COMPARISON OF ASHRAE STANDARD-90.1, AND IECC CODES FOR LARGE OFFICE BUILDINGS IN TEXAS

Transcription

1 COMPARISON OF STANDARD-, AND IECC CODES FOR LARGE OFFICE BUILDINGS IN TEXAS Jaya Mukhopadhyay Juan-Carlos Baltazar, Ph.D. Hyojin Kim, Jeff S. Haberl, Ph.D., P.E., Cyndi Lewis, Bahman Yazdani, P.E. Energy Systems Laboratory Texas A&M University 20 th October 2011 New York Energy Systems Laboratory Texas A&M University System October 2011

2 STRUCTURE BACKGROUND METHODOLOGY CLIMATE ZONE DECRIPTION BASE CASE DESCRIPTION RESULTS SUMMARY 2/30

3 BACKGROUND Codes compared: IECC The purpose is to assess the stringency of each code - selected as the base-case 3/30

4 METHODOLOGY Performance option outlined in the codes used to design the base case DOE-2.1e used for simulations Analysis conducted for Site energy usage Source energy usage 4/30

5 CLIMATE ZONES Three counties selected for analysis Each county represents a climate zone Harris (Climate Zone 2A) Tarrant (Climate Zone 3A) Potter (Climate Zone 4B) POTTER TARRANT HARRIS The counties cover the major population hubs in the state 5/30

6 BASE-CASE The input was categorized into the following categories: Program Form Fabric Equipment FRACTION OF OCCUPANCY FRACTION OF OCCUPANCY HOUR OF DAY HOUR OF DAY 6/30

7 BASE-CASE: Program Operating Schedules Schedules include: Occupancy Infiltration Service hot water demand Lighting Equipment HVAC system & fan - used as reference Assumed same for all codes, except equipment schedules modified to reflect 50% of receptacle outlets switched off when not in use FRACTION OF OCCUPANCY FRACTION OF POWER FRAC. OF WATER USAGE HOUR OF DAY LIGHTING & EQUIPMENT HOUR OF DAY OCCUPANCY SHW USAGE HOUR OF DAY 7/30

8 BASE-CASE: Program Space Temperatures 70 F for space heating 75 F for space cooling Thermostat setback of 5 F Ventilation Requirements Peak occupancy: 275 sq.ft. / person 62.1 used to calculate the ventilation requirements Energy Code Ver. of 62.1 cfm/per. cfm/sqft Resultant OA cfm IECC /30

9 BASE-CASE: Form Six story office building: Footprint area: 14,884 sq.ft. Total floor area: 89,304 sq.ft. Floor to floor height: 13 ft. Floor to ceiling height: 9 ft. Window to wall area ratio: 40% No shading except - (PF for South: 0.50) Aspect ratio: For -: 2.5:1 For other models: 1.5:1 Four perimeter zones & core zone for each floor: 15 ft. deep 9/30

10 BASE-CASE: Fabric Infiltration - requires cfm/sq.ft. No specifications for whole building infiltration in -, 2004, 2007 or IECC Air-barriers mandatory in the & - Air Change method used When HVAC system ON, infiltration reduced by 75% Energy Code & IECC Operating Hours ACH Non-Operating Hours ACH Core Zones Perimeter Zones & - Core Zones Perimeter Zones /30

11 BASE-CASE: Fabric Building Envelope Characteristics Steel frame walls Roof insulation entirely above metal deck Slab-on-grade for the floor Increase in Stringency Climate Zone 2007 IECC 2010 Steel Frame Walls 2A R-6.5 R-13 R-13 R-13 R-13 R-13+R-5 c.i 3A R-6.5 R-13 R-13+R3.8 c.i R-13+R3.8 c.i R-13+R3.8 c.i R-13+R-5 c.i 4B R-16.5 R-13 R-13+R7.5c.i R-13+R7.5c.i R-13+R7.5c.i R-13+R10 c.i Insulation Entirely Above Roof 2A R-13.5 c.i R-15 c.i R-20 c.i R-20 c.i R-20 c.i R-25 c.i 3A R c.i R-15 c.i R-20 c.i R-20 c.i R-20 c.i R-25 c.i 4B R-15.5 c.i R-15 c.i R-20 c.i R-20 c.i R-20 c.i R-25 c.i Metal Frame Window U-Value 2A U-1.15 U-1.22 U-0.75 U-0.75 U-0.75 U A U-1.15 U-1.22 U-0.65 U-0.65 U-0.65 U B U-0.81 U-0.46 U-0.55 U-0.55 U-0.55 U-0.45 Window SHGC 2A A B Slab On Grade 2A N.R N.R N.R N.R N.R N.R 3A N.R N.R N.R N.R N.R N.R 4B N.R N.R N.R N.R N.R R-10 at 4ft. 11/30

12 BASE-CASE: Fabric Roof & Wall Absorptance Energy Code Roof / Wall Absorptance / 0.7 IECC 0.75 / CZ 2&3: 0.45 / 0.7 CZ 4 : 0.7 / / 0.7 Roof & Wall Emittance Energy Code Roof / Wall Emittance / IECC 0.75 / / /30

13 BASE-CASE: Equipment Lighting Systems Daylight diming controls assumed for and codes Energy Code Plug Loads Lighting Power Density (W/sq.ft.) IECC W/ sq.ft. assumed across all the codes 13/30

14 BASE-CASE: Equipment HVAC Systems - Office building > 75,000sqft or > 3 floors SYSTEM 5 Specifications for SYSTEM 5 Built-up VAV w/ reheat Supply fan static pressure 4 in. w.c. Total fan efficiency 55% Fan control Variable speed drive Cooling Chiller Heating Hot water boiler 14/30

15 BASE-CASE: Equipment HVAC Systems -, 2004, 2007, 2010 & IECC Water Fossil Fuel System 2 Specifications for SYSTEM 2 Built-up VAV w/ reheat Fan control Variable speed drive Cooling Chiller Heating Hot water boiler 15/30

16 BASE-CASE: Equipment HVAC Systems - Office building > 75,000sqft or > 3 floors SYSTEM 7 System 7 Specifications for SYSTEM 7 VAV with perimeter reheat Supply fan control VAV Cooling system Chilled water Heating system Hot water fossil fuel boiler 16/30

17 Select base-case system Start RUN 1 From SVA report pick up: Cooling capacity Fan electricity usage To decide economizer and type of fan Climate zone2a,3a,4b Pick SS-P output report Pick PV-A output report From PV-A report Pick up size of equipment to decide number of chillers and boilers: - HW-BOILER -HERM-CENT-CHILLER Pick SV-A output report To select type of fan Table A Budget System Descriptions, Note 4 To select economizer Table Minimum System Size for which an Economizer is Required Power > 25 HP? No Fan control: Inlet vane Calculation of chiller size Btu/hr/12000 = tons Calculation of boiler size Btu/hr Yes Fan control type: Variable speed drive Table B Number of chillers Table A, Budget System Descriptions, Note 6 Chiller size >300 tons? No # of chillers = 1 Boiler size >600 kbtu/hr? No # of boilers = 1 Yes Yes Chiller size >600 tons? No # of chillers = 2 # of boilers = 2 Yes # of chillers 2 800tons From SS-P report Pick up size of SHW-heater to decide efficiency of SHW Select SHW efficiency according to size. Table Performance Requirements for Water Heating Equipment Select chiller type according to size of each chiller. Table C Water chillers types Select chiller efficiency according to size of each chiller. Table 6.2.1C Water Chilling Packages - Minimum Efficiency Requirements Select boiler efficiency according to size. Table 6.2.1F Gas and Oil-Fired Boilers, Minimum Efficiency Requirements RUN 2 STOP

18 BASE-CASE: Equipment Chillers & Boilers Increase in Stringency Climate Zone Chiller Type and Specifications 2007 IECC A 3A Recip. COP 3.8 Recip. COP 3.8 Screw COP 4.45 Screw COP 4.45 Screw COP 4.45 Screw COP 4.45 Screw COP 4.54 Recip. COP 4.54 Screw COP: 4.54 Recip. COP: 4.54 Screw COP: 4.54 Screw COP: B Recip. COP 3.8 Screw COP 4.45 Screw COP 4.45 Recip. COP 4.54 Recip. COP: 4.54 Screw COP: 4.54 Gas Boiler Type and Specifications (Et % ) 2A 3A 4B 80 % Number: 2 80 % Number: 2 80 % Number: 2 75 % Number: 2 80 % Number: 2 89 % 18/30

19 BASE-CASE: Equipment Economizers Requirements for implementing economizers more stringent with newer versions of the codes Trade-offs are provided in some codes by increasing cooling efficiency Climate Zone A 3A 4B (Note 1) Min. Size of System Diff. Drybulb 65 kbtu/hr Fixed Drybulb 65 kbtu/hr Table Fixed Drybulb 65 kbtu/hr Table Diff. Drybulb 65 kbtu/hr Table IECC Diff. Enthalpy Trade-off: 15% Diff. Drybulb 54 kbtu/hr Table (2) 2010 Diff. Enthalpy Trade-off: 17% Diff. Enthalpy Trade-off: 27% Diff. Drybulb 54 kbtu/hr Table 6.5.1A Diff. Enthalpy Trade-off: 15% Diff. Drybulb 33 kbtu/hr Table A 19/30

20 BASE-CASE: Equipment Service Hot Water Gas fired storage water heater with a hot water recirculation loop The gallons/hour per person required was set at 0.4 gallons/hour Assumed 100,000 Btu/hr input rating for 106 gallon tank All Other Codes Standard Specifications Min. Specifications Fuel Type: Gas Storage Capacity: 100 gals Input Rating: 75,000 Btu/hr Et: 77% SL: /V Et: 80% SL: Q/ x(V)^0.5 20/30

21 BASE-CASE: Equipment Supply Air Fans & Fan Control Requirements more stringent with newer versions of the codes Fan Control IECC 2010 VSD 25 hp VSD < 25 hp Inlet vane 5 hp VSD Fan Specifications Supply Total SP: 4 in wc Eff.: 55% For VAV fans 20,000cfm 1.5 hp/1000 cfm For VAV fans 1.5 hp/1000 cfm For VAV fans 1.35 hp/1000 cfm 21/30

22 BASE-CASE: Equipment Renewable Energy Systems Standard - requires not less than 6 kbtu/sq.ft. of on-site renewable energy For the base case building of 89,304 sq.ft. area: Annual on-site renewable energy MMBtu Several options available to generate this amount of energy on-site: Solar thermal systems Photovoltaic systems 22/30

23 RESULTS Site Energy Consumption BUILDING ENERGY PERFORMANCE SUMMARY (MMBtu) IECC DIFFERENCE w/ (%) IECC Climate Zone 2A ELEC GAS TOTAL Climate Zone 3A ELEC GAS TOTAL Climate Zone 4B ELEC Energy Consumption (MMBtu GAS % % % % % % TOTAL IECC ELECTRICITY GAS TOTAL 2010 % Above Climate Zone 2A 23/30 23/30

24 RESULTS Site Energy Consumption BUILDING ENERGY PERFORMANCE SUMMARY (MMBtu) IECC DIFFERENCE w/ (%) IECC Climate Zone 2A ELEC GAS TOTAL Climate Zone 3A ELEC GAS TOTAL Climate Zone 4B ELEC GAS TOTAL Energy Consumption (MMBtu % 32.6% 33.9% 35.3% 47.7% 54.9% IECC 2010 ELECTRICITY GAS TOTAL % Above Climate Zone 3A Energy Systems 24/30

25 RESULTS Site Energy Consumption BUILDING ENERGY PERFORMANCE SUMMARY (MMBtu) IECC DIFFERENCE w/ (%) IECC Climate Zone 2A ELEC GAS TOTAL Climate Zone 3A ELEC GAS TOTAL Climate Zone 4B ELEC % % % % % % GAS TOTAL Energy Consumption (MMBtu IECC 2010 % Above Climate Zone 4B Energy Systems ELECTRICITY GAS TOTAL 25/30

26 RESULTS Source Energy Consumption BUILDING ENERGY PERFORMANCE SUMMARY (MMBtu) IECC DIFFERENCE w/ (%) IECC Climate Zone 2A ELEC GAS TOTAL Climate Zone 3A ELEC GAS TOTAL Climate Zone 4B ELEC GAS TOTAL Conversion from Site to Source Energy: Electricity : 3.13 x Site Electricity Consumption Source Natural Gas: 1.1 x Site Natural Gas Consumption 26/30

27 RESULTS Source Energy Consumption BUILDING ENERGY PERFORMANCE SUMMARY (MMBtu) IECC DIFFERENCE w/ (%) IECC Climate Zone 2A ELEC GAS TOTAL Climate Zone 3A ELEC GAS TOTAL Climate Zone 4B ELEC 18, % % % % % % GAS ,000 TOTAL Energy Consumption (MMBtu 14,000 12,000 10,000 8,000 6,000 4,000 2, ELECTRICITY 2007 IECC 2010 GAS % Above Climate Zone 2A 27/30

28 BUILDING ENERGY PERFORMANCE SUMMARY (MMBtu) IECC DIFFERENCE w/ (%) IECC Climate Zone 2A ELEC GAS TOTAL Climate Zone 3A ELEC GAS TOTAL Climate Zone 4B ELEC % % % % % % GAS 18, TOTAL 16, Energy Consumption (MMBtu RESULTS Source Energy Consumption 14,000 12,000 10,000 8,000 6,000 4,000 2, ELECTRICITY 2007 IECC 2010 GAS % Above Climate Zone 3A Energy Systems 28/30

29 BUILDING ENERGY PERFORMANCE SUMMARY (MMBtu) IECC DIFFERENCE w/ (%) IECC Climate Zone 2A ELEC GAS TOTAL Climate Zone 3A ELEC GAS TOTAL Climate Zone 4B ELEC 18, % % % % % % GAS ,000 TOTAL ,000 Energy Consumption (MMBtu RESULTS Source Energy Consumption 12,000 10,000 8,000 6,000 4,000 2, ELECTRICITY 2007 IECC 2010 GAS % Above Climate Zone 4B Energy Systems 29/30

30 SUMMARY Site vs. Source Energy Consumption Improvement over : SITE ENERGY SOURCE ENERGY %-18.6% 14.5%-15.0% %- 32.6% 21.6%-27.2% %-33.9% 23.5%-28.4% IECC 27.4%-35.3% 23.4%-25.8% %-47.7% 41.8%-45.7% %-54.9% 44.5%-51.8% 30/30

31 Thank You! Energy Systems Laboratory Texas A&M University System October 2011