High Performance, Energy Efficient Design for Wood Frame Buildings

Transcription

1 Disclaimer: This presentation was developed by a third party and is not funded by WoodWorks or the Softwood Lumber Board. Please add relevant logo here High Performance, Energy Efficient Design for Wood Frame Buildings Mixed-Use & Multi-Family: Designing Wood-Frame Buildings for Occupant Comfort Presented by: Peter J. Arsenault, FAIA, NCARB, LEED-AP

2 High Performance, Energy Efficient Design for Wood Frame Buildings The Wood Products Council is a Registered Provider with The American Institute of Architects Continuing Education Systems (AIA/CES), Provider #G516. 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. High Performance, Energy Efficient Design for Wood Frame Buildings

3 Course Description Occupant comfort may not be an expressed design objective in the International Building Code, but it s very important to the success of a project. This workshop will provide practical information for designing wood-frame multi-family and mixed-use buildings to avoid common comfort-related pitfalls. Discussion will cover designing high-performing, acoustically-rated assemblies, minimizing floor vibration and methods for meeting or exceeding energy-efficiency objectives. Details and code provisions will be presented for each topic, along with example projects featuring real-world issues and solutions. Attendees can expect to gain a better understanding of the most common occupant complaints, and how to avoid them through proper building design. High Performance, Energy Efficient Design for Wood Frame Buildings

4 Learning Objectives 1. Identify potential comfort issues in multi-family and mixed-use buildings and how to address them through proper building design. 2. Review code requirements for energy efficient design in multifamily and mixed-use buildings. 3. Highlight options for high-performing, energy efficient woodframe assemblies, including walls and roofs. 4. Discuss options for meeting or exceeding energy-efficiency objectives and energy code requirements using wood-frame assemblies. High Performance, Energy Efficient Design for Wood Frame Buildings

5 AGENDA 1. Occupant Comfort and Energy Performance Overview 2. Energy Codes Minimum Required Performance 3. Beyond Energy Codes Higher Performance Standards 4. Wood Construction Assemblies Requirements and Strategies 5. Conclusions High Performance, Energy Efficient Design for Wood Frame Buildings

6 AGENDA 1. Occupant Comfort and Energy Performance Overview 2. Energy Codes Minimum Required Performance 3. Beyond Energy Codes Higher Performance Standards 4. Wood Construction Assemblies Requirements and Strategies 5. Conclusions High Performance, Energy Efficient Design for Wood Frame Buildings

7 What is comfort in a building? Specifically, what is thermal comfort?

8 What determines comfort in a building? 1. Temperature Specifically Air Temperature and Radiant Temperature of walls, floors, ceilings, etc.

9 What determines comfort in a building? 2. Humidity Both by itself and linked to air temperature

10 What determines comfort in a building? 3. Fresh Air - wanted From ventilation system or operable windows

11 What determines comfort in a building? 3. Fresh Air - Unwanted Drafts are unwanted air infiltration cause discomfort to people.

12 What determines comfort in a building? 4. Natural Daylight - Wanted Connection to the outdoors plus feeling of warmth or cool

13 What determines comfort in a building? 4. Natural Daylight - Unwanted Glare is excessive light and needs to be controlled

14 What determines comfort in a building? Answer: All 4 of the above Fortunately, we can control all these things in buildings primarily based on design of building envelope, including wood framing systems

15 What determines comfort in a building? Variables Other subjective items we can t control like human metabolism and clothing.

16 What determines building energy performance? Energy Conservation the most cost-effective factor: Reduce need for energy in the first place in building design. Energy Efficiency: MULTI FAMILY BUILDING

17 What determines building energy performance? 1. Temperature Air Temperature based on heating or cooling energy and Radiant Temperature based on building enclosure/ envelope and indoor temperature

18 What determines building energy performance? 2. Humidity Controlling humidity to help control comfort relative to temperature Energy required to control humidity and temperature

19 What determines building energy performance? 3. Fresh Air Wanted Mechanical ventilation requires energy Natural ventilation reduces need for energy

20 What determines building energy performance? 3. Fresh Air - Unwanted Controlling drafts / unwanted air infiltration that leak heating, cooling, moisture, and need more energy to counteract

21 What determines building energy performance? 4. Natural Sunlight - Wanted In addition to daylight sun can provide some warmth in heating season

22 What determines building energy performance? 4. Natural Sunlight - Unwanted In cooling season, glazing needs to reflect back solar heat and UV radiation to reduce energy for cooling

23 What determines building energy performance? Answer: All of the same 4 things that determine comfort A building that is more energy efficient controls the same things that make it a more comfortable building

24 How to design for both comfort and energy performance? Design of buildings that are both comfortable and energy efficient is an iterative process often requires different iterations of design of different aspects to balance and optimize building

25 AGENDA 1. Occupant Comfort and Energy Performance Overview 2. Energy Codes Minimum Required Performance 3. Beyond Energy Codes Higher Performance Standards 4. Wood Construction Assemblies Requirements and Strategies 5. Conclusions High Performance, Energy Efficient Design for Wood Frame Buildings

26 2015 IECC International Energy Conservation Code Applies to both Residential and Commercial Six chapters for Residential Six similar chapters for Commercial Some key differences to understand between building codes and energy code

27 IECC Residential vs. Commercial Multifamily 3 stories or less follows residential portion of IECC more stringent for building envelope Multifamily over 3 stories follows commercial portion of IECC more stringent for lighting and mechanical Which applies to these photos?

28 IECC Which code do you use for each project? R C #1 #3 C #2 #5 C NOTE: 1 energy filing required if submitting entire building #4 C

29 IECC ASHRAE 90.1 Code option that can be applied to any commercial building, including multi-family or mixed use Recognized by IECC as equivalent path to compliance Some differences in requirements compared to IECC Design teams must choose which one to use as basis for non-residential buildings.

30 IECC Both IECC and ASHRAE 90.1 rely on identifying which of 8 climate zones a building is located in same for residential or commercial

31 IECC Compliance Prescriptive Path Prescriptive R-values Affect Temperature/ Energy use Start with Climate Zone R-values are based purely on insulation not total assembly. Wood framed walls are shown as minimum cavity insulation plus continuous insulation depending on climate zone. TABLE R

32 IECC Compliance - Commercial Make sure to select correct occupancy - commercial or Group R TABLE C Building Code identifies Commercial Occupancies including Group R Energy Code differentiates for Group R Multifamily Commercial IECC differentiates between wood and metal framing

33 IECC - Temperature Prescriptive requirements are designed overcome thermal bridging in framed construction Thermal bridging from inside Thermal bridging from outside

34 IECC - Temperature Nominal R-Value R-20 cavity insulation installed between wood 16 oc What is the effective R-value of the assembly? Effective R-Value R-15 Continuous insulation prevents heat loss Thermal bridge at studs and top plate

35 IECC - Temperature Steel Stud Correction Factors Steel studs recognized as having more dramatic thermal bridging than wood Table based on stud depth and spacing extent of dramatic thermal bridging. R-value of cavity insulation is adjusted by a correction factor to determine the Effective R-Value (ER) that must be followed

36 IECC - Temperature Nominal R-Value R-21 cavity insulation w/ steel 16 oc What is the effective R-value of the assembly? Effective R-Value R-7.35 Continuous insulation prevents heat loss Thermal bridge at studs and top plate

37 IECC - Compliance Prescriptive U-Factors U-Factors are inverse of R-Values - U = 1/R Start with Climate Zone U-Factor is based on total construction assembly, not just insulation as in R-value tables. Basis for calculations need to be documented from identified sources

38 IECC Compliance: U-Factor Cavity Frame (0.036 x 0.75) + (0.068 x 0.25) = /0.044 = Climate Zones 64 & 5

39 IECC - Compliance Simple Performance Alternative Showing IECC compliance with the Performance Path relies on computer software to show overall compliance Some trade-offs are allowed Non-compliant prescriptive portions of building can be offset by other over-compliant portions within building system i.e. envelope

40 IECC - Compliance Total Building Performance Alternative Uses Energy Model to compare design to a baseline or Standard Reference Design Building Energy Cost must be less than 85% of standard reference design Must comply with DOE2 tool such as Energy Plus or equest

41 IECC - Humidity Primarily addressed in International Building Code (IBC) Controlling moisture in buildings 1. Bulk water 2. Capillarity 3. Air infiltration 4. Vapor diffusion

42 IECC / IBC Vapor Barriers and Vapor Retarders Humidity / vapor control - IBC requires retarders based on Climate Zones in IECC

43 IECC Ventilation (Fresh Air) Mechanical code says: Energy code says: Provide ventilation! Control ventilation!

44 IECC Ventilation (Fresh Air) Rather than simply throwing away air that the building owner spent money heating or cooling, an ERV recovers the energy in the return air before exhausting it

45 IECC Ventilation (Fresh Air) Natural ventilation, including operable windows, IS an option.

46 IECC Ventilation (Fresh Air) Stack ventilation or solar chimneys can help larger multi-family buildings too

47 IECC Air Infiltration (Unwanted) Addresses air infiltration with mandatory requirements: Helps with humidity and unwanted ventilation Air infiltration barriers must be: 1. Continuous 2. Located on inside or outside of the building envelope 3. Secure, durable and attached to thermal boundary 4. All penetrations caulked or gasketed

48 IECC Air Infiltration Blower Door Testing: Required in Residential IECC Option in Commercial IECC Residential: Whole-building or individual units must achieve air leakage rate better than 3ACH50 Commercial: Maximum air leakage must be 0.40 cfm/ft2 when tested at a pressure differential of 0.3 inch water gauge (75 Pa)

49 IECC Daylight: Window to Wall Ratio (WWR) Vertical fenestration area (for WWR calculation only) Includes windows Does not include opaque doors and opaque spandrel panels PRESCRIPTIVE ALLOWED IF WWR 30% of the gross above-grade wall area. WWR Meets prescriptive requirements Requires Daylighting Requires Energy Model

50 IECC Daylight Zones: Windows Daylight Zone = Portion of a building s interior floor area that is illuminated by natural light Sidelight zone (daylit area from vertical window) is most common 2 from window jamb (both sides) SECTION VIEW Depth into room = H H= Distance floor to window head) PLAN VIEW

51 IECC Daylight: Lighting Controls Daylight Responsive Lighting Controls required for ALL lighting in all Daylight Zones

52 IECC Overall Envelope: Continuity is key! Walls R-value affects heat loss/gain Below Grade Walls R-value affects heat loss/gain Roofs R-value and SRI affect heat loss/gain Everywhere Air seal everything Detail to avoid thermal bridging Windows U-factor affects heat loss/gain SHGC affects heat gain VT affects daylighting Operation affects natural ventilation Make sure air barrier aligns with thermal barrier!

53 IECC Interaction of Components Design Professionals calculate heat load based on: Quality of envelope design Quality of envelope construction Equipment size is based on heat load calculations

54 IECC Interaction Between Design and Construction IECC requires commissioning and inspections to assure that construction matches design IF Envelope is built as designed Envelope NOT built as designed THEN COMFORT DISCOMFORT

55 AGENDA 1. Occupant Comfort and Energy Performance Overview 2. Energy Codes Minimum Required Performance 3. Beyond Energy Codes Higher Performance Standards 4. Wood Construction Assemblies Requirements and Strategies 5. Conclusions High Performance, Energy Efficient Design for Wood Frame Buildings

56 Energy Performance Trends 1975 Energy Code = 100% ASHRAE IECC Code-compliant buildings today will use almost 50% as much energy as a similar building constructed in 1975 Projections to 2030 assuming same rate of change as last 9 years Year Net Zero Building (Produces energy equal to the amount it uses over a year)

57 Energy Performance Trends A $43.8 Billion Green Building Materials Market Expected to Grow 9.5% Through 2019* *U.S. Market for green building materials. CAGR over

58 ENERGY STAR for Buildings Designed to earn the Energy Star or to achieve it means a minimum score of 75. Generally about 20% better than typical building in terms of energy performance which would score a 50.

59 Common Measurement: EUI Total Annual Energy Use accounted for and converted to BTUs Divided by building square footage Expressed in thousands of BTUs (kbtu) per sf per year

60 ENERGY STAR Metrics Designer inputs basic building and energy information Results Table shows: EPA s ENERGY STAR score The percent energy reduction relative to median Source EUI (kbtu/ft2/yr) Site EUI (kbtu/ft2/yr) Source energy (kbtu/yr) Site energy (kbtu/yr) Energy cost ($/yr) Total GHG emissions (CO2-eq/yr)

61 ENERGY STAR Multifamily High Rise (MFHR) Program Voluntary proof of your leadership Designed to be at least 15% more efficient than ASHRAE Energy Conservation Measures are Tested and Verified Benchmarking Performance

62 ENERGY STAR Qualified MFHR Building Features Effective Insulation Properly Sized Equipment Tight Construction and Ducts Testing and Verification ES Lighting High Efficiency Appliances High Performance Windows

63 The U.S. Green Building Council Focused on improving building performance on multiple fronts for greener, more sustainable buildings

64 A Voluntary Third Party Certification Standard Different rating systems for different building types New and Major Renovation Existing Buildings Specific Building Types: Schools Healthcare Homes

65 LEED v. 4 and Energy Efficiency Energy & Atmosphere Prerequisite: Demonstrate improvement of 2-5% in the proposed building performance rating compared baseline building performance according to ASHRAE Standard , Credits: 6% 50% improvement for 1 20 points depending on building type, new or renovation, or core and shell. Largest single potential for points in LEED. Environmental Quality Daylighting/Views provide views to outside and natural daylight instead of electric lights Increased Ventilation natural ventilation instead of mechanical ventilation

66 The 2030 Challenge Initiated by Architecture 2030, a non-profit, non-partisan organization. Established by architect Edward Mazria in 2002.

67 The 2030 Challenge The goal is to get to zero fossil fuel energy energy is still needed just not fossil fuels which pollute the air and environment 2014

68

69 Passive House Institute Overall Approach: Superinsulation and airtight construction provide unmatched comfort even in extreme weather conditions. Continuous mechanical ventilation of fresh filtered air provides superb indoor air quality. A comprehensive systems approach to modeling, design, and construction produces extremely resilient buildings. Passive building principles offer the best path to Net Zero and Net Positive buildings by minimizing the load that renewables are required to provide.

70 Passive House Institute Targets 75% energy savings or better net zero possible with renewables

71 Passive House Institute In the ideal case, passive houses require no furnace, no air conditioners, and, in fact, no thermostat. The airtight dwellings maintain a perfectly even and comfortable temperature by means of a ventilation system that automatically brings fresh air in from the outside, heating it to the proper temperature via exchangers and other low-energy systems.

72 Passive House Institute Air Infiltration Size of equivalent hole based on air leakage area of 2,500 sq. ft. home Old leaky house 20 ACH50 = 700 sq. in. Typical Current New House 10 ACH50 = 350 sq. in. REQUIRED by 2015 IECC 3 ACH50 = 150 sq. in. Passive House 0.6 ACH50 = 21 sq. in.

73 Multifamily construction is the fastest growing area of Passive House in the US

74 AGENDA 1. Occupant Comfort and Energy Performance Overview 2. Energy Codes Minimum Required Performance 3. Beyond Energy Codes Higher Performance Standards 4. Wood Construction Assemblies Requirements and Strategies 5. Conclusions High Performance, Energy Efficient Design for Wood Frame Buildings

75 Wood Construction Key to High Performance Assure that critical barriers are in place and are continuous across all parts of construction

76 Wood Construction Slab on grade Code: insulate to minimum of R-10 and extend insulation to a depth of 2 feet Climate Zone 6: insulate to depth of 4 feet

77 Wood Construction Slab on grade Best practice A truly continuous line of insulation and other barriers from foundation, up through wood framed construction

78 Wood Construction Framed Floor Crawl Space best practice: Seal the crawl space, insulate the walls, and put down a vapor barrier

79 Wood Construction Framed Floor Provide continuity of insulation, air sealing, and other barriers from basement wall up to floor framing, up to wall framing. ABOVE- GRADE WALL RIM JOIST BASEMENT WALL Source: Insofast.com

80 Wood Construction Framed Floor Code requires: Floor framing-cavity insulation must be installed to maintain permanent contact with the underside of the subfloor decking Exception: If the floor cavity insulation goes from top to bottom on the perimeter near the walls, it is permitted to rest on the sheathing. Wood-based subfloor Sheathing Cavity insulation Air space

81 Wood Construction Framed Floor CONTINUOUS Air seal at all vertical and horizontal joints along beams and rim joist

82 Wood Construction Walls Conventional construction materials can be used as continuous air barrier tape all seams, corners, and joints Taped seams, corners, and joints Engineered Wood with integral barriers and tape system

83 Wood Construction Walls Maintain continuity of insulation Seal everything horizontally and vertically: Junction of the foundation and sill plate Junction of the top plate and the top of the exterior walls Knee walls

84 Wood Construction Walls Avoid thermal breaks through construction detailing Many resources to help designers improve insulation installation such as: Passive House Institute Building Science Corporation

85 Wood Construction Roofs Code Requires R-49 If insulation is full height over exterior wall top plate, R-38 min. complies with code

86 Wood Construction Roofs TABLE C Roof insulation entirely above roof deck must be R-30 continuous insulation Attic and all other roof assemblies require minimum R-38 / 49 depending on climate zone

87 Wood Construction Roofs Eave Baffle: Install eave baffles so the insulation doesn t block the vents (especially important with blown-in insulation) Attic Hatches & Doors Insulate all accesses to conditioned space

88 AGENDA 1. Occupant Comfort and Energy Performance Overview 2. Energy Codes Minimum Required Performance 3. Beyond Energy Codes Higher Performance Standards 4. Wood Construction Assemblies Requirements and Strategies 5. Conclusions High Performance, Energy Efficient Design for Wood Frame Buildings

89 Energy and Comfort Perform Together Best approach recognized as starting with Design as basis, particularly envelope. Efficiency and Conservation then reduce the need for energy further. The small amount of energy then required can come increasingly from renewables instead of fossil fuels.

90 Energy and Comfort Perform Together Codes establish the basic minimums Voluntary standards like ENERGY STAR and LEED raise the bar on performance and comfort Programs like Passive House and the 2030 Challenge achieve net zero energy and high comfort

91 Energy and Comfort Perform Together Wood construction can achieve the highest levels of comfort and energy performance. Designs and construction that pay attention to the details will be the most successful.

92 Questions? THANK YOU This concludes The American Institute of Architects Continuing Education Systems Course Peter J. Arsenault, FAIA, NCARB, LEED-AP High Performance, Energy Efficient Design for Wood Frame Buildings