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Energy Efficient Design Strategies for Residences in Hot-Dry and Hot Humid Climates A Study of External Wall, Roof, Glazing and Shading Devices

August 4th , 2011 Master of Science in Sustainable Design Sharanya Srinivasan School of Architecture Carnegie Mellon University


Abstract

This study analyzes the design of energy efficient building envelopes for residences in hot-dry and hot-humid climates. This study focuses on the effects of exterior wall insulation, shading, solar absorptances of exterior building components and various glazing types for air-conditioned buildings in an effort to reduce cooling loads.


F l o r i d a Te s t R e s i d e n c e – Wa l l I n s u l a t i o n S t u d y


Florida Solar Energy Center – Wa l l I n s u l a t i o n S t u d y


Building Enclosure –

Reduction in Cooling Energy

% Reduction in Cooling Energy / Wall R-Value (After) Single and Multi-Family Residences in Hot and Humid Climates 60

% Reduction in Cooling Energy

50

40

R² = 0.3729 30

20

10

0 0

5

10

15

20

25

Wall R-value (After) (h-ft2-°F/Btu) Single Family Residence

Multi-Family Residence

30


Building Enclosure –

Reduction in Cooling Energy

% Reduction in Cooling Energy / Wall R-Value (After) Single Family Residences in Hot and Humid Climates

% Reduction in Cooling Energy / Wall R-Value (After) Single Family Residences in Hot and Dry Climates 45

60

40 50

% Reduction in Cooling Energy

% Reduction in Cooling Energy

35

R² = 0.7252 40

30

20

R² = 0.6203 30

25 20 15 10

10 5 0

0 0

5

10

15

20

25

Wall R-value (After) (h-ft2-°F/Btu)

30

0

5

10

15

20

25

Wall R-value (After) (h-ft2-°F/Btu)

30


Building Enclosure –

Cooling Energy Comparison

Cooling Energy Use Comparison (Before and After) 100.00

Annual Cooling Energy Use (kWh/m2/yr)

90.00

80.00

70.00

60.00

50.00

40.00

30.00

20.00

10.00

0.00 HH-MF3

HH-MF5

HH-SF1

HH-SF2

HH-SF3

HH-SF11 HH-SF12 HH-SF13 HH-SF14 HH-SF15 HH-SF16 HH-SF17

Cooling Energy Before

Cooling Energy After


Building Enclosure –

Peak Load Reduction % Reduction in Peak Cooling Loads / Wall R-Values (After) Single and Multi-Family Residences in Hot and Dry Climates

50

50

45

45

40

40

R² = 0.5274

% Reduction in Peak Cooling Loads

% Reduction in Peak Cooling Loads

% Reduction in Peak Cooling Loads / Wall R-Values (After) Single and Multi-Family Residences in Hot and Humid Climates

35 30 25 20 15 10

R² = 0.7613

35 30 25 20 15 10 5

5

0

0 0

5

10

15

20

Wall R-value (After) (h-ft2-°F/Btu)

25

30

0

5

10

15

Wall R-value (After)

20 (h-ft2-°F/Btu)

25

30


Building Enclosure –

Wa l l S o l a r A b s o r p t a n c e

Comparison of Annual Cooling Use (Before and After) Wall Solar Absorptances

Annual Cooling Energy Use (kWh/m2/yr)

100

80

60

Measured Solar absorptances of wall surfaces – Paints White on Plywood 0.15 White in wood siding 0.25 White Stucco 0.25 Flesh color stucco 0.4 Cream Color 0.41 Light gray aluminium siding 0.45 Light gray color stucco 0.5 Medium gray / blue color 0.65 Tan/Brown color 0.8

40

20

0 HHM1 HHM3 HHM5 HHS12 HHS13 HHS14 HHS15 HHS16 HDS1 Cooling Energy (Before)

Cooling Energy (After)

HDS2

HDS3

Measured Solar absorptances of brick walls Light colored 0.35 - 0.50 Light red 0.50 - 0.60 Burnt red 0.65 - 0.70


Florida Solar Energy Center – Roof Reflectance study


Florida Solar Energy Center – Roof Reflectance study


Building Enclosure –

Roof Solar Reflectance

% Reduction in Cooling Energy vs. Roof Absorptance Value 50 45

% Reduction in Cooling Energy

40 35

R² = 0.2042

30 25 20

15 10 5 0 0

0.05

0.1

0.15

0.2

Roof Solar Absorptance Value

0.25

0.3


High Rise Housing , Hong Kong– Shading Study


High Rise Housing , Hong Kong– Shading Study


Recommendations Wall Insulation • The optimum amount and location of thermal insulation is using 5 to 10 cm of insulation located outside or inside. Adding this insulation to the external surface of the uninsulated building envelope prevents heat gain to the interior. • Comfort conditions are reached faster if insulation is placed along the inside of the external wall.


Recommendations Wall Solar Absorptance Reducing the wall solar absorptance from 0.6 (average – medium colored wall) to white wall (0.2) helps reduce the annual cooling energy by 18% and peak cooling load by 23% compared to base case.


Recommendations Roof Insulation and Reflectance: Provide a white reflective roofing system with maximum R-19 insulation. This will help reduce the annual cooling energy by an average of 25% compared to dark shingle roof with no insulation.


Performance analysis and HVAC design simulation for TRAILERs Introduction This project is aimed at analyzing and investigating the performance of a trailer for stars with respect to variations in HVAC system type for various configurations and arrangement patterns for the trailers. Two main types of HVAC systems are compared- single duct VAV reheat system and CRV system. OBJECTIVES OF PROJECT: 1. Analyze the performance of the Star Trailer (Pittsburgh, PA) with respect to the HVAC system. 2. Compare the CRV system in the building chosen with the single duct VAV reheat system to analyze which is a better system for the building in terms of a. Satisfying heating demands b. Satisfying cooling demands c. Occupant comfort level in the zones


Performance analysis and HVAC design simulation for STAR TRAILERs Trailer Option 2

Trailer Option 1 Trailer Option 3


Performance analysis and HVAC design simulation for STAR TRAILERs

Plan , Elevation and Section of the trailer Floors Climate data Heating degree days (base 65째) Cooling degree days (base 65째) Summer design day temp (째C) Humidity value Month and day of the year Winter design day temp (째C) Humidity value Month and day of the year

5968 654 31.7 22.5 15-Jul -16.8 -16.8 15-Jan

Stand alone trailer 1 floor

Gross Area 31 m2

Floors 1st floor Stacked trailer 2nd floor Floors Side by side trailers

Gross Area 31 m2 31 m2 Gross Area

1st floor

62 m2


Performance analysis and HVAC design simulation for STAR TRAILERs Development and analysis of the Trailer in design builder v2.0.4.002:

Step 1: The initial trailer model with its physical parameters like : building geometry, glazing and opening characteristics, construction materials, occupant density, lighting and indoor equipments was developed in design builder V2.0.4.002. Step 2 : The thermal zones were also considered to be constant for the parametric simulation process the detailed HVAC systems were modeled to analyze the performance of the building. Step 3 : The model with required parameters was then exported to energy plus version 4.0.0.024.


Performance analysis and HVAC design simulation for STAR TRAILERs Development and analysis of the Trailer in design builder v2.0.4.002: Envelope construction materials Construction

External Walls External Floor Flat roof

Material

FORMAWALL 3" Insulated panel 2" (polyisocianurate) Bitumen, sheet - thickness 0.01m Polyisocianurate 4" (0.1016m)

Specific heat (J/kg-k) 1503

1000

Density R-value (kg/m3) 44.85 21

U-factor

16.27

0.061

28

0.036

28.18

0.035

1100

Metal decking 2" (0.0508m) External doors

Windows

Complete Roof assembly External door (HM)Expanded Polystyrene insulation Windows - Double LowE Clr 3/ 13mm Argon filled, VT .85, SHGC 0.69

15

1400

2.04


Performance analysis and HVAC design simulation for STAR TRAILERs Thermal zones , occupancy schedules & equipments – Option 1 – Single trailer Zone details

Net Area (m2)

Occupancy (people/m2)

Lighting (W/m2)

Plug and process* (W/m2)

Under Floor Plenum - Plenum UF

Unconditioned

28.7

0

0

0

Module 1 - Mech room South

Conditioned

0.68

0

3

0

Module 1 - Mech room North

Conditioned

0.86

0

3

0

Module 1 - Bathroom

Conditioned

3.68

0.5

9

0

Module 1 - Mod 1_amb 1

Conditioned

23.68

3.1

25

25

Total Area

VAV System System

Source

Capacity (W)

CRV System

Efficiency

Single Duct Variable Air Volume Reheat CHILLER Electric BOILER

Gas

57.6

5356.01

1.73

16421.76

0.75

System Source Capacity (W) Constant volume DX (unitary multi-zone) AHU Cooling Coil (DX Single speed) Electric 6395.34 AHU Heating Coil (Gas) Gas 9433.79 AHU Supply fan Electric 303.71

Efficiency (W/W)

3 0.8 0.7


Performance analysis and HVAC design simulation for STAR TRAILERs VAV – Block Model


Performance analysis and HVAC design simulation for STAR TRAILERs VAV – Nodal Model


Performance analysis and HVAC design simulation for STAR TRAILERs CASE 1- single duct VAV (variable air volume) reheat system: Time Not Comfortable Based on Simple ASHRAE 55-2004 3000 2500 2000

Trailer (Facility) Option 1

1500

Trailer (Facility) Option 3

1000 500

Trailer (Facility) Option 3

0 Winter Summer Summer or Clothes [hr] Clothes [hr] Winter Clothes [hr]

Setpoint and setback temperatures Heating period (°C) Heating Heating set back Cooling period (°C) Cooling Cooling set back 300

VAV - kWh/m2

250 200 150 100

Hours of Temperature Set point not met

50 0

50 45 40 35 30 25 20 15 10 5 0

Option 1

Option 2

Option 3 Heating

Trailer (Facility) Option 1

Cooling

Trailer (Facility) Option 2

Interior equipment

Trailer (Facility) Option 3 During Heating During Cooling [hr] [hr]

During Occupied Cooling [hr]

Interior lighting Fans Pumps

Kwh

Total Energy Consumption – By End Use

22 12 24 28


Performance analysis and HVAC design simulation for STAR TRAILERs Monthly Energy Consumption for VAV systems in trailers

Total (kWh/m2)

Total (kWh/m2) 30.00

30.00 25.00

25.00

20.00

20.00

15.00

15.00

10.00

10.00

5.00

5.00

0.00

0.00

Trailer Option 1

Trailer Option 2

Total (kWh/m2) 25.00 20.00 15.00 10.00 5.00 0.00

Trailer Option 3


Performance analysis and HVAC design simulation for STAR TRAILERs CASE 2- CONSTANT REHEAT VOLUME SYSTEM- WITH MINIMUM HUMIDITY: Time Not Comfortable Based on Simple ASHRAE 55-2004 3000 2500 2000

Trailer (Facility) Option 1

1500

Trailer (Facility) Option 3

1000 500

Trailer (Facility) Option 3

0 Winter Summer Summer or Clothes [hr] Clothes [hr] Winter Clothes [hr]

Setpoint and setback temperatures Heating period (°C) Heating Heating set back Cooling period (°C) Cooling Cooling set back

By end use Kwh

Hours of Temperature Set point not met 4000 3500

Heating

3000

Cooling

2500

Trailer (Facility) Option 1

2000

Trailer (Facility) Option 2

1500 1000

Interior lighting Interior equipment Fans Pumps

Trailer (Facility) - Option 3

500 0 During During Heating [hr] Cooling [hr]

During During Occupied Occupied Heating [hr] Cooling [hr]

Total Energy Consumption – By End Use

22 12 24 28


A Strategic Opportunity for the Renovation of Dormitory at Carnegie Mellon 8 April 2011

48-723 Performance of Advanced Building Systems

Prof. Volker Hartkopf


Goals Reduce Energy Consumption

Improve Thermal Comfort Improve Air Quality + Occupant Health

Meter, Verify, and Report Actual Performance for Different Decision Makers Educate Students about consumption habits Provide Data for Research Turn an “eyesore� into a gem

Overview

Health + Comfort

Energy Metering + Consumption Commissioning

Education + Research

Campus Appeal


EXISTING FAÇADE Single Pane window Blue colored glass – bad quality Daylighting No insulation Very poor thermal quality

Poor Indoor air quality Over heating in summer conditions Leaky façade

No maintenance No privacy for occupants

Overview

Health + Comfort

Energy Metering + Consumption Commissioning

Education + Research

Campus Appeal


PROPOSED FAÇADE – option 1

• Heat Loss/Gain Control • Natural Ventilation • Privacy and Solar Control • Daylighting • Visual Access • Glare Control


PROPOSED FAÇADE – option 1


PROPOSED FAÇADE – option 2


PROPOSED FAÇADE Polycarbonate sheet - Allows diffused light Internal shades for glare control

Awning window -Natural ventilation and -Thermo siphoning effect

5” thk. Polyisoboard Insulation – CMU construction

Overview

Health + Comfort

Energy Metering + Consumption Commissioning

Education + Research

Campus Appeal


Illuminance

Existing Faรงade

Proposed Faรงade


Luminance

Existing faรงade without shading (June 22)

Proposed faรงade with shading (June 22)


Energy Performance & CO2 Emissions


Energy Performance & CO2 Emissions


Energy Performance comparison Energy Performance

Space conditioning demand

200 180 160 120

kBtu/ft2 yr

kBtu/ft2 yr

140 100 80 60 40 20 0

Existing faรงade

Site energy

Retrofit faรงade

Source energy

100 90 80 70 60 50 40 30 20 10 0

Existing faรงade

Retrofit faรงade

Heating demand

Cooling demand

Percentage reduction

Site energy Source energy

Overview

Health + Comfort

72% 68%

Energy Metering + Consumption Commissioning

Education + Research

Campus Appeal


Portfolio - Research and Energy Modeling