Energy Efficiency: Designing Wood-Frame Buildings for Occupant Comfort

Transcription

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

2 Energy Efficiency: Designing Wood-Frame Buildings for Occupant Comfort 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. Energy Efficiency: Designing Wood-Frame Buildings for Occupant Comfort

3 Course Description This session focuses on options for meeting and exceeding 2015 International Energy Conservation Code requirements in wood-frame buildings. Code provisions and significant changes in recent editions will be addressed, as will compliance path options and design considerations unique to wood-frame assemblies. Details will be included throughout with an emphasis on practical information and maximizing occupant comfort in commercial and multi-family wood-frame buildings. Energy Efficiency: Designing Wood-Frame Buildings for Occupant Comfort

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. Energy Efficiency: Designing Wood-Frame Buildings for Occupant Comfort

5 AGENDA 1. Occupant Comfort and Energy Performance Relationship 2. Choosing Project Goals Code Minimum or Better? 3. Foundation Design for Comfort and Energy Performance 4. Exterior Wall Design for Comfort and Energy Performance 5. Roof Design for Comfort and Energy Performance 6. Conclusions Energy Efficiency: Designing Wood-Frame Buildings for Occupant Comfort

6 AGENDA 1. Occupant Comfort and Energy Performance Relationship 2. Choosing Project Goals Code Minimum or Better? 3. Foundation Design for Comfort and Energy Performance 4. Exterior Wall Design for Comfort and Energy Performance 5. Roof Design for Comfort and Energy Performance 6. Conclusions Energy Efficiency: Designing Wood-Frame Buildings for Occupant Comfort

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

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

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

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

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

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

13 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

14 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

15 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

16 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

17 AGENDA 1. Occupant Comfort and Energy Performance Relationship 2. Choosing Project Goals Code Minimum or Better? 3. Foundation Design for Comfort and Energy Performance 4. Exterior Wall Design for Comfort and Energy Performance 5. Roof Design for Comfort and Energy Performance 6. Conclusions Energy Efficiency: Designing Wood-Frame Buildings for Occupant Comfort

18 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

19 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?

20 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.

21 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

22 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

23 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

24 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

25 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

26 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

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

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

29 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

30 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)

31 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

32 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!

33 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

34 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)

35 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.

36 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

37 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

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

39 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

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

41 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

42 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.

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

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

45 AGENDA 1. Occupant Comfort and Energy Performance Relationship 2. Choosing Project Goals Code Minimum or Better? 3. Foundation Design for Comfort and Energy Performance 4. Exterior Wall Design for Comfort and Energy Performance 5. Roof Design for Comfort and Energy Performance 6. Conclusions Energy Efficiency: Designing Wood-Frame Buildings for Occupant Comfort

46 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

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

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

49 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

50 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

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

52 AGENDA 1. Occupant Comfort and Energy Performance Relationship 2. Choosing Project Goals Code Minimum or Better? 3. Foundation Design for Comfort and Energy Performance 4. Exterior Wall Design for Comfort and Energy Performance 5. Roof Design for Comfort and Energy Performance 6. Conclusions Energy Efficiency: Designing Wood-Frame Buildings for Occupant Comfort

53 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

54 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

55 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

56 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

57 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

58 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

59 AGENDA 1. Occupant Comfort and Energy Performance Relationship 2. Choosing Project Goals Code Minimum or Better? 3. Foundation Design for Comfort and Energy Performance 4. Exterior Wall Design for Comfort and Energy Performance 5. Roof Design for Comfort and Energy Performance 6. Conclusions Energy Efficiency: Designing Wood-Frame Buildings for Occupant Comfort

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

61 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

62 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

63 AGENDA 1. Occupant Comfort and Energy Performance Relationship 2. Choosing Project Goals Code Minimum or Better? 3. Foundation Design for Comfort and Energy Performance 4. Exterior Wall Design for Comfort and Energy Performance 5. Roof Design for Comfort and Energy Performance 6. Conclusions Energy Efficiency: Designing Wood-Frame Buildings for Occupant Comfort

64 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.

65 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

66 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.

67 Questions? THANK YOU This concludes The American Institute of Architects Continuing Education Systems Course Peter J. Arsenault, FAIA, NCARB, LEED-AP Energy Efficiency: Designing Wood-Frame Buildings for Occupant Comfort