A Prototype Visualization Tool for Hygrothermal Analysis

Vamshi Gooje, BEMP, CEM, LEED AP BD+C Senior Associate

Building Energy 2016, Boston

March 9, 2016

Lead Computational Designer | CORE

Matthew Naugle

Building Certification

Energy Analysis

Existing Building Sustainability

Sustainability Education & Training

Sustainable Strategies

Sustainability Practice

1. Integration of hygrothermal analysis into early design phases

2. Sequential steps in evaluating hygrothermal failure criteria

3. A novel data visualization tool integrating varied sets of data

Learning Objectives

Basics of

Hygrothermal

Analysis

Hygrothermal Conditions

Reference: “Building Envelope Design” by SAB Magazine

Soil Environment: Temperature, Relative Humidity

Interior Environment: Temperature, Relative Humidity, Air pressure

Solar Radiation

Rain

Wind

Occupant Activities

Mechanical Equipment

Air Leakage

ENVIRONMENTAL LOADS ON THE BUILDING ENVELOPE

Load: Vapor Pressure Difference

Load: Air Pressure Difference

Load: Temperature Difference

Building Envelope

Reference: Whole Building Design Guide

structure external finish

finish support

air barrier

thermal insulation

vapor barrier

interior finish

structure

Large moisture buffer, ease of

wetting and drying

Low to moderate moisture buffers,

wetting and drying process more complicated

Hygrothermal Conditions

Inputs

Simulation

Grid

Material

Properties

Initial

Conditions

Climatic

Data

Surface

Transfer

Parameters

Time

Steps

Update thermal coefficients

Calculate temperature field

Update moisture coefficients

Calculate moisture field

satpp pDt

w

satpp pDt

w

Convergence?

Output Temperature fields

Temperature fluxes

Moisture fields

Moisture fluxes

Yes No

Coupled Transport Equations

Moisture Modeling Using WUFI

Reference: H.M. Künzel, A. Karagiozis, and A. Holm, WUFI Fundamentals

PROCESS

INP

UT

S

OU

TP

UT

S

Material Properties Initial Conditions Climatic Data (Outdoor) Surface Transfer Coefficients Climatic Data (Indoor)

Moisture Content of Component Moisture Content of Assembly Temperature and Dewpoint Limiting Isopleths

Moisture Modeling Using WUFI

Integration of

Hygrothermal Analysis

into Early Design Phases

Integrated Project Delivery Graphic by HOK

LESS EFFECTIVE

MORE EFFECTIVE

Image : HOK

Design Workflow Evolution

18,000

18,200

18,400

18,600

18,800

19,000

19,200

19,400

19,600

19,800

1+Wall R-18 1+Wall R-25 1+Wall R-28 1+Wall R-38

Gas U

se (

in T

herm

s)

Graphic by HOK

PROCESS

OPERATING ENERGY OPTIMIZATION

Disaggregated Data Challenges

HYGROTHERMAL PERFORMANCE

Trending moisture content indicating potential failure of

assembly & individual component

0

10

20

30

40

50

60

70

80

90

18,000

18,200

18,400

18,600

18,800

19,000

19,200

19,400

19,600

19,800

1+Wall R-18 1+Wall R-25 1+Wall R-28 1+Wall R-38

MC

%

Gas U

se (

in T

herm

s)

Graphic by HOK

Challenges in Data Integration

Hygrothermal performance

Energy performance

Sequential Steps in

Evaluating Hygrothermal

Failure Criteria

Graphic by HOK

PROCESS

ASHRAE 160 STANDARD

• 30-day running average (RH<80%, Temperature > 41°F and < 104°F)

• Criteria is evaluated for materials prone to mold.

Failure Criterion 1

(Minimize Surface Mold Growth)

Graphic by HOK

PROCESS Failure Criterion 2

(Moisture Content: Individual Components)

ply

wood

insu

lation

gyp

board

vapor barr

ier

stucc

o p

last

er

This rot/decay applies to wood based products

Graphic by HOK

PROCESS Failure Criterion 3

(Moisture Content: Entire Assembly)

ply

wood

insu

lation

gyp

board

vapor barr

ier

stucc

o p

last

er

The assembly is evaluated to ensure hygric equilibrium is achieved by

the end of study period.

Graphic by HOK

Failure Criterion 4

(Surface Condensation Potential)

ply

wood

insu

lation

gyp

board

vapor barr

ier

stucc

o p

last

er

Material surfaces are evaluated for potential condensation from humid

interior air. Evaluated for potential condensing surfaces

Graphic by HOK

PROCESS Failure Criterion 5

(Isopleths for Mold Growth)

ply

wood

insu

lation

gyp

board

vapor barr

ier

stucc

o p

last

er

Identifies potential mold growth on the interior surfaces. Mold growth is

possible when the conditions lie above the limiting isopleth lines.

Graphic by HOK

PROCESS

• Frost Damage (Primarily for Masonry)

• Fungi Growth (Using WUFI-BIO)

Failure Criterion 6 & 7

A

Data Visualization Tool

Integrating Varied Data Sets

15,000

15,500

16,000

16,500

17,000

17,500

18,000

18,500

19,000

19,500

20,000

1+Wall R-18 1+Wall R-25 1+Wall R-28 1+Wall R-38

Ga

s U

se

(in

Th

erm

s) FC 1

FC 2

FC 3

FC 4

FC 5

FC 6

FC 7

FC 1

FC 2

FC 3

FC 4

FC 5

FC 6

FC 7

FC 1

FC 2

FC 3

FC 4

FC 5

FC 6

FC 7

FC 1

FC 2

FC 3

FC 4

FC 5

FC 6

FC 7

PROCESS

PASS

FAIL

Integrated Data Analysis

Component 1 Outside Inside

Component 2

Component x

Full Assembly

WC

WC

Y1

WC

Temp RH MC DP

Temp RH MC DP

Temp RH MC DP Y2

Y(n)

Potential Total Number of Data Points=

8760 x (Number of Simulation Years) x (1 + 4 x Number of Assembly Components)

E.g. a simulation run for seven years with six components in the assembly would yield approximately

1.5 million data points

Temp RH MC DP

Temp RH MC DP

Temp RH MC DP

Temp RH MC DP

Temp RH MC DP

Temp RH MC DP

Scale of Data

PROCESS Grasshopper

Screenshot showing the

Grasshopper

programming

environment and an

associated visualization

PROCESS

Read file and extract

Temperature & RH data,

along with time steps

Generate visualizations

for results Run analytics

Grasshopper

Import simulation results data

Extract temperature, RH data & total assembly water content

Run analytics for the different failure criteria

FC1

Generate visualizations showing pass/fail in

components

Generate detailed graphs for failures

Import material data

FC 2 FC 3 FC 4 FC 5

Extract material densities, calculate dew point &

moisture content

.asc files

.xml files

Run WUFI simulations WUFI

GRASSHOPPER

Modify simulation parameters if necessary

Proposed Workflow

PROCESS

{Video Demo}

Visualization Environment

Wrap Up

PROCESS

• Preliminary testing showed that this visualization tool can effectively

address some of the challenges of post-processing the data from WUFI.

• The visualization style adopted by this tool aims to reduce the complexity of

the data and the associated evaluation criteria into an easily digestible

format that would speed up the evaluation process, and also facilitate for its

integration with other performance criteria.

Key Conclusions

• Carrying out batch runs, for creating a two-way connection from

Grasshopper that would send and receive data.

• Integrate the data from hygrothermal simulations with other design

criteria such as energy performance.

• Converting visualizations into interactive objects, rather than as static

graphs. This would allow the user to manipulate different aspects of the

analysis such as the threshold criteria, and observe the changes that

occur.

Future Work

Thank You

Vamshi Gooje

vgooje@thorntontomasetti.com

Questions

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© Thornton Tomasetti Inc. 2016