Understanding the Impact of Urban Heat Island in Phoenix · Understanding the Impact of Urban Heat Island in Phoenix ... Data-processing Presentation ... (G-4): Combined heating

Arizona State University

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

Thesis Chair:

Prof. Harvey Bryan

MS Built Environment

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The U.S. buildings sector in 2008

• 8% 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 1980

• 39% CO2 of emissions of U..S. Average

URBAN HEAT ISLAND (UHI)

BUILDING SECTOR: 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

FIG.1 Energy Consumption

FIG.4 Thermal imaging of Urban Centers in

Phoenix showing impact of Urbanization

DAYTIME THERMAL IMAGE

NIG

HT

TIM

E

TH

ER

MA

L

Conclusion INTRODUCTION Methodology Results / Analysis

Impact of UHI

• Increasing Nighttime Min Low Temperature

• Increasing Cooling Energy Consumption

• Increasing air pollutants and GHG.

• Compromised human health and discomfort

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Arizona State University Conclusion INTRODUCTION Methodology Results / Analysis

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 non-

existent during the day

Most intense at night

or predawn and in the

winter

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)

Typical Identification

Method Indirect measurement:

Remote sensing

Direct measurement:

Fixed weather stations

Mobile traverses

Typical Depiction Thermal image Isotherm map

Temperature graph

URBAN HEAT ISLAND

The Urban Heat Island is defined as

the phenomenon due to which urban

centers characteristically have higher

air temperatures than their

surrounding rural areas.

• Surface Urban Heat Island

• Atmospheric Urban Heat Island

o Canopy Layer UHI

o Boundary Layer UHI

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.

• Pronounced after sunset.

• Dependent of the urban density &

character, geographical location

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OBJECTIVE:

Conclusion Introduction METHODOLOGY Results / Analysis

• Retro-Analysis of ‘building energy model’ - 1950 - 2005 (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

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• Recorded Annual Weather Files National Climatic Data Center (Surface Airways )

Phoenix Sky Harbor Airport

• Typical Meteorological Year (TMY) TMY 1 (1952-1975) (SOLMET/ERSATZ data base),

TMY2 (1961-1990) (NSRDB data base), and

TMY3 (1976-2005) (NSRDB data base)

• Climate Change Future (2020,2050,2080) Intergovernmental Panel on Climate Change -

Climate Change World Weather file Generator

ASHRAE 90.1 - PROTOTYPE MODELS (PNNL)


2020, 2050, 2080 TMY 1/2/3 1950-2005

Multiyear Annual Simulations

90.1 prototype building models

Preparation of Prototype Models + Iterations for Medium Office + Single Family Residential Model

Energy Plus

Annual recorded weather data Creation of Future Weather files

Sourcing TMY1, 2 & 3 files

EPW format – 1950-2005, 2020, 2050, 2080, ‘TMY 1/2/3’

Simulation results

Analysis

Weather data analyzed

Regressions and Analysis

Conclusions

PROCESS DIAGRAMMING:

• 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

WEATHER FILES

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SIMULATION SETUP:


Energy Plus

EP-Launch

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

DATA PROCESSING Seasons

• Summer - Start date : 15th May,

End date : 15th September

• Winter - Start date : 1st January,

End date : 28th February &

Start date : 1st November,

End date : 31st December

• Spring/Fall - Start date : 1st March,

End date : 14th May &

Start date : 16th September,

End date : 31st 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 - 15.5˚C & 18.3 ˚C

Energy Conversion Factor (Site to Source)

• Electricity: 3.2 source Btu per site Btu

• Natural Gas: 1.090 source Btu per site Btu

National Average Energy Prices

• Electricity: $0.0939/kWh

• Natural Gas: $1.22/therm

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Arizona State University Conclusion Introduction Methodology ANALYSIS/RESULTS

WEATHER ANALYSIS:

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BUILDING TYPOLOGY:

Conclusion Introduction Methodology ANALYSIS/RESULTS

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.

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BUILDING TYPOLOGY:


SMALL OFFICE

3-D view of Small Office –

Prototype ASHRAE 90.1

Plan of the thermal zones.

Form

• Total Floor Area (Sq Ft)

5500 (90.8 ft x 60.5 ft)

• Aspect Ratio - 1.5

• Number of Floors - 1

• Window Fraction - 24.4% 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


HVAC Control

• Thermostat Set-point

75˚F (23.8 ˚C) Cooling

70˚F (21.1 ˚C) Heating

• Thermostat Setback



• 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 - 0.085cfm/ft2

(ASHRAE Ventilation Standard 62.1)

Demand Control Ventilation

ASHRAE 90.1 Requirements

Energy Recovery


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BUILDING TYPOLOGY:

SMALL OFFICE

SMALL OFFICE

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BUILDING TYPOLOGY: SMALL OFFICE

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BUILDING TYPOLOGY:


LARGE OFFICE

3-D view of Large Office –



Form

• Total Floor Area (Sq Ft) -

498,600 (240 ft x 160 ft)


• Number of Floors - 12(Plus-Basement)

• Window Fraction - 40% of above-

(Window-to-Wall Ratio) grade gross walls.




Thermal Zoning

• Perimeter zone depth-15 ft.


one core & an attic.



HVAC -System type

• Heating type - Gas boiler

• Cooling type - Two water-cooled

centrifugal chillers


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



• Heating


HVAC Control





85˚F (29.44 ˚C) Cooling



Max110˚F (44.33 ˚C)

Min 52˚F (11.1 ˚C)

• Chilled water supply Temp –

44˚F (6.66 ˚C)

• Hot water supply Temp -

180 ˚F (82.22 ˚C)

Economizers

Air-side Econimizers.






Energy Recovery


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BUILDING TYPOLOGY:

SMALL OFFICE

LARGE OFFICE

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BUILDING TYPOLOGY: LARGE OFFICE

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BUILDING TYPOLOGY: MEDIUM OFFICE

3-D view of Medium Office –



Form

• Total Floor Area (Sq Ft)

53600 (163.8 ft x 109.2 ft)


• 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)




Thermal Zoning

• Perimeter zone depth-15 ft.


one core.



HVAC -System type

• Heating type - Gas furnace inside

the package air conditioning unit.

• Cooling type - Packaged air

conditioning 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



• Heating


HVAC Control


75˚F (23.8˚C) Cooling

70˚F (21.1˚C) Heating


80˚F (26.6˚C) Cooling



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.






Energy Recovery


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• Iterations–


o 100% OA,

o 24hr-7Day Work schedule & 100% OA

• Iterations–


o 100% OA,




• Medium Office - Prototype ASHRAE 90.1

Normal Working hours – 5 Day Week

Outside Air - 0.085cfm/ft2


• Iterations 24 hrs 7 Day Week–

24hr-7Day Work schedule,



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• Iterations–


o 100% OA,


• Iterations–


o 100% OA,








• Iterations 100% Outside Air–

5 Day Work schedule,

Outside Air – 100% Outside Air

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• Iterations–


o 100% OA,


• Iterations–


o 100% OA,








• Iterations 24hr-7Day Work schedule & 100% OA

24Hr -7 Day Work schedule,

Outside Air – 100% Outside Air

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• Medium Office – 100% Outside Air (5day Week Schd)

• Medium Office - 24hr-7 Day Work schedule

• Medium Office - 24hr-7 Day Work schedule, 100% OA

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Arizona State University CONCLUSION Introduction Methodology Analysis/Results

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

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Arizona State University CONCLUSION Introduction Methodology Analysis/Results

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

Documents

Understanding the Impact of Urban Heat Island in Phoenix · Understanding the Impact of Urban Heat Island in Phoenix ... Data-processing Presentation ... (G-4): Combined heating