Super TowerSeoul, South Korea

Energy Cost Analysis

Building Performance Modeling

1. Background (Climate Summary)

2. Energy Model Inputs and Results

3. Glazing Studies

4. Shading Studies

30% DD Phase Review

Background – Climate Summary

Cooling 560 CDD

Heating 2782 HDD Comfort

Source: TMY2 Weather Data

Annual Rainfall 53 inches

Total Annual Energy Total Annual Cost

ASHRAE Baseline 266,212 MMBtus $6,416,198

Proposed Design 189,374 MMBtus $4,485,136

Energy/Cost Savings 76,838 MMBtus $1,931,062

Percentage Savings 28.9% 30.1%

YRG developed a baseline case energy model compliant with ASHRAE 90.1 YRG developed a Proposed Design case energy model representing the actual project design with all Energy Efficiency MeasuresThe model was able to estimate energy savings of the project relative to the ASHRAE baselineUtilizing energy costs of the project for the site, these energy savings translate to operational cost savingsThe energy model predicted return on investment of the project within 4 years of the project operations

Energy Analysis Results

10 LEED Points

Total Annual Energy Total Annual Cost

Energy/Cost Savings 76,838 MMBtus $1,931,062

Energy Analysis Results

Energy Analysis Results- Cost Savings Breakdown

30.1%

The energy model determines energy savings in all aspects of the building, particularly in Ventilation and Heating systems

38.7%

25.5%

26.2%

Energy Cost Savings by Space Type

The project consists of different space typesThe energy model was able to identify that the cost savings with energy efficiency would be more in the residential portion followed by the hotel and offices.

Background – Building Energy Picture

Energy Use vs. Energy Cost

BaselineProposed Baseline Proposed

Shading Analysis – Sun Path

S E S E S

N W N W

Shading Analysis – Solar Exposure

06:00 07:00 08:00 09:00 10:00 11:00 12:00 13:00 14:00 15:00 16:00 17:00 18:00 19:00Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

06:00 07:00 08:00 09:00 10:00 11:00 12:00 13:00 14:00 15:00 16:00 17:00 18:00 19:00Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

North-facingFaçade(s)

East-facingFaçade(s)

Higher Cooling Cost

Glare Potential

Shading Analysis – Solar Exposure

Summer ConditionEast and West façades

Impact: Direct and high

altitude solar gains

Best Practice: Use

shading screens, vertical

fins

East Facade

West Facade

Shading Analysis – Solar Exposure

Winter ConditionAll façades

Impact: Low solar altitude

and desirable heat gain

Best Practice: Use low-e

thermal glass, interior

roller shades for glare

protection

Glazing – Range of Performance- U value

U-Value Sensitivity Test

U-ValueBtu/h-ft2-°F

Solar Heat Gain Co-efficient (SHGC)

Visible Light Transmittance (VLT)

U-0.35

0.28 0.45

U-0.30

U-0.25

U-0.20

U-0.15

Improved

Improved

YRG developed parametric models of glazing performance to identify energy and daylight impact

Glazing – Energy Cost to U valueProposed Case U Value: 0.29

Annual Building Energy Cost

Glazing – Spandrel Glass Performance (46.55% of wall area)

Comparing Building Energy Cost

0.49%

0.61%

YRG developed parametric models of spandrel glass performance to identify energy savings

Results

Changing shading property (SHGC) would be more valuable than moving to a triple glazed window

Improving the U-Value of spandrel glass can save an additional 0.5% in annual energy cost

Shading Fins – Range of Performance

1:4 1:3 1:2 1:1

Depth-to-Distance RatiosVertical Fins

As Designed

Shading System Optimization- Solar Radiation Analysis

30%

All Horizontal Shades

40%

Combination

All Vertical Fins

20%

Shading Fins – Range of Performance

Depth-to-Distance RatiosHorizontal Fins

Max Incline Condition

1 to 2.8 ratio

Façade (~84°)

Façade (~90°)

Tower Interior

Max Summer (75.9°)Max Winter (29.0°)

Tower Interior

Max Summer (75.9°)Max Winter (29.0°)

Fin

Fin

Typical Condition

1 to 3.6 ratio

Shading Devices – Summer Heat Gain Comparison

Cumulative Solar Exposure, Summer Season

H-Fins + V-Fins

West External Shading Screen Analysis

10% 40% 70%Screen Opacity

~55% opacity W screen comparable to H-Fins+V-Fins on N, E, S faces

Comfort Optimization- Daylight Analysis

Library Project

Fort Collens, CO

Envelope Construction Cooling Plant Impact

Unshaded,Fully Glazed

Fully Shaded,Fully Glazed

Fully Shaded,Partially Glazed

YRG evaluated envelope systems for reduction in cooling peak demand

Shading Impact on Total Energy Use

TotalEnergy

CoolingBreakdown

SolarBreakdown

Other Consumption

85%

Cooling15%

Solar13%

Conduction 2%

Diffused 5%

Direct Up to 8%(Shading)

Climate

Wind

Temperature

Thermal Stress

Site

Concept Design Energy Analysis for Optimized Design

Climate and Site

Red is the warm temperature Blue is the cold temperature Inner circle are high and low

temperature identifying coldest and hottest days

Green is comfort temperature and humidity

Recommendations- Explore natural ventilation and

passive conditioning like night flushing in July and August

Temperature and Humidity

HDD(64.4) = 6574.6CDD(50.0) = 2900.7

The climate is 3 times more likely to need heating as cooling

Green bars are comfortable hours which allow passive strategies

The climate needs heating majority of the time.

Wind Direction Distribution %

JulMar

DecSep

Dec to Mar- North Winds Mar to Jul- East Winds July- Sep – Not too many winds Sep- Dec- South winds

Daylight and Shading Study – Oriented on East-West Axis

June 21st

March 21st

December 21st

Daylight analysis found 33.6% area over 25 fc threshold

Building Loads

Distribution of loads in order of high to low

HeatingHeat loss through walls and roofVentilation load for distribution of hot airInfiltration into the building (assumed to be average per ASHRAE loads calculation)

CoolingPeople generate heat (assumed to be 50 sf/p)Lighting generates heatSmall equipment loads in computersSolar radiation Conduction through walls and roofInflitration of cool air to outside

Preliminary Energy Analysis

Energy Analysis AssumptionsBuilding Type - College/University

Built Area- 168,000 SF

Floors Above Ground- 4

Envelope- ASHRAE 90.1 2007 BaselineWindow Wall Ratio- 44%

HVAC- Dual Duct VAV system

Design Building Energy Use Intensity:- 93 kBTU/ft2

Average Building Energy Use Intensity- 120 kBTU/ft2

Proposed Building Carbon intensity - 46.59 lbCO2/ft2

Proposed Building Carbon emissions- 3913.1 tons CO2/yr

Location: Denver/Stapleton Int`l Airport, Colorado (40.02N,105.28W)Climate file: DenverStapletonTMY.fwtAnalysis Period: 01/Jan - 31/Dec