Exterior envelopes for Passive Houses in very cold climates have not been developed, tested, and used as extensively as those in more mild climates such as central Europe. The purpose of this investigation was to push that development further by testing and comparing the performance of a variety of North American and Scandinavian envelope types that have been used in limited numbers for Passive Houses in those regions. A group of eight envelopes were selected and tested with a number of software analyses: Athena life cycle analysis, WUFI hygrothermal modeling, and THERM and EN ISO 6946 2-D U-value calculations for thermal bridging. Finally, the Passive House Planning Package (PHPP) was used to confirm that the envelopes met Passive House energy performance requirements in a very cold climate using a basic passive solar house design. Although significant variation was found in the performance of these eight envelope types, almost all of them were found capable of meeting the energy efficiency and thermal bridging requirements of the Passive House certification in a very cold climate, while maintaining moisture safety, durability, and significant life-cycle energy and carbon savings. These findings demonstrate that even in cold climates, a variety of envelope types can be used successfully for certified Passive Houses.
Envelope types: 1) Advanced 2x6 framing24” on center with interior cross strapping and exterior insulation, insulated with mineral wool, 2) Advanced 2x6 framing24” on center, insulated with high-density spray polyurethane foam and exterior rigid foam, 3) Double 2x4 stud wall with studs 16” on center, insulated with blown cellulose, 4) I-joist (TJI) balloon framing 24” on center, insulated with blown fiberglass, 5) Insulated concrete form wall (ICF), using integral rigid EPS foam insulation, 6) Concrete block wall, insulated with exterior mineral wool, 7) Massivtre/Structural engineered panel (SEP), insulated with exterior rigid foam, and 8) Structural insulated panel (SIP), using integral EPS rigid foam insulation. For comparison, a base option was also studied: Standard 2x6 framing 16” on center with fiberglass batt insulation. See Appendix for diagrams of each envelope.
Inhaltsverzeichnis (Table of Contents)
- Acknowledgements
- Table of Contents
- Abstract
- Introduction
- Envelope Descriptions/Diagrams
- Envelope Selection and Thermal Resistance (2DR value modeling)
- Part A) Research location and climate comparison
- Part B) Passive House case studies and development of target R values
- Part C) Terms and concepts in stud wall R value calculations
- Part D) R value: Methods of calculation
- Part E) R value: Results
- Thermal Bridges (THERM modeling)
- Part A) Terms and concepts in thermal bridge analysis
- Part B) Thermal bridges investigated
- Part C) Thermal bridges: Methods of calculation/modeling
- Part D) Thermal Bridges: Results
- Passive House Verification and House Model (PHPP modeling)
- Part A) Passive House verification: House Model
- Part B) Passive House verification: Methods of calculation
- Part C) Passive House verification: Results, Envelope Types
- Part C) Passive House verification: Results, Climate Locations
- Part C) Passive House verification: Results, Parametric Studies
- Hygrothermal Performance and Risk (WUFI modeling)
- Part A) Terms and concepts in moisture performance
- Part B) Terms and concepts in moisture risk
- Part C) Moisture performance and Risk: Methods of calculation/modeling
- Part C) Moisture performance and Risk: Results, Air leakage
- Part C) Moisture performance and Risk: Results, Moisture Balance
- Part C) Moisture performance and Risk: Results, Moisture Storage
- Part C) Moisture performance and Risk: Results, Mold Growth Risk
- Life Cycle Environmental Impact Analysis (Athena LCA modeling)
- Part A) Terms and Concepts in Environmental Impact Analysis
- Part B) Environmental Impact Analysis: Methods of calculation/modeling
- Part C) Environmental Impact Analysis: Results, Impacts Across all Indicators
- Part C) Environmental Impact Analysis: Results, Impacts on Key Indicators
- Part C) Environmental Impact Analysis: Results, Envelope Breakdown
- Part C) Environmental Impact Analysis: Results, Operational Impacts and Lifecycle Savings
- Summary and Conclusion
- Part A) Envelope Selection and Thermal Resistance (2DR value modeling)
- Part B) Thermal Bridges (THERM modeling)
- Part C) Passive House Verification and House Model (PHPP modeling)
- Part D) Hygrothermal Performance and Risk (WUFI modeling)
- Part E) Life Cycle Environmental Impact Analysis (Athena LCA modeling)
- Part F) Performance Summary
- Appendix A) Detailed Methodology
- Envelope Selection and Thermal Resistance (2DR value modeling)
- Thermal Bridges (THERM modeling)
- Passive House Verification and House Model (PHPP modeling)
- Hygrothermal Performance and Risk (WUFI modeling)
- Life Cycle Environmental Impact Analysis (Athena LCA modeling)
- Appendix B) Common Material Properties: Thermal Resistance
- Appendix C) Common Material Properties: Vapor Permeance
- Appendix D) Energy Modeling Assumptions
- Appendix E) WUFI Modeling Assumptions
- Appendix F) Moisture Storage @ 80 RH and 68°F (20°C)
- Appendix G) Athena Modeling: Envelope Materials and Layer Thicknesses
- Appendix H) THERM Modeling: Thermal Bridge Details
- Works Cited
- Additional Sources
Zielsetzung und Themenschwerpunkte (Objectives and Key Themes)
This research explores the performance of eight Passive House envelope types commonly used in cold climates. The study aimed to identify envelope types that meet Passive House energy efficiency standards, demonstrate moisture safety, and provide lifecycle savings in energy and carbon emissions. Key themes examined in the research include:- Insulation value and the impact of thermal bridges on overall performance.
- The potential for moisture damage and mold growth in highly insulated and airtight envelopes.
- The embodied energy and lifecycle environmental impacts of different envelope types.
- The effectiveness of different envelope designs and materials in achieving Passive House standards in cold climates.
- The importance of careful detailing to minimize thermal bridges and moisture problems.
Zusammenfassung der Kapitel (Chapter Summaries)
Envelope Selection and Thermal Resistance (2DR value modeling)
This chapter introduces the research location and climate zones of interest. It analyzes eight different envelope types selected from case studies of Passive Houses and low-energy homes built in cold climates. The chapter focuses on the thermal resistance (R-value) of each envelope type, comparing their performance to the target R-values. The effects of framing factors and thermal bridges on overall R-value are analyzed.Thermal Bridges (THERM modeling)
This chapter examines the performance of various thermal bridge details for each envelope type. It covers the difference between structural and geometric thermal bridges and explains how they are modeled using THERM software. The analysis focuses on the psi values calculated for different thermal bridge locations, including wall corners, rim joists, and foundation intersections.Passive House Verification and House Model (PHPP modeling)
This chapter introduces the model house used for Passive House energy performance simulations using the Passive House Planning Package (PHPP). The chapter outlines the house layout, mechanical systems, and assumptions for energy modeling. It then analyzes the performance of each envelope type based on the specific space heat demand and specific primary energy demand, comparing them to the Passive House certification requirements. The chapter also examines the sensitivity of the house model to climate variations, airtightness, and glazing type.Hygrothermal Performance and Risk (WUFI modeling)
This chapter focuses on the hygrothermal performance of the envelope types. It explores how different design strategies and material choices impact the moisture balance and drying potential of each envelope. The chapter analyzes the use of vapor retarders and air barriers, the importance of ventilation, and the risk of mold growth in different envelope configurations. It also examines the role of material properties in moisture storage and the impacts of air leakage on overall moisture performance.Life Cycle Environmental Impact Analysis (Athena LCA modeling)
This chapter analyzes the environmental impacts of the envelope types using Athena software. It discusses the importance of functional equivalence in environmental comparisons and details the method for modeling the environmental impacts of each envelope. The chapter then presents the results of the analysis, examining the embodied energy, global warming potential, and other environmental indicators. The chapter also considers the operational impacts of the house model, calculating payback periods for energy and carbon emissions and comparing these results to the base case standard frame envelope.Schlüsselwörter (Keywords)
This research focuses on cold climate Passive Houses, envelope performance, thermal resistance, thermal bridges, moisture management, mold growth risk, embodied energy, lifecycle environmental impacts, energy modeling, hygrothermal simulations, and climate zone comparisons. It analyzes envelope types like advanced framing, double stud walls, insulated concrete forms, structural insulated panels, and engineered wood panels. It also covers important concepts such as air leakage, vapor retarders, ventilation, and the influence of material properties on overall performance.- Quote paper
- Rolf Jacobson (Author), 2011, Performance of 8 Cold-Climate Envelopes for Passive Houses, Munich, GRIN Verlag, https://www.grin.com/document/200508
