A User’s Perspective on IES Modeling

Shem Heiple PE, LEED AP, GGP Amy Jarvis PE, LEED AP BD+C

Why IES?

Ability to Model Complex HVAC Systems

Sketch Up Import

Early Stage Modeling

HVAC Loads and Energy Modeling

Bulk Airflow

CFD

Daylighting Integration

Sample Project ─ Shading & Daylighting

Suncast for early design feedback

Radiance-daylight analysis

Radiance integrated with energy model Output daylight file for

sensor location Daylight control profile

Integrated Daylighting & Energy Optimization

ARCHITECTURAL INFORMATION

DAYLIGHTING MODEL

DAYLIGHTING ANALYSIS

ENERGY MODEL: EQUEST

ENERGY ANALYSIS

Daylighting Results

Integrated Daylighting & Energy Optimization

ARCHITECTURAL INFORMATION IES MODEL

DAYLIGHTING ANALYSIS: IES MODEL

Daylighting Results

ENERGY ANALYSIS

Daylighting (RadianceIES)

Daylighting (RadianceIES)

Daylighting (RadianceIES)

Daylighting (RadianceIES)

Daylighting Optimization

Daylighting (RadianceIES)

Daylighting Analysis

Daylighting Results

Energy Analysis

Daylighting (RadianceIES)

Building Shading Analysis

Shading Options Comparison

Sample Project–CFD

Applications

No transient model

Creates surface boundary conditions based on energy model and solar analysis

Natural ventilation and thermal comfort

Wind studies

HVAC Load Calculations

ARCHITECTURAL INFORMATION RESULTS RESULTS

RECONCILIATION

HVAC LOAD CALCULATIONS

ENERGY MODELING

TRANE TRACE

EQUEST

ARCHITECTURAL INFORMATION RESULTS IES

HVAC LOAD CALCULATIONS

ENERGY MODELING

HVAC Load Calculations

Multiple load calculation methods used in the industry.

eQuest: Weighting Factor Method (WF) Uses 8760 file for peak conditions.

IES-VE and EnergyPlus: Heat Balance Method (HB)–most accurate.

Trace: Radiant Time Series (RTS)–Other methods available.

Results differing as much 40% when applied to the same building.

DOE2 Auto Sizing Comparison

BUILDING TYPE DOE2 COOLING (BTU/HR/SF)

DESIGN COOLING (BTU/HR/SF)

PERCENT DIFFERENCE FROM DOE2

LOAD CALCULATION

SOFTWARE

Office 20.6 24.4 15.7% CHVAC (Elite)

Gov Office (24/7) 35.2 29.8 -18.2% Trace

Police Station 11.3 14.3 20.7% CHVAC (Elite)

Community College 27.7 27.3 -1.4% CHVAC (Elite)

Office (PUD) 25.4 19.0 -34.2% CHVAC (Elite)

Using IES for HVAC Load Calculations

Interface and reports are designed for energy analyses, not for mechanical design

Energy analyst and mechanical designer must work together

High level of input complexity for load calculations

Inputs for load calculations and energy model not clearly defined

Load profiles and diversity must be manually reset

IES HVAC Load Output Files

Difficult to understand by non-IES user

Some information needed for engineering validation not provided

Use of Vista required for load validation

System Sizing Plant Loads

Model Validation Using Vista

Model Validation Using Vista

Model Validation Using Vista

Energy Performance Verification

No automated output report

Only report created by PRM navigator

Input verification can be time consuming

Limited reports for fan power or total airflow–must sum up individually

Time consuming to QA/QC

Revit integration

Thank you!

shemh @ interfaceeng.com amy.jarvis @ zgf.com

Shem Heiple PE, LEED AP, GGP Amy Jarvis PE, LEED AP BD+C