Renovation 4th Edition

by Michael Litchfield

  The images indicate temperature differences

  between surfaces, so the camera is most effec-

  tively used when there is a temperature difference

  of at least 10°F from the inside to the outside.

  Using a blower door in conjunction with the

  infrared camera can help accentuate and locate

  problem areas.

  Infrared cameras have become more common

  as they’ve become more affordable ($1,500 to

  $5,000), but interpreting the information can be

  subtle. Generally, darker colors indicate cold air,

  whereas lighter hues indicate warm air. With a

  typical color palette, cold air leaks tend to appear

  as blue fingers. As with any tool, using an infra-

  red camera takes training and practice, without

  which results can be difficult to interpret.

  duCT TESTInG

  Take thermal images in early morning, when the temperature differences (delta T) between inside

  Duct testing is important because leaky ducts

  and outside air are the greatest. The greater the delta T, the greater the color contrasts in the

  can be responsible for as much as 30% of lost

  thermal image.

  energy, to say nothing of heat-starved rooms or,

  in some cases, a buildup of carbon monoxide in

  living spaces.

  The auditor starts by temporarily sealing

  heat registers and supply grilles. He connects a

  variable-speed duct blower to a central air return,

  a supply plenum, or the HVAC system’s fan cabi-

  net. You can test ducts without pressurizing the

  inside of the house. However, as Donn Davy of

  www.greenhomesavvy.com points out, “If one

  pressurizes the interior of the house to 25 pascals

  and then adjusts the duct to equalize that pres-

  sure in the duct system, the reading will reflect

  ‘leakage to the outside,’ which is more useful for

  calculating real energy losses, since leakage with-

  in the envelope still heats (or cools) the interior,

  just not as effectively.”

  To find and fix individual leaks, a theatrical

  fog generator is often placed next to the duct

  blower. Ducts fill with “smoke,” which then

  escapes out of duct connections, missing end

  caps, faulty register-to-boot seals, or leaky con-

  nections at the plenum. Occasionally, flexible

  ducts in crawlspaces get crushed or gashed by

  clumsy “repairmen,” and some types of older

  flexible ducts degrade over time and develop

  holes and tears. Predictably, the largest leaks are

  sealed first, with special attention given to leaks

  Leaky ducts in a forced hot-air system can squander energy.

  in return-ducts near combustion appliances such After sealing heat registers and air intakes, an energy auditor

  as gas water heaters. There, leaking ducts could

  uses a fan to pressurize the ductwork, sometimes blowing

  create negative pressure, pulling dangerous flue

  theatrical smoke as well, so technicians can see just where

  gases back into living spaces. Sealing ductwork is ducts are leaking.

  covered on p. 396.

  Energy Conservation and Air Quality

  389

  TESTInG CoMBuSTIon And

  gobble more than two-thirds of the kitchen total.

  Ovens, microwaves, cooktops, and dishwashers

  HouSEHold ApplIAnCES

  account for the remaining third.

  Because heating and cooling appliances can affect

  energy costs, health, and safety, many home

  THE AudIT REpoRT

  audits include those devices, as well as gas-fired

  Reports vary, but those based on a whole-house

  water heaters. According to a GreenHomes®

  energy audit such as the widely used HERS-II*

  America spokesman, “We see potentially serious

  (home energy rating system) will typically include:

  combustion safety and gas leak issues in as many

   An energy-efficiency rating that places

  as 25% of the homes we visit before we touch

  the house along a continuum, with a 0 rating

  anything. And equipment that has poor or mar-

  (net zero) meaning that the house’s net

  ginal draft before an air-sealing—or any retrofit

  purchased energy is zero, and a 100 rating

  project—can be made even worse. Carbon mon-

  indicating that it meets 2008 IRC energy specs.

  oxide is deadly, and even chronic low levels can

  Ratings for most existing homes are

  make people sick.”

  considerably above 100, showing a need for

  Auditors use digital combustion analyzers to

  improvements. HERS ratings are helpful to

  see how efficiently your furnace, boiler, or gas

  homeowners because they can see, at a glance,

  water heater is consuming fuel. Such tests can

  their home’s relative efficiency.

  also detect problems within a furnace, such as a

   Scoring individual components. The

  cracked heat exchanger, which could allow

  aggregate HERS score is broken down to show

  exhaust gases to enter ducting—and living spaces. the efficiency of each house system. Based on

  To test the draft in flue pipes, the auditor will

  the auditor’s diagnostic tests, the report

  shut all doors and windows, turn on all exhaust

  includes duct leakage, ACH or cfm numbers,

  fans in the house in an attempt to create negative insulation R-values, windows’ solar heat gain

  pressure, and then insert a digital probe into the

  coefficient (SHGC) ratings and U-values,

  flue pipe. A good auditor will also look for telltale furnace AFUE scores, and so on. A companion

  signs of earlier backdrafting, such as rust or

  document, usually software generated,

  scorch marks near the draft hood of a furnace or

  explains scores and industry acronyms at

  water heater. Audits with health and safety com-

  greater length and suggests probable savings

  ponents routinely check gas pipe and meter con-

  based on improvements such as, say,

  nections for leaks as well.

  increasing roof insulation.

  A thorough audit will also employ electricity-

  usage monitors to determine how efficient house-

   Auditor’s recommendations. Here,

  hold appliances are. Kitchens are fertile testing

  skilled and personally committed auditors can

  grounds: They account for nearly 30% of the util-

  really shine. Having gotten to know you and

  ity bill, and refrigerators and freezers together

  your house, they can make specific

  recommendations on where you should spend

  to improve efficiency, safety, health, and

  comfort. For example, “If you want to get

  serious about air quality—which makes sense

  with a 2-year-old in the house—I would seal

  the crawlspace with plastic sheeting, 9-mil or

  better.” Above all, an auditor’s recommend-

  ations should be objective, putting

  homeowners’ needs above anything else.

  * In California, there are two types of HERS

  reports: One has to do with Title 24 verification,

  relat
ing to 14 measures in the energy code. HERS-

  II is a whole-house verification, projecting how a

  house will use energy over the years.

  How To FInd An EnERGy AudIToR

  The best way to find a reputable energy consul-

  tant, architect, or contractor is to ask a building

  professional whose opinion you trust. Two com-

  panies that have helped develop energy-auditing

  Digital combustion analyzers see how efficiently a furnace, boiler, or gas water heater is consuming standards now certify independent auditors and fuel. An audit may also test the draft in flue pipes.

  390 Chapter 14

  A whole-house energy audit, such as

  the HERS-II (home energy rating

  system) report shown here, will

  typically rate a house’s energy profile

  so homeowners can see at a glance

  how energy-efficient their home is.

  maintain databases of consultants. They are the

  Air-Sealing

  Residential Energy Services Network (www.

  As noted early in the chapter (“How Heat

  resnet.org) and Building Performance Institute

  Moves”), most insulation achieves its full R-value

  (www.bpi.org). The Department of Energy’s

  only when used with an air barrier. Air leaks

  Energy Star website, www.energystar.gov, also

  allow conditioned air to escape, but they also

  has a list of certified auditors and contractors.

  prevent insulation from doing its job. In new

  Given the growth in energy audits, a number

  construction—or when gutting finish surfaces

  of contractors have become home performance

  in a renovation—installing a continuous air bar-

  contractors who do both the audits and the

  rier is a straightforward task because access is

  remedial work. This niche is so promising that

  easy. But in most energy retrofits, upgrading the

  GreenHomes America, which offers energy

  air barrier means finding air leaks in the build-

  audits, does retrofit work, and helps homeowners ing envelope and sealing them one at a time. As

  “secure low-interest financing or government…

  tedious as this task can be, it’s time and money

  incentives to offset the cost”, will soon have

  well spent because, dollar for dollar, sealing air

  26 locations in 14 states.

  leaks is the most cost-effective energy retrofit

  The question invariably arises: Can a company you’ll undertake—especially if the attic is uncon-

  doing the work also be an unbiased auditor?

  ditioned (unfinished and unheated). Air infil-

  Clearly, an independent energy auditor has fewer tration can account for 20% to 30% of energy

  conflicts of interest. But it has become clear that

  losses, especially when a home has fiberglass

  more energy retrofits are actually completed

  batts or cellulose insulation.

  when homeowners hire a combined auditing-

  contracting company. Having one entity oversee

  CAulkS, SEAlAnTS, And oTHER AIdS

  the retrofit and sift through a slew of government

  incentives simplifies things for homeowners.

  Because this section is about sealing air leaks,

  Careful air-sealing takes a lot of

  So does knowing exactly whom to call if you’re

  sealants is probably the best overall term for dif-

  time—and many cans of expanding

  not happy how the work was done. Whatever

  ferent materials that stop air infiltration. Most of polyurethane spray foam. Local codes

  auditing-contracting model you choose, interview

  may require the use of fire-rated

  us use caulk or caulking when filling building

  foams to seal penetrations and gaps

  carefully, call references, check the company’s

  gaps and cracks, but here let’s use “caulk” to

  that could become fire updrafts.

  record with the state licensing board, and get a

  denote a flexible sealant that is squeezed out of a

  second opinion if ever you’re feeling pressured

  tube and doesn’t expand to fill the gap or crack.

  or uncertain.

  By the way, sprayed-on foam insulation—

  sometimes called flash foam—is often used to

  Energy Conservation and Air Quality

  391

  insulate and air-seal building seams but I’ll dis-

  Polyurethane foam sealants expand to fill gaps.

  cuss it in the following section on insulating.

  They are the workhorses of air-sealing, typically

  applied using 12-oz. to 33-oz. aerosol cans with

  caulk choices. Caulks are covered in chapter 4,

  straw-type applicators. Though their formulas

  so let’s keep it short and specific here. Caulks are

  vary slightly, for the most part they are rigid once

  best used for gaps less than 1⁄2 in. wide; for wider

  cured, so they should not be used to fill gaps that

  gaps, start with a foam backer rod, then apply

  will be subject to movement. They should not be

  caulk. Surfaces being caulked need to be clean,

  exposed to weather or used outside. Important:

  stable, and dry or the caulk may not stick.

  All foam sealants expand, and some so aggres-

  Scraping away flaky substrates, blowing or wip-

  sively they can bow window frames. When

  ing away dust, and drying the surface are impor-

  choosing a foam, first decide whether the task

  tant prep steps. Important: Caulks have become

  requires low-, moderate-, or high-expanding

  extremely specific, so choose a type well suited to foam. By naming foam products for their intend-

  your task. Here’s an overview of general categories:

  ed uses—“Windows and Doors,” “Gaps and

   Water-based caulks, which include latex,

  Cracks,” “Maxfill,” “Fireblock”—manufacturers

  vinyls, and acrylics, are easy to work with and

  have made choosing a little easier.

  probably the best choice if you’re sealing

  Because foam sealants make contact when

  around interior door and window casings and

  they’re wet and then expand to fill the space, sur-

  other moldings. Because they are so easy to

  face prep is not as critical as it is with caulks to

  clean up, you can use a wet finger to tool

  ensure adhesion. Ideally, though, the surface

  (shape and compress) caulk joints. They can

  should be stable (not loose) and reasonably free

  be painted.

  of debris. And there’s a limit to the width of the

   Silcone-based caulks are famously

  gaps they can fill, so if a gap is wider than 1 in.

  tenacious, weather well and stay flexible,

  you may want to first pack it with loose fiber-

  adhere to many different substrates, and aren’t

  glass and then seal it with foam. For the most

  affected by UV rays. Solvent-based, they can be

  part, foam sealants are benign, but read the

  difficult to work with. Pure silicone can’t be

  labels and take appropriate safety precautions,

  painted, but siliconized acrylics can be.

  including adequate ventilation, turning off pilot

   Synthetic-rubbe
r caulks adhere well and

  lights and not using around open flame, and

  stay stretchy, so they are a good choice for

  wearing a respirator and safety glasses.

  sealing gaps in exterior trim and wood siding.

  Weatherstripping, discussed at length in

  Once cured, they can be painted with latex.

  chapter 6, is the sealant of choice when a gap or

  Note: They are volatile until they cure. Wear a

  opening will be subject to movement, such as the

  respirator when applying, don’t use them

  perimeter of an attic hatch, a basement’s bulk-

  indoors, and check local VOC regulations to

  head door, or a leaky basement window. Tubular

  see if they’re allowed.

  stripping made of neoprene or sponge foam can

   Modified silicone polymer caulks are as

  be compressed to seal out drafts.

  easy to work as latex and as tenacious as

  silicone. They stay flexible in cold weather, can

  Foam outlet and switch plate gaskets can be

  be painted with water-based paints, don’t

  quickly installed beneath the cover plates of elec-

  shrink, and aren’t as volatile as synthetic

  trical receptacles and switches. Typically the

  rubbers. They are the most expensive caulks,

  gaskets are sponge foam or, in tech-speak,

  however, and don’t have as long a track record

  “UL-listed, cross-linked close cell polyethylene

  as the others.

  insulating foam.” Bought in bulk, they’re cheap

  enough to use throughout the house.

  Sprayable caulk is intended to seal new-building

  seams before installing fiberglass batts, but it

  might be a fast way to seal gutted walls or an

  addition. There are presently two brands of

  Fire-Blocking cAUlkS And FoAmS sprayable caulks—EnergyComplete™ and

  EcoSeal™—both developed by fiberglass insula-

  Holes in an attic floor allow heated air to escape from conditioned spaces and so

  tion makers. Both caulks are quite thick and

  waste energy. In the event of a fire, penetrations in top plates especially can hasten

  must be applied by high-pressure sprayers to the

  the spread of fire from one floor to the next. To fill such penetrations, local codes may

  inside of stud bays, as shown in the top photo on

  specify fire-barrier (fire-blocking) foams or caulks. Being intumescent, these caulks

  the facing page.

  and foams expand when exposed to superheated air and can withstand direct flame.

  Neither product touts any appreciable