Presented at Technical Seminar: Ventilative Cooling & Overheating Risk - Cork Institute of Technology, 20th April 2016 This half day seminar for researchers, designers, engineers & architects, is organised in collaboration with IEA-EBC Annex 62 and will present state of the art in utilising ventilation for reducing cooling energy demand and addressing the risk of overheating in low energy buildings. The presentation focuses on natural ventilation modelling features in the IES-VE Virtual Environment and case study of the application of some of these features as part of the ASHRAE LowDown ShowDown Competition 2015.

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