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Renovation 4th Edition

Page 90

by Michael Litchfield


  housewrap, or building paper and, increasingly, rigid insu-

  The nagging feeling that if you don’t whip your

  lation; interior air barriers are usually drywall. In either

  house into airtight, energy-sipping, good-as-

  case, sealing the seams and gaps of materials in the build-

  green shape right now, you’re not doing your

  ing envelope is the key to making air barriers continuous

  part. Fact is, an all-at-once deep energy retrofit

  and airtight.

  that cuts energy use 50% to 90% can cost

  *Spray foam and rigid-foam panels effectively stop

  $100,000 and up.

  airflow and may not require separate air barriers.

  Energy Conservation and Air Quality

  385

  GETTInG GREEn

  and a few passive intake vents (p. 400). The only

  downside of this solution is that it draws uncon-

  wITHouT GoInG BRokE

  ditioned air into the house, which will need to be

  The good news is that you don’t have to get green heated (or cooled). The solution to that waste of

  all at once. With planning, patience, and paying

  energy, a somewhat more costly and complicated

  as you go—rather than going into hock—you can fix, is incorporating a heat-recovery ventilator

  lower utility bills incrementally and feel good

  (HRV) into the house’s HVAC ductwork. There’s

  P R O T I P

  about the progress you’re making. It’s still a green an illustration of an HRV system on p. 403 but, in

  path; it just meanders a bit more.

  brief, an HRV uses the heat of stale exhaust air to

  If the attic is insulated, you’ll

  The nine steps below are a logical progres-

  temper fresh incoming air.

  need to put on gloves and a face

  sion—which renovations rarely are. So if your

  Step 4: Insulate, starting at the top. Because

  mask and move that insulation

  home has a pressing need, tend to that first, and

  hot air rises, few energy retrofits are more effec-

  before you can seal openings in

  as you do so, try to find solutions that will

  the attic floor. But don’t merely

  tive than insulating an attic or roof. If you need a

  improve the energy profile as well. In the remodel

  cuss those batts; examine them.

  new roof, stripping it and installing rigid-foam

  described on p. 40, for example, the homeowners

  Fiberglass batting actually filters

  panels before reroofing is a pricey but premium

  had a drafty house with asbestos siding. After

  dirty air, so look for blackened

  route to take. If you want to convert the attic to

  stripping the siding, they built up 2x4 studs into

  areas on the undersides of

  living space, spraying foam to the underside of

  2x6s, sealed air leaks, and insulated—all from the

  batts, where heated air has

  the sheathing is a viable and less expensive way

  exterior. This, in turn, meant that interior finish

  blown through ceiling cracks

  to insulate from the inside. But if your attic is

  surfaces were undisturbed.

  into the attic.

  unfinished and accessible, blowing in cellulose is

  The rest of this chapter more or less follows

  hands-down the most cost-effective way to go—

  this sequence—with the exception of upgrad-

  after you’ve sealed drywall gaps, pipe chases,

  ing windows, which is covered at length in

  electrical penetrations, the framing around the

  chapter 6. So search below for a fuller explana-

  chimney, and so on. Especially in cold climates,

  tion of most steps.

  more is better: Roughly 17 in. of blown-in cellu-

  Step 1: Get an energy audit. A thorough energy lose will get you an R-60 attic floor.

  assessment is essential because it’s a specific

  Step 5: Insulate inside the basement.

  analysis of your house. Using diagnostic equip-

  Basement walls are an easy energy retrofit

  ment such as blower doors, duct blaster fans

  because they’re accessible. Insulating rim joists

  and infrared cameras, audits can pinpoint where

  and basement walls is worth the money in the

  heated or cool air is escaping. If mechanical

  Cold Belt; less so in sunny climes unless you want

  ventilation is needed, an audit will note that, too. to convert the basement to conditioned living

  After the inspection, you will get a report that

  space. In either case, correct moisture problems

  includes the home’s energy rating, along with an

  first. If you can’t afford to insulate the walls, do

  estimation of annual energy use and costs. The

  insulate the rim joists. To insulate basement walls,

  report will usually include recommended energy

  use rigid-foam panels, as described on p. 417.

  retrofits and their costs, as well as the potential

  Heat loss through floors is negligible, so insulat-

  annual savings and probable payback times for

  ing them makes little financial sense unless you

  each improvement.

  intend to install a finish floor over the concrete.

  Step 2: Seal air leaks. It has been estimated

  Step 6: Upgrade wall insulation. If you’re gut-

  that up to 30% of the heat loss in some houses

  ting finish surfaces and exposing studs, insulat-

  is due to leaks in the thermal envelope, so air-

  ing walls is a romp. Dense-pack cellulose and

  sealing should always precede insulation. In a

  fiberglass batts are both effective. More often,

  “gut” renovation when the sheathing is exposed,

  older homes have some wall insulation, but it has

  it’s a straightforward task to seal building seams

  settled or was never installed uniformly. Blower-

  and openings. In a selective retrofit, an audit is

  door and smoke-stick testing and thermal imag-

  invaluable in tracking down elusive leaks, such as ing can show cold spots that need air-sealing and

  gaps where drywall panels don’t quite meet,

  supplemental insulation. Typically, insulation is

  under or over wall plates, around the perimeter

  added by prying up siding, drilling holes in

  of the attic, and around openings for electrical

  sheathing, blowing in dense-pack cellulose or

  outlets or plumbing penetrations.

  injecting foam, plugging holes, and restoring sid-

  Step 3: Add or upgrade mechanical ventila-

  ing. It can be cost-effective, but takes great skill

  tion. Once you’ve cut infiltration by sealing air

  to do a thorough job that doesn’t look piecemeal.

  leaks, stale air may build up inside the house.

  Step 7: Replace or upgrade windows.

  This problem can be remedied inexpensively,

  Replacing all single- or double-pane windows

  however, by adding a whole-house exhaust fan

  with high-efficiency, full-thickness (13⁄8-in.) triple-

  not much bigger than a standard bathroom fan

  386 Chapter 14

  pane windows is a huge expense: Installed, new

  units cost $900 to $1,200 each. Those without<
br />
  EnERGy Rebates And IncEntIvES

  tens of thousands of dollars on hand might

  choose instead to replace one wall of windows at

  Renovators looking for ways to finance energy retrofits should start at the Department

  a time or, yet more frugally, to weatherstrip exist-

  of Energy’s website, www.energy.gov.

  ing windows and then install low-e storm win-

  From there you’ll find additional links and descriptions of federal, state, and

  dows. Good-quality storm windows can achieve

  private programs:

  about half the U-factor of new windows at roughly

   Approved Energy-Efficient Appliance Rebate Programs: www.energysavers.gov/

  one-sixth the cost.

  financial/70022.html

  Step 8: Upgrade your heating system.

   Database of State Incentives for Renewables and Efficiency: www.dsireusa.org

  Compared with the cost of replacing windows,

   Energy-Efficient Mortgages and Financing: www.energysavers.gov/financial/

  installing a 92% AFUE (annual fuel-utilization

  index.cfm/mytopic=70030

  efficiency) furnace for $4,000 to $6,000 seems

  This last site has additional links to:

  like a bargain. It’s not higher on the list because

   Financing an Energy-Efficient Home: www.energysavers.gov/your_home/

  without improvements to the thermal envelope

  designing_remodeling/index.cfm/mytopic=10380

  you’re not making the most of the investment.

  This fact sheet from the Department of Energy features an overview of energy-

  Further, by tightening the house you can reduce

  efficient financing programs from mortgages to home improvement loans.

  the size of a new furnace or boiler. If you want to

  save money beforehand, seal leaky ductwork,

   U.S. Department of Housing and Urban Development: Energy-Efficient Mortgage

  guided by the Duct Blaster® testing of your ener-

  Program: http://portal.hud.gov/hudportal/HUD?src=/program_offices/housing/sfh/

  gy audit. Sealing and repairing ducts is relatively

  eem/energy-r

  cheap—$300 to $400—and in winter months can

  The Energy-Efficient Mortgage Program is one of many Federal Housing Authority

  save up to 20% on utility bills.

  programs that insure mortgage loans to encourage lenders to make mortgage credit

  Step 9: Install renewable energy devices. A

  available to borrowers, such as first-time homebuyers, who would not otherwise

  solar panel or some other renewable-energy

  qualify for conventional loans on affordable terms.

  device may be part of your new HVAC system.

   Energy Ratings and Mortgages: www.resnet.us/home-energy-ratings

  More commonly in retrofits, solar hot water or

  Energy-efficient homes may qualify for mortgages that take into account a home’s

  photovoltaic panels that generate electricity can

  efficiency. Residential Energy Services Network (RESNET) provides information on

  supplement an existing system. Incorporating

  home energy rating systems, energy-efficient mortgages, and finding certified energy

  renewable components into existing HVAC sys-

  raters and lenders who know how to process energy-efficiency mortgages.

  tems can be a costly and complex undertaking,

   Refinancing for Energy-Efficiency Improvements: http://ase.org/topics/saving-

  but, presently, there are a number of federal and

  money-and-energy

  state incentives for renewables, including energy-

  An overview of refinancing to make energy-efficiency improvements from the

  efficient mortgages and financing, as explained

  Alliance to Save Energy.

  at right. Passive solar designs reduce energy costs

  by taking advantage of solar energy. Although the

  basic ideas are fairly simple, putting them into

  practice can be complex, requiring the help of a

  design professional.

  Getting an Energy Audit

  Improving a home’s energy profile begins with a

  homeowners have access to incremental rebates,

  careful diagnosis of where it’s losing heat. This

  based on the number of energy-saving measures

  diagnosis can be intuitive, based on years of

  they implement. As of 2010, 25 states had adopted

  remodeling houses. Most energy loss is due to air climate action plans to reduce greenhouse gases,

  infiltration, after all, and old houses leak air in

  so many cities now require energy audits as part

  predictable places—attic floors, for example.

  of the permit approval process. Typically, energy

  Moreover, you can feel cold air entering a leaky

  audits are triggered by some combination of a

  window on the back of your hand. Yet as building project’s size and valuation—say, a project size of

  science has become more pervasive, the pressure 500 sq. ft. or more and a $50,000 budget.

  for rigorous scientific audits has become irresist-

  Lastly, there are emerging state and federal

  ible. That trend will continue as energy prices

  incentives for energy-efficient mortgages and

  continue to rise.

  financing, all of which require energy ratings as a

  Regulations and incentives have also increased condition for lending (see above). It’s worth not-

  the need to verify causes—and remedies—in a

  ing that bank loan officers who keep abreast of

  scientific manner. From federal tax credits and

  such programs also smile on energy-efficient

  programs to state or utility incentives, many

  mortgages because borrowers with lower monthly

  Energy Conservation and Air Quality

  387

  Blower-door testing helps quantify

  envelope has been tightened, blower-door testing

  the amount of conditioned air (and

  is also an essential tool to determine if a house

  hence energy) being lost through

  needs mechanical ventilation and to make sure

  leaks. As the blower depressurizes the

  that combustion appliances have adequate air

  house, outside air is pulled in through

  supply and that running bath fans, range hoods,

  holes in the thermal envelope.

  and other fans won’t cause backdrafting.

  SMokE pEnCIlS And

  THEATRICAl SMokE

  When the house is depressurized, an auditor may

  use a smoke pencil (also called smoke toys or

  smoke sticks) to help make individual air leaks

  visible. Smoke pencils emit a chemical smoke, so

  you can see the air being pulled in through leaks.

  Theatrical smoke, as the name implies, is a drama-

  tic volume of “smoke” generated by a theatrical

  fog generator, primarily used to indicate duct leaks.

  Who requests the audit usually determines

  how the information is used. When a homeowner

  gets an audit to satisfy a city planner or a mort-

  gage lender, the smoke demonstration is usually

  educational. Seeing air leaks in unexpected places

  utility bills are better loan prospects and their

  often convinces homeowners that they need to

  homes are more highly valued than comparables

  spend a little more to get a tighter house. If, on


  that waste energy.

  the other hand, an auditor is working with a home

  Now let’s look at diagnostic tests that may be

  performance contractor, the blower door, smoke

  part of a scientific home energy audit, which

  pencil, and thermal images shown here are used

  takes four to six hours to complete.

  to direct the retrofit work. Typically, the blower

  BlowER-dooR TESTInG

  keeps running as the crew seals air leaks—until a

  targeted (lower) leakage rate is attained.

  Because air infiltration is the major cause of

  energy leaks, auditors first try to quantify the vol-

  THERMAl IMAGInG

  ume of air being lost. After closing exterior doors An infrared camera’s ability to see invisible

  and windows, turning off combustion appliances sources of heat loss can inform even a pro,

  such as furnaces and gas water heaters, closing

  whether he’s trying to track down elusive air leaks

  flues and shutting fireplace dampers, the auditor

  or develop a retrofit strategy. Thermal images

  uses a blower door to depressurize the house.

  This pulls outside air into the house, in effect

  exaggerating the holes in the thermal envelope.

  A blower-door assembly includes an airtight,

  expandable frame, a calibrated fan, and a

  manometer—a pressure gauge with two chan-

  nels. One of the manometer channels measures

  the difference between inside and outside pres-

  sure, while the other measures the difference

  between the calibrated fan and the inside. The

  door fan blows air out of the house until the pres-

  sure difference reaches 50 pascals (Pa), a stan-

  dard reference basis. Once pressure readings are

  steady, the manometer calculates the total flow of

  all leaks in the house. That airflow can be mea-

  sured as air changes per hour (ACH) or in cubic

  feet per minute (cfm).

  Getting an aggregate figure for house air leak-

  age will suffice for some audits, but a blower-

  door fan can also be used in tandem with other

  devices to help pinpoint leaks, as described

  below. It’s important to note that once the house

  A smoke pencil helps make air leaks visible.

  388 Chapter 14

  show not only air leaks but also settled or absent

  insulation and thermal bridging (heat loss through

  relatively poor insulators, such as framing). It

  can also help locate and identify moisture issues.

 

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