LEED-NC v2.1 Energy & Atmosphere Credit 1 Final Submittal

 

by Donald W. Cott, PhD, PE, LEED AP

Thermal Systems Engineering, North Pole, Alaska

don.cott@ak.net, / http://home.gci.net/~tse

 

October 2007

 

PURPOSE

 

This document constitutes the Final Summary Submittal for an application for Leadership in Energy and Environmental Design (LEED) certification under the ground rules of the United States Green Building Council (USGBC, www.usgbc.org) in accordance with the LEED New Construction Version 2.1 Reference Guide (LEED-NC 2.1).  It summarizes the supporting documentation in pursuit of credit for Energy & Atmospheric Credit 1 (EAc1).

 

This submission is in behalf of the Cold Climate Housing Research Center (CCHRC), of Fairbanks, Alaska, for the new building called the Research & Test Facility (RTF) under construction at 1000 Fairbanks Ave, Fairbanks, Alaska 99708; on the campus of the University of Alaska Fairbanks (UAF).

 

HISTORY

 

This document and the supporting documentation was first submitted in Nov 2006 in an initial submittal version.  Since this is the first LEED application this author has performed, an assortment of critiques were noted by the LEED Review Team, and communicated to CCHRC on 20 Aug 2007, with a 30-day deadline for response.  The critique was communicated to me on 28 Aug 2007, and this document represents a part-time effort through the intervening two months.  My thanks for the additional month of grace after I fell on my face trying to make the first deadline.  All the critiques are addressed, although the result is not optimized.  This Summary and all the supporting documentation will be posted on the web at http://home.gci.net/~tse within the next few hours.  Many of the links are local, and so will only work with the on-line version.

 

ENERGY MODEL

 

The supporting documentation constitutes an Energy Model of the RTF, using the Department of Energy (DOE) supported computer code DOE-2.2, version 2.2-44e4; fronted by eQUEST version 3.61 build 5360.  This useful software was developed by James J. Hirsch & Associates of Camarillo, CA (http://www.energydesignresources.com/).  If the reader desires to execute and experiment with the RTF energy model, the eQUEST/DOE-2 software and documentation is available as a free download from http://www.doe2.com/eQUEST/.  In that event the input files for the LEED Comparison are: 118-DEC.inp.txt, 118-DEC.pd2.txt, 118-DEC.SIM.txt, 120-ECB.SIM.txt, 120-ECB.pd2.txt, 120-ECB.inp.txt.  The .txt is appended to facilitate handling over the Internet, they should be removed for the files to be recognized by eQUEST and DOE-2.  The weather file used for these simulations is FAIRBAAK.bin, the TMY2 file for Fairbanks, Alaska, downloaded from the eQUEST web site in September of 2007.   All the required input files for the RTF energy model are bundled herein, or if they have been separated, may be downloaded for free from Thermal Systems Engineering at http://home.gci.net/~tse/.

 

The electricity rates used for all computations are those charged by the Golden Valley Electric Association, Fairbanks, Alaska, for General Service 2(1).  They are broken down into block, demand, tax, fuel, & minimum charges for each month in “REPORT- ES-E Summary of Utility-Rate”, near the end of each of the .SIM files (118-DEC.SIM.txt & 120-ECB.SIM.txt).  The fuel oil charges were highly volatile during the construction period, and suppliers wouldn’t even venture a guess beyond “today.”  It was rather arbitrarily assumed that the delivered price would be $2.50/gal the first year, with a heating value of 138,000 Btu/gal, independent of any demand charges, basic service charges, taxes, ratchets, etc.

 

 

“REAL” VS. “LEED” ENERGY MODEL

 

The USGBC LEED development team had the formidable task of developing a methodology that would allow comparison of actual designs (Design Energy Cost DEC case) and minimum standard compliant designs (Energy Cost Budget ECB case) for a remarkably wide range of climactic conditions, but most especially for subtropical construction emphasizing cooling for occupant comfort.  People in subtropical zones are very lightly dressed, and wish to be comfortable in light clothing while they work inside the subject buildings.  Hence the rather narrow comfort criterion of Table 3 LEED NC 2.1 pg 140 is required.  People in Fairbanks, Alaska, just don’t dress that way, and would be complaining about the heat in the above referenced comfort range (65F-75F).  In Fairbanks winter conditions everyone wears heavily insulated clothing, and long johns would be insufferable for occupants in the required comfort range.  So for the LEED comparison autosizing of HVAC systems is used in eQUEST, and the controls are set to maintain the required “Comfort Criteria” (CC).  Requirements are as follows “To conduct the simulation, an analog mechanical system must be created.  The simulation must be a thermodynamically similar model that can be used to simulate passive conditioning schemes.”  (LEED NC 2.1 pg 141)  Further, “Both the ECB Method and the LEED EMP [slightly modified DEC] assume that even if a heating or cooling system is not installed at the time of construction, future occupants might elect to use energy-consuming temporary measures for conditioning needs.  Special cases of absent heating or cooling systems require the modeling of a default system to establish the ECB.” (ibid, pp 141-142)

 

The actual RTF design has no cooling system other than opening windows during office hours.  But the LEED DEC and ECB cases both use identical (but differently sized) DX cooling systems for comparison purposes.  The actual RTF design allows a wider variation in temperature.  The actual RTF simulation file is included as Real-RTF.SIM.txt, and the corresponding input files are Real-RTF.pd2.txt and Real-RTF.inp.txt.  This simulation uses a Sherman-Grimsrud algorithm to relate outside wind direction and magnitude to ventilation with open windows (“Energy Simulation Training for Design & Construction Professionals”, Sept 2004, James J. Hirsch & Associates, pg 16).  In this simulation the office basement zone gets quite warm due to the always operating 6 KW Information Technology (IT) room.  There is actually an auxiliary ventilation system for that room, but that additional system isn’t yet modeled in the actual RTF simulation.  The actual-RTF simulation is included only for academic interest, since it isn’t required for the LEED comparison.  It is interesting that the projected annual operating energy cost of the actual-RTF is $23,600 (Report ES-D of Real-RTF.SIM.txt); compared to $25,953 for the DEC’’ case and $35,041 for the ECB’’ case in Table 1 below.  So natural ventilation saves about $2,353 annually.  Note that the actual-RTF and DEC cases are identical in terms of envelope components.  This latest set of runs actually are different in the treatment of the NFS fill below the building, but that should be negligible with 4” of insulation under the slab.  The main difference is natural ventilation.  The much higher cost of utilities in the ECB’’ case is because of the much reduced “standard” insulation in the envelope components.  So above standard insulation saves about $9,088 annually.  No estimate has been made of the increased capital cost of the actual RTF vs. the “standard” RTF, most of the really high resistance components were donated by various venders. 

 

 

DEC/ECB COMPARISON

 

The LEED EAc1 requirement is that the proposed building be modeled, and the actual design, the Design Energy Cost (DEC) model, be compared to the minimum-cost standard prescriptive design as prescribed by the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE, http://www.ashrae.org/) Energy Standard for Buildings Except Low-Rise Residential Buildings Standard 90.1-1999 (ASHRAE 90.1-1999).  ASHRAE refers to the minimum-standard prescribed design as the Energy Cost Budget (ECB) design.  For Fairbanks, Alaska, the appropriate prescribed building envelope requirements are in Table B-24 of ASHRAE 90.1-1999 pg 114; as specified in Table D-1, pg 126 of the same reference.

 

Table 1a summarizes the energy distribution in the building for the DEC case, as follows:

 

Table 1a. DEC/BEPU excerpt from 118-DEC.SIM.txt.

 

118 - LEED EAc1 Final Submittal         Fan Tuning HRVs DEC Sim                  DOE-2.2-44e4   9/24/2007     2:02:57  BDL RUN  1

Modeler: Don Cott; don.cott@ak.net;     http://home.gci.net/~tse/                                                      

REPORT- BEPU Building Utility Performance                                                   WEATHER FILE- Fairbanks    AK TMY2

---------------------------------------------------------------------------------------------------------------------------------

 

                         TASK     MISC    SPACE    SPACE     HEAT    PUMPS     VENT    REFRIG  HT PUMP   DOMEST    EXT

               LIGHTS   LIGHTS   EQUIP   HEATING  COOLING   REJECT   & AUX     FANS   DISPLAY  SUPPLEM  HOT WTR   USAGE    TOTAL

              -------  -------  -------  -------  -------  -------  -------  -------  -------  -------  -------  -------  --------

 

EM1  ELECTRICITY    

    KWH        21113.    1446.   82059.       0.   20252.       0.    6811.   12349.       0.       0.    1374.       0.   145404.

 

FM1  FUEL-OIL       

     GAL           0.       0.       0.       0.       0.       0.       0.       0.       0.       0.       0.       0.        0.

 

BFOM FUEL-OIL       

     GAL           0.       0.       0.     219.       0.       0.       0.       0.       0.       0.       0.       0.      219.

 

GFOM FUEL-OIL       

     GAL           0.       0.       0.    1092.       0.       0.       0.       0.       0.       0.       0.       0.     1092.

 

TFOM FUEL-OIL       

     GAL           0.       0.       0.     746.       0.       0.       0.       0.       0.       0.       0.       0.      746.

 

 

 

 

           TOTAL ELECTRICITY    145404. KWH        10.673 KWH     /SQFT-YR GROSS-AREA   10.673 KWH     /SQFT-YR NET-AREA

           TOTAL FUEL-OIL         2057.  GAL        0.151  GAL    /SQFT-YR GROSS-AREA    0.151  GAL    /SQFT-YR NET-AREA

 

 

           PERCENT OF HOURS ANY SYSTEM ZONE OUTSIDE OF THROTTLING RANGE =  4.1

           PERCENT OF HOURS ANY PLANT LOAD NOT SATISFIED                =  0.0

 

           NOTE:  ENERGY IS APPORTIONED HOURLY TO ALL END-USE CATEGORIES.

 

 

Table 1b summarizes the energy distribution in the building for the ECB case, as follows:

 

Table 1b. ECB/BEPU excerpt from 120-ECB.SIM.txt.

120 - LEED EAc1 Final Submittal         PSZ/Furnace/NFS/Eff Mods to ECB Sim      DOE-2.2-44e4  10/01/2007     6:20:06  BDL RUN  1

Modeler: Don Cott; don.cott@ak.net;     http://home.gci.net/~tse/                                                      

REPORT- BEPU Building Utility Performance                                                   WEATHER FILE- Fairbanks    AK TMY2

---------------------------------------------------------------------------------------------------------------------------------

 

                         TASK     MISC    SPACE    SPACE     HEAT    PUMPS     VENT    REFRIG  HT PUMP   DOMEST    EXT

               LIGHTS   LIGHTS   EQUIP   HEATING  COOLING   REJECT   & AUX     FANS   DISPLAY  SUPPLEM  HOT WTR   USAGE    TOTAL

              -------  -------  -------  -------  -------  -------  -------  -------  -------  -------  -------  -------  --------

 

EM1  ELECTRICITY     

    KWH        27894.    1446.   82059.       0.    7734.       0.    2890.    5840.       0.       0.    1377.       0.   129240.

 

FM1  FUEL-OIL       

     GAL           0.       0.       0.     267.       0.       0.      49.       0.       0.       0.       0.       0.      316.

 

BFOM FUEL-OIL       

     GAL           0.       0.       0.     845.       0.       0.      81.       0.       0.       0.       0.       0.      926.

 

GFOM FUEL-OIL       

     GAL           0.       0.       0.    4574.       0.       0.     216.       0.       0.       0.       0.       0.     4790.

 

TFOM FUEL-OIL       

     GAL           0.       0.       0.     401.       0.       0.      48.       0.       0.       0.       0.       0.      450.

 

 

 

 

           TOTAL ELECTRICITY    129240. KWH         9.486 KWH     /SQFT-YR GROSS-AREA    9.486 KWH     /SQFT-YR NET-AREA

           TOTAL FUEL-OIL         6482.  GAL        0.476  GAL    /SQFT-YR GROSS-AREA    0.476  GAL    /SQFT-YR NET-AREA

 

 

           PERCENT OF HOURS ANY SYSTEM ZONE OUTSIDE OF THROTTLING RANGE =  3.3

           PERCENT OF HOURS ANY PLANT LOAD NOT SATISFIED                =  0.0

 

           NOTE:  ENERGY IS APPORTIONED HOURLY TO ALL END-USE CATEGORIES.

 

 

 

Oil gallons and electric KWH are combined for the above two tables into present value US$ by Table ES-D in the above referenced data files, as follows for the DEC case:

 

Table 1c. DEC/ES-D excerpt from 118-DEC.SIM.txt.

 

118 - LEED EAc1 Final Submittal         Fan Tuning HRVs DEC Sim                  DOE-2.2-44e4   9/24/2007     2:02:57  BDL RUN  1

Modeler: Don Cott; don.cott@ak.net;     http://home.gci.net/~tse/                                                      

REPORT- ES-D Energy Cost Summary                                                            WEATHER FILE- Fairbanks    AK TMY2

---------------------------------------------------------------------------------------------------------------------------------

 

                                                                           METERED             TOTAL      VIRTUAL

                                                                            ENERGY            CHARGE         RATE   RATE USED

UTILITY-RATE                       RESOURCE           METERS              UNITS/YR               ($)     ($/UNIT)   ALL YEAR?

--------------------------------   ----------------   -----------   -------------------   ----------   ----------   ---------

 

GVEA Gen Serv 2(1)                 ELECTRICITY        EM1              145404. KWH            20811.       0.1431      YES

 

Fuel Oil Rate                      FUEL-OIL           FM1   BFOM         2057.  GAL            5142.       2.5000      YES

                                                      GFOM  TFOM

 

                                                                                          ==========

                                                                                              25953.

 

 

                                                             ENERGY COST/GROSS BLDG AREA:      1.90

                                                               ENERGY COST/NET BLDG AREA:      1.90

 

And for the ECB case:

Table 1d. ECB/ES-D excerpt from 120-ECB.SIM.txt.

 

120 - LEED EAc1 Final Submittal         PSZ/Furnace/NFS/Eff Mods to ECB Sim      DOE-2.2-44e4  10/01/2007     6:20:06  BDL RUN  1

Modeler: Don Cott; don.cott@ak.net;     http://home.gci.net/~tse/                                                       

REPORT- ES-D Energy Cost Summary                                                            WEATHER FILE- Fairbanks    AK TMY2

---------------------------------------------------------------------------------------------------------------------------------

 

                                                                           METERED             TOTAL      VIRTUAL

                                                                            ENERGY            CHARGE         RATE   RATE USED

UTILITY-RATE                       RESOURCE           METERS              UNITS/YR               ($)     ($/UNIT)   ALL YEAR?

--------------------------------   ----------------   -----------   -------------------   ----------   ----------   ---------

 

GVEA Gen Serv 2(1)                 ELECTRICITY        EM1              129240. KWH            18835.       0.1457      YES

 

Fuel Oil Rate                      FUEL-OIL           FM1   BFOM         6482.  GAL           16205.       2.5000      YES

                                                      GFOM  TFOM

 

                                                                                          ==========

                                                                                              35041.

 

 

                                                             ENERGY COST/GROSS BLDG AREA:      2.57

 

For DEC vs. ECB comparison purposes, the data from the above Tables 1a – 1d are transferred into Table 1e for further comparison and adjustment:

 

 

Table 1e.  Adjusting eQUEST / DOE-2 Output to LEED NC 2.1 Requirements.

 

Annual Energy End Use

ECB

DEC

Comments

Ceiling Lights (kWh)

27,894

21,113

BEPU1 (difference is daylighting controls in DEC but not ECB)

Task Lighting (kWh)

1,446

1,446

BEPU1

Plug & Process Load (kWh)

82,059

82,059

LEED NC 2.1 Table 3 Plug Load from BEPU1, includes Information Technology (IT) Room Load of 6 kW continuous to be removed from both ECB & DEC below

Space Cooling (kWh)

7,734

20,252

BEPU1 (more cooling required for DEC because it’s better insulation holds the solar heat better than the ECB, both of which receive about the same solar heat despite the longer overhangs on the DEC

Pumps & Auxiliary Equipment (kWh)

2,890

6,811

BEPU1 (comparing hydronic pumping required in DEC to combustion furnace unit heaters in each zone for ECB, actual ECB would be a central furnace with lots of duct losses, not included here)

Ventilation & Unit Heater Fans (kWh)

5,840

12,349

BEPU1 (HRV fan losses for DEC, no HRV’s in ECB)

Domestic Hot Water (kWh)

1,377

1,374

BEPU1 (slight difference due to less Hot Water system heat loss to slightly warmer average air temperature in DEC)

Total Annual Electrical Load (kWh)

129,240

145,404

BEPU1 (this still contains the 6 kW continuous IT room load, which is non-regulated, LEED NC 2.1 pg 146)

IT Room Load (6 kW continuous non-regulated)

-52,596

-52,596

(6 kW)(24 hr/day)(365.25 day) = 52,596 kWh

 

ECB’

DEC’

 

Total Regulated Annual Building Electrical Load (kWh)

76,644

92,808

(prime means non-regulated load subtracted out, LEED NC 2.1 pg 145)

Regulated Annual Electricity Cost

$11,167

$13,281

Multiplying the Regulated Electrical Load above by the rates of $.1457/KWH for the ECB and $.1431/KWH for the DEC (main reason for rate difference is that the base service charge is spread over more KWH for the DEC)

PV Contribution for DEC but not ECB

-$0

-$19242

=$1924, 4.7 for 2-axis tracker [Fairbanks weather & insolation per WBAN #26411 (Solar Data)], 16% panel eff, 77% inverter eff, no on-site battery storage at present - net metering with GVEA.

Adjusted Regulated Annual Electricity Cost

$11,167

$11,357

 

Space Heating Fuel Oil (gal)

6,482

2,057

BEPU1, Tables 1a & 1b.

Solar heat for DEC but not ECB (gal oil equiv.)

-0

-235

Three south-facing solar/hydronic heating panels angled back at about 50º on Atrium roof including piping & pumping losses in 85% efficiency, 3.4 from Fairbanks weather table, WBAN #26411 (Solar Data), latitude-15º from horizontal, south azimuth. 3

 

ECB’

DEC’’

(double-prime means renewable energy contribution included)

Space Heating Fuel Oil corrected by Solar Heat (gal)

6,482

1,822

Solar-Adjusted heating oil equivalent

Space Heating Fuel Oil adjusted Cost

$16,205

$4,555

Solar-Adjusted Heating Oil Cost, (gals above x $2.50/gal)

Total Annual Energy Cost

$27,372

$15,912

Adjusted Regulated Electricity Cost + Solar-Adjusted Heating Oil Cost

% Savings

42%

Equation 1, LEED NC 2.1 pg 145

EAc1 LEED Points

6

LEED NC 2.1 pg 133

1 BEPU Table from DEC & ECB runs reproduced herein as Tables 1a & 1b.

2Unknown why this value is about $300 above that calculated by Greg Egan in EAc2.  The efficiencies came from him.  As a full-time solar specialist, he may know something this generalized modeler doesn’t regarding what GVEA charges vs. what it pays for net metering. See http://www.gvea.com/alternative-energy/snap/producer.php for an overload of feel-good PR and Obfuscatory Legalese, but no “SNAP No. 1 – Producer Schedule”, which supposedly contains the formula for calculating the payments or offsets to producers.  It is herein assumed that only the 77% conversion/storage/offset efficiency is applicable to PV power produced on-site.  The % of PV produced energy is presently low enough that plenty of other options exist for re-directing the PV power without trading it to GVEA, if justified by developing economics.

3One panel is actually domestic water, but that heat goes to the building space heat through leakage from the propylene glycol to potable water heat exchanger, hot water plumbing and the inside septic tank in the atrium basement.  The 85% assumed efficiency is speculative and subject to experimental verification.  It assumes the solar-thermal panels will be used for the low-temperature preheat only of the entire hydronic flow (~95F), with the higher-temperature heat supplied by the oil-fired boilers.

 

where the tabulated performance data for the ECB and DEC cases is taken from Tables 1a – 1d.  Note each of these files prints out from 1600 to 1900 pages long, so it isn’t trivial for a new user to find the desired data.  Search on the reference in the Comments column above (BEPU or ES-D) to find the referenced datum.  If you have downloaded eQUEST, then drop the .txt and the SIM Viewer bundled with eQUEST will display the lengthy tabular output in a formatted & organized manner.