INTERNATIONALENERGYAGENCY energyconservationinbuildingsand communitysystemsprogramme ResidentialPassiveVentilationSystems: EvaluationandDesign JamesW.Axley Residential Passive Ventilation Systems: Evaluation and Design A Critical Evaluation of the Potential for Adapting European Systems for use in North America and Development of a General Design Method James W. Axley Residential Passive Ventilation Systems: Evaluation and Design © Copyright Oscar Faber Group Ltd. 2001 All property rights, including copyright are vested in the Operating Agent (Oscar Faber Group Ltd.) on behalf of the International Energy Agency. In particular, no part of this publication may be reproduced, stored in a retrieval system or transmitted in any form by any means, electronic, mechanical, photocopying, recording or otherwise, without the prior written permission of the Operating Agent. ii AIVC Technical Note 54 Residential Passive Ventilation Systems: Evaluation and Design About the Author James W. Axley Professor Yale University School of Architecture James Axley teaches structural and environmental technology courses and related seminars at the graduate level and an introductory structures course at the undergraduate level. Prior to joining the Yale faculty, he taught at U.C. Berkeley, Cornell University, and MIT over a 15 year period. In the professional realm, he has served as technical consultant to a number of influential architectural firms including those of Christopher Alexander, Fernau & Hartman, Lyndon & Buchanan, and Koetter & Kim and worked as a research engineer at the U.S. National Institute of Science and Technology. He has published and presented a series of papers relating to the development of computational and experimental techniques for building thermal, airflow, and air quality analysis; serves as consultant and adviser to the U.S. Environmental Protection Agency, U.S. Department of Energy, and National Institute of Science and Technology; and is an associate editor of the journal Indoor+Built Environment. He received his B.S. from the University of Wisconsin, Madison, and his M.Arch., M.S., and Ph.D. from the University of California at Berkeley. As a visiting researcher at the AIVC in 1998, James Axley undertook the background research for this report. This report is part of the work of the IEA Energy Conservation in Buildings and Community Systems Programme (ECBCS) Publication prepared by Annex V Air Infiltration and Ventilation Centre Document AIC-54-2001 Additional copies of this report may be obtained from: AIVC Participating countries of the AIVC: University of Warwick Science Park Belgium, Denmark, Finland, France, Unit 3a, Sovereign Court Germany, Greece, the Netherlands, New Sir William Lyons Road Zealand, Norway, Sweden, United Kingdom Coventry CV4 7EZ and the United States of America. Great Britain AIVC Technical Note 54 iii Residential Passive Ventilation Systems: Evaluation and Design iv AIVC Technical Note 54 Residential Passive Ventilation Systems: Evaluation and Design Preface International Energy Agency The International Energy Agency (IEA) was established in 1974 within the framework of the Organisation for Economic Co-operation and Development (OECD) to implement an International Energy Programme. A basic aim of the IEA is to foster co-operation among the twenty four IEA Participating Countries to increase energy security through energy conservation, development of alternative energy sources and energy research development and demonstration (RD&D). Energy Conservation in Buildings and Community Systems (ECBCS) The IEA sponsors research and development in a number of areas related to energy. In one of these areas, energy conservation in buildings, the IEA is sponsoring various exercises to predict more accurately the energy use of buildings, including comparison of existing computer programs, building monitoring, comparison of calculation methods, as well as air quality and studies of occupancy. The Executive Committee Overall control of the programme is maintained by an Executive Committee, which not only monitors existing projects but also identifies new areas where collaborative effort may be beneficial. To date, the following projects have been initiated by the Executive Committee (completed projects are identified by *): 1. Load Energy Determination of Buildings * 2. Ekistics and Advanced Community Energy Systems * 3. Energy Conservation in Residential Buildings * 4. Glasgow Commercial Building Monitoring * 5. Air Infiltration and Ventilation Centre 6. Energy Systems and Design of Communities * 7. Local Government Energy Planning * 8. Inhabitant Behaviour with Regard to Ventilation * 9. Minimum Ventilation Rates * 10. Building HVAC Systems Simulation * 11. Energy Auditing * 12. Windows and Fenestration * 13. Energy Management in Hospitals * 14. Condensation * 15. Energy Efficiency in Schools * 16. BEMS - 1: Energy Management Procedures 17. BEMS - 2: Evaluation and Emulation Techniques * 18. Demand Controlled Ventilating Systems * 19. Low Slope Roof Systems * 20. Air Flow Patterns within Buildings * 21. Calculation of Energy and Environmental Performance of Buildings* 22. Energy Efficient Communities * 23. Multizone Air Flow Modelling (COMIS) * 24. Heat Air and Moisture Transfer in Envelopes * 25. Real Time HEVAC Simulation * 26. Energy Efficient Ventilation of Large Enclosures * 27. Evaluation and Demonstration of Domestic Ventilation Systems 28. Low Energy Cooling Systems* AIVC Technical Note 54 v Residential Passive Ventilation Systems: Evaluation and Design 29. Daylight in Buildings 30. Bringing Simulation to Application 31. Energy Related Environmental Impact of Buildings 32. Integral Building Envelope Performance Assessment 33. Advanced Local Energy Planning 34. Computer-aided Evaluation of HVAC System Performance 35. Design of Energy Efficient Hybrid Ventilation (HYBVENT) 36. Retrofitting in Educational Buildings - Energy Concept Adviser for Technical Retrofit Measures 37. Low Exergy Systems for Heating and Cooling of Buildings 38. Solar Sustainable Housing. 39. High Performance Thermal Insulation (HiPTI) vi AIVC Technical Note 54 Residential Passive Ventilation Systems: Evaluation and Design CONTENTS Contents vii Tables x Figures x Synopsis xv Acknowledgment xv Nomenclature xvi 1 Introduction 1 1.1 Energy Conservation 5 1.2 Air Quality Control 6 1.3 Organization 6 2 Review of European Passive Ventilation Methods 7 2.1 Passive Stack Ventilation (PSV) Systems 7 2.1.1 Operating Principles 9 2.1.2 Performance 11 2.1.2.1 Long-Term Performance – Traditional PSV Systems 11 2.1.2.2 Seasonal Performance– Traditional PSV Systems 12 2.1.2.3 Short-Term Performance – Traditional PSV Systems 13 2.1.2.4 Performance of Innovative PSV Systems 15 2.2 The PSVH Research Initiative 16 2.3 Related Design Issues 18 2.4 Airflow Systems Interaction 18 2.5 Comfort, Health & Safety 19 3 Alternative Passive Ventilation Options 21 3.1 Centralized Passive Stack Ventilation System 21 3.2 Subfloor Inlet Plenum 21 3.3 Balanced Wind Stack (BWS) System 22 3.4 Cross-Ventilation with Self-Regulating Vents 23 AIVC Technical Note 54 vii Residential Passive Ventilation Systems: Evaluation and Design 3.5 Conclusion 24 4 Analytical Methods – Simulation & Design 25 4.1 Simulation Methods 25 4.1.1 System Idealization 25 4.1.2 Microscopic Modeling 26 4.1.3 Macroscopic Modeling 28 4.1.4 Summary – System Idealizations 29 4.1.5 Analytical Categories 29 4.1.6 Common Assumptions for Residential Ventilation Analysis 31 4.1.6.1 Airflow/Thermal Analysis Coupling 31 4.1.6.2 Contaminant Dispersal/Airflow Analysis Coupling 31 4.1.6.3 Contaminant Dispersal Analysis 31 4.1.7 Outline of Macroscopic Airflow Analysis Theory 32 4.1.7.1 Component Flow Models 33 4.1.7.2 Surface Wind Pressures 33 4.1.7.3 Buoyancy Pressures 34 4.1.7.4 System Equations 34 4.1.8 Applications to Passive Ventilation Systems 35 4.1.8.1 Calibrated Simplified Single-Zone Models 35 4.1.8.2 Detailed Single-Zone & Multi-Zone Models 39 4.1.9 Passive Ventilation Component Models 41 4.1.9.1 Quadratic Component Model 41 4.1.9.2 Self-Regulating Inlet Vent Components 41 4.1.9.3 Stack Components 44 4.1.9.4 Constant Cross-Section Duct Length Components 44 4.1.9.5 Duct Fitting Components 46 4.1.10 Modeling Uncertainties 47 4.2 Design Methods 48 4.2.1 Ventilation Design Tasks 48 4.2.2 Component Sizing Methods 49 4.2.2.1 Existing First-Order Methods 50 5 A First-Order Design Method Based on Loop Equations 53 5.1 Basic Theory 53 5.1.1 Wind & Hydrostatic Pressures 54 5.1.2 Boussinesq Approximation 57 5.1.3 Pressure Loop Equations 57 5.1.4 Design Example 1: Sizing Components of a Traditional PSV System 59 5.1.4.1 Design Conditions 59 5.1.4.2 Design Criteria 59 5.1.4.3 Loop Equation 59 5.1.4.4 Feasible Design Surfaces & Asymptotes 60 5.1.4.5 Additional Constraints & Design Rules 61 5.1.4.6 Operational Strategies 62 5.1.4.7 Conclusion to Design Example 1 62 5.1.5 Outline of the Loop Equation Design Method 63 5.1.6 Design Example 2: Sizing Components of an Innovative PSV System 64 5.1.6.1 Loop Equation & Limiting Asymptotes 64 5.1.6.2 Non-Technical Constraints & Design Rule 65 5.1.6.3 Conclusion to Design Example 2 66 5.2 Accounting for Infiltration 66 5.2.1 Design Example 3: Accounting for Infiltration 68 viii AIVC Technical Note 54 Residential Passive Ventilation Systems: Evaluation and Design 5.2.1.1 Estimated Envelope Pressure Drops 69 5.2.1.2 Estimated Envelope Airflows 71 5.2.1.3 Iterative Correction for Infiltration 72 5.2.1.4 Conclusion to Design Example 3 73 5.3 Design Criteria & Design