Computer Simulation For Building Energy

Efficiency, Module 5 – Computer Simulation

R e v i s i o n 2 ( 3 r d O c t o b e r 2 0 1 4 )

I r . H . P. L o o i ( m e k t r i c o n @ g m a i l . c o m )

B . E n g ( H o n s ) , F I E M , J u r u t e r a G a s

w w w. j k r. go v. m y/ b s e e p

SEMINAR ON PASSIVE & ACTIVE DESIGN

FOR ENERGY EFFICIENT BUILDINGS 3rd October 2014

Holiday Inn Resort, Batu Ferringhi, Penang

2 SYNOPSIS

‘PASSIVE DESIGN measures are key considerations in the design of building for low energy

and environmental performances. The importance of Passive Design is underscored by its

precedence over Active Design measures in green and low energy building.

PASSIVE DESIGN measures (which are principally architectural in nature) aims to embed

features into a building which are intrinsically green and low energy in nature. Active

measures are design features which requires ‘active intervention’ of building systems (such

as air conditioning, mechanical ventilation, lighting systems etc) which will contribute to

green and/or low energy performances. Current pressing requirements for green design and

low energy in building which are increasingly driven by mandatory building codes (e.g.

recent revision to the UBBL incorporating parts of MS1525) requires knowledge of Passive

Design as in the skill set of the design architect.

TRAINING FOR PASSIVE DESIGN is structured into 6 Modules:

(1) Introduction to Passive Design;

(2) Building Thermal Envelope;

(3) Natural ventilation;

(4) Day-lighting;

(5) Simulation.

(6) Case Studies

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3 SYNOPSIS – MODULE 5, SIMULATION

COMPUTER MODELLING is increasing moving into mainstream commercial

application as cost comes down and computing power increases. The use of

computer modelling, fast becoming norm in industry practice, is an essential tool

for designing low energy building. Computer modelling is particularly relevant in

the context of passive design both at design concept and development stages.

THIS PRESENTATION focuses on computer simulation in the building design life

cycle with the following topical subject:

(1) The building design life cycle

(2) Tools in the building design life cycle

(3) Building Information Modelling in 5 minutes

(4) Types of computer simulation

(5) Developing the simulation model

(6) Simulation software

This Module assumes that participants have an

understanding of “Passive Design” , building thermal envelope

and building energy and covered in Modules 1 to 4 of this training series.

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Passive design are features which

are intrinsic (or part of ) the building

form which contributes to good

environmental qualities such as

provides shelter or insulation

against the hot tropical sun or its

layout is such that it ensures quality

environment for occupant.

Active design features are M&E

systems which actively ‘intervene’

to ensure good or adequate

environmental qualities in a

building. Active measures include

lifts, air conditioning, mechanical

ventilation , artificial lighting etc.

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5 RECAPITULATION – PASSIVE DESIGN

Passive design features can be listed as the following design measures:

1. Building Orientation (sun path)

2. Building thermal envelope (OTTV)

3. Roof thermal envelope (RTTV)

4. Micro climate of surrounding (landscaping)

5. Naturally ventilated building

6. Natural day lighting by windows, daylighting system such as light

tube, light shelf etc.

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6 THE BUILDING ENERGY MODEL

Building design features which contributes to building cooling energy

can be illustrated as follows:

Heat gain

thro’ walls

Heat gain thro’ windows

Air Infiltration (doors/

windows/ cracks)

Fresh Air

Intake People

heat gain Electric

Appliance

heat gain

Heat gain & solar heat

gain thro’ roof (RTTV)

Lighting

heat gain Electric

Motor

heat gain

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7 RECAPITULATION – BUILDING ENERGY

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8 THERMAL COMFORT IN RESIDENTIAL BUILDING

Thermal comfort is defined by

ASHRAE as that state of mind

which expresses satisfaction with

the thermal environment.

Factors:

(a) Air Temperature

(b) Mean radiant

temperature of

surfaces

(c) Humidity

(d) Air flow

(e) Mean temperature of

occupant clothing.

9 EXAMPLE; THERMAL COMFORT Based on the PMV-(Predicted Mean Value), ceiling fan (1 m/s)

is sufficient to maintain Thermal Comfort.

10 EXAMPLE; THERMAL COMFORT

Based on the PMV-(Predicted Mean Value), table/stand fan

(2 m/s) is sufficient to maintain Thermal Comfort.

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11 RECAPITULATION – BUILDING ENERGY

Some Conclusion

Building façade contributes to about 15% of cooling energy

Roof contribution is proportional to the ratio of roof space to total

built-up

Air intake or how ‘leaky’ a building is contributes up to a

whopping 25% to building cooling energy.

Electrical equipment inside building contributes a major 30%.

This component unfortunately is usually not influence by building

designers but by the M&E engineer. However building designed

with minimal or less dependency on electrical equipment will be

have significant effect on building energy.

People or occupant only contribute from 15%-20% of B.E.

Understanding above and building usage pattern can assist

designers in building low energy building.

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13 THE BUILDING LIFE CYCLE

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14 CONCEPT DEVELOPMENT

The Design Life Cycle traditionally do not include assessment of building

performance at conceptual and design development stage.

Traditional concept development differs from current 3-D Sketchup programs.

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15 GOOGLE SKETCHUP – PARADIGM SHIFT

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16 THE BUILDING LIFE CYCLE

Concept Sketch

Visualisation

Architectural

eLibrary

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17 DESIGN DEVELOPMENT

Civil Structural

Structure eLibrary

Revit for

Structural

Engineering

MyCESSM Malaysia Civil Engineering

Standard Method of

Measurement 3 r d O c t o b e r 2 0 1 4

18 DESIGN DEVELOPMENT

MEP eLibrary

Mechanical Electrical

www.dialux.de

Fluent

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19 TYPES OF SIMULATION

Building Energy

Solar Insolation

Thermal Massing

Air Flow - CFD

Thermal Comfort

Day light Simulation

Lighting Simulation

Façade Modelling

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20 TYPES OF SIMULATION

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Building Energy Modelling

Passive

• Solar Intensity (facade)

• Thermal envelope

• Thermal Mass

• Day lighting

• Air infiltration

Active

• AC system configuration

• Ventilation & air infiltration

• Usage pattern

• People occupancy flow

• Artifical lighting

• Electrical equipment & appliances

Thermal Comfort (Naturally Vented Space)

Thermal Envelope

Thermal Mass

Ambient temperature

PMV thermal comfort

Natural air flow (CFD)

21 TYPES OF SIMULATION

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Thermal Comfort (Naturally Vented Space)

Thermal Envelope

Thermal Mass

Ambient temperature

PMV thermal comfort

Lighting

Sun position/ shadow

Day light mapping

Daylight scatter from light shelf

Artificial lighting

Scene rendering

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Qin

Tin

(22°C)

23 UNDERSTAND COMPONENTS IN BUILDING ENERGY

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24 SIMULATION FOR BUILDING ENERGY

Services Factors Air Conditioning System design (a) Direct solar heat gain through glazing

and walls Thermal Envelope (OTTV), weather

data (b) Solar heat gain through roofs and walls Thermal Envelope (OTTV), weather

data (c) Air Infiltration Building leakiness, weather data

(d) Human population Time-based human traffic (e) Lighting load Time-based human traffic; day light

pattern (d) Machine load Occupancy pattern (e) Utilities Building design, occupancy pattern

(f) Parasitic Load Building security & system design

Lighting System design (a) Artificial Lighting Occupancy pattern (b) Day Lighting Sun position Power / Plug Point Load Occupancy pattern Lifts Occupancy pattern, human traffic

Utilities Occupancy pattern, system design

UNDERSTANDING PARAMETERS WHICH AFFECT ENERGY PROFILE &

COMPONENTS WHICH ARE PASSIVE AND ACTIVE FEATURES

25 BUILDING ENERGY

1. Solar heat gain and transmission:

(a) Sun position calculator

(b) Building Thermal Mass calculator (OTTV and RTTV)

2. Human occupancy pattern

Depending on the building usage type (office, retail, hotel, hospital

etc), load profile due to occupancy pattern can be modelled with

reasonable accuracy. Occupancy pattern can also deemed to be

‘expert’ input in a rigorous energy model.

3. System Design

Issues relating to system design are varied and are usually NOT

amenable to mathematically modelling. In case, an ‘expert’ system

input is required. Examples are:

(a) Air infiltration due to building design;

(b) Chiller system design which affects performance (such as

efficiency, chiller sizing and part-loading, hydraulic efficiency, air

side efficiency etc)

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26 UNDERSTANDING ENERGY PROFILE

ENERGY MODELLING; ENERGY DEMAND PROFILE

Demand Diversity Cd Max. Demand (kW) = Connected Load (kW) x Cd

Total kWh = MD (kW) x Hour Run (hr) x CL Load Diversity CL

Time

kW

Connected Load

Transformer capacity

Energy consumed =

Area under curve =

kWh

Max. Demand

Average

Demand

Hour run/day

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27 IDENTIFYING PARAMETERS IN MODEL

What is the Building Model ?

Define the Building Model

Maths Model / Expert System

Identify the Parameters

and Boundary Conditions

Interpret Results

Redefine Parameters & Boundary Conditions

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Explanation of Terms.

Values affecting energy use. PARAMETERS

BOUNDARY CONDITIONS Boundaries defining the building model e,g, surfaces

delimiting a zone.

INTERNAL BOUNDARIES Walls, ceiling, windows, roofs, floors:

Parameters Uvalues, reflectance,

EXTERNAL BOUNDARIES Sky conditions, Sun position:

Outdoor temperature, humidity.

28 IDENTIFYING PARAMETERS IN MODEL

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29 UNDERSTANDING CONCEPTS IN MODELLING

Explanation of Terms – Mathematical Modeling.

The behaviour of a system which can be defined by a mathematical model and then

automatically calculated to predict its behaviour.

1. SUN POSITION (SOLAR AZIMUTH AND HORIZONTAL) BASED ON TIME OF DAY AND LATITUDE.

2. SOLAR IRRADIANCE (ENERGY/HEATING) VALUE CALCULATED BASED ON SUN POSITION AND ATMOSPHERIC CONDITIONS (LINKE INDEX).

3. THE SOLAR SHADING COEFFICIENT OF A SHADING DEVICE BASED ON ITS GEOMETRY AND SUN POSITION.

4. HEAT TRANSMISSION BASED ON (WEATHER DATA) TEMPERATURE DIFFERENTIAL BETWEEN A BOUNDARY AND UVALUE OF BOUNDARY.

5. THE ENERGY CONSUMED BASED ON CHILLER COP AND LOADING PATTERN, HYDRAULIC LOSS (FLUID FLOW), AIR SIDE LOSS (STATIC LOSS), AIR LEAKAGES ETC.

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Explanation of Terms – Expert System.

The behaviour of a system which CANNOT be modelled mathematically but react

based on a ‘table of conditions and reaction’.

1. ASSIGNING VALUES FOR PARAMETERS WHICH ARE ESSENTIALLY EMPIRICAL IN NATURE, E.G. VALUES FOR ‘PLUG-LOADS’, DIVERSITY OF ELECTRIC LOADS ETC.

2. DEFINING LOAD PROFILE BASED ON AN UNDERSTANDING OF SPACE USAGE AND BUILDING TYPE.

3. OTHER LOADS CONTRIBUTING TO ENERGY DEMAND, E.G. LIFTS, PUMPS, APPLIANCES.

4. PARAMETERS WHICH ARE SIMPLIFICATION OF MATHEMATICAL MODELING E.G. INSTEAD OF RIGOROUSLY CALCULATING THE ENERGY DEMAND OF AC SYSTEM DUE TO HYDRAULIC LOSSES AND STATIC HEAD, A SIMPLIFICATION ‘DIVERSITY FACTOR’ MAY BE APPLIED. THE VALUES ASSIGN TO THIS PARAMETER IS AN ‘EXPERT SYSTEM’ DECISION.

30 UNDERSTANDING CONCEPTS IN MODELLING

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31 UNDERSTANDING CONCEPTS IN MODELLING

The Main Parameters in Energy Modeling.

Summary of Energy Consumption

1. AIR CONDITIONING (COOLING) – 40% TO 60%.

2. LIGHTING – 15% TO 25%.

3. PLUG-LOAD (POWER OUTLETS) – 5% TO 15%

4. LIFTS AND ESCALATORS – 2% TO 8%

5. PUMPS AND HYDRAULICS – HYDRAULICS

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33 FIRST STEP

You need to build up a 3-D model of your building.

1. Import 3-D model from the architect OR

2. Develop from scratch a 3-D model.

3. Developing a complex 3D model is time consuming! A complex

3D model may also require too much from your PC and may take

too long to calculate.

4. Simplify your building model. Simulate regions /zones of your

building in piece-meal fashion.

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34

34 BIM – COLLABORATIVE MODELLING

Courtesy of Autodesk

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35 BIM – COLLABORATIVE MODELLING

Parametric

Information Reuse

Representation

Integration

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36 BIM – COLLABORATIVE MODELLING

Building Information Modelling (BIM)

1. 3D Modelling is the norm.

2. Drawing is a collection of objects and models (in traditional CAD,

drawing elements are collection of lines, arcs and planar

objects). E.g. in BIM walls are objects which may have levels of

complexity while in traditional CAD walls are a collection of lines

and planes.

3. Collecting and managing library of standard objects.

4. Collaborative design by disparate design team members

5. Extraction of DATA for analysis e.g. BQ extraction, clash analysis

6. Cross platform exchange of data (This is still a PROBLEM).

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37 THE 3-D MODELLING PROBLEM

Building Information Modelling

•Building elements, e.g. walls, roof, slabs, ceilings etc are objects. These objects may also have levels of complexities depending on the BIM model i.e. 3D, 4D or 5D

•Data extraction for ALL building elements possible.

Energy simulation

•Model recognises 3D space (zones) only. Thermal space are closed and bounded by surfaces. Elements bounding a zone/space (walls, glazing etc.) have parameters such as U and SC values.

•Building orientation and local weather data is essential for the model.

•BIM model with too much architectural detailing may slow down the simulation

Lighting simulation

•Model recognise surfaces only and surfaces has values related to lighting and optics (reflectance, .colour etc).

•Architectural complexities are not recognised. Complex surface slows down calculation (simplify surface as much as possible).

• Shading devices and reflectors must be properly tagged for recognition.

•Building orientation and location is essential.

Air Flow Simulation (CFD)

•Model recognises surfaces. Most CFD software generates surface-mesh from surfaces.

• Surfaces which are too complex will burden the model e.g. niche and columns in walls etc. Simplify surfaces. In outdoor air flow, ground surfaces are also recognised

• Issues of importing 3-D files from CAD software.

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38 BUILDING ENERGY SOFTWARE

BEIT Free http://www.acem.com.my Energy 10 Public domain http://www.nrel.gov/buildings/energ

y10.html Energy Plus Public domain http://www.energyplus.gov/

ESPr Public domain http://www.esru.strath.ac.uk IES VE Commercial http://www.iesve.com TAS Commercial http://www.edsl.net/main/ BSims Commercial http://www.bsim.dk DOE-2 Commercial http://simulationresearch.lbl.gov/

Ecotect Commercial http://usa.autodesk.com

Revit Commercial http://usa.autodesk.com Google SketchUp

Public domain http://www.sketchup.com

Energy Software

3D Model

39 BUILDING ENERGY SOFTWARE

Dialux Free http://www.dial.de Radiance Public domain http://radsite.lbl.gov/radiance/HOM

E.html Rayfront Commercial http://www.schorsch.com/

Fluent Commercial http://www.iesve.com FloVent Commercial http://www.flovent.com/ ANSYS CFX Commercial http://www.ansys.com/products/fl

uid-dynamics/cfx/ List of CFD Softwares (free and commercial)

http://www.cfd-online.com/Wiki/Codes

Lighting & Day Lighting.

CFD

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41 TRADITIONAL MANUAL CALCULATION

Traditionally building heat load is manually calculated using a spread sheet

type calculator. Each thermal space is calculated and the total thermal load

for the building added. This model assumes a ‘worst case basis’. 3 r d O c t o b e r 2 0 1 4

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42 TRADITIONAL MANUAL CALCUATION

A painstakingly more rigorous method may calculate energy consumption

based on usage pattern which fluctuates with the time of day.

43 BEIT (BUILDING ENERGY INDEX TOOL)

www.acem.com.my Association of Consulting engineers Malaysia

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44 BEIT (BUILDING ENERGY INDEX TOOL)

A simple but effective building energy tool which gives good estimates. The BEIT tool is easy

to use and requires simplification of building model (no drafting of complex 3-D model

required). The BEIT is useful during design development

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45 BEIT (BUILDING ENERGY INDEX TOOL)

Navigate back to ‘Proposed OTTV’

Change back all U values for Glazing

to 5.7.

Navigate back to ‘Input Data’ page

(a) Delete costing for glazing.

(b) Scroll down to 7 ACMV

In Baseline Building we assume ACPU

with CoP of 2.6

In Proposed Building we assume

(mini) chilled water system with CoP

of 3.9

We assume water eff. For proposed

building at 12% (small building)

CASE 3 – USE CHILLED WATER SYSTEM INSTEAD OF ACPU FOR AC

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Navigate to ‘Print Report’ Page

We find a summary of report:

(a) Based on 38sen/kWh

(b) Savings is RM 45,571 per year

(c) For investment of RM 285,000

RoI is 6.3 years

46 BEIT (BUILDING ENERGY INDEX TOOL)

47 ECOTECT

Autodesk – Ecotect

You don’t have a 6-figure budget for a highly sophisticated software like IES

(Integrated Environmental Solutions), Autoesk, Eotect may be the solution for you:

1. Interoperable with Autodesk ACAD software.

2. BIM model in Autodesk Revit can be exported to Ecotect.

3. Relatively simple

Dynamic Energy Model

Thermal Simulation

Sun Path

Shading Device

Natural Ventilations

Wind Directions Study

Acoustic Response

Exportable to (FREE) simulation software:

EPS-r, EnergyPlus

WinAir (CFD)

NIST FDS (CFD smoke)

Radiance / POV Ray 3 r d O c t o b e r 2 0 1 4

48 ECOTECT

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49 ECOTECT – DEVELOPING THE MODEL IN REVIT

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50 EXPORTING REVIT TO ECOTECT GBLXML FORMAT

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51 THE ECOTECT DAYLIGHT MODEL

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52 ECOTECT ENERGY MODEL

0 2 4 6 8 10 12 14 16 18 20 22

00

100000

100000

200000

200000

300000

300000

400000

400000

W

500000

HVAC Load Conduction SolAir Direct Solar Ventilation Internal Inter-Zonal

HOURLY GAINS - All Visible Thermal Zones Friday 6th July (187) - KUALA LUMPUR - MYS, WMO#=486470

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53 ECOTECT ENERGY MODEL

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

00

40000000

40000000

80000000

80000000

120000000

120000000

160000000

160000000

W

200000000

Heating Cooling

MONTHLY HEATING/ COOLING LOADS - All Visible Thermal Zones KUALA LUMPUR - MYS, WMO#=486470

MONTHLY THERMAL LOAD

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54 REVIT AUTODESK SUN PATH SHADOW

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55 DIALUX & LIGHTING

Dialux is a FREE lighting software. Download www.dial.de

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56 DIALUX & LIGHTING

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57 DIALUX & LIGHTING

The following is a simulation of office as shown above. The front part of the

office comprise full glass. Case 1 normal clear glass 70% VLT and case 2

opaque glass 11% VLT

58 DIALUX & LIGHTING

59 EXAMPLE; THERMAL COMFORT

THE MODEL

60 EXAMPLE; THERMAL COMFORT

Bedroom 1

61 EXAMPLE; THERMAL COMFORT

62 EXAMPLE; THERMAL COMFORT

Passive Design Index

63 AIR FLOW CFD

OpenFoam is an opensource CFD

software. However its GUI is difficult. Other

popular software is Fluent, WinAir4 etc.

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Computer Simulation For Building Energy

Efficiency, Module 5 – Computer Simulation

R e v i s i o n 2 ( 3 r d O c t o b e r 2 0 1 4 )

I r . H . P. L o o i ( m e k t r i c o n @ g m a i l . c o m )

B . E n g ( H o n s ) , F I E M , J u r u t e r a G a s

w w w. j k r. go v. m y/ b s e e p

SEMINAR ON PASSIVE & ACTIVE DESIGN

FOR ENERGY EFFICIENT BUILDINGS 3rd October 2014

Holiday Inn Resort, Batu Ferringhi, Penang