Energy Conserving Design Details
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Energy Conserving Design Details

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This two-hour lecture will cover residential design features and choices that may help to conserve energy. The discussion will include building siting and orientation issues, building envelope......

This two-hour lecture will cover residential design features and choices that may help to conserve energy. The discussion will include building siting and orientation issues, building envelope details, glazing, shading structures & devices, thermal mass and energy-conserving landscape elements. We will also briefly discuss how interior space lay-out can affect energy efficiency.

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  • 1. The Green Roundtable and Energy Conserving Design Details
  • 2. Green Roundtable Consulting, education, training and strategic planning to create healthy environments by integrating principles of sustainability into mainstream planning, design and construction. The Green Roundtable (copyright © Green Roundtable 2007)
  • 3. Objectives - Introduce you to basic concepts of energy conserving design - Help you develop the right mind-set & approach to guide and inform future projects - Provide some specific strategies/ elements to get you started - Demonstrate ways that these measures provide benefits beyond energy conservation The Green Roundtable (copyright © Green Roundtable 2007)
  • 4. Food for thought…. The Green Roundtable (copyright © Green Roundtable 2007)
  • 5. The Green Roundtable (copyright © Green Roundtable 2007)
  • 6. A sobering fact… It has been estimated that in order for the current population of the Earth to live at the same quality of life as the industrialized nations, it would require the resources of four ‗Earth equivalents‘. The Green Roundtable (copyright © Green Roundtable 2007)
  • 7. More sobering facts… Half of U.S. greenhouse gas emissions come from buildings (construction/ operation) Buildings account for nearly half of the total energy use in the United States Buildings represent the single largest energy consumer in the U.S., followed by the transportation sector The Green Roundtable (copyright © Green Roundtable 2007)
  • 8. The Green Roundtable (copyright © Green Roundtable 2007)
  • 9. Additional housing sector facts… There are more than 76 million residential buildings in the USA today The average size of a U.S. single-family house has increased by 33% since 1975 Estimates of residential energy consumption as a proportion of the nation‘s total energy load range from around 20 – 40% From 2000 to 2005, winter heating costs for natural gas increased by 115%, oil by 135%, and electricity by 18% The Green Roundtable (copyright © Green Roundtable 2007)
  • 10. Additional housing sector facts… According to HUD, if Americans can reduce home energy use by 10% over the next ten years (a doable number!), it will be the energy equivalent of 40 new power plants (600 Mw) and the greenhouse gas equivalent of 25 million vehicles The vast majority of the total life-cycle energy consumed by a home is operating energy (vs. the energy that goes into building it) The Green Roundtable (copyright © Green Roundtable 2007)
  • 11. A key focal point in green design: Since buildings are so energy-intensive in their construction, operation and maintenance, much of green design focuses on ways to moderate this energy consumption The Green Roundtable (copyright © Green Roundtable 2007)
  • 12. General approaches - Work with nature; take advantage of site - Choose design approaches that improve efficiency - Pay attention to building envelope details - Use natural/ passive ventilation & cooling strategies - Improve efficiency through effective space layout - Use efficient lighting & equipment - Consider scale! The Green Roundtable (copyright © Green Roundtable 2007)
  • 13. Low-hanging Fruit The Green Roundtable (copyright © Green Roundtable 2007)
  • 14. Low cost, big return • Insulate hot water pipes (pipes closest to water heater first) • Install low-flow shower heads • Install faucet aerators & automatic faucets • Install a programmable thermostat • Carefully weatherstrip & air seal • Use expanding foam insulation to plug obvious holes in building envelope • Use gasketed/ enclosed electrical receptacles The Green Roundtable (copyright © Green Roundtable 2007)
  • 15. Low cost, big return- continued • Use CFLs! • Install dimmer switches & occupancy sensors • Use zone lighting • Put timer switches on bathroom fans • Use motion sensor outdoor lights • Buy Energy Star anything! (if it affects energy use) The Green Roundtable (copyright © Green Roundtable 2007)
  • 16. Site/ Building Orientation • Know the site! Visit during different times of year. Set up on-site monitoring; Collect data from various resources. • Understand: - Prevailing winds - On-shore & off-shore breezes - Sunshine patterns (insolation) - Shading/ obstructions - Topography The Green Roundtable (copyright © Green Roundtable 2007)
  • 17. Climate data/ maps • http://www.nrel.gov/gis/maps.html- Solar, Wind resources •Topographical maps: http://store.usgs.gov/scripts/wgate/ZWW20/!?~langua ge=en&~theme=GP&OSTORE=USGSGP&~OKCOD E=START •Sunpath diagrams: http://www.luxal.eu/resources/daylighting/sunpath.shtml • OLIVER- MassGIS Online Data Viewer: http://maps.massgis.state.ma.us/massgis_viewer/index.htm The Green Roundtable (copyright © Green Roundtable 2007)
  • 18. The Green Roundtable (copyright © Green Roundtable 2007)
  • 19. The Green Roundtable (copyright © Green Roundtable 2007)
  • 20. The Solar Pathfinder The Green Roundtable (copyright © Green Roundtable 2007)
  • 21. Using the site • Take advantage of existing vegetation if possible- deciduous trees for shading; coniferous trees as wind breaks • Site structure on south-facing slope for maximum solar gain; take advantage of wind & solar resources • Use natural terrain features to protect structure from cold winter winds • Site structure downwind from lakes, ponds, wetlands for natural cooling • Take advantage of hills that funnel breezes • Use earth-berming if topography permits The Green Roundtable (copyright © Green Roundtable 2007)
  • 22. The Green Roundtable (copyright © Green Roundtable 2007)
  • 23. Building orientation/ layout • Orient structure along East-West axis; i.e. long side facing south • Minimize glazing area on north, northeast & west- facing walls • Maximize glazing on south-facing walls to maximize winter solar gains • Incorporate buffer spaces in structure- closets along outside walls, vestibules, enclosed porches, etc. • Minimize surface area-to-volume ratio The Green Roundtable (copyright © Green Roundtable 2007)
  • 24. The Green Roundtable (copyright © Green Roundtable 2007)
  • 25. Green Practice: Improving the Building Envelope The Green Roundtable (copyright © Green Roundtable 2007)
  • 26. Building envelope, definition All of the elements of a building that separate and isolate the outdoor environment from the indoor environment. This may include walls and wall finishes, roofs and roof finishes, doors, windows, skylights and basement floors and walls. The Green Roundtable (copyright © Green Roundtable 2007)
  • 27. Key Principle- Saving home energy As a general rule, for the average home/ homeowner, the greatest energy savings will be achieved through managing the demand side of the equation, rather than the supply side. In other words, you’ll get better bang for your buck through energy conservation measures, like insulating & minimizing air infiltration, than incorporating expensive renewable energy systems such as wind and solar. The Green Roundtable (copyright © Green Roundtable 2007)
  • 28. An exception: Exceptions to this may include passive solar, and situations where you qualify for a substantial rebate and/or credit for other renewable energy systems (keep in mind the embodied energy of systems though!) There are other compelling reasons to perform upgrades like this, such as reduced reliance on foreign energy resources, promotion of renewable energy & local industry, passive survivability, etc. The Green Roundtable (copyright © Green Roundtable 2007)
  • 29. Preventing heat loss • Insulate • Air seal (prevent infiltration) • Use landscape features- vegetative shields, etc. • Address lifestyle issues • Best bang for buck through air sealing! Begin here! The Green Roundtable (copyright © Green Roundtable 2007)
  • 30. Building envelope, functions • Protect structural elements and interior of structure from weather, esp. moisture • Help to maintain proper thermal regime within structure • Help to maintain proper humidity regime within structure • Prevent infiltration of outside air and contaminants • Acoustically isolate interior of structure from outside noise • In essence, act as ‗membrane‘ for the structure The Green Roundtable (copyright © Green Roundtable 2007)
  • 31. Building envelope failure • Air leaks leading to: -Infiltration of unconditioned air/ Drafts -Direct escape of conditioned air to outside -Infiltration of outdoor contaminants • Excessive accumulation of interior moisture in wall cavities causing structural/ insulation failure & mold • Excessive heat transfer from inside to outside • External water leaks leading to: -Damaged structural elements -Damaged interior finishes -Insulation failure -Damaged interior furnishings and appliances -Mold problems The Green Roundtable (copyright © Green Roundtable 2007)
  • 32. Building envelope components • Exterior finish- wood siding, fiber-cement, brick, etc. • Weather membrane/ air barrier/ drainage plane- building paper, Tyvek, Typar, etc. • Exterior sheathing- usually plywood or OSB • Wall/ ceiling cavities (inc. structural members & insulation) • Vapor retarders/ barriers • Doors & windows • Interior wall finish The Green Roundtable (copyright © Green Roundtable 2007)
  • 33. High-performance wall section A high- performance wall section (proposed for consideration) The Green Roundtable (copyright © Green Roundtable 2007)
  • 34. High-performance wall section, key Envelope Layer Option 3 R-Value Permeance Cedar (Eastern white) or fiber-cement 1 clapboards 0.87 (Cedar) Pactiv GreenGuard Raindrop 2 Housewrap/ Rainscreen1 N/A 3 3/4" XPS Foam insulation 3.75 1.2 1/2" Homasote sheathing (Structural bracing; high recycled content; 4 formaldehyde-free) 1.2 17 5 1/2" Stud cavity (2 x 6 walls; 24" o.c.) w/ Fiberglass batts or polyurethane 5 spray foam 19/ 37* Thermo-ply sheathing (Vapor retarder; 6 R-value from radiant barrier effect) 3.5 .53 -.63 0.45 (0.90 w 7 5/8" GWB (Dbl. layer for thermal mass) dbl. layer) 1 1/2" thick wood furring strips (for radiant barrier effect; also, can move 8 electricals within thermal envelope) N/A 9 Air space 1 120 Total R-Value 29.77/ 47.77* *w/ poly foam The Green Roundtable (copyright © Green Roundtable 2007)
  • 35. Codes and standards • Sixth edition of MA building code was officially superseded by 7th edition as of January 1st, 2008 • New MA energy code based on 2006 International Energy Conservation Code; more stringent • Better to follow Energy Star Homes or HERS guidelines for maximum energy efficiency and code compliance (see resources slide) The Green Roundtable (copyright © Green Roundtable 2007)
  • 36. Minimizing air infiltration (sealing building envelope) • Min .35 Air changes per hour (ACH) for good ventilation; max .50 for energy efficiency (Energy Star) • Seal obvious openings- pipe penetrations, attic scuttles, electrical receptacles, recessed lights, etc. • Openings to attic spaces are some of worst offenders • Any place where two building planes meet is good candidate for air sealing • For additions/ new construction, use exterior air barrier to minimize infiltration The Green Roundtable (copyright © Green Roundtable 2007)
  • 37. Housewrap to minimize air infiltration & protect from moisture The Green Roundtable (copyright © Green Roundtable 2007)
  • 38. Blower door test to measure air leakage The Green Roundtable (copyright © Green Roundtable 2007)
  • 39. Air leakage pathways The Green Roundtable (copyright © Green Roundtable 2007)
  • 40. Air leakage proportion through various pathways The Green Roundtable (copyright © Green Roundtable 2007)
  • 41. Attic hatches/ scuttles are a major leakage pathway The Green Roundtable (copyright © Green Roundtable 2007)
  • 42. A commercial solution for attic openings See also www.efi.org The Green Roundtable (copyright © Green Roundtable 2007)
  • 43. Insulate header/ rim joists w/ rigid foam & expanding foam The Green Roundtable (copyright © Green Roundtable 2007)
  • 44. Seal joints between intersecting planes w/ expanding foam The Green Roundtable (copyright © Green Roundtable 2007)
  • 45. The Green Roundtable (copyright © Green Roundtable 2007)
  • 46. The Green Roundtable (copyright © Green Roundtable 2007)
  • 47. Fireplaces are usually NOT an effective heating appliance! They lead to excessive heat loss via drafts up chimney. The Green Roundtable (copyright © Green Roundtable 2007)
  • 48. Air sealing, online product sources • efi.org • conservationtechnology.com The Green Roundtable (copyright © Green Roundtable 2007)
  • 49. Insulating • Resistance to heat flow (insulating ability) measured in R-value; not important to know how this is derived; mainly need to know that it‘s a relative scale of effectiveness, and the higher the R value, the better the insulating value • Code represents absolute minimum; newer code has more stringent requirements; tied to window area; R-49 ceiling, R-21 walls, R-30 floors, R-13 basement typical The Green Roundtable (copyright © Green Roundtable 2007)
  • 50. Insulating guidelines • Go for low-hanging fruit- e.g. add more attic insulation first if it is accessible and is not well insulated; Don‘t forget the basement! • Remember that if you use A/C you are minimizing cooling expense by buttoning up your house as well as heating expense • Try to eliminate bridging (perimeter) heat loss through structural elements, as it greatly reduces overall insulation effectiveness • Look for additional opportunities to insulate (other than typical wall/ ceiling cavity insulation) The Green Roundtable (copyright © Green Roundtable 2007)
  • 51. The Green Roundtable (copyright © Green Roundtable 2007)
  • 52. Bridging heat loss • Conductive heat loss through structural members • Eliminate with: -Double wall construction (very expensive!) -Foam skin -Cross-banding attic batt insulation The Green Roundtable (copyright © Green Roundtable 2007)
  • 53. Bridging heat loss- snow melts over roof rafters The Green Roundtable (copyright © Green Roundtable 2007)
  • 54. Bridging heat loss caused wall-staining over structural members The Green Roundtable (copyright © Green Roundtable 2007)
  • 55. Bridging heat loss through sill plates The Green Roundtable (copyright © Green Roundtable 2007)
  • 56. Layer of foam minimizes bridging loss through sill; top of concrete foundation wall will also receive layer of foam The Green Roundtable (copyright © Green Roundtable 2007)
  • 57. Provide continuous vent (ridge) here Continuous airflow (blue) from soffit to ridge; minimizes risk of ice dams, minimizes moisture accumulation in Insulation baffle rafter cavities, keeps living space (green) cooler in summer and may extend life of roof Rafter cavity insulation (fiberglass typical.) 2” XPS foam board insulation Attic living space Install continuous soffit vents here The Green Roundtable (copyright © Green Roundtable 2007)
  • 58. Insulation Baffle The Green Roundtable (copyright © Green Roundtable 2007)
  • 59. Fiberglass batt insulation • R 3.3 – 3.5 per inch • Relatively inexpensive • Look for formaldehyde-free binders and recycled content • Need to avoid inhaling dust during installation • Can be rendered permanently useless if it gets wet • No inherent air-sealing characteristics • Moderate to high embodied energy The Green Roundtable (copyright © Green Roundtable 2007)
  • 60. Cellulose insulation • R 3.5 per inch; 3.7 if wet blown • Relatively inexpensive • Usually contains high recycled content (made from newsprint) • Need to avoid inhaling dust during installation • Moisture tolerant; can dry out and remain effective • Provides air-sealing characteristics if wet blown (―damp spray‖; ―dense pack‖); professionally installed • Low embodied energy The Green Roundtable (copyright © Green Roundtable 2007)
  • 61. Extruded polystyrene (XPS) • R 5.0 per inch • Relatively expensive • Acts as vapor barrier at thicknesses > ¾ inch • Can be difficult to install • Must be protected from flame with min. ½ in drywall or equivalent • Good air-sealing characteristics if edges foamed and seams taped; closed-cell, moisture-resistant • High embodied energy; many use HCFC blowing agents The Green Roundtable (copyright © Green Roundtable 2007)
  • 62. Polyisocyanurate rigid foam • R 7.0 per inch • Relatively expensive • Acts as radiant barrier if foil faced (and facing ¾‖ min. air space) • Can be difficult to install • Good air-sealing characteristics if edges foamed and seams taped; somewhat moisture resistant (esp. foil-faced) • High embodied energy The Green Roundtable (copyright © Green Roundtable 2007)
  • 63. Icynene™ spray foam • R 3.6 per inch • Expensive • Does not produce harmful smoke; does not burn • Professionally installed • Very good air-sealing characteristics; moisture-resistant • Relatively high embodied energy The Green Roundtable (copyright © Green Roundtable 2007)
  • 64. Polyurethane spray foam • R 6.7 per inch • Expensive • Closed-cell; moisture resistant; may add structural integrity • Professionally installed • Excellent air-sealing characteristics • Relatively high embodied energy • Soy-based equivalents now available (see biobased.net for one example) The Green Roundtable (copyright © Green Roundtable 2007)
  • 65. Icynene application The Green Roundtable (copyright © Green Roundtable 2007)
  • 66. Additional Insulating Opportunities • Be creative! • Examples: - Behind built-in bookcases - Behind cabinets - Closet walls & ceilings • Capitalize on opportunities to insulate, such as when you have exposed exterior wall cavities during remodeling projects The Green Roundtable (copyright © Green Roundtable 2007)
  • 67. Thermograph to check heat loss through walls (insulation effectiveness) The Green Roundtable (copyright © Green Roundtable 2007)
  • 68. Ventilation & Vapor Barriers Issues: • Moisture control as it relates to: -Mold potential -Structural failure -Insulation failure -Aesthetic issues • Indoor air quality (IAQ) The Green Roundtable (copyright © Green Roundtable 2007)
  • 69. Ventilation • It‘s almost impossible to make an old house too tight • Even in a tight house a bathroom fan is generally enough to provide adequate ventilation; control w/ timer (and/or humidistat) • Control internal sources of excessive moisture • Provide dedicated combustion air sources for large combustion appliances like furnaces & fireplaces • Proper attic ventilation may extend life of roof and help to eliminate ice dams • Extremely tight houses may need heat-recovery or multi-port supply ventilation systems The Green Roundtable (copyright © Green Roundtable 2007)
  • 70. Vent bathroom vans to outside! The Green Roundtable (copyright © Green Roundtable 2007)
  • 71. The Green Roundtable (copyright © Green Roundtable 2007)
  • 72. Other ventilation strategies • Heat recovery ventilators • Multi-port exhaust ventilation The Green Roundtable (copyright © Green Roundtable 2007)
  • 73. Vapor barriers/ Retarders • Prevent transfer (and accumulation) of internal moisture into wall/ ceiling cavities • Always on warm side of insulation (winter) for this part of country (northeast U.S.) • In this part of country, vapor retarders are generally better than vapor barriers; vapor retarders allow wall to dry from the inside as well as outside • Asphalt-impregnated kraft paper is excellent vapor retarder The Green Roundtable (copyright © Green Roundtable 2007)
  • 74. Vapor barriers, continued • Eliminating air leaks in inside wall finishes minimizes vapor transfer into wall cavities • For retrofit of vapor barrier (w/ blown-in insulation for instance), consider a vapor barrier paint • New ‗smart‘ materials like Certainteed‘s Membrain create variable vapor barrier The Green Roundtable (copyright © Green Roundtable 2007)
  • 75. Windows • Typical heat loss through windows about 20% • Performance measured in ―U-value‖; inverse of R- value; measure of material‘s ability to conduct heat; the lower the U-value, the better • Look for U-value of .35 or less • Double-glazed, argon filled preferred; Diminishing returns with triple glazing • ‘Low-e’ coating reflects heat back into structure • Always look for Energy Star & NFRC labels (energystar.gov; nfrc.org) The Green Roundtable (copyright © Green Roundtable 2007)
  • 76. NFRC Label The Green Roundtable (copyright © Green Roundtable 2007)
  • 77. Windows • Used ‗tuned‖ glazing strategies • E.g., Use windows w/ low SHGC on west-facing windows; high SHGC on south-facing • Incorporate/ install overhangs & other shading devices where appropriate • Provide nighttime insulation The Green Roundtable (copyright © Green Roundtable 2007)
  • 78. The Green Roundtable (copyright © Green Roundtable 2007)
  • 79. Window insulation Dbl-wall, cellular shades provide insulating value The Green Roundtable (copyright © Green Roundtable 2007)
  • 80. Window insulation Guide rails/ tracks minimize air leakage at edges The Green Roundtable (copyright © Green Roundtable 2007)
  • 81. Energy Conserving Design Strategies (a sampling) The Green Roundtable (copyright © Green Roundtable 2007)
  • 82. The jumping off point… Scale Scale Scale The Green Roundtable (copyright © Green Roundtable 2007)
  • 83. Design Strategies: Thermal mass Thermal mass: • Can be used to store heat in winter • Can help to moderate temperatures year-round • Key element in passive solar design The Green Roundtable (copyright © Green Roundtable 2007)
  • 84. Thermal mass: How to incorporate • Masonry veneers on exterior walls • Masonry finishes on interior walls & floors • Fireplaces, chimneys & interior masonry features • Thickened walls- e.g.double drywall layer • Cob & masonry construction • Green roofs • Water features/ elements The Green Roundtable (copyright © Green Roundtable 2007)
  • 85. Thermal mass: additional benefits • Acoustic comfort • Increased structural integrity in some situations The Green Roundtable (copyright © Green Roundtable 2007)
  • 86. Design Strategies: Green roofs • Properly designed, can pay for themselves in 10 – 15 years via reduced energy cost • Especially effective in reducing cooling costs • By some estimates, can reduce cooling costs by up to 30% in single-story structures • See www.greenroofs.com (industry ass‘n) & www.conservationtechnology.com (supplier example) The Green Roundtable (copyright © Green Roundtable 2007)
  • 87. The Green Roundtable (copyright © Green Roundtable 2007)
  • 88. Modular green roof system See: http://www.liveroof.net/ & http://www.westonsolutions.com/pdf_docs/B-D066- GreenGrid.pdf The Green Roundtable (copyright © Green Roundtable 2007)
  • 89. Green roofs: additional benefits • Can provide stormwater management • Reduce urban heat islands • Help to minimize global warming by conserving energy • May extend the life of your roof • Provide green space & wildlife habitat • Improve acoustic comfort The Green Roundtable (copyright © Green Roundtable 2007)
  • 90. Design Strategies: Passive solar The Green Roundtable (copyright © Green Roundtable 2007)
  • 91. Passive solar Free heat from the sun; ‗greenhouse effect‘ (good kind!); good southern exposure/ solar aperture needed Basic requirements: • Collect it… • Store it… • Retain it… • Distribute it… The Green Roundtable (copyright © Green Roundtable 2007)
  • 92. 5 Major elements of Passive Solar • Aperture/ Collector (glazing) • Absorber • Thermal storage (mass) • Distribution • Control The Green Roundtable (copyright © Green Roundtable 2007)
  • 93. The Green Roundtable (copyright © Green Roundtable 2007)
  • 94. Requirements • Glazing area to collect sunlight- 7% rule- So.-facing • Thermal mass- needed to store heat if net window area is more than 7% of total floor area • Window insulating system (and good building envelope insulation) to keep heat in at night • Shading—vegetation (deciduous), or shading structures like awnings, roof overhangs and pergolas, to prevent overheating during warmer mos. The Green Roundtable (copyright © Green Roundtable 2007)
  • 95. Requirements,cont. • Distribution system—to remove excess heat to other parts of house where it may be needed in winter • Ventilation system—to remove excess heat to outside during warm weather The Green Roundtable (copyright © Green Roundtable 2007)
  • 96. Passive Solar Rules-of-Thumb • Orientation of aperture area should be within 30 degrees of true south • Aperture should ideally be shade-free from 9am – 3pm • South-facing glass should be vertical and should have some kind of overhanging to shade from summer sun • Direct gain systems are most common and easiest to integrate into most designs; glazing should not exceed 12% of building floor area • Thermal mass can help to moderate temperature in summer as well as store heat in winter The Green Roundtable (copyright © Green Roundtable 2007)
  • 97. Passive Solar Rules-of-Thumb • In sunspaces, may need powered ventilation to minimize summer overheating • Skylights should be avoided on all but north and northeast-facing roof surfaces, as they can otherwise contribute to overheating in the summer, and won‘t provide appreciable gains in the winter due to low angle of sun • Deciduous trees can provide good summer shading, but should not be located too close to house/ sunspace, as trunk/ branches may provide too much shade in winter • Well designed passive solar can provide 5 –25% of space heating needs with no added cost The Green Roundtable (copyright © Green Roundtable 2007)
  • 98. The Green Roundtable (copyright © Green Roundtable 2007)
  • 99. Angled glass may not be the best configuration, especially without an overhang! The Green Roundtable (copyright © Green Roundtable 2007)
  • 100. The Green Roundtable (copyright © Green Roundtable 2007)
  • 101. Skylights may contribute to summer overheating and winter heat loss. The Green Roundtable (copyright © Green Roundtable 2007)
  • 102. Design strategies: Advanced Framing • Improves thermal envelope of building– more places to insulate! • Saves on framing lumber expense • Reduces lumber disposal cost/ impact • Saves on labor cost since fewer ―sticks‖ installed • Savings estimates range to 20% of overall framing expense The Green Roundtable (copyright © Green Roundtable 2007)
  • 103. Advanced framing & efficiency • Provides more room for insulation! • Reduces bridging heat loss The Green Roundtable (copyright © Green Roundtable 2007)
  • 104. Advanced Framing • Features 2 x 6 studs on 24‖ centers • Single top plate if trusses/ roof rafters placed directly over wall studs • Jack studs eliminated at window openings • ―Right-sized‖ headers; insulated, engineered headers • No headers in non-load bearing partitions • Open corner framing (2-stud corners) • Ladders at T-intersections The Green Roundtable (copyright © Green Roundtable 2007)
  • 105. The Green Roundtable (copyright © Green Roundtable 2007)
  • 106. The Green Roundtable (copyright © Green Roundtable 2007)
  • 107. The Green Roundtable (copyright © Green Roundtable 2007)
  • 108. Frost-protected Shallow Foundations • Improves thermal performance • Reduce excavating expense • Reduce material expense • Reduce site impact The Green Roundtable (copyright © Green Roundtable 2007)
  • 109. The Green Roundtable (copyright © Green Roundtable 2007)
  • 110. Design Strategies: Natural daylighting • Can reduce lighting loads and cooling loads • Improves indoor environmental quality • Residential systems typically consist of skylights, clerestory windows or tubular daylighting devices (TDD‘s; ―sun tubes‖ or ―light tubes‖) The Green Roundtable (copyright © Green Roundtable 2007)
  • 111. Design Strategies: Natural daylighting • Skylights in south, southwest and west-facing roofs can contribute to summer overheating • Skylights in more north-facing roof surfaces can contribute more light on cloudy days • TDDs may contribute less to overheating The Green Roundtable (copyright © Green Roundtable 2007)
  • 112. The Green Roundtable (copyright © Green Roundtable 2007)
  • 113. Sky tube (TDD) The Green Roundtable (copyright © Green Roundtable 2007)
  • 114. The Green Roundtable (copyright © Green Roundtable 2007)
  • 115. Natural daylighting • Light-colored walls reflect light deeper into structure • Light shelves can serve the same purpose, and accomplish this w/o excessive glare; they provide shading as well • Wide windowsills/ shelves can reflect light as well, but may contribute to glare • Combine daylighting strategies with photo-resistor controlled lights to avoid excessive lighting during daytime • Landscape features can be utilized for reflecting light into interior as well (paved surfaces, water features, etc) The Green Roundtable (copyright © Green Roundtable 2007)
  • 116. Light shelves shade window while providing natural daylight via light reflected from top surface Can help light to penetrate deeper into structure The Green Roundtable (copyright © Green Roundtable 2007)
  • 117. The Green Roundtable (copyright © Green Roundtable 2007)
  • 118. Suggested Room Surface Reflectances: Ceilings: > 80% Walls: 50%-70% Floors: 20%-40% Furnishings: 25%-45% The Green Roundtable (copyright © Green Roundtable 2007)
  • 119. Lighting & Daylighting Analysis RADIANCE is a lighting and daylighting visualization tool developed by LBNL and is available over the web: http://radsite.lbl.gov/radiance/ The Green Roundtable (copyright © Green Roundtable 2007)
  • 120. Alternative building technologies • Structural Insulating Panels (SIPs) • Insulating concrete forms (ICFs) • Modular construction • Hydronic radiant floor heating systems • PEX (cross-linked polyethylene) domestic water supply piping • Google these! The Green Roundtable (copyright © Green Roundtable 2007)
  • 121. Green Practice: HVAC/ Plumbing The Green Roundtable (copyright © Green Roundtable 2007)
  • 122. HVAC & Plumbing Systems • ―Right-size‖ systems using analysis tools (Manual J) rather than rule-of-thumb methods; a right-sized system can be up to 40% smaller than a conventionally-sized system • Use zoned heating • Use demand pumps in DHW supply system (gothotwater.com) • Use heat recovery devices on DWV pipes (gfxtechnology.com) • Use instantaneous hot water heaters (tankless) • Use structured plumbing & PEX piping The Green Roundtable (copyright © Green Roundtable 2007)
  • 123. The Green Roundtable (copyright © Green Roundtable 2007)
  • 124. Tankless water heaters • Examples of brands: Rinnai, Noritz, Takagi • Gas-fired typically more responsive and can provide needed capacity more effectively • Cost more than standard water heaters but last longer • More choices as to location/ placement • Direct-venting; e.g. can exhaust through wall • Look for min. flow rates of 0.3 – 0.5 gal./min. • Save energy by eliminating standing heat loss (vs. conventional tank-style water heater); estimated savings 24 – 34% The Green Roundtable (copyright © Green Roundtable 2007)
  • 125. High-efficiency heating • Choose Energy Star! Right-size systems! (did I mention that before?!) • Make sure heating systems have Annual Fuel Utilization Efficiency (AFUE) of at least 83% for oil- fired and 90% for gas-fired, and Seasonal Energy Efficiency Rating (SEER) of at least 13 for cooling systems • Boilers tend to have higher AFUE than furnaces • Closed-cycle, condensing-type boilers and furnaces are more efficient; they extract additional heat from warm flue gases • These systems often don‘t need conventional flue pipe, they can side vent, but they require a dedicated combustion air source (coaxial flue pipe) The Green Roundtable (copyright © Green Roundtable 2007)
  • 126. The Green Roundtable (copyright © Green Roundtable 2007)
  • 127. Ductwork • Move duct runs into conditioned spaces (thermal envelope) if possible • Seal ducts; use duct mastic for this if possible, otherwise make sure duct tape is UL listed • Insulate ducts in unconditioned spaces; for cooling (A/C) ductwork, make sure insulation has external vapor barrier to minimize condensation • When insulating ducts in unconditioned basement, you may make basement too cold; insulate basement walls instead The Green Roundtable (copyright © Green Roundtable 2007)
  • 128. Lighting • Use zone lighting • Use solar landscape lights • Use motion sensor outdoor lights • Put timer switches on bathroom fans • Use natural daylighting strategies The Green Roundtable (copyright © Green Roundtable 2007)
  • 129. Appliances • Buy Energy Star! • Specify horizontal axis washing machines They save water and energy • Specify dishwashers w/ booster heater (and lower water heater to 120 deg) • Don‘t specify oversized AC equipment! The Green Roundtable (copyright © Green Roundtable 2007)
  • 130. The Green Roundtable (copyright © Green Roundtable 2007)
  • 131. Cooling Use ceiling fans w/ cathedral or high ceilings to eliminate temperature stratification (both heating and cooling season) Locate AC/ heat pump condensers on N or NE or NW side out of direct sun! Shade air conditioner and heat pump condensers w/ vegetation or artificial shading (be careful w/ deciduous vegetation) if you have to locate on sunny side The Green Roundtable (copyright © Green Roundtable 2007)
  • 132. Cooling Install awnings, overhangs and other shading structures, such as pergolas Use retrofit heat-reflecting window films on west- facing windows (look for NFRC label); for new windows, choose units w/ low solar heat gain coefficient (SHGC) Make sure attic space is well vented Use whole-house fans to exhaust warm air from house in summer; run mainly at night to flush w/ cool air; close windows during very hot days The Green Roundtable (copyright © Green Roundtable 2007)
  • 133. Cooling Install radiant barriers on underside of roof rafters; can help to warm in winter and cool in summer; don‘t interrupt ventilation pathways Use deciduous vegetation on south, SW and west sides of structure for summer shading; use vines on trellises too Use coniferous (evergreen) trees/ shrubs to redirect breezes/ wind The Green Roundtable (copyright © Green Roundtable 2007)
  • 134. Cooling Take advantage of prevailing winds for natural cooling Maximize cross-ventilation Use building elements to funnel winds (e.g. casement windows) Use light-colored shingles or roof membrane on very low pitched or flat roofs Use high-performance double roof or ―cool‖ roof, esp. w/ cathedral ceilings The Green Roundtable (copyright © Green Roundtable 2007)
  • 135. General analysis tools A general list of tools offered by the U.S. Department of Energy are available over the web at: http://www.eere.energy.gov/buildings/tools_directory/sub jects.cfm/pagename=subjects/pagename_menu=whole_b uilding_analysis/pagename_submenu=load_calculation The Green Roundtable (copyright © Green Roundtable 2007)
  • 136. Standards/ Ratings/ Resources • LEED for Homes (LEED-H)- www.usgbc.org • Energy Star Homes- www.energystar.gov • HERS (http://www.energy.ca.gov/HERS) • International Energy Conservation Code (IEEC)- http://www.iccsafe.org/ • Building America- http://www.eere.energy.gov/buildings/building_america/a bout.html • Environmental Building News/ Greenspec- http://www.buildinggreen.com) •http://www.austinenergy.com/Energy%20Efficiency/Progr ams/Green%20Building/Sourcebook/index.htm The Green Roundtable (copyright © Green Roundtable 2007)
  • 137. Use NEXUS as your green resource! • Upcoming workshops • Reference library • Samples library • Cyber Lounge • Online resources at nexusboston.com (in the pipeline) • Local green building community The Green Roundtable (copyright © Green Roundtable 2007)
  • 138. Local Resources The Green Roundtable (copyright © Green Roundtable 2007)
  • 139. THANK YOU www.greenroundtable.org info@greenroundtable.org 617-374-3740 The Green Roundtable, Inc. (GRT) is an independent non-profit organization whose mission is to mainstream green building and sustainable design and become obsolete. We work toward this goal by promoting and supporting healthy and environmentally integrated building projects through strategic outreach, education, policy advocacy and technical assistance. Located in downtown Boston, NEXUS welcomes all to come ask questions, research topics, and attend tours and www.nexusboston.com events on green building and 38 Chauncy Street, Boston sustainable design innovation. The Green Roundtable (copyright © Green Roundtable 2007)