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SimScale to IES for Building Simulation

SimScale teams up with Greenlite, a provider of regulatory and building analysis services, to explore how cloud-based CFD software can be used by engineers and architects to quickly and accurately calculate wind pressure coefficients for projects in the built environment. Importing simulation files into IES and thermal modeling tools gives designers an extra advantage to evaluate ventilation and possible overheating.

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SimScale to IES for Building Simulation

  1. 1. SimScale to IES (VE) for Building Simulation
  2. 2. We created the world’s first cloud-based engineering simulation platform. ● Fluid dynamics (CFD) ● Solid mechanics (FEA) ● Thermodynamics All accessible via a web browser. About SimScale What we do
  3. 3. Building physics and compliance consultancy. ● Thermal modelling ● Overheating risk analysis ● HVAC design and optimisation ● Part L, BREEAM, SAP, Passivhaus We work with consultants, contractors, and architects. About Greenlite What we do
  4. 4. Simulation Tools for the Built Environment SimScale to IES (VE) for Building Simulation
  5. 5. Simulation Tools for the Built Environment ANALYSIS TYPE SOFTWARE TYPE OUTPUTS CAD/BIM TOOLS Energy (whole building) Dynamic, time-series, climate file Zone level, single point, assumptions Loads (heating, Cooling) Dynamic, steady state, design parameters Zone level, used for sizing hvac equipment Compliance dynamic e.g. Part L (UK) Compliance metrics Daylight DF, UDI, DA Zone and sub-zone, detailed outputs Solar Steady values, dynamic solar gains and shading with climate data Solar gains, glare, internal and external, shading Fabric Mostly dynamic, 3D heat transfer analytical models Temps, moisture, condensation, dT Acoustic Analytical, Noise and sound levels, Site/Masterplan External comfort, wind, safety, vegetation, climate Temps, velocities, comfort indices, Flow, thermal, CFD, FVM, LBM, Sub-zone, detailed, Structural FEA, Loads, Pressure, Forces Loading, stress, strain, energy Sizing (pipes, ducts) M&E Sizes, quantities, costs HVAC Component level sizing Energy, pressure drop, flow rates
  6. 6. What Are Thermal Modelling Tools Used For? SimScale to IES (VE) for Building Simulation
  7. 7. What Are Thermal Modelling Tools Used For? Dynamic thermal modelling tools are used for zone level calculations: Inputs ● Solar gains ● Fabric gains ● Internal gains (people, equipment, lighting etc.) ● Heating/cooling energy added or removed ● Uncontrolled gains e.g. infiltration ● External environment (Ambient temp, wind speed, direction, RH etc.) for calculation of air exchange between inside and outside - (nat vent) Outputs ● Calculation of heating and cooling loads / zone ● Energy KWh, KWh/annum, room/building level ● Internal space temperatures at zone level ● Internal air quality e.g. CO2 at zone level ● Output data relating to specific industry benchmarks (eg CIBSE TM59, BB101 etc)
  8. 8. What Is CFD Used For? SimScale to IES (VE) for Building Simulation
  9. 9. What Is CFD Used For? CFD modelling tools are used for ZONE & SUB-ZONE level calculations: OUTPUTS ● Temperature distribution and gradient within a space ● Air velocities and distribution within a space ● Visualizing air and temperature phenomena ● CO2 spatial mapping ● Calculating actual wind pressure coefficients based on surrounding buildings, wind profile, and facade pressures ● Coupling the external and internal wind/air environment ● HVAC ● Smoke/pollutant extract and dispersion ● Building aerodynamics ● Porous media ● Thermal comfort
  10. 10. Corner Acceleration Velocity contour at 1.5 m height What are the different wind effects generated by buildings? From south west
  11. 11. Channeling Effect What are the different wind effects generated by buildings? (Source) Velocity must increase as it passes through a constriction. Buildings and other obstructions will force an increase in wind speed through city streets and other unobstructed channels. From south west
  12. 12. Downwash effect What are the different wind effects generated by buildings? Wind velocities at 6.5 m/s at low altitude From south west
  13. 13. 3D Slice What are the different wind effects generated by buildings?
  14. 14. 8.049 m/s8.049 m/s Front side Back and right side viewLeft side Wind Loading and Facade Pressures What are the different wind effects generated by buildings?
  15. 15. 1. Natural and mechanical ventilation 2. Thermal comfort & compliance with standards 3. Indoor air quality 4. Contamination spread and control 5. Smoke propagation & extraction Thermal Comfort & Indoor Environment 15
  16. 16. ● Evaluate design scenarios and variations ● Visualize the flow field (speed, direct, temperature) ● Comply with industry standards (ASHRAE 55, ASHRAE 90.4, EN 15251, etc.) HVAC 16
  17. 17. Cut Section Views Below Front Diffusers
  18. 18. Wind Pressure Coefficients SimScale to IES (VE) for Building Simulation
  19. 19. 1. The wind pressure at an opening (Pw) and hence ΔP - difference between internal and external pressure determines how building simulation tools calculate air flow (natural ventilation, fresh air etc.) through windows/openings. 1. This air exchange will have a ΔT - difference between internal and external temperature. 1. Therefore the amount of air coming in/out of openings has a direct impact on building: a. Fresh air and air exchanges - are you calculating the ventilation and air quality values correctly? b. Heating and cooling loads - because the amount of air coming in/out of your building at a certain temperature will either add or remove thermal energy from your spaces c. Energy - Gas and electricity due to heating and cooling costs d. Thermal comfort - air speed, distribution, temperature and quantity of flow rate. Why Are Wind Pressure Coefficients (Cp) So Important?
  20. 20. Most thermal modelling and building simulation tools use simple airflow network models to calculate bulk air movement. They DO NOT capture the following effects: ● Wind turbulence ● External wind conditions ● Local building context ● Terrain is an oversimplified constant ● Exposure types are poorly understood and seldom applied. They are also based on very simplified wind tunnel testing conducted a long time ago. Have you ever thought of how your wind pressure coefficients can be more accurately calculated? What Factors Should You Watch Out For?
  21. 21. ● All these wind directions are computed in parallel, a transient (real-time wind) simulation takes less than 2 hours. ● Results are exported on the building surfaces. 16 Directions, At Once!
  22. 22. These pressure coefficients can then be used for a plethora of purposes—including increasing the accuracy of thermal models. Import Into Thermal Modelling Software
  23. 23. Results at 0° for SW Direction Nearby Building
  24. 24. Case Study SimScale to IES (VE) for Building Simulation
  25. 25. ● Densely populated city centre location ● 5 story building ● Naturally ventilated ● High risk of summertime overheating due to building type ● CIBSE TM59 compliance required ● DTM simulation tool used: IES VE Case Study: Student Accommodation, Nottingham
  26. 26. 26 Import Geometry Setup and Run Simulation Export Cp Values in Table Form 1 3-Part Workflow 1. Import the geometry and point file 2. Follow our 2-minute setup workflow to run a simulation 3. Export the data and run an automated script How do we assess impacts of buildings on pedestrian comfort? 2 3
  27. 27. N Step 1 ● Simply export the geometry from IES as an STL file and upload it to SimScale. This should include relevant context. Import Geometry
  28. 28. Step 1 ● The points uploaded to SimScale should contain a label (this is used to later reference in IES, so ensure a well documented naming convention) and the X, Y, Z coordinates for the centre of each window. ● In this instance, each face is labeled, floor and window, to make it easier to reference (opposed to naming each window 1-130). The windows are referenced left to right. Import Geometry - Points Face 1 Face 2 Face 3 Face 4 Floor 0 Floor 3 Window 1 Window 11
  29. 29. 29 Define region Define wind rose Upload point locations 1 3 2 minute setup It’s that simple. 1. Define region 2. Define wind rose 3. Upload point locations Step 2 2
  30. 30. Step 3 ● Data processing is simple with a python script with some prerequisites. ○ The data is organised as pictured. ○ The model specific information is defined in the script. ● Once this is completed, the text file can then be put into the IES file system and used. Process the Data
  31. 31. Surface Pressures 31 31 ● Surface pressures are used to obtain pressure coefficients. ● The reference velocity is the velocity in the wind profile at that height.
  32. 32. 32 32 ● Graph shows natural ventilation flow rates during a hot week in July. ● When using Simscale data, natural ventilation flow rates can be more than twice those modelled when using IES default data. Results (Ventilation)
  33. 33. 33 33 Results (Temperatures) ● Room temperatures when using SimScale are up to 2oC +/- from temperatures recorded when using IES defaults. ● Summertime room temperatures assessed to be generally cooler when using SimScale data, owing to increased ventilation flow rates.
  34. 34. 34 34 Use of SimScale data alone can provide a TM52 ‘pass’, where otherwise a room would be found to fail. Results (Compliance)
  35. 35. When comparing to pressure coefficients obtained in building simulation models we see the following: ● Pressure higher up the building is greater in comparison to standard methods used, where flow is faster than expected for this wind profile due to upstream obstruction. ● Lower down, it is much less as surrounding buildings are actively obstructing airflow. ● Up to 100% difference in Cp values across the length and width of the building. ● Imagine the errors which propagate through to calculating air flow rates, loads, comfort and more! How will this impact on your: ○ Overheating assessments? ○ Fresh air rates? ○ Energy/loads? ○ Compliance? Summary