Download Building Performance Simulation

Building
Performance
Simulation
Bojan Andjelkovic, P.Eng. LEED® AP
Power Smart ENGINEERING
October, 2007
Some Building Facts
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Buildings annually consume more than 40% of the total
energy and more than 71% of the electricity used
in the U.S.
Energy Use in Buildings
¾ “..is the single greatest environmental
impact of a building..!”
¾ 50% for HVAC and Lighting
Energy Use of HVAC Systems
¾ 35% for Space Heating, Cooling &
Ventilation Loads
¾ 65% for Energy Transport – “Parasitic Losses” !!
Indoor Air Quality (IAQ)
¾ Majority of us spend 90% of our time indoors
¾ Indoor pollutant concentration is typically higher
> than corresponding outdoor pollutant level !
¾ “Sick Building Syndrome”
Building Energy Consumption
Total - US Energy
Consumption
40% - Building
Energy
Consumption
Rocky Mountain Institute
More facts …
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Developers and investors typically want fast, cheap buildings.
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Few mechanical consulting companies perform building performance simulations, even though
they cost only 0.1 – 0.5% of project cost for most commercial office space.
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Usually building owners try to avoid unnecessary design cost, but pay much more later for
increased maintenance and energy use.
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The opportunities for energy savings are largest at the conceptual design stage.
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Just proper choice of architectural form, envelope, and orientation can often save upwards of a
third of the building‘s energy at no extra cost.
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Being unfamiliar with critical building loads (often “not yet known”), the mechanical designer is
likely to guess high or “round up” when in doubt: nobody ever got fired for making a mechanical
system too big.
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Oversizing, with safety margins of 50 to 100 percent, is wholly inappropriate for HVAC systems
and leading to, not only increased capital and energy costs, but also to increased maintenance
cost.
Source: A. B. Lovins, "Energy -Efficient Buildings: Institutional Barriers and Opportunities"
Smart Alternative
• Building performance simulation
• as an integral part of
• Integrated design process
Naming
Building Performance Simulation
Building Energy Analysis
Whole Building Simulation
Building Modeling
Energy Modeling
Dynamic Thermal Simulation
Heating / Cooling Load Calculation
Definition
The shortest definition of building performance simulation:
Using a (computer) model (= virtual building) to predict
what will happen in the real world.
It allows design team to accurately assess various “what-if” scenarios during all
building design stages, optimize and integrate different systems (such as
lighting and HVAC) and explore synergies between them.
Building Performance Simulation Software
VisualDOE
4.0
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ESP
-r
Ecotect
EDSL
Tas
IES <VE>
TRNSYS
TRACETM 700
HCC-V
HAP
ASHRAE Standard 140 - 2004
IES <Virtual Environment> Modules
Interoperability
Autodesk
Applications
2D CAD
Drawings
3D Studio Viz
REVIT
gbxml
Consulting
Methodology – 3D Model
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Plan and create 3D Model – using
architectural 2D or 3D drawings
and inputs from Architects and
Engineers.
Detailed Solar Shading Analysis
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It can be used at the earliest stage of the design process to optimize site orientation, obtain
solar shading information for each external and internal surfaces.
Passive solar shading features modeling
Detailed Solar Shading Analysis
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Can display shadows over any day of the year to find hot-spots and decide on
where shading could be most effectively applied.
Detailed Solar Shading Analysis
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Perform solar geometry studies on a building and its site.
Detailed Solar Shading Analysis
Sun Shading – SW – September 21. – Zoomed In
Note:
Some walls and ceilings
have been made invisible
for better observation of
the interior sun shades
Detailed Solar Shading Analysis
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How the Sun sees the building…
3D Lighting Simulation – Radiance
Lux Levels on September 21, at 16:30 (Sunny)
3D Lighting Simulation – Radiance
Lux Levels on September 21, at 16:30 (Cloudy)
3D Lighting Simulation – Radiance
Lux Levels on September 21, at 16:30 (Cloudy)
-Lighting is ON-
3D Lighting Simulation – Radiance
September 21, at 16:30 (Sunny)
Glare Analysis
Day Lighting Simulation – Radiance
Day lighting image of a whole building 6th floor – The actual building is shown on upper right side.
Simulated day: June 21, at 12:00 (Sunny)
Day lighting image of a whole building 6th floor.
The green colour represent areas where daylighting criteria has not been met.
Concept Design – Building Shape Analysis
Common building parameters:
- Total floor area: 13000 m2
- Glazing percentage: 29% of the total wall area
Option 1
Option 2
Option 3
Dynamic Thermal Simulation
• What does Dynamic Thermal Simulation do?
¾ Heat Transfer Calculations in 3D:
‣ conduction, convection, radiation calculations using hourly
weather data to produce a multitude of results, such as:
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peak heating load
peak cooling load
heating energy
cooling energy
solar gain
infiltration / ventilation
internal gains
frequency of internal /
external temperatures
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dry bulb temperature
resultant temperature
mean radiant temperature
surface temperatures
humidity
ACH
aperture air flows
building heat transfer
and much more…
Graphical Display of Indoor and Outdoor
Conditions
Graphical Display of Indoor and Outdoor Conditions –
Natural Ventilation
The diagrams below represent thermal comfort comparison between reference and proposed building for not very hot
summer day (outside air parameters are suitable for natural ventilation).
ASHRAE Reference
Proposed EBP Building
Room cooling load and CO2 level
are much lower in comparison with
reference case.
Natural ventilation is ON.
Outside air parameters are
within usable limits.
Natural Ventilation Stack Simulation
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Comfort Check (People Dissatisfied)
Note:
In the reception area there are 225 hours per year where
at least 35% of the population will be uncomfortable. The
worst condition in the North Office is 1 hour with 27.5% of
the population uncomfortable.
Detailed HVAC Plant Modeling/Simulation
Application areas:
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Example: Dynamic simulation in one typical VAV system with
economizer and multiple zones
HVAC system
design
Component
sizing
HVAC control
design
Mixed mode
system design
Energy
consumption
prediction
Dynamic
humidity
modeling
Air Flow Analysis (CFD Simulation)
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What does CFD simulation do?
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Computational Fluid Dynamics (CFD) simulation is numerical
simulation of air flow and heat transfer. It gives building
designers information they need for detailed prediction of air
flow and heat transfer processes in and around building
spaces – taking into account boundary conditions such as
effect of climate, internal energy sources and HVAC
systems.
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CFD software simulates internal and external air flows,
enabling us to address design issues such as:
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Predicting occupant comfort
Optimize supply grille placement
Investigating natural ventilation and
mixed mode ventilation
Analysing outdoor wind flow effects
Methodology – CFD Thermal Comfort Simulation
Detailed 3D model
CFD simulation
Detailed solar
shading calculation
Dynamic thermal simulation
Advanced Thermal Comfort and Air Flow Simulation
- Figure 1
Air temperature distribution for a
Conference Room with UFAD
system (with radiant cooling
panels turned on).
This analysis helped the design
team to optimize size and location
of radiant cooling panels.
- Figure 2
Air temperature distribution for
the same Conference Room with
UFAD system (with radiant
cooling panels turned off).
The effect of radiant cooling
panels is obvious.
Advanced Thermal Comfort and Air Flow Simulation
- Figure 3
Air temperature distribution at ankle
level for a Conference Room with
displacement system (with radiant
cooling panels turned on).
This analysis helped the design
team to optimize location of
displacement diffusers, as well as
supply air temperature.
- Figure 4
Air temperature distribution for an
university office room with
displacement system and active
radiant heating panel.
The analysis has shown that
S/A t-re of even 65°F (18°C)
provides acceptable thermal
comfort in occupied zone.
Conference Room (CFD) Simulation
Animation of air temperature distribution for Conference
Room - displacement system and ceiling radiant cooling panels
Operating Room (CFD) Simulation
Temperature distribution with ceiling
laminar diffuser configuration
Temperature distribution with air curtain
and laminar diffuser configuration
Hospital Examination Room
Air Temperature Distribution in Cooling Mode
Overhead system
Displacement system
Hospital Examination Room
Air Velocity Distribution in Cooling Mode
Overhead system
Displacement system
Hospital Examination Room
Air Particle Paths in Cooling Mode
Overhead system
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Arrows designate source of the particles
Displacement System
Lecture Theater (CFD) Simulation
Temperature distribution for 200 seats Lecture Theater –
displacement ventilation system with radiant cooling ceiling panels.
Energy Analysis
Hospital Research Project
Energy analysis
Economic Analysis
• Usually building performance simulation programs can:
• Provide a comprehensive value engineering approach to
building design. Uses a range of building performance
indicators to compare different design options at any stage of
design process.
• Perform customized capital cost estimates.
• Perform LCC analysis (take into account operating costs of a
building over its life time).
Power Smart High Performance Building (HPB) Program
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Provides incentives, tools and recognition to help developers and their design
teams to design and create better, more energy efficient buildings.
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Encourage building performance simulation as an integral part of integrated
design process.
Where is the Future of Building Technology ?
• Sustainable Design
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Focus on Energy Efficient Building Design
Maximize the Use of Passive Building Elements
Shape, Layout, Orientation, . . .
Thermal Mass
External Shading
Cooling by Natural Ventilation
Integrated Design
• Thermal Comfort Control & IAQ
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Temperature Control
Radiant H&C
Ventilation
Displacement Type & Natural
“The more information you have, the more creative you can be.”
John Gibson, AIA
Thank you for your attention