[Bldg-sim] Percent Energy Savings

Varkie C Thomas thomasv at iit.edu
Sat Mar 7 08:00:18 PST 2009


Professor Edna Shaviv and I have been corresponding on this subject and she has given me permission to post her comments on the Bldg-Sim website.  Her views are expressed in two papers that are not attached.  
Varkie
From: "Prof. Edna Shaviv" <eshaviv at tx.technion.ac.il>
To: "'Varkie Thomas'" <varkie.thomas at yahoo.com>
Cc: "'Guedi Capeluto'" <arrguedi at technion.ac.il>
Message contains attachments
ENPER_TEBUC_EP_EPMAX-page 58.pdf (3196KB)
Paper No 371: Passive and Low Energy Architecture (PLEA)  VS Green Architecture (LEED) (3498KB)
Dear Varkie,
 I fully agree with:
(2) a combination of situations, building types, locations and rules with one bottom-line numerical result.
and this is what we implement in our Energy Building Code.
I was always against the ASHRAE approach that agrees to keep all Architectural parameters even if they are wrong. This means that if the building envelop is crazily ZIGZAG, the reference building can be as ZIGZAG as well. I believe that the best energy performance should start with the Architecture of the building and its envelope and not only by the U value of it, or its mechanical equipment. We presented the influence of the Geometrical design parameters of the building, on its energy performance, a long time ago in: 
           Shaviv E. & I. G. Capeluto, 1992. “The Relative Importance of Various Geometrical Design Parameters in Hot-Humid Climate”. "ASHRAE Trans.", V. AN-92-1. Atlanta . (pp 589-605).
Also. when I participated in the ENERGY – TUBUC project, I have already presented this idea there. See the attached file on page 58.
 So, this is the approach we have adopted in our energy performance approach of our Energy Building Code. However, the problem is how to define the rules, so that the one bottom-line numerical number, to be compared with, will be sensitive enough and enhance good bio-climatic architecture and energy savings. Only last week we had found the rules how to define this reference building.
I am sorry that we will not be able to present our ideas in the coming IBPSA, as we did not write the paper yet, but I still think that I will come to IBPSA in Glasgow .
 You may circulate my email to the bldg-sim group, if you think it might be of interest to them.
Sincerely yours, 
Edna Shaviv
-----------------------------------------------------------------
Professor Edna Shaviv, LEED AP
The Alfred and Marion Bar Chair in Architecture.
Head Climate and Energy Laboratory in Architecture,
Faculty of Architecture and Town planning     
Technion, Israel Institute of Technology, Haifa , Israel 32,000
Tel-Fax: 04 829 4053 Cel: 0545 7654 41
eshaviv at tx.technion.ac.il
 



From: Varkie Thomas [mailto:varkie.thomas at yahoo.com] 
Sent: יום ו 06 מרץ 2009 21:52
To: Prof. Edna Shaviv
Cc: 'Guedi Capeluto'
Subject: Percent Energy Savings
 Edna,
I was thinking of visiting Glasgow during the IBPSA meeting in July.  It was 40 years ago in May 1969 that I obtained my Ph.D. from Strathclyde in Glasgow.
I learnt more about LEED by reading your paper.  I have highlighted some of the points you made.  My interest is mainly E&A which includes the building envelope.  The Bldg-Sim message below defines the dilemma -  (1) one rule to measure building energy efficiency OR (2) a combination of situations, building types, locations and rules with one bottom-line numerical result.  I think the latter would be the fair solution to optimize building design and it would also be in the best interest of the environment and society.  The formula can part of the energy analysis program.  
 From: Xavier Garcia Casals <xgcasals at telefonica.net> 
Friday, March 6, 2009 4:18 am
To: bldg-sim at lists.onebuilding.org 
Subject: Re: [Bldg-sim] Percent Energy Savings
“I do not think that the 'modelling accuracy' argument supports the Variable Reference Comparison Methodologies (VRCM: percent better methodology) in front of the Fixed Reference Comparison Methodologies (FRCM: EUI as kbtu/sf/yr).”

 
Architects today try to maximize the percent glass of the envelope.  This creates a better living environment and increases the productivity of its occupants which also saves energy.  The first costs, construction costs and operating costs of glass high-rise buildings are low.  The construction time is short – I watched the 92 above grade floors of the Trump Tower in Chicago being completed in less than two years.  Glass buildings are lighter and therefore today’s choice for all types of high-rise buildings – residential and commercial.
The main source of energy savings of a glass building is day-lighting.  The vertical glass could have PV properties with a small overall efficiency of converting light to 110V electricity.  Both energy savings features require day-light.  8,760 hours per year of building usage is more efficient use of the building but the percent energy savings of this building is going to be less compared to an office building that operates during the day only and with the same envelope.  
Because ASHRAE Std 90 suggests a perimeter zone depth of 15 feet for HVAC, it also means that you cannot get the maximum day-lighting credit for buildings that are 90% glass and with high ceilings.  These glass buildings are not going to meet Std90 envelope requirements.  1 watt/sf lighting is very stringent for an office building and so also are the mechanical systems standards.  It is not practical to achieve LEED Silver with percent energy savings for high-rise buildings in urban locations, particularly with buildings that operate 8760 hours per year.
50 years ago the average US family of 6 lived in a 2,000 sf house, close to their place of work and used public transportation.  Today the family size is 4, the house size is 4000 sf, they live 30 miles away in the suburbs, both adults drive to work in separate gasoline guzzling SUVs, and they spend 4 weeks in their vacation home 3000 miles away that must be heated all winter to prevent the pipes from breaking.  This trend is not being discouraged to save energy but we try to squeeze a few BTUs out of building energy use with codes and standards.  
There is push for sustainable townships today that looks at both buildings and transportation. Check out this University of Kentucky website: http://www.cscdesignstudio.com/. I heard that there are plans to develop sustainable townships in India. An easier way to save energy, the environment (rain forests) and reduce water pollution is to control the human population.  
Best wishes
Varkie
-----------------------------------------------------------------------------------------------------
--- On Thu, 3/5/09, Prof. Edna Shaviv <eshaviv at tx.technion.ac.il> wrote:
From: Prof. Edna Shaviv <eshaviv at tx.technion.ac.il>
Subject: Hello
To: "'Varkie Thomas'" <varkie.thomas at yahoo..com>
Cc: " 'Guedi Capeluto' " <arrguedi at technion.ac.il>
Date: Thursday, March 5, 2009, 9:01 PM
Dear Varkie
Yes, I am still there. 
It was nice to find that you remember me. 
 As Guedi wrote you, we were lately involved in developing the energy Code for buildings in Israel , and we are still working on it, trying to define the perfect performance method, the perfect reference building, etc. and had many discussions about it. We thought to present our ideas at the coming IBPSA, and even sent an abstract that was accepted, but we are still working on it, and could not write the paper before having conclusions.  
 I am also working on the Israeli Green Building Code, which is quite new and suffers from not being rigorous enough. However, I don’t think that we should adopt LEED, which has its own defaults. As I don’t believe that I can improve LEED, while I believe that I can contribute my effort to improve the Israeli Green Building Code, therefore, I prefer our Code.
Please find attached a paper I wrote lately about LEED and PLEA.
 Sincerely yours, and hope to see you again,
Edna
-----------------------------------------------------------------
Professor Edna Shaviv, LEED AP
The Alfred and Marion Bar Chair in Architecture.
Head Climate and Energy Laboratory in Architecture,
Faculty of Architecture and Town planning     
Technion, Israel Institute of Technology, Haifa , Israel 32,000
Tel-Fax: 04 829 4053 Cel: 0545 7654 41
eshaviv at tx.technion.ac.il
  
 From Guedi Capeluto <arrguedi at technion.ac.il> 
 Sent Tuesday, March 3, 2009 1:08 pm
 To 'Varkie C Thomas' <thomasv at iit.edu> 
 Cc 'Guedi Capeluto' <arrguedi at technion.ac.il> 
 Subject RE: [Bldg-sim] Percent Energy Savings
  Sorry Varkie for my Hebrew message, I tried to forward it to my colleagues here and replied by error.
We are having a very similar discussion here developing the Israeli Energy Code, and find your post very interesting and relevant.
All the best,
Guedi Capeluto
Arch. Guedi Capeluto, D.Sc.
Faculty of Architecture and Town Planning
Technion - Israel Institute of Technology
Technion City ,   Haifa 32000. Israel
Tel:+972.4.8294012  Fax:+972.4.8294617
email:   arrguedi at tx.technion.ac.il
web  :   http://www.technion..ac.il/~arrguedi/



From: bldg-sim-bounces at lists.onebuilding.org [mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Varkie C Thomas
Sent: 2009-03-03 18:26
To: bldg-sim at lists.onebuilding.org
Subject: [Bldg-sim] Percent Energy Savings
 ASHRAE Std90 for the baseline is already stringent and specifies the commonly used systems & plants based on building type and size.  Based on the CCGT building, high percentage energy savings for LEED certification can be achieved with low-rise buildings with a high exposure to floor surface areas to locate PV panels, high but efficient glass to wall area for day-lighting, the use of GSHP (which requires a large site area which may not be available in city blocks), and low common energy consuming systems in baseline and proposed which increases “percentage” energy savings.  
 A school building is low-rise, is low in process loads (increases % savings) and is high in occupancy ventilation which allows for air-to-air heat recovery. It operates only during the day increasing the impact of day-lighting. It is closed in summer, reducing the annual cooling load and increases the impact of solar heating during the rest of the year in cold climates.  So it is possible to achieve zero energy usage.  
 
The choices are limited in the case of inner city high-rise buildings.  Today’s high-rise office building design tries to maximize the glass percentage which increases the impact of day-lighting.  The glass could have PV properties with a very small overall efficiency of converting light to 110V electricity.  The ASHRAE Std90 baseline for Systems and Plants for such a building is considered normal design.  UFAD and other options are not typical.  The proposed envelope has to offset the 40% Window-Wall-Ratio specified by ASHRAE.   If the office building envelope is used for a hospital or hotel, which operate 8760 hours/year, then the percent energy savings will go down.  
 
High percent energy savings does not therefore necessarily mean a better or optimized designed building in terms of the client’s interests.  Percent energy savings should therefore not be the criteria for energy efficient building design.  It should be based on Energy Conservation Measures (ECM) used for the given building that are more energy efficient compared to ASHRAE Std90 for the given building type and size which usually results in increased first costs. The ECMs are going to be different for different types of buildings in different locations.  If the ECM used is inappropriate, then the client pays a price for the high percent energy savings.


 
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.onebuilding.org/pipermail/bldg-sim-onebuilding.org/attachments/20090307/e66e18a2/attachment-0002.htm>


More information about the Bldg-sim mailing list