Daniel Coakley of IES spoke on the topic of “Modelling Natural ventilation in the IESVE: Case studies & Research Outlook” at a half day seminar on 20th April 2016, organised by Cork Institute of Technology (CIT), for researchers, designers, engineers & architects.

1. Modelling Natural Ventilation in IES-VE:
Case studies & Research Outlook
Daniel Coakley BE PhD CEM MIEI MEI
Research Fellow, Integrated Environmental Solutions Ltd.
Adjunct Lecturer, National University of Ireland Galway (NUIG)
Secretary, ASHRAE Ireland
Technical Seminar: Ventilative Cooling & Overheating , April 20, CIT, Cork

2. Structure
• Introduction to IES
• Nat Vent Simulation in IES-VE
• ASHRAE ‘Zero-Net Energy’ (ZNE) Challenge
• Research outlook: Building Operations

3. IES Background
• Founded 1994 with HQ in Glasgow;
• Offices in UK, Ireland, USA, India;
• Delivering sustainable solutions from building to city-scale;
• Main software:
– IES-VE (Building simulation)
– IES-SCAN (Building operations)

4. IES-VE Software
Building Performance Analysis Technology
- Traditionally our focus was on creating
analysis tools for building design.
- Our tools now encompass a bigger picture
of the built environment allowing for
analysis on a bigger scale (e.g. city or
community level) and at different building
life stages.
- Understanding and analysing ‘real’ data at
the Building Operation stage can drive
actions which:
- Improve occupancy comfort.
- Reduce energy use & CO2.
- Reduce costs

5. IES SCAN / ERGON
ERGON - Import,
manage and interrogate
real building data /
schedules and use them
inVE simulations.
IES-SCAN is a
customisable web based
portal and integrated
data environment for
operational data analysis
complete with capability
for energy forecasting,
simulation

6. NAT-VENT SIMULATION IN IES-VE

7. Nat Vent Simulation Studies
• Assess occupant comfort conditions (PMV) with respect
to air temperature, velocity, air quality etc.;
• Demonstrate energy / cost savings by reducing need for
mechanical ventilation / cooling;
• Minimise overheating risk;
• Analysis of effectiveness of various ventilation
strategies, based on location / climate:
– Natural, Mechanical or Mixed-mode strategies;
• Evaluate feasibility of designs such as:
– Single-sided ventilation, DSF, cross-ventilation, whole-building
ventilation, Conventional systems, Displacement, Buoyancy, etc.;
– Novel performance components – PCM, Solar collectors,
Windcatcher etc.

8. Relevant Modules
Key IES-VE Simulation modules:
• MacroFlo – Simulate bulk air-flow driven
by wind pressure and buoyancy forces
using a fast multi-zone thermo-fluid solver;
• MicroFlo – CFD analysis engine for internal
/ external air flow studies;
• ApacheHVAC – detailed HVAC design and
analysis;
• ApacheSim – dynamic thermal simulation
for building performance and load
forecasting;
• VistaPro – results visualisation and
analysis engine.

9. MacroFlo
Incorporates models of:
• external wind pressure based on empirical
data;
• stack effect (buoyancy);
• flow characteristics of cracks / large
openings;
• two-way flow;
• resistance due to grilles and wall friction;
• Rayleigh instability.
Inputs:
• Building geometry & constructions;
• Opening properties (e.g. wind exposure,
free opening area etc.)
• Weather data (wind speed, direction etc.)
• ApacheSim / HVAC information;
• ERGON profiles (if required)
Outputs:
• Air-flow mass / volume for openings;
• Air-flow velocities;
• Aggregated room / zone level air flows etc.

10. MicroFlo
Features
• Air flow and heat transfer in and around buildings;
• Simulate both internal and external air flow and
thermal problems;
• Pre-set initial conditions for quicker convergence;
• Discretisation options: Upwind (default), Hybrid
and Power Law;
• A simulation monitor enables you to run, pause
and re-start calculations.
Inputs:
• Boundary conditions (Air / surface
temperatures, mass-flows, gains etc.)
• Surface object properties (e.g. grilles);
• Shading surfaces (e.g. buildings,
topographical etc.)
• CFD components (e.g. Radiators, air heat
source)
Outputs:
• internal air flow temperature, direction and
velocity
• external air flow direction and velocity
• external static pressure

11. VistaPro result Visualisation
• Visualisation and analysis (Post-processing);
• Room and Node state display
• HVAC process display
– Sensible cooling & heating,
– Humidification and heating
– De-humidification and cooling
– Adiabatic mixing, cooling
• Time stepping
• Comfort Zones
• State frequency provides a very powerful
visual overview of a node’s air conditions for
a given date

12. Performance Components
• Pre-built manufacturer assemblies imported
to the Virtual Environment, providing a mix of
geometry and thermal data as per
manufacturer specification
• Components fall into three distinct categories:
– Object – placed within rooms (e.g. CFD heat source,
Monodraught CoolPhase)
– Space – part of the building model geometry (e.g.
Windcatcher)
– Panel – placed on a surface (e.g. ActiMass activated
concrete thermal mass)

13. ASHRAE NET-ZERO ENERGY CASE STUDY
Credit to Liam Buckley (IES) and the ASHRAE IES ZNE Team

14. 5,000 m2 (53,600 ft2), 3- storey commercial office:
• Minimum window-to-wall ratio: 30%
• Minimum Energy Code: ASHRAE 90.1-2010
• Maximum Site Energy Use Intensity (EUI): 0
• Occupants: 268
• Minimum ventilation: ASHRAE 62.1-2007
• Plug loads: 8 W/m2 (0.75 W/ft2)
• Occupied Heating Setpoint: 21°C (70°F)
• Occupied Cooling Setpoint: 24°C (75°F)
• Data Centre Load: 6 kW
• Elevators: 2 Elevators in Core of Building
• Service Hot Water: 1 gallon/day/person
• Utility Rates: US-EIA Flat rates
• The use of one design tool
ASHRAE ZNE Challenge

15. Zero-Net Energy Design Model
The Design Team’s Meetings
• Realistic design in a challenging climate
• Boulder, Colorado
• TMY15 (2000-2014)
• -4° to 93°F [-20 to 34oC] ext. dry bulb
• 6% to 100% ext. RH
• Large diurnal swings (30°F)

16. Zero-Net Energy Design Model
Early Baseline EUI Target
• Baseline EUI: 33 kBtu/ft2/yr
• Renewables: 20 kBtu/ft2/yr
• Target EUI Reduction: 13 kBtu/ft2/yr

17. Zero-Net Energy Design Model
The Final Architectural Design • New Baseline EUI: 53 kBtu/ft2/yr
• Renewables: 20 kBtu/ft2/yr
• Target EUI Reduction: 33 kBtu/ft2/yr

18. Zero-Net Energy Design Model
60 Second Virtual Tour of The Final Architectural Design

19. Zero-Net Energy Design Model
Solar Shading & PV-T Optimization
• Limit Solar Gains in Summer
• Maximize Solar Gains in Winter
• Maximize PV-T Potential
Incident Solar Radiation:

20. Zero-Net Energy Design Model
Renewable Wind Energy
• Net Zero Goal – More Renewables!
• Building shape funnels wind (+3ft/sec)
• Wind = power
• PV-T Panels
• PV-T and waste heat combo
• Payback <5 years
Predominant Westerly Winds

21. Zero-Net Energy Design Model
ECM: Natural Ventilation and Adaptive Thermal Comfort
• Run Natural Ventilation simulations with operable windows/vents; overheating.
• Relocate printer stations & coffee stations to north office areas. Re-evaluate.
• Utilize summertime diurnal swing and night-purge.
• Expose thermal mass of internal floors.
• No offices above 25°C for 5% of
occupied time (104 hours/year).
• No offices above 27°C
for 1% of occupied
time (21 hours/year).

22. Zero-Net Energy Design Model
• Diurnal Swing ~ 30 degrees.
• Summertime heating setpoints were relaxed to
(65°F/58°F) in cooling season.
• Analysis of operative temperature:
ECM: Natural Ventilation and Adaptive Thermal Comfort
Outside Dry-Bulb
Temperature (°F)
Effective Night Purge Control (11pm-3am)
PPD (%) Snapshot:

23. Zero-Net Energy Design Model
ECM: Natural Ventilation and Adaptive Thermal Comfort
• Internal Operable Windows to Atrium
• Atrium is Negatively Pressurized.
Temp.OP (°F) Snapshot: 60-80°F PPD (%) Snapshot: 0-20%

24. Zero-Net Energy Design Model
• Proof of Concept:
ECM: Atrium Design

25. Zero-Net Energy Design Model
Adaptive Thermal Comfort in the Offices
• Office Cross-Ventilation in Summer • Office Cross-Ventilation in Spring/Fall
• Warm air rising and mixing. • Cool air falling, but radiant floor eliminates cold
draughts at ankles.
During winter, preheated OA is mechanically supplied to spaces.

26. Zero-Net Energy Design Model
Future-Proofing the ZNE Status
• WeatherShift morphed the weather file 50 years.
• (2000-2014) to (2046-2065).
• Projected EUI improved!?!
• Warmer Winters
• Warmer Summers
• 1,500 more hours between 60-75°F
• Internal Adaptive Comfort Ranges were uncomfortable.
• Some cooling is required

27. Zero-Net Energy Design Model
Future-Proofing ECM: Passive Down-Draught Evap. Cool Tower
Moisture
Content
Added
Air
Temperature
Decreased

28. Zero-Net Energy Design Model
Thank You – Questions/Comments

29. Research Outlook

30. EINSTEIN Project
• EINSTEIN: Simulation Enhanced Integrated
Systems for Model-based Intelligent Control(s)
• Funding: EU-funded Marie Curie IAPP Project
(3 years)
• Partners: IES and TCD
• Topics
– Fault Detection
– Prediction
– Optimisation
– Overall system integration

31. Fault Detection
– Knowledge / Rule-based:
uses expert user
experience
– Data-driven: uses
historical building data,
Statistical Methods,
Empirical Data, Machine
Learning
– Model-based; uses a
calibrated detailed system
model

32. Prediction / Optimisation
• Multi-objective control optimisation;
• Complies with user-specified
constraints (e.g. comfort);
• Fault-tolerant control;
• Integrates predicted weather
conditions, building thermal response,
occupancy and economics (i.e.
electricity / gas tariff);

33. Overall Integration
Building Data
IES-SCAN
Modelling /
Prediction
Fault Detection
/ Optimisation
Intervention
(DSS / Controls)

34. Useful Links
IES-VE Software
• MacroFlo: https://www.iesve.com/software/ve-for-engineers/module/MacroFlo/462
• MicroFlo: https://www.iesve.com/software/ve-for-engineers/module/MicroFlo/463
• DiscoverIES Blog: https://www.iesve.com/discoveries/
ASHRAE Lowdown Showdown Case Study
• CIBSE Article: http://www.cibsejournal.com/technical/down-to-zero-winner-of-ashrae-modelling-
competition/
• IES Blog: http://blog.iesve.com/index.php/2015/10/14/the-ashrae-lowdown-showdown-we-won/
• LowDown Showdown Video Overview: https://www.youtube.com/watch?v=xsbms0uB6w8

35. Thank you!
Daniel Coakley BE PhD CEM MIEI MEI
Research Fellow, Integrated Environmental Solutions Ltd.
Adjunct Lecturer, National University of Ireland Galway
Secretary, ASHRAE Ireland
Email: daniel.coakley@iesve.com
Web: www.iesve.com
Technical Seminar: Ventilative Cooling & Overheating , April 20, CIT, Cork