adding insulation to an older home: the good, the bad, and the ugly?

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Historic Buildings & Green Design Cape-Wide Historic Preservation Workshop. Adding Insulation to an Older Home: The good, the bad, and the ugly?. __________________________________________________ . - PowerPoint PPT Presentation


  • Adding Insulation to an Older Home:The good, the bad, and the ugly?Historic Buildings & Green DesignCape-Wide Historic Preservation Workshop__________________________________________________ Sally Zimmerman, Historic New EnglandMarch 25, 2010

  • Theres always breaking news on the energy front . . . and emerging news on green impacts and preservationNew York Times, March 18,, March 6, 2010

  • What you need to know before you insulate an older homeWhat is most often recommended (and how these recommendations are changing)

    Why these may not be right for the older or historic home

    What you can do to upgrade for energy savings in an older or historic home appropriately!

  • A green house glossary Super-insulationInsulating the interior or exterior to far exceed current building and energy codesNet zeroA net zero, or zero energy, structure in general is one that generates more energy than it uses; it can be, but usually is not, disconnected from the power grid. Strictly defined, net zero structures generate no carbon emissions

    Deep energy retrofitSuper-insulation, plus the addition of renewable energy sources or other measures to further reduce the carbon footprint (passive and active solar systems, geothermal, wind power, water use reduction, landscaping)Passive homeA passive home is so tightly constructed that it needs no heating or cooling source

  • HERS Index: Home Energy Rating System Set by Residential Energy Services Network (RESNET)

    Scoring system scaled from 0 - 200

    Zero net energy home = 0

    Reference new home = 100

    Most older homes = well over 100

    Each 1 point decrease in HERS = 1% reduction in energy consumed

    HERS measures: -Building Enclosure -Mechanical Systems -Lighting/Appliances -Renewable Energy

  • Massachusetts: acting to reduce energy use ahead of federal changesFirst major step towards Zero Net Energy Buildings: amend the State Building CodeMassachusetts adopted the International Energy Conservation Code (IECC) 2009 as its new state building code, effective January 1, 2010 Increases energy efficiency requirements by 10% over the current base codeZNEB establishes regulatory and financial incentives for deep-energy retrofitsDirects utilities to pilot 250 deep-energy retrofits in existing homes

  • Stretch code: local option allows more stringent energy standard that stretches the base code requirements

    Residential alterations & renovations can meet stretch code byPrescriptive pathPerformance pathPrescriptive meets: Energy Star for Homes requirement (HERS 80)Performance meets: HERS of 80(houses over 2000 sf) HERS of 85(houses less than 2000 sf)

  • HERS case study for stretch code: Cambridge MA triple-decker, 2009Existing = vinyl replacement windows , R-10 ceiling insulation; 11 ACH @ 50 Pascals pressure; no mechanical ventilationInitial HERS rating = 143

    Retrofitted with R-13 wall insulation, R-30 ceiling insulation, air sealed to 5 ACH @ 50 Pascals, bath fans addedImprovement cost = $14,847Improved HERS = 85

    With 3 new gas boilers @ 86% AFUEUpgraded cost = $29,395Upgraded HERS = 80

  • What is recommended generally (in the rest of the US)Oak Ridge National Laboratory:Insulation Recommendations for Existing Wood-Framed Houses

  • Most energy interventions assume your house looks like this . . .

  • but what if your house looks like this?

  • Traditional active and passive interventions support energy efficiency in an old houseTraditional practices and design provide the starting point for energy savings

    Passive and active energy measures are: Economical Reversible Work with the historic structure and materialsGeorge Nash, Renovating Old Houses

  • Preservation concerns in insulating older and historic houses . . . We dont know how these materials and techniques will respond over time (we need more materials science research)

    Its complex: contractors are unlikely to know how to properly install them (we need standards for training weatherization contractors on old houses)

    Its expensive to do it right (so how many people will be able to afford to retrofit right?)Boston Globe, January 18, 2009Arlington house may blaze new trail in energy conservation

  • Super-insulation/deep energy retrofits of old houses require careful planning and affect historic materials and finishes

  • Save energy costs and reduce consumption in an older home without losing historic material and character KISSS: Keep it simple, start small

    Air Seal-Energy audits using a blower door test show areas of air leakage-Caulk inside and out to close gaps and stop air movement-Weatherstrip windows and doors

    Insulate Attics-Seal areas of air infiltration-Add loose fill or batt insulation

    Seal and Insulate Ducts

    Insulate Hot Water Heaters and Pipes

    . . . and REPAIR your wood windows!

  • Air Infiltration: Blower door test diagnoses sources

  • Infrared camera monitors locations of heat loss

  • Comprehensively seal sourcesof air infiltration by caulking gaps

    Exterior: Use modified silicone polymer or backer rod and expanding polyurethane foam (foam must be painted to resist weather)

    Interior: Use water-based latex

  • Insulate attics with fiberglass or other batting, or loose-fill insulation; air seal gaps before installing insulationGeorge Nash, Renovating Old Houses

  • Seal and insulate ducts; insulate hot water pipes

  • High efficiency appliances

  • But what about insulating walls? The big question for old house ownersWall insulation is often recommended for energy retrofits in existing housesAdding insulation to exterior wall cavities is difficult unless the walls are openWhen walls are insulated, comprehensive measures to air seal, provide proper moisture barriers, and adequately ventilate interior air must also be taken

  • Wall insulation: not right for all housesSprayed in place open or closed cell foam insulation:Provides superior insulationComprehensive air sealing andGood moisture controlBUT it also:Requires removal of interior finishes and plaster and whole house ventilationObscures historic fabricIs not reversible

  • Blown-in cellulose: the jury is still out on this . . .Rely on Department of Energy/Oak Ridge National Laboratory web sites for information

    DOE and ORNL advise:adding insulation to an old house is complex and difficult

    older wiring in walls retrofitted with insulation can be a fire hazard

    potential moisture problems must be mitigated through 1) excluding water entry, 2) ventilating interior moisture, 3) stopping air leaks, and 4) providing proper attic ventilation

    More data would help a lot!

  • The preservationists nightmare

  • Proactive approaches to balancing preservation and energy goalsOlder houses (1870-1950) Use modern dimensional lumber, balloon/platform framing Originally included central heating systems Often built with stock millwork, trim, architectural elements

    Should be able to accept wall insulation without serious loss of integrity

    Tailor interventions to age, building type, or significance?

  • Avoid energy improvement experiments on the oldest and most significant propertiesHistoric houses (1680-1850) Use pre-industrial timber or Eastern braced framing Not constructed with central heating systems


    Very significant or rare houses

    May not be suitable for wall insulation energy retrofits at all

  • Insulation Interventionsfor Older and Historic HousesTo summarize:Keep it simple, start smallAir SealInsulate AtticsSeal and Insulate DuctsInsulate Hot Water PipesExtensive energy retrofits are costly, complex, and potentially destructive of historic character and materialsBe wary of wall insulationConsider information sources carefully

  • With care and common sense, every old house can be GREEN!

    *Every day there is more news about energy issues: tripartisan! group in Senate (Kerry, Lieberman, Graham) working on energy bill; not clear how it will affect historic bldgs (previous version had one paragraph out of 900 page bill allowing additional incentives for energy retrofits to NR listed buildings)

    But money is starting to flow from American Recovery and Reinvestment Act (signed 2/17/09 stimulus bill) with $16.8 billion for the office of Energy Efficiency and Renewable Energy (EERE) programs

    $5B for Weatherization Assistance Program; $3.2B for the Energy Efficiency and Conservation Block Grant program: money is already flowing to the states ($177m for Massachusetts)

    March 6 energy circle blog raises specter that the section 106 reviews that will be required for various energy stimulus programs will impede their implementation, but on February 5, the Advisory Council on Historic Preservation produced a Prototype Programmatic Agreement with the Dept of Energy that exempts the majority of routine retrofits basically as long as they are not publicly visible. *What is recommended: only trust government sites: US DOE, Oak Ridge Nat Lab, RESNET/Lawrence Berkeley Lab; commercial and contractor sites are not reliable

    Why may not be right: even when dealing with existing houses, none of the public information/education material available on the web looks at historic or older houses

    There ARE ways to work energy savings into older and historic homes*As an old house owner, you need to be prepared for what you will read about and be