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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
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
3 r d O c t o b e r 2 0 1 4
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.
3 r d O c t o b e r 2 0 1 4
3 r d O c t o b e r 2 0 1 4
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.
3 r d O c t o b e r 2 0 1 4
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.
3 r d O c t o b e r 2 0 1 4
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
3 r d O c t o b e r 2 0 1 4
7 RECAPITULATION – BUILDING ENERGY
3 r d O c t o b e r 2 0 1 4
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.
3 r d O c t o b e r 2 0 1 4
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.
3 r d O c t o b e r 2 0 1 4
15 GOOGLE SKETCHUP – PARADIGM SHIFT
3 r d O c t o b e r 2 0 1 4
16 THE BUILDING LIFE CYCLE
Concept Sketch
Visualisation
Architectural
eLibrary
3 r d O c t o b e r 2 0 1 4
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
3 r d O c t o b e r 2 0 1 4
19 TYPES OF SIMULATION
Building Energy
Solar Insolation
Thermal Massing
Air Flow - CFD
Thermal Comfort
Day light Simulation
Lighting Simulation
Façade Modelling
3 r d O c t o b e r 2 0 1 4
20 TYPES OF SIMULATION
3 r d O c t o b e r 2 0 1 4
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
3 r d O c t o b e r 2 0 1 4
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
3 r d O c t o b e r 2 0 1 4
Qin
Tin
(22°C)
23 UNDERSTAND COMPONENTS IN BUILDING ENERGY
3 r d O c t o b e r 2 0 1 4
3 r d O c t o b e r 2 0 1 4
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
3 r d O c t o b e r 2 0 1 4
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
3 r d O c t o b e r 2 0 1 4
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
3 r d O c t o b e r 2 0 1 4
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.
3 r d O c t o b e r 2 0 1 4
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
3 r d O c t o b e r 2 0 1 4
3 r d O c t o b e r 2 0 1 4
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.
3 r d O c t o b e r 2 0 1 4
34
34 BIM – COLLABORATIVE MODELLING
Courtesy of Autodesk
3 r d O c t o b e r 2 0 1 4
35 BIM – COLLABORATIVE MODELLING
Parametric
Information Reuse
Representation
Integration
3 r d O c t o b e r 2 0 1 4
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).
3 r d O c t o b e r 2 0 1 4
3 r d O c t o b e r 2 0 1 4
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.
3 r d O c t o b e r 2 0 1 4
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
3 r d O c t o b e r 2 0 1 4
3 r d O c t o b e r 2 0 1 4
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
3 r d O c t o b e r 2 0 1 4
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
3 r d O c t o b e r 2 0 1 4
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
3 r d O c t o b e r 2 0 1 4
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
3 r d O c t o b e r 2 0 1 4
3 r d O c t o b e r 2 0 1 4
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
3 r d O c t o b e r 2 0 1 4
49 ECOTECT – DEVELOPING THE MODEL IN REVIT
3 r d O c t o b e r 2 0 1 4
50 EXPORTING REVIT TO ECOTECT GBLXML FORMAT
3 r d O c t o b e r 2 0 1 4
51 THE ECOTECT DAYLIGHT MODEL
3 r d O c t o b e r 2 0 1 4
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
3 r d O c t o b e r 2 0 1 4
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
3 r d O c t o b e r 2 0 1 4
54 REVIT AUTODESK SUN PATH SHADOW
3 r d O c t o b e r 2 0 1 4
55 DIALUX & LIGHTING
Dialux is a FREE lighting software. Download www.dial.de
3 r d O c t o b e r 2 0 1 4
56 DIALUX & LIGHTING
3 r d O c t o b e r 2 0 1 4
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.
3 r d O c t o b e r 2 0 1 4
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