Dynamic Simulation Modelling

Presented by: Declan Alcock MSc MIEI 20th May 2014

Varming International Alliance

Dublin London Sydney Copenhagen Hong KongCork Edinburgh CanberraRoscommon

La Grande ArcheParis

Tate GalleryLondon

The British Library London

Opera HouseSydney

Government BuildingsDublin

AMNCH Tallaght HospitalDublin

Background

Project Director (Sustainability) - VarmingMSc Energy & Sustainable Building DesignCertified European PassivHaus DesignerIES level 3&4 Energy AssessorNon-Domestic BER AssessorDisplay Energy Certificate (DEC) Assessor

15 years experience in Sustainability in the Built Environment.Project Analysis on 150+ projects

Director Engineers Without Borders (EWB-Ireland)www.ewb-ireland.orgMember of Engineers Ireland BIM Working Groupwww.engineersireland.ieMember of CITA Skillnet Steering Committeewww.cita.ie

Overview

Building Design Process

Site Optimisation

Climate

Location

Solar

Light

Visualisation

Planning

Building Form

Building Fabric

Renewable Potential

Carbon Footprint

Sustainability Concept

Design Concept

LCC Comparison of options

Concept Detailed Design

Plant Loads

Daylight

Air flow

Renewable Energy

CFD Studies

Energy Compliance

Sustainability Compliance

Analysis

Daylight

Ventilation

Overheating

Indoor Air Quality

BER

BREEAM

Lifecycle Costs

BIM Environment Dynamic Simulation Modelling

Building Performance Analysis

Sustainable Building Design and Simulation• Sustainable Building Design requires an understanding of how a building

will perform which in turn requires computer-based simulation software for building analysis.

Dynamic thermal simulation can provide• Insight into energy use• Environmental performance impact• Thermal comfort analysis• Life cycle costing information

Design Process• Iterative by nature • Room functions and adjacencies change• Model follows building geometry changes.

Building Performance Analysis

Simulation Modelling• Time consuming • Detailed data input for model• Long simulation times

Implications / Limitations• Need for remodelling• Running repeat simulations• Post processing of results• Interpretation & reporting on models • Requires training and experience • Accurate detailed outputs not available until detailed design stage

• Significant proportion of fee can be expended in model preparation

• At what stage should dynamic simulation be undertaken in order to minimise duplication of effort and avoid abortive design time?

Source: IES Ltd.

Building Information Modelling

Civil/Site ModelArchitectural Model

Structural Model MEP Model

3D Coordination

4D Sequencing

5D Cost Control

6D Sustainability

Analysis

7DFacilities Management

BIM for Architecture

BIM is a process, not a software package.

• Architecture• Autodesk Revit Architecture• Graphisoft ArchiCAD• Nemetschek Allplan Architecture• Gehry Technologies – Digital Project Designer• Nemetschek Vectorworks Architecture• Bentley Architecture• 4MSA IDEA Architectural Design (IntelliCAD)

BIM for Sustainability

• Sustainability• Autodesk Ecotect• Autodesk Green Building Studio• Graphisoft Eco Designer• IES Virtual Environment (VE-Pro)• Bentley TAS, • Bentley Hevacomp• Design Builder• Vasari

Building Performance Analysis – IES VE-Pro

Detailed Design Stage Analysis - IES Virtual Environment (VE-Pro)

• Most commonly used software• Knowledge and confidence in use• Can model systems and control strategies with accuracy

• Temperature, C02, humidity set points etc• External and internal conditions

• Provides a high degree of control over inputs• Can Interrogate the model and results in detail

Early Stage Analysis – Vasari, IES Toolkits

The choice of software depends on the required output, level ofaccuracy and stage of project

Range of Outputs from Dynamic Simulation Modelling

Thermal Analysis

CFD Analysis of ventilation options

<VE> Model

Solar Shading Analysis

00:00 06:00 12:00 18:00 00:00

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ture

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Gain (kW

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CO

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pm)

Date: Thu 19/Jul

Dry resultant temperature: L00_Classroom 3 (temp and co2 annual.aps) Solar gain: L00_Classroom 3 (temp and co2 annual.aps)

Room CO2 concentration: L00_Classroom 3 (temp and co2 annual.aps)

Daylight Analysis

Building Regulations Visualisation

Site Optimisation

• Maximise winter solar gains to reduce heating demand.

• Minimise summer solar gains to avoid overheating.

• Evaluate the effect of self shading and shading from surrounding buildings.

• Optimise location of ventilation openings.

Solar Overheating

TGD L 2008 - Avoiding Solar OverheatingNatural Ventilation;Show that in the absence of mechanicalcooling or mechanical ventilation, the spacetemperature will not exceed 28°C for more than 1% of the period of occupancy.

Mechanical Ventilation;To ensure spaces that incorporate mechanicalventilation or cooling do not require excessive plantcapacity to maintain the desired space conditions.

Show that the average daily solar heat load per unitfloor area during the period of occupancy would notbe greater than 25 W/m2.

Solar Overheating Evaluation

20%30%25%Sixth

20%16%32%Fifth

16%10%20%Fourth

13%13%Third

Second

First

Ground

WestEastSouthNorth

0.220.220.220.32Sixth

0.250.280.220.32Fifth

0.280.280.250.32Fourth

0.280.320.280.32Third

0.320.320.320.32Second

0.320.320.320.32First

0.320.320.320.32Ground

WestEastSouthNorth

G-Value requirements

% Solid construction requirements

Airflow Modelling

Macroflo• Calculates wind and buoyancy driven air flow.

CIBSE Guide A (also quoted in Part L of IrishBuilding Regulations)• Space temperature should not exceed 28°C for

more than 1% of the annual occupied hours.

Dept of Education (taken from BRE “office ofthe future” report)• The dry resultant temperature should not

exceed 25°C for more than 5% of the school year in all habitable rooms and teaching spaces.

Mon Tue Wed Thu Fri Sat Sun Mon

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Vol

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flow

(l/s

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Speed (m

/s)

Date: Mon 19/Sep to Sun 25/Sep

MacroFlo external vent: STFR-01-Staff Room (latest rooms.aps)

Wind speed: Dublin89.fwt (Dublin89.fwt)

Macroflo controls

Example Macroflo Controls

Manual OpeningBetween 8am and 6pm:(ta>23|co2>1000)

Automatic OpeningBetween 8am and 6pm:ramp(ta,22,0,23,1) | gt(co2,1000,700)

Night CoolingBetween 8am and 6pm:ramp(ta,22,0,23,1) | gt(co2,1000,700)

Between 10pm and 2am:(ta>18) & (to>12)

Thermal Mass with Night Cooling

00:00 02:00 04:00 06:00 08:00 10:00 12:00 14:00 16:00 18:00 20:00 22:00 00:00

2.01.5

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-1.0

-1.5-2.0

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Gai

n (k

W)

Date: Tue 20/Jun

3 (exposed slab night cooling.aps)

3 (ceiling tiles daytime vent.aps)

00:00 02:00 04:00 06:00 08:00 10:00 12:00 14:00 16:00 18:00 20:00 22:00 00:00

343230282624222018161412

Tem

pera

ture

(°C

)

5.04.54.03.53.02.52.01.51.00.50.0

Gain (kW

)

Date: Tue 20/Jun

Dry resultant temperature: _ (exposed slab night cooling.aps)

Dry resultant temperature: _ (ceiling tiles daytime vent.aps)

Solar gain:

Internal gain

Conduction gain - roof:

Conduction gain - roof:

Thermal mass is used to reduce peak cooling demands and stabilise internal radiantand air temperatures.

Evaluating Indoor Air Quality

Methodology• CIBSE AM10 recommends using CO2 concentration as an indicator of indoor air

quality (IAQ) to show that the required ventilation rate is being achieved. • This is done by showing that the IAQ achieved by the natural ventilation strategy

is equivalent to that provided using a constant ventilation rate of 10l/s/p duringoccupied hours.

• Based on Pettenkofer Treshold

Mon Tue Wed Thu Fri Sat

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CO

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ncen

tratio

n (p

pm)

Date: Mon 13/Mar to Fri 17/Mar

Room CO2 concentration: 00-GENERAL CLASSROOM 02 (am10 windows.aps)

Room CO2 concentration: 00-GENERAL CLASSROOM 02 (am10 constant.aps)

Computational Fluid Dynamics

Numerical simulation of air flow and heatprocesses occurring within and aroundBuilding.

Enables the designer to gain greaterunderstanding of the effectiveness of theventilation strategy.

Includes the effects of;• Climate• Internal energy sources

(occupants, lights, equipment)• HVAC systems

Microflo CFD – Computer Room

Sydney Opera House – Auditorium CFD

Sydney Opera House – Auditorium CFD

Daylight and Glare Analysis

Radiance is used to visualise the interaction ofnatural and artificial light through ray tracing.

• This allows the levels and uniformity of daylight to be accurately evaluated and the risk of glare to be established.

• This information can be used in conjunction with DSM to model the benefits of daylight controlled lighting.

Daylight Dimming• Ramp(e1,0,1,300,0.4)• Modulates the lighting gain as a function

of the available illuminance on the working plane at sensor e1.

Energy Analysis – MVEC Multi-User Campus

Monaghan VEC Education Campus2490m2 Primary School3978m2 Post Primary School7042m2 Further Education Institute1325m2 Sports Hall1940m2 Theatre

Passive FeaturesNatural VentilationEnhanced InsulationAirtightness < 3m3/h/m2@50Pa

Active FeaturesLighting Controls (Dimming & PIR)Monitoring and Targeting

Energy Analysis – MVEC Multi-User Campus

Comparison of Options• Solar Water Heating• Photovoltaics• Ground Source Heat Pumps• CHP• Wind Power• Biomass District Heating

Cost saving of 50% per year410 Tonnes of CO2 per year

Energy and Carbon

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Energy Efficiency Options

Energy (kWh/m2/year) 279 218 206 194 181 157 151 149

Carbon (kgCO2/m2/year) 63 48 46 43 40 36 34 33

Base Case

Option 1 Option 2 Option 3 Option 4 Option 5 Option 6 Option 7

BIM Model

Ecotect Wind Tunnel

Ecotect Sun Path

Ecotect Solar Radiation

Early Stage BIM Analysis using Vasari

Early Stage BIM Analysis using Vasari

Ecotect Sun Path

Ecotect Solar Radiation

Vasari Mass Model

Ecotect Solar Radiation• Radiation on different facades and levels• Likelihood of glazing requirements and

positioning of solar panels• Maximise solar potential• Optimise Glazing ratio and location

Ecotect Sun Path• Shows shading of building from adjacent

structures and planting• The effect on neighbouring buildings

Site Optimisation Using Vasari

Ecotect Wind Tunnel

• Quick visual representation of wind wake and tunnelling• Identifies implications for pedestrian comfort

Vasari Comparative Analysis

• Quickly compare options for;– Building Orientation– Building form– Envelope– Glazing (% and location)– Passive Strategies (Daylight, natural vent)– HVAC Systems

• Indicative comparison of:– Energy– Fuel– PV Potential

• Helps communicate the design to client and design team

Comparative Analysis using Vasari

BIM Based Analysis Tools

Objectives and Limitations

Key Objectives• Obtain quick response to design options• Seek to influence and direct early stage building design. • Identifyy areas for final validation and fine tuning• Produce early documentation for code compliance• Promote inclusive design team collaborative working

Main Limitations and Barriers • Needs to rely on generic inputs for the analysis of systems, fabric and

occupancy for use• Performed at Concept Stage and leads only to indicative evaluation

BIM Based Analysis Tools

Impact on Building Performance Analysis

• Provides easy method of bringing forward the investigation of alternative design strategies to an earlier stage of the design process.

• Can perform basic analysis with a simple mass model• Eliminates the requirement for importing and exporting between separate

software packages and building of separate models for each analysis• Guides the design team in assessing the implications of alternative design

options• Provides a more cost effective method of model building by beginning in

BIM before exporting from BIM to DSM

Exporting from BIM to DSM

Potentially can achieve a more efficient workflow

Traditional Workflow

Streamlined Workflow

Exporting from BIM to DSM

The Green Building XML (gbXML) schema• Facilitates transfer of building properties stored in BIM

to engineering analysis tools. • Has the support of leading 3D BIM vendors.

Industry Foundation Classes (IFC)• IFC is the international standard for openBIM• As an open format, IFC does not belong to a single

software vendor; it is neutral and independent of a particular vendor’s plans for software development.

BIM model needs to be developed with its workflow considered.• Architects model constructed to represent the final

building early on in the cost process.• Energy model requires less complex geometry and

objects.

Not a seamless process yet!!

gbXML import to IES VePro

Revit 2014 Architectural Model

gbXML import to IES VePro

Revit 2014 Architectural Model IES gbXML import

IES gbXML import

IFC import to IES VePro

IFC import to IES

Exporting from BIM to DSM

Architects ModelConstructed to meet the design and contractdeliverables and represent the final building earlyon in the cost process.

• Architects model at concept or early design stage is too complex to import to IESVE

• L100 – geometric object – no properties• L200 – geometric object basic properties• L300 – detailed design• L400 – installation object• L500 – manufacturers or as fitted object

Revit File sizes are large- they can be up 250 MbThe GBXML export will be larger than the limitthat IES can accept – ie 2.5 Mb

Exporting from BIM to DSM

Dynamic Simulation Model Requirements;Simpler less complex geometry, i.e. a Level 100object, not a level 300 to 500 object

• Construction properties relevant to the calculation – i.e. u values/SC applied to all constructions.

• Glazing in the correct location – recesses clearly identified

• Rooms and ceiling voids defined correctly

• Define walls and roofs shading contribution in a manner which is recognised by IES.

Building Regulations Compliance / Energy Analysis

TGD Part L of Building Regulations 2008

SBEM (Simplified Building Energy Model)• Steady State Calculation• Monthly average weather data• Monthly Energy and Carbon Data

DSM (Dynamic Simulation Modelling)• Dynamic Thermal Simulation at 6min intervals• Hourly real weather data• Hourly Energy and Carbon Data• Solar shading & bulk airflow• Thermal storage of fabric

DSM more accurate, only SBEM accredited in Ireland

Energy Analysis/ Building Energy Rating

Compliance Calculation

Includes regulated energy use• Heating• Hot Water• Cooling• Lighting• Ventilation• Fixed occupancy and operating hours

Does not include unregulated energy use• ICT (servers, telecoms etc)• Small power• Lifts, medical equipment etc• Extended operating hours or occupant density

Energy Analysis - The Performance Gap

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Car

bon

Emis

sion

s - k

gCO

2/m2 /y

ear

General Office Schools UniversityCampus

Hospitals

Sectors

The Performance Gap

PredictedActual

62%55%

128%

124%

Energy Analysis - The Performance Gap

Causes of The Performance Gap

Use of Simplified Models• Assumptions at early stage• Simplified Calculation

Building changes during Design Process• Building fabric, extent of services and controls• Workmanship• Hours of Operation

Occupants• Uncertainties associated with occupant behaviour

Commissioning, Controls, Energy Management• Control of building systems

IES Research Projects

IESVE IMPACT• Materials selection• Lifecycle Costing (LCC)• International BREEAM Assessments• Connection of BIM and IES Models

VE-SCAN• Actual recorded information from operational

building data.• Compares simulated and actual energy

consumption.

EINSTEIN• Predictive analysis taking account of future

weather predictions and occupant use.

Conclusions

The BIM paradigm can accommodate earlier building performance analysisinput but is not suited to using Dynamic Simulation Modelling software fordetailed analysis at Concept Stage.

However, during early planning and concept stages, the opportunity exists forresults obtained from BIM based comparative analysis to evaluate thefeasibility of design concepts, allowing earlier engagement with the designand documentation process.

At detailed design stage Dynamic Simulation Modelling can then be used in acost effective manner for the testing, validation, fine-tuning and incorporationof design features established earlier.

In future there is potential for Dynamic Simulation and BIM models to be usedfor post-occupancy energy monitoring and predictive evaluation of futureweather scenarios.