Arizona State University. Understanding the Impact of Urban Heat Island in Phoenix

Transcription

1 Understanding the Impact of Urban Heat Island in Phoenix ( ) Summer Night-time 'min-low' temperatures and its impact on the energy consumption of various building typologies Presented By: Sandeep Doddaballapur MS Built Environment Thesis Chair: Prof. Harvey Bryan

2 NIGHTTIME THERMAL BUILDING SECTOR: ENERGY CONSUMPTION The U.S. buildings sector in % of global primary energy consumption. 40% of primary energy consumption. 73% of U.S. Electricity Consumption o Residential (37%), Commercial (36%) 50% higher energy consumption than % CO 2 of emissions of U..S. Average URBAN HEAT ISLAND (UHI) FIG.1 Energy Consumption FIG.2 UHI effect-a daytime oasis effect and a night-time hysteresis lag effect. 1 FIG.3 Temperature Plots-Sky Harbor Airport & Casa Grande Natl. Monument Impact of UHI DAYTIME THERMAL IMAGE Increasing Nighttime Min Low Temperature Increasing Cooling Energy Consumption Increasing air pollutants and GHG. Compromised human health and discomfort FIG.4 Thermal imaging of Urban Centers in Phoenix showing impact of Urbanization INTRODUCTION Methodology Results / Analysis 2

3 URBAN HEAT ISLAND The Urban Heat Island is defined as the phenomenon due to which urban centers characteristically have higher air temperatures than their Feature Surface UHI Atmospheric UHI Temporal Development Present at all times of the day and night Most intense during the day and in the summer May be small or nonexistent during the day Most intense at night or predawn and in the winter surrounding rural areas. Surface Urban Heat Island Atmospheric Urban Heat Island o Canopy Layer UHI o Boundary Layer UHI Peak Intensity (Most intense UHI conditions) More spatial and temporal variation: Day: 10 to 15 C (18 to 27 F) Night: 5 to 10 C (9 to 18 F) Less variation: Day: -1 to 3 C (-1.8 to 5.4 F) Night: 7 to 12 C (12.6 to 21.6 F) This study deals with the Atmospheric Canopy Layer UHI, the zone from the ground up to the top of trees and roofs. energy consumption of buildings. Typical Identification Method Indirect measurement: Remote sensing Direct measurement: Fixed weather stations Mobile traverses Pronounced after sunset. Dependent of the urban density & character, geographical location Typical Depiction Thermal image Isotherm map Temperature graph INTRODUCTION Methodology Results / Analysis 3

4 OBJECTIVE: Retro-Analysis of building energy model (Annual Simulations) Energy impact - daytime oasis effect, night-time hysteresis lag effect in a Hot-Arid Climate Analyzing impact of increasing Night-time Minimum low temperature on various typologies Base-study - bottom-up engineering estimate, of the impact of UHI on the City, Region and U.S. Building stock Influence energy efficiency programs for UHI mitigation targeting specific building typologies To document the methodologies and processes, to enable similar studies in other cities in hot-arid regions or other climatic regions. Use of IPCC Climate change future weather files to comprehend building s performance in the future. Analyzing the impact of use of Typical Meteorological Year (TMY) s for energy simulations in lieu of UHI Introduction METHODOLOGY Results / Analysis 4

5 WEATHER FILES Recorded Annual Weather Files National Climatic Data Center (Surface Airways ) Phoenix Sky Harbor Airport Typical Meteorological Year (TMY) TMY 1 ( ) (SOLMET/ERSATZ data base), TMY2 ( ) (NSRDB data base), and TMY3 ( ) (NSRDB data base) Climate Change Future (2020,2050,2080) Intergovernmental Panel on Climate Change - Climate Change World Weather file Generator Annual recorded weather data Creation of Future Weather files Sourcing TMY1, 2 & 3 files EPW format , 2020, 2050, 2080, TMY 1/2/3 Weather data analyzed PROCESS DIAGRAMMING: Energy Plus 90.1 prototype building models Preparation of Prototype Models + Iterations for Medium Office + Single Family Residential Model ASHRAE PROTOTYPE MODELS (PNNL) Small Office Medium Office Iterations o 24hr-7Day Work schedule, o 100% OA, o 24hr-7Day Work sched & 100% OA Large Office Mid-Rise Apartment Single-family (Detached) Residential Hospital Retail Standalone Warehouse Multiyear Annual Simulations 2020, 2050, 2080 TMY 1/2/3 Simulation results Analysis Regressions and Analysis s Introduction METHODOLOGY Results / Analysis 5

6 DATA PROCESSING Seasons Summer - Start date : 15 th May, End date : 15 th September Winter - Start date : 1 st January, SIMULATION SETUP: Energy Plus EP-Launch End date : 28 th February & Start date : 1st November, End date : 31 st December Spring/Fall - Start date : 1 st March, End date : 14 th May & Start date : 16 th September, End date : 31 st October Diurnal Profile Day-time Hours - 6 AM to 8 PM Night-Time Hours - 8 PM to 6 AM Cooling & Heating Degree Hours Base Temperature C & 18.3 C Energy Conversion Factor (Site to Source) Electricity: 3.2 source Btu per site Btu Natural Gas: source Btu per site Btu National Average Energy Prices Electricity: $0.0939/kWh Natural Gas: $1.22/therm Group of Input Files (TAB) 12 IDF(Building Energy model) 62 Weather files Batch-run Results (Folders) 12 Building Typologies 62 Annual Simulations each Results (Files) FileNameTable.html (Consolidated report) FileNameMeter.csv (Hourly reports personalized) Results Data-processing Presentation - Graphs & Tables Introduction METHODOLOGY Results / Analysis 6

7 WEATHER ANALYSIS: 7

8 GRAPHS - DETAILS Graph 1 (G-1): Energy Consumption for Cooling and Heating. Each data point on the graph represents the Annual energy consumption value (site) for heating or cooling in the respectively series on the primary Y axis with the secondary Y axis plotting the Heating and Cooling Degree hours with the year of simulation on the X axis. Graph 2 (G-2): Summer and Night-time Cooling This plot segregates and plots the cooling energy consumption (site) (electrical) (kwh) data on the Y axis with the year of simulation on the X axis primarily for the summer season with diurnal split and total energy consumption values in their representative series. Graph 4 (G-4): Combined heating and cooling energy use The energy consumption values for heating and cooling (Gas - Heating, Electric Heating and Cooling) obtained from the hourly metered output are combined and are represented in series for the respective seasons (seasons as defined in the methodology) along with that for the annual consumption. This shows clarity in seasonal changes to the energy consumption values, which might be due to the increasing cooling energy requirement or decreasing heating energy requirement. Graph 3 (G-3): Summer Daily Cooling Energy (24Hrs Weekdays only) This box-and-whisker plot is used to conveniently present the six descriptive statistical analysis data with each data point on the graph represents the total cooling energy of any one day in the season of that particular year. Graph 5 (G-5): Cooling Energy Consumption Vs. Cooling Degree Hours A definite correlation has been established between the cooling degree hours and the energy consumption. This plot tries to explore the relation to try to fit a linear trend line that would help predict the impact of increasing cooling degree hours on the energy consumption annually and also in lesser time frames of interest such as summer season and summer day and night time. 8

9 SMALL OFFICE Form Total Floor Area (Sq Ft) 5500 (90.8 ft x 60.5 ft) Aspect Ratio Number of Floors - 1 Window Fraction % S & (Window-to-Wall Ratio) 19.8% N, E & W (6.0 ft x 5.0 ft Punch) Windows Locations Evenly distributed along four facades Shading Geometry- none Thermal Zoning Perimeter zone depth-16.4 ft. No. of Zones - Four perimeter, one core & an attic. Percentages of floor area Perimeter 70%, Core 30% HVAC -System type Heating type - Air source Heat Pump (Gas furnace back-up) Cooling type - Air-Source heat Pump Distribution and terminal unit Single zone, constant air volume, air distribution, one unit per occupied thermal zone HVAC Efficiency Air conditioning ASHRAE 90.1 Requirements; Heating ASHRAE 90.1 Requirements; HVAC Control Thermostat Set-point 75 F (23.8 C) Cooling 70 F (21.1 C) Heating Thermostat Setback 80 F (21.1 C) Cooling 60 F (15.5 C) Heating Supply air temperature Max104 F (40 C) Min 55 F (12.7 C) Chilled water supply Temp - NA Hot water supply Temp - NA Economizers Varies by climate location and cooling capacity. Control type: differential dry bulb Ventilation cfm/ft 2 (ASHRAE Ventilation Standard 62.1) Demand Control Ventilation ASHRAE 90.1 Requirements Energy Recovery ASHRAE 90.1 Requirements 3-D view of Small Office Prototype ASHRAE 90.1 Plan of the thermal zones. 9

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12 LARGE OFFICE Form Total Floor Area (Sq Ft) - 498,600 (240 ft x 160 ft) Aspect Ratio Window Fraction - 40% of above- (Window-to-Wall Ratio) grade gross walls. Windows Locations Evenly distributed along four facades Shading Geometry- none Thermal Zoning Perimeter zone depth-15 ft. No. of Zones - Four perimeter, one core & an attic. Percentages of floor area Perimeter 33%, Core 67% HVAC -System type Heating type - Gas boiler Cooling type - Two water-cooled centrifugal chillers Distribution and terminal unit VAV terminal box with damper and hot-water reheating coil. Zone control type: minimum supply air at 30% of the zone design peak supply air. HVAC Efficiency Air conditioning ASHRAE 90.1 Requirements; Heating ASHRAE 90.1 Requirements; HVAC Control Thermostat Set-point Number of Floors - 12(Plus-Basement) 75 F (23.8 C) Cooling 70 F (21.1 C) Heating Thermostat Setback 85 F (29.44 C) Cooling 60 F (15.5 C) Heating Supply air temperature Max110 F (44.33 C) Min 52 F (11.1 C) Chilled water supply Temp 44 F (6.66 C) Hot water supply Temp - Economizers Air-side Econimizers. 180 F (82.22 C) Control type: differential dry bulb Ventilation cfm/ft 2 (ASHRAE Ventilation Standard 62.1) Demand Control Ventilation ASHRAE 90.1 Requirements Energy Recovery ASHRAE 90.1 Requirements 3-D view of Large Office Prototype ASHRAE 90.1 Plan of the thermal zones. 12

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15 MEDIUM OFFICE Form Total Floor Area (Sq Ft) (163.8 ft x ft) Aspect Ratio Number of Floors - 3 Window Fraction - 33% (163.8 ft x 4.29 ft on long side) (109.2 x 4.29 ft on the short side) Windows Locations Evenly distributed along four facades Shading Geometry- none Thermal Zoning Perimeter zone depth-15 ft. No. of Zones - Four perimeter, one core. Percentages of floor area Perimeter 70%, Core 30% HVAC -System type Heating type - Gas furnace inside the package air conditioning unit. Cooling type - Packaged air conditioning unit Distribution and terminal unit VAV terminal box with damper and electric reheating coil. Zone control type: minimum supply air at 30% of the zone design peak supply air. HVAC Efficiency Air conditioning ASHRAE 90.1 Requirements; Heating ASHRAE 90.1 Requirements; HVAC Control Thermostat Set-point 75 F (23.8 C) Cooling 70 F (21.1 C) Heating Thermostat Setback 80 F (26.6 C) Cooling 60 F (15.5 C) Heating Supply air temperature Max104 F (40 C) Min 55 F (12.7 C) Chilled water supply Temp - NA Hot water supply Temp - NA Economizers Varies by climate location and cooling capacity. Control type: differential dry bulb Ventilation cfm/ft 2 (ASHRAE Ventilation Standard 62.1) Demand Control Ventilation ASHRAE 90.1 Requirements Energy Recovery ASHRAE 90.1 Requirements 3-D view of Medium Office Prototype ASHRAE 90.1 Plan of the thermal zones. 15

16 MEDIUM OFFICE Medium Office - Prototype ASHRAE 90.1 Normal Working hours 5 Day Week Outside Air cfm/ft 2 (ASHRAE Ventilation Standard 62.1) Iterations 24 hrs 7 Day Week o 24hr-7Day Work schedule, o 100% Outside OA, Air cfm/ft 2 (ASHRAE Ventilation Standard 62.1) o 24hr-7Day Work schedule & 100% OA 16

17 MEDIUM OFFICE Medium Office - Prototype ASHRAE 90.1 Iterations 100% Outside Air Normal Working hours 5 Day Week Outside Air cfm/ft 2 (ASHRAE Ventilation Standard 62.1) o o o 24hr-7Day 5 Work Work schedule, schedule, 100% Outside OA, Air 100% Outside Air 24hr-7Day Work schedule & 100% OA 17

18 MEDIUM OFFICE Medium Office - Prototype ASHRAE 90.1 Iterations 24hr-7Day Work schedule & 100% OA Normal Working hours 5 Day Week Outside Air cfm/ft 2 (ASHRAE Ventilation Standard 62.1) o o o 24hr-7Day 24Hr Work schedule, 100% Outside OA, Air 100% Outside Air 24hr-7Day Work schedule & 100% OA 18

19 MEDIUM OFFICE Medium Office - Prototype ASHRAE 90.1 Medium Office - 24hr-7 Day Work schedule Medium Office 100% Outside Air (5day Week Schd) Medium Office - 24hr-7 Day Work schedule, 100% OA 19

23 CONCLUSION: Rising Summer Nighttime Minimum temperature, indication of hysteresis lag effect typical of Hot-Dry Desert climates. Cooling Degree hours increasing yearly while the Heating Degree hours drops Almost commercial building typologies show increased Cooling and Combined (cooling and heating) Energy Consumption. (exceptions Hospital, Warehouse & Large office building) Typical Meteorological Year files, fail to capture effects of UHI Climate change weather files (IPCC), does not include influences of UHI, hence all predictions are for climate change, with UHI impacts on energy consumption much higher Buildings with 24Hr work schedule, pay huge penalties due to UHI, more than typologies that require just 100% Outside Air Increased loads on utilities for electrical energy in peak and off-peak, hours/seasons Gas consumption reduces as heating loads decrease Environmental costs Vs. Dollar cost Site to Source and Carbon-emissions calculations due to increase in UHI a point to ponder Use of localized and current weather trends imperative to understand the energy performance of buildings Introduction Methodology Analysis/Results CONCLUSION 23

24 FUTURE RESEARCH: Similar research simulation runs, carried out for weather data from urban centers and rural fringe areas of a City for recent time periods of recorded data. Synthesized of short term weather data files to analyze UHI, Similar methodology could be used to analyze impact of UHI in similar or varying climatic zones Base-study - bottom-up engineering estimate, of the impact of UHI on the City, Region and U.S. Building stock Use of localized and current weather trends imperative to understand the energy performance of buildings Introduction Methodology Analysis/Results CONCLUSION 24