Passive House Northwest

Transcription

1 Passive House Northwest AIA CEU Provider Window Workshop- A Window on the Future Course# phnw Daniel Haaland, RDH Building Science February 15th, Credit(s) earned on completion of this course will be reported to AIA CES for AIA members. Certificates of Completion for both AIA members and non- AIA members are available upon request. This course is registered with AIA CES for continuing professional education. As such, it does not include content that may be deemed or construed to be an approval or endorsement by the AIA of any material of construction or any method or manner of handling, using, distributing, or dealing in any material or product. Questions related to specific materials, methods, and services will be addressed at the conclusion of this presentation. 2 1

2 Course Description This presentation will address a range of design and performance characteristics relevant to those who select, and specify windows for durability and energy efficiency. 3 Learning Objectives At the end of the this course, participants will be able to: 1. Audience members will understand the fundamentals of window performance from a thermal and comfort performance perspective including surface temperature, cold air drafts, and overheating 2. Audience members will understand the heat transfer mechanics in window frame and glass components, and the technologies used to improve thermal performance.. 3. Audience members will understand the significance of installation details on the effective thermal performance of windows and will be advised of ways to mitigate the thermal performance loss.. 4. Audience will learn how durability of the building envelope can be affected by proper installation of high-performance windows. 4 2

3 LEARNINGOBJECTIVES Building Science of High- Performance Windows Course Approved for CPHC Continuing Education Credits 1. Understand the fundamentals of window performance for thermal comfort. 2. Understand the heat transfer mechanisms in window frame & glass components 3. Understand the significance of installation details on effective thermal performance 4. Learn how durability of the building envelope can be affected by proper installation Earn 1 CPHC CEU Self-report link: 5 Outline The Motivation The Building Science of Windows The Universe of U-values The Path to High-Performance 6 3

4 Definition of High Performance Cheap Durable Fast Comfortable Healthy Energy Efficient Resilient Adaptable Easily Renewed/Repaired Mostly talking about this today, but also impacts others. 7 Outline The Motivation The Building Science of Windows The Universe of U-values The Path to High-Performance 8 4

5 Recent window attention why? Windows significantly influence the performance of the whole building envelope. Essentially, windows are the weakest thermal element in the building envelope. Think about what R-3 windows do to R-20 insulated walls. The technology and products already exist in the market to significantly improve window and thus whole-building thermal performance 9 Where is heat loss occurring? Yellow/red/white = hot = high heat flow/high U-value Blue = Cold = low heat flow/low U-value 10 5

6 Window to Wall Ratio Impacts 11 Cold glass causes discomfort 12 6

7 Cold glass causes stratification Typical Window (U w = 0.35 Btu/hr ft² F) 20 C 17 C Source: Passive House Institute

8 Warm glass does not require a radiator 15 What s in a Window? 16 8

9 Review of Window Types & Terminology 17 Window frame materials Wood Vinyl, PVC Aluminum Fiberglass 18 9

10 Hybrid and advanced window frames 19 Control functions in fenestration Air Barrier Insulation 20 10

11 Control functions in fenestration AB Insulation 21 Control functions in fenestration AB Insulation 22 11

12 Control functions in fenestration AB Insulation 23 Insulating Glazing Units = IGUs IGU Components: 1. Surface 1 (exterior) 2. Surface 2 (interior side of exterior lite) 3. Surface 3 (exterior side of interior lite) 4. Surface 4 5. Low-e coating 6. Edge spacer (separate glass panes) 7. Desiccant (to dry air) 8. Primary edge seal (vapor) 9. Secondary edge seal (structure) 24 12

13 Heat flow through an IGU Losses Gains 25 Low-e Coatings Control Radiation 26 13

14 Low-e coatings Low-emissivity (Low-e) thin metallic coating: changes optical properties (visible, Infrared, UV), is spectrally selective, reduces emissivity of glass surface Soft Coat (Sputtered) very low emissivity, good U-values, typically lower solar heat gain Hard Coat (Pyrolytic) moderately low emissivity, U-values not as low as soft coat, higher solar heat gain U-factor (imperial) U-factor Versus Low-E Coating Emittance Coating Emittance Air U-factor Argon U-factor 27 Influence of low-e coatings on U-value Triple glazing 25% 28 14

15 Edge deletion Typical full edge deletion Incomplete edge deletion 29 Low-e corrosion & delamination 30 15

16 Gas Filled Layers The center of window performance 31 Influence of gas fill on U-value Triple glazing 32 16

17 Argon fill failures 2 recent projects in North America Glazing Units from one Manufacturer Argon was specified Tested ~100 units in the field at 2 job sites IGUs were manufactured 1-4 months previously Argon concentration varied: 3% of units had concentrations above 90% Argon 25% between 75-90% 11% between 50-75% 61% had below measurable Largely batch related consistencies No apparent loss with age 33 Edge Spacers 34 17

18 Types of IGU edge spacers 35 Thermal performance of IGU edge spacers Thermally improved spacers decrease the window U-value and raise internal surface temperature 49 F 53 F 55 F Standard Aluminium Stainless-steel Thermix U w Btu/(hr ft² F) U w Btu/(hr ft² F) (-7%) U w Btu/(hr ft² F) (-11%) Calculation of the window U-value with: Ug = 0.12 Btu/(hr ft² F) = 0.13 Btu/(hr ft² F) U f, 36 Source: PHI Berthold Kaufmann 18

19 Failures of IGU edge spacers Defect in edge seal = fogged IGU Single Seal IGUs have limited lifespan. Hot-melt, butyl, swiggle, polysulfide IGU seal under very large stresses from thermal, wind pressure. Several thousands of Pascals Always specify a dual seal IGU PIB primary seal (moisture), Silicone secondary seal (structural) excellent track record 37 Sagging spacer bar IGUs under negative pressure due to elevation change Thermoplastic sealant crept at high temperatures 38 19

20 Solar Shading Keeping it cool 39 Solar heat gain 40 20

21 41 Sunny day breaks 42 21

22 Thermal stress breakage Breakages occurred on sunny days on elevations with solar shades Annealed glass was specified and installed Breaks always intersect at 90 degrees to edge Installation of glazing units conformed to IGMA guidelines Conclusion: Thermal stress breakage A 50 degree Fahrenheit difference in glass temperature is often sufficient to cause breakage of annealed glass. Solar shading allows part of the glass to be exposed to the sun while shading other parts of the same lite causing a significant temperature difference. Reflective coatings and solar selective low-e coatings compound this effect. Heat strengthened glass should always be used on projects with solar shading devices or when using reflective or heat absorbing glass products. 43 Outline The Motivation The Building Science of Windows The Universe of U-values The Path to High-Performance 44 22

23 It can be a bit confusing ISO vsnfrc European standard: ISO International Organization for Standardization (ISO) ISO and for frame and whole window U-value EN 673 for glazing U-value EN 410 for glazing solar heat gain (g-value) Passive House Modified ISO North America: NFRC National Fenestration Rating Council (NFRC) NFRC 100 for U-value, NFRC 200 for SHGC 46 23

24 ISO vs NFRC: Differences Boundary conditions (temperatures & air film resistances) Standard size of window Method of accounting for edge of glass effects Calculation methodologies (algorithms) for glazing unit airspace, frame U-value SHGC (g-factor) for whole window or centre of glass Treatment of sloped glazing 47 How do these differences affect performance? RDH study evaluated U-value, solar heat gain of three windows using NFRC and ISO/PHI methods North American Vinyl Frame North American Fibreglass Frame European Vinyl Frame Each window had same glass, gas fill and spacer Showed how same product performs under different rating systems 48 24

25 Key difference: Centre of Glass U-Value Triple glazing, argon gas fill, two low-e coatings Centre of Glass U-Value, W/m 2 -K Big difference between U-values for NFRC and ISO methods at standard temperatures 0.9 (0.16) 0.8 (0.14) 0.7 (0.12) 0.6 (0.10) NFRC optimal gap size is approx. ½ ISO optimal gap sizes are larger, approx. 5/ Gap Size, mm NFRC, -18 C (-0.4 F) ISO, 0 C (32 F) 49 ISO vs NFRC: Edge effects NFRC U-Value Passive House U-Value U frame x A frame U frame x A frame 2.5 U edge x A edge ψ spacer x L glazed perimeter U glazing x A glazing U glazing x A glazing ψ install x L window perimeter U frame, U edge,u glazing used to calculate overall U-value U frame, ψ spacer, U glazing, ψ install entered into PHPP 50 25

26 ISO vs NFRC: Edge effects North America/NFRC Passive House/ISO 51 No simple conversion method Neither NFRC nor ISO system is better for all applications Today products are optimized to perform best under the rating regimes in effect in Europe, North America 52 26

27 Outline The Motivation The Building Science of Windows The Universe of U-values The Path to High-Performance Windows 53 The Perpetual Question +? 54 27

28 We have come a long way st Century 56 28

29 Continually evolving best practices 57 Fundamentals: Following & connecting the critical barriers Water Shedding Surface (WSS) Water Resistive Barrier (WRB) Air barrier (AB) 58 29

30 So what is changing? Trend towards more efficiently insulated building enclosures due to higher energy code targets & uptake of passive design strategies Greater attention to reducing thermal bridging in building enclosures Window installation practices are evolving to incorporate new and/or imported window frames into more highly insulated wall Ongoing need to balance thermal and durability considerations 59 Old window installation details aren t often good enough for high-performance projects Too much wood Too much insulation displaced & too large of metal flashing Too much wood Key considerations: Avoid metal flashings that bypass framing or insulation Reduce wood framing around window Over-insulatethe window frames where feasible Air tight (and properly water managed) 60 30

31 Thermally improved window details 61 Window Psi Install Ψ Ψ Window installation heat loss is the additional heat flow through the interface, gap, framing, flashings, etc., between the wall and window 62 31

32 Psi-Value Case Study: What matters & how much? Window: Fiberglass fixed window with high performance triple glazing (U-0.125, R-8.0) Walls: Split insulated 2x6 wood frame filled with fiberglass batt and 6 exterior mineral wool with long screws through insulation to support cladding (R-40 effective) Windows installed at inner, middle and exterior of wall 63 Standard install Ψ = (Btu/hr F ft) 14.7 o C 58.5 o F U window = (Btu/ft² F hr) Ψ install = (Btu/hr F ft) U installed = (Btu/ft² F hr) % change = 18% (worse) R installed = 5.8 (hr ft2 of/btu) Ψ = (Btu/hr F ft) 13.1 o C 55.6 o F 14.7 o C 58.5 o F U-value gets 18% worse just by installing it into the wall! Ψ = (Btu/hr F ft) 64 32

33 Impact of placement in R.O. No over-insulation Inner Middle Outer U window (Btu/ft² F hr) Ψ install (Btu/hr F ft) U installed (Btu/ft² F hr) % change (%) 19% 18% 13% R installed (hr ft 2 of/btu) Window towards the exterior is better thermally, small impact on interior surface temperatures Based on window size of 4.0 x 4.9 ft 65 Over-insulating frames Ψ = (Btu/hr F ft) U window = (Btu/ft² F hr) Ψ install = (Btu/hr F ft) U installed = (Btu/ft² F hr) % change = 4% (worse) R installed = 6.6 (hr ft2 of/btu) 16.3 o C 61.3 o F 13.1 o C 55.6 o F 16.3 o C 16.3 o F Ψ = (Btu/hr F ft) 18% loss in window U-value for no over insulation vs 4% with Watch temperatures if insulating on inside! If over-insulating at sill watch drainage! Ψ = (Btu/hr F ft) 66 33

34 67 Building description 6-storey apartment building, 60+ residential units constructed over two levels of below grade parking spaces. R IP -10 walls & U IP thermally broken aluminum windows 68 34

35 Typical approach U window,1 U wall,3 U wall,2 U wall,1 U window,2 U-Factors are assigned to the areas 69 Effective building enclosure R-Value Windows are 24% of the area, but 57% of the heat flow

36 Window uninstalled vs. installed B B 20.0 o C 16.0 o C 12.0 o C 8.0 o C 4.0 o C B B 20.0 o C 16.0 o C Ψ install 0.0 o C -4.0 o C 12.0 o C o C 8.0 o C 4.0 o C θsi min = 1.59 o C A-B f = Rsi 0.0 o C -4.0 o C o C θ si mina-b = 8.88 o C f Rsi = U-0.38 (R-2.6) A A U-Value 55% U-0.59 (R-1.7) A 71 Case study Impact on overall effective enclosure Window install can reduce overall enclosure thermal performance by 33%! Uninstalled 6.5 Installed

37 Key Conclusions Windows have a large part to play in the overall performance of our enclosures Long history of iterative progress in the design of and installation of windows many past failures and successes Evolution is continuing with higher performance windows 73 Discussion + Questions FOR FURTHER INFORMATION PLEASE VISIT OR CONTACT US AT dhaaland@rdh.com 74 37

38 This concludes The American Institute of Architects Continuing Education Systems Course 75 REMINDER SELF-REPORT CPHC CEUs Course Approved for CPHC Continuing Education Credits Earn 1 CPHC CEU Self-report link: Enter verification code: