticity of weather, occupancy and other stochastic parameters and in developing uncertainty profiles for important parameters that are not stochastic. There is also opportunities for industry to develop the wrappers to take the info and create the DOE2 wrappers.
Am I alone on this or do others feel the same way?
Ralph T Muehleisen
PhD, PE, LEED AP, INCE Board Certified, FASA
Principal Building Scientist
Argonne National Lab
9700 S. Cass Ave, Bldg 221
630-252-2547, rmuehleisen at anl.gov
On Thu, Jul 26, 2012 at 2:31 PM, Joe Huang <yjhuang at whiteboxtechnologies.com> wrote:
Chris, others,
Since as you've raised the question of how significant would be adding extra precision to the weather data in DOE-2, I was sent a copy of a recent paper by Annie-Claude Lachapelle of the Univ. of Calgary given at eSim Canada 2012 on this exact topic, "DOE2 Dry-Bulb Temperature Precision Level Impact on Sensible Economizer Performance". With the author's permission, I've attached the paper with this post.
Joe
Joe Huang
White Box Technologies, Inc.
346 Rheem Blvd., Suite 108D
Moraga CA 94556
yjhuang at whiteboxtechnologies.com
www.whiteboxtechnologies.com
(o) (925)388-0265 <tel:%28925%29388-0265>
(c) (510)928-2683 <tel:%28510%29928-2683>
"building energy simulations at your fingertips"
On 7/25/2012 10:45 AM, Joe Huang wrote:
Chris,
My attention on this issue was first raised about 15 years ago when I was working with non-US weather data , i.e., the rest of the world, that are all reported in 0.1 C. I've noticed since that US stations have also moved to the use of metric units, i.e., 0.1 C for temperature. The DOE-2 weather format is still in integer F, which leads to three unfortunate effects: (a) hourly records can be off by as much as 0.5 F, (b) clumping of the temperature distribution, and (c) statistics such as degree-days will be off by a percent or two compared to the original data. Now, one can say that all this is immaterial in the bigger picture of things, which has been the default attitude so far, but since it's really quite simple to fix, why not get it right, i.e., doesn't it feel much better to see the same temperatures in the DOE-2 outputs as in the original weather data?
BTW, all the weather data that I've looked at are records of conditions on the hour, not the average over the hour, except for solar radiation.
Joe
On 7/25/2012 9:53 AM, Chris Jones wrote:
Joe
Given that the time steps are an hour, and the fact that weather data is averaged over an hour, plus the fact that the building local will have variations from the weather station local, would an extra decimal point provide more useful information?
At 07:43 AM 25/07/2012, Joe Huang wrote:
This is not possible at present without changing the DOE-2.2 source code to read a weather input file with decimal values. When DOE-2 was first designed in the early 1980's, memory was a big concern, so the weather data was reduced to integers and then packed, which is why the DOE-2 *.BIN file is so small (146K). I have actually developed a modified file format for *.BIN where I save an extra digit of precision, i.e., temperatures to 0.1F instead of 1 F, but the source code would also need to be changed slightly to read this extra information. I've mentioned this to the developer of eQUEST/DOE-2.2 and will be experimenting with making this change to the source code. If and when it's proven to work and gets incorporated into DOE-2.2, I'll let everyone know. I welcome anyone who thinks this is a useful modification to send me an e-mail. It might spur me on to do something! Joe On 7/23/2012 2:44 AM, è”¡æ˜€èŠ wrote: > Hi, everyone: > > We know that eQUEST can edit personal weather data. > But the dry-bulb and wet-bulb temperature in weather data can only > enter integers. > Is it possible to have more precise temperature to decimal place? > Thank you very much. > > > _______________________________________________ > Equest-users mailing list > http://lists.onebuilding.org/listinfo.cgi/equest-users-onebuilding.org > To unsubscribe from this mailing list send a blank message to > EQUEST-USERS-UNSUBSCRIBE at ONEBUILDING.ORG > -- Joe Huang White Box Technologies, Inc. 346 Rheem Blvd., Suite 108D Moraga, CA 94556 (o) (925)388-0265 <tel:%28925%29388-0265> (c) (510)928-2683 <tel:%28510%29928-2683> www.whiteboxtechnologies.com "Building energy simulations at your fingertips" _______________________________________________ Equest-users mailing list http://lists.onebuilding.org/listinfo.cgi/equest-users-onebuilding.org To unsubscribe from this mailing list send a blank message to EQUEST-USERS-UNSUBSCRIBE at ONEBUILDING.ORG </x-flowed>
>>
Christopher Jones, P.Eng.
Suite 1801, 1 Yonge Street
Toronto, ON M5E1W7
Tel. 416-203-7465
Fax. 416-946-1005
email cj at enersave.ca
_______________________________________________
Equest-users mailing list
http://lists.onebuilding.org/listinfo.cgi/equest-users-onebuilding.org
To unsubscribe from this mailing list send a blank message to EQUEST-USERS-UNSUBSCRIBE at ONEBUILDING.ORG
_______________________________________________
Equest-users mailing list
http://lists.onebuilding.org/listinfo.cgi/equest-users-onebuilding.org
To unsubscribe from this mailing list send a blank message to EQUEST-USERS-UNSUBSCRIBE at ONEBUILDING.ORG
_______________________________________________
Equest-users mailing list
http://lists.onebuilding.org/listinfo.cgi/equest-users-onebuilding.org
To unsubscribe from this mailing list send a blank message to EQUEST-USERS-UNSUBSCRIBE at ONEBUILDING.ORG
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.onebuilding.org/pipermail/equest-users-onebuilding.org/attachments/20120729/ded3e761/attachment.htm>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: asset_rating_faq.pdf
Type: application/pdf
Size: 377122 bytes
Desc: not available
URL: <http://lists.onebuilding.org/pipermail/equest-users-onebuilding.org/attachments/20120729/ded3e761/attachment.pdf>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: Adamowski-BEPA Overview-ASTM.pdf
Type: application/pdf
Size: 561151 bytes
Desc: not available
URL: <http://lists.onebuilding.org/pipermail/equest-users-onebuilding.org/attachments/20120729/ded3e761/attachment-0001.pdf>
More information about the Equest-users
mailing list