Thermal Comfort Assessment: Comply with EN 15251 and EPBD
2 likes•586 views
This document discusses how computational fluid dynamics (CFD) simulations can help validate compliance with EN 15251 thermal comfort standards for HVAC design. It presents a case study where two different HVAC designs for an auditorium are simulated and analyzed. The first design performs poorly, with drafts, large temperature variations, and thermal discomfort predicted for some occupants. The second design performs much better, with smooth airflow, even temperatures, and thermal comfort predicted for all occupants, validating EN 15251 compliance. CFD simulations are shown to provide insights that can improve designs and validate comfort standards earlier in the design process.
Thermal Comfort Assessment: Comply with EN 15251 and EPBD
- 1. How CFD can help to validate EN 15251 Compliance March 2018 HVAC Design and Thermal Comfort
- 2. Why is Design for Thermal Comfort Hard? Image Source: U.S. Energy Information Administration, 2012 Commercial Buildings Energy Consumption “By managing thermal comfort, you are likely to improve morale and productivity as well as health and safety.” Health and Safety Executive UK
- 4. Scenario: Design for Thermal Comfort HVAC Design Constraints: ● Possible Inlets / Outlets ● Occupant Metabolic Heat ● Clothing Insulation in winter ● Category II EN 15251 Compliance
- 5. Design 1: Fresh Air Supply from Top Inlets Floor Outlets Positioned under all seats Stage Outlets Left, Right and Center Air Inlets Over Occupant Region Occupants Metabolic Heat Sources
- 6. Metrics of Thermal Comfort: PMV & PPD Predicted Mean Vote (PMV) ● Heuristic metric to quantify comfort level ● Velocity and temperature information ● Depends on occupant parameters: ○ Metabolic Rate (MET) ○ Clothing Coefficient (CLO) Predicted Percentage of Dissatisfied (PPD) ● Computed from PMV ● Represents the percentage of uncomfortable occupants ● Comfort if PPD < 10% (Green Coloring) For EN 15251 Compliance: -0.5 < PMV < 0.5 PPD < 10%
- 7. Why SimScale? Create a free account (no credit card required)
- 8. SimScale – World’s First Cloud-Based Simulation Platform Zero hardware and software footprint. Unlimited computing power via a web browser. Accessible Flexible pricing model with low entry prices and on-demand computing power. Cost-efficient Easy to use via collaboration functionality, real time support and a large community. For everyone
- 9. End-to-End Simulation Workflow Completely via Web Browser 2) Simulation Setup All steps to define and run a simulation are done within SimScale 3) Design Decision Use the simulation insights to make better design decisions faster and earlier 1) CAD Import Upload your CAD model or import it from other cloud services into SimScale
- 10. Multiple AEC Flow Analysis Types in One UI ● Internal airflows ● Urban wind flow ● Convective flows ● Smoke extraction ● etc. Internal airflow analysis Pedestrian Comfort Analysis Thermal Comfort in Occupant Spaces Safety and contamination control
- 11. Demo Time! Watch the full webinar recording for free
- 12. Design 1: Baseline Results Seat Outlets Positioned under all seats Stage Outlets Left, Right and Center Top Inlets Poorly Adjusted Diffusers Occupants Metabolic Heat Sources
- 13. Interpretation ● Strong drafts in occupied zone ● Inlet flow poorly distributed ● Flow around occupants dominated by small vortices Design 1: Air Flow Velocity
- 14. Design 1: Temperature Distribution Interpretation ● Large temperature differences across occupied zone ● Some occupants experience very cold air ● Poor thermal efficiency - evidenced by relatively warm air
- 15. Design 1: PMV Interpretation Some occupants outside comfort standard (–0.5< PMV <+0.5)
- 16. Design 1: PPD Interpretation Small occupied regions below comfort standard
- 18. Design Study: 2 Different Layouts Side Outlets Behind Occupant Zone Floor Inlets Under all seats Stage Inlets Left, right and centerDesign 1 Design 2
- 19. Design 2: New Results Side Outlets Behind Occupant Zone Floor Inlets Under all seats Stage Inlets Left, right and center
- 20. Design 2: Air Flow Velocity Interpretation ● No strong drafts near occupants ● Relatively large scale convection current renewing air near occupied zone
- 21. Design 2: Temperature Distribution Interpretation ● All occupants within Temp. comfort region ● Air Temperature showing significant stratification ● More thermally efficient (overall cooler)
- 22. Design 2: PMV Interpretation ● No discomfort measured for any occupant location ● Occupants very well within comfort limits
- 23. Design 2: PPD Interpretation ● Less than 5% occupants should report any sort of discomfort ● Compliant with En- 15251
- 24. Cleaner air flow Chaotic air flow Strong draft Design Comparison: Air Velocity Design 1 Design 2
- 25. Smooth large scale convection current Strong vortex generates strong draft Design Comparison: Air Velocity Design 1 Design 2
- 26. Smoother temperature distribution Overall cooler | higher thermal efficiency Design Comparison: Temperature Design 1 Design 2 Very high temperature gradient
- 27. Cold air column barely diffuses Smooth temperature field Design Comparison: Temperature Design 1 Design 2
- 28. Comfortable in all occupied region Too drafty and cold Design Comparison: PMV Design 1 Design 2
- 29. Very comfortable through entire occupied area Design Comparison: PMV Design 1 Design 2 Uncomfortable region just above occupant’s head
- 31. Design Comparison: PPD Very comfortable for all occupants EN 15251 compliant Uncomfortable region just above occupant’s head
- 32. Wrap-up Read this blog article to learn more
- 33. Simulation ROI – In a Nutshell Investment ● ~4h manual time ● ~12h computing time ● ~1,200 core hours Return ● Design confidence & risks mitigated ● Significant Time Savings Design 1: Design 2: ~15Uncomfortable Occupants 0Uncomfortable Occupants
- 34. How to start? 1 2 Two Steps: 1. www.simscale.com 2. Individual Demo - or - Try for free