Category THE ENERGY-SMART HOUSETHE

For more information on siting principles, additional detailing, and solar-design strate­gies for houses, as well as the mathematical formulas required to analyze these strate­gies for their potential energy savings, check out the second edition of Sun, Wind & Light: Architectural Design Strategies by G. Z. Brown and Mark DeKay (John Wiley & Sons Inc., 2000).

Although out of print, another good resource available at used-book stores and libraries is Climatic Building Design: Energy – Efficient Building Principles and Practice by Donald Watson and Kenneth Labs (McGraw – Hill, 1993). Both books contain a wealth of helpful charts, meteorological data, and ex­amples of solar siting and building design.

M. Joe Numbers is an architect with Gile-Buck & Associates in Boise, Idaho.

Guidelines for Shaping an Energy-Efficient House

A house with a high ratio of interior space to exterior surface costs less to heat and cool. In very cold or very hot areas, then, houses should be more square than rectangular. In temperate areas, shape is not critical, but in humid areas, a long, narrow house allows for cross ventilation.

In hot, arid climates, a house whose long side is 1.3 to 1.6 times the length of its short side offers the best ratio of cool indoor space to exterior wall area.

Generally, summer and winter winds come from different directions. It’s usually pos­sible to divert winter winds and to channel
summer breezes by carefully locating the house in relation to its surroundings. Check with your local airport, meteorological sta­tion, or state energy office to determine the prevailing summer – and winter-wind direc­tions for your area. Also, this data can be obtained from the U. S. Department of Com­merce National Climatic Center in Asheville, N. C. (www. ncdc. noaa. gov/oa/climate/ climatedata. html).

Study the adjacent topography, trees, and buildings during your initial site inspection. Look for those existing conditions that can block or divert cold winter winds around the building site. Locate the house in these lee – side areas (see the top drawing on p. 134).

In warm or humid climates, place the house in a part of the site that maximizes summer ventilation. For example, the pro­
cess of evaporation cools summer breezes as they pass over water bodies. These water bodies don’t have to be big to have an effect. Locate the house to catch prevailing sum­mertime breezes coming off lakes, ponds, rivers, and even streams.

Conversely, in cool and temperate cli­mates, avoid locations near bodies of water on the lee side of prevailing winter winds. In other words, if winter winds generally blow from the north, avoid sites at the south end of a water body.

Water isn’t the only medium that induces cold winter winds. Landforms, vegetation, and buildings all can increase wind veloci­ties because of a phenomenon called the Venturi effect.

The Venturi effect occurs when any mov­ing medium—in this case air—squeezes

through a constricted opening. To maintain a constant volume of air passing through the opening, the wind velocity increases accordingly. That’s why it’s so windy at the base of tall buildings.

Keep away from topography, adjacent buildings, or vegetation that funnels cold winter winds at increased velocities. If you do have a problem because of the Venturi ef­fect, you can position adjacent outbuildings and evergreen trees and shrubs where they will block winter winds.

Conversely, locate the house (and any new vegetation, fences, or outbuildings) to take advantage of increased wind velocities created by the Venturi effect during summer months (see the bottom drawing on p. 134). Use buildings and vegetation to channel summertime breezes into the house. As a rule, try to orient the house within 30 de­grees of perpendicular to prevailing summer winds to maximize their cooling effects.

If solar orientation and siting for wind are at cross-purposes (that is, if optimum solar orientation is perpendicular to optimum sit­ing for wind), then solar orientation should take precedence because it has a greater cu­mulative effect on the heating and cooling of a house.

House Shape Should Fit the Climate

Are you familiar with the aluminum heat – radiating fins that can be slipped over hot – water pipes in a basement? They’re supposed to turn hot-water pipes into heating ele­ments to heat the basement space. The prin­ciple behind the fins is that they increase the heated surface area so that more heat es­capes from the pipe with the fins than from the bare pipe.

The same principle applies to a house’s shape, or configuration. As a house’s surface area increases, so does the amount of heat it loses. To hold on to the heat, configure the house so that it is relatively compact. Com­pact shapes, such as cubes, lose less heat through the building skin than narrow or elongated shapes.

As a general rule for siting a house in cold regions, the long dimension of the house should be approximately 1.1 to 1.3 times the length of the short side. This proportion yields a high ratio of heated interior space to exterior skin. Remember that the longer side of the house is oriented along the east – west axis.

For temperate climates, the configura­tion is not as important. There is less envi­ronmental stress on the building skin, so the designer has more freedom in terms of building configuration. For this region, a ratio between 1.6:1 and 2.4:1 provides good energy performance.

In hot, arid climates, the environmental stresses are greater, so buildings should be shaped similarly to cold-climate configura­tions. A ratio somewhere between 1.3:1 and 1.6:1 is the most energy-conserving for hot, arid climates.

In warm or humid climates, elongated shapes with openings on the long sides al­low for cross ventilation. Generally, ratios in the range of 1.7:1 to 3.0:1 are preferred. When these elongated plans are oriented with the long side on the east-west axis, summer overheating at the short east and west elevations is avoided.

Try to keep corners on the house to a minimum. Unnecessary corners mean more exterior-wall surface is exposed to wind, which increases heating loads on the house.

Regardless of wind direction and particu­larly in areas where wind direction changes frequently, a good overall strategy is to use a compact, low-profile house design. Avoid tall facades and roof designs that block or trap wind. For example, a tall, broad gable is less aerodynamic than a hip roof, which allows for smoother airflow around and over the house. Orient the narrowest dimension of the house into prevailing winter winds to minimize wind exposure.

Control Exposure to the Wind

Use plants and outbuildings to direct prevailing summer breezes into the house and to divert prevailing winter winds away from the house. Once you know the direction of prevailing winter winds, choose a site where topography, vegetation, and other buildings offer protection.

Prevailing summer breezes are funneled by deciduous trees into the house at increased velocity due to the Venturi effect.

Configure the house and its surround­ings to funnel or channel cooling summer breezes into windows and screened-door openings. For example, you can orient breezeways and window openings to accept these summer winds. Use roof overhangs to
trap incoming breezes and channel them into window openings. On the other hand, locate and configure the house to avoid channeling any cold winter winds into doors and windows.

Placing the long side of a house along the east – west axis exposes the south elevation to year – round light and warmth. In summer, this orientation minimizes overheating on the short east and west elevations. Grouping private and unoccupied spaces on the north side of the house, where they act as insulators for the south-facing public Bedroom rooms, maximizes the benefit of southern exposure.

North

Finding True North

At the bottom margin of U. S. Geologi­cal Survey maps, there are three north bearings: magnetic north, true north, and grid north Magnetic north is compass-needle north, but it’s not helpful for solar siting, which calls for true north, indicated by the star. The difference between these bearings is the declination, in this case,

13.5 degrees.

from the rest of the house), much like the closed airspace in a thermos keeps the cold air outside from cooling the warm liquid inside.

Hillside Lots Are Cooler, So Plan Accordingly

Donald Trump once said that the three most important considerations when buying real estate are location, location, and location.

I doubt that he was referring to the potential for lower heating and cooling costs, but a house’s location on a piece of land can make it less expensive to heat and cool.

If you’re considering building on a hill­side, for example, locate the house accord­ing to its most appropriate zone. In cold or temperate climates, it’s best to locate a house midway between the ridge and the valley.

There, the house is not exposed to increased wind velocities at the ridge or to subsiding cold air that settles at the valley bottom.

In hot, humid climates—the Gulf Coast states and the Southeast—ridges generally provide the most exposure to year-round cooling breezes. In hot, arid climates such as the Desert Southwest, valley floors tend to collect cold air overnight that helps to cool a house. You can trap this cold air by opening doors and windows at night and by closing them during the day.

Building on a south-facing slope, or as­pect, of a landform increases the exposure of the house and surrounding grounds to the low-angle rays of the sun during the winter. In cold and temperate climates espe­cially, you should avoid north-facing aspects whenever possible.

You should also take a good look at the adjacent area to the south of the building

Window Height ^ Shade Factor = The Right Overhang

An effective window overhang shades summer sun but allows for winter-sun penetration. The overhang’s depth depends on the shade-line factor, ‘

determined by the house’s geographic latitude and the direction the window faces. See the chart below, and also measure the overhang’s – height above the windowsill; then plug those numbers into the equation above to get the overhang’s ideal depth.

SHADE-LINE FACTORS

Latitude in Degrees

site. Avoid building on areas that will be shaded during winter by tall buildings, co­niferous trees, or landforms (ridges, etc.).

If you’re in a cold or temperate climate, where it’s best to build midway along the hillside rather than at the ridge or in the valley, you should study the contours of the hillside. Any natural drainages or depres­sions in the topography are poor choices for a building site (see the drawing on p. 132). A natural drainage or depression channels cold air down the hillside. This cold air collects behind obstructions to its natural flow, so a house should be built away from these cold – air flows. If you simply cannot follow this strategy, use evergreen vegetation or solid fencing to divert cold air around and away from the house.

Whenever possible, recess the north, east, and west sides of the house into the natu­ral slope of the site, or pile soil against the house on these sides. These earth-berming
strategies provide additional, permanent in­sulation against both winter winds and sum­mer overheating.

Earth-berming strategies require careful detailing to prevent water damage to the structure. They are generally more expen­sive than typical aboveground construction. When properly done, however, earth berm – ing provides long-term, low-maintenance energy savings.

If you are not familiar with earth-berming strategies but have a site that is suitable, consult an architect or a designer experi­enced in this type of construction.

BY M. JOE NUMBERS

rchitecture professors love a good riddle. Here’s one: How do ancient Greek town grids, Anasazi Indian pueblos, and New England saltbox houses differ from most residential construction today? Give up? Each culture understood how to site a
house. The ancient Greeks oriented their town grids to receive winter sun and sum­mer shade. The Anasazi Indians located their dwellings beneath cliff overhangs to take advantage of natural shading. Early Ameri­can settlers oriented and configured their saltbox houses to minimize the cold north­ern facade and to maximize the warm southern facade.

Regrettably, the siting lore known to our ancestors has practically disappeared because of central-heating and – cooling systems. That’s too bad, because a house’s energy efficiency, comfort, and marketability are all affected by its siting. A house that’s sited to take advantage of the sun, the wind, and the topography costs less to heat and cool, and lets you enjoy indoors and outdoors longer, two strong selling points.

In the site-design classes I used to teach, we divided solar-siting strategies into three categories: orientation, or which way the house faces; location, or where the house sits; and configuration, or how it’s shaped. Figuring out the best orientation, location, and configuration requires a little knowledge of local climatic conditions and an analysis

of the site and its surroundings. Here, I’ll discuss what to look for and where to find the information you need to reap the ben­efits of a properly sited house.

Long Side Faces South

When siting a house, the most effective strategy you can use is to orient the building with the long side aligned on the east-west axis. This orientation places the long side of the building where it can be reached and heated by the low-angle rays of the winter sun. Conversely, it places the short sides of the building to the east and west to mini­mize solar gains during the overheated peri­ods of summer.

Your house doesn’t have to be exactly on the east-west axis; somewhere within 15 degrees of this axis is fine. What’s more important is that the house is oriented toward true south, not magnetic south. Compass needles point to magnetic north, which deviates from true north by as much as 20 degrees. The difference between mag­netic north and true north is declination, and it varies across the United States (see the sidebar on pp. 130-131). Information on declination can be found on U. S. Geological Survey topological maps or the NOAA web­site (http://www. ngdc. noaa. gov/geomag/ geomag. shtml).

Once you know your area’s declination angle, it’s a matter of spinning the dial on a compass. For example, in Boise, Idaho, the declination angle is approximately 14 degrees east. Line up a compass on mag­netic north, then rotate the dial until the needle is pointing to 14 degrees east of the north mark on the dial; now the dial mark­ings (not the needle) point to true north.

Lots of related strategies make a true – south orientation more effective. One is to reduce openings (i. e., windows and doors), especially on the north side of the house, because doors and windows conduct more heat than a well-insulated wall. In cold cli­mates, only about 5% to 10% of non-south­facing walls should be openings. In warmer climates, you can get away with slightly more openings as long as the house is well insulated.

On south elevations, increase openings for winter solar gain, but shade them during summer months. Deciduous trees provide summer shading, as do awnings. You can also build overhangs, but they shouldn’t be so deep that they block the sun in winter (see the drawing on p. 131).

To figure out the optimal depth for over­hangs in your area, use the shade-line-factor formula: The depth of an overhang equals the height from the bottom of a window to its overhang divided by the shade-line factor. This number varies with latitude, so you’ll need to know your location’s geo­graphic latitude to choose the right shade­line factor. Most maps of the United States and most state maps show latitude.

Another way to make a southern expo­sure work harder for you is to coordinate the floor plan with the house’s orientation. Locate public living spaces, such as the liv­ing room, the dining room, the kitchen, and such, to the south side of the house, where they will receive light and warmth through­out the year. Locate private and unoccupied rooms—bedrooms, utility rooms, storage rooms, etc.—to the north, where they will act as insulating buffers for the home’s public spaces (see the floor plan on p. 130). These buffer spaces serve as a form of insula­tion (particularly if they can be closed off

ir-to-air heat pumps use pressurized Freon® gas to absorb heat from the air outside and transfer it to your home. When the thermostat calls for heating, Freon is pressurized, it condenses, and then it turns
is distributed through registers in the floors, walls, and ceiling. At the same time, a fan in the condenser sends cold air outside. You can reverse the cycle for cooling in the summer. (Ground-source heat pumps

to hot liquid. A blower forces air across warm Freon-
use a water/glycol mixture to exchange heat energy

filled coils and through a system of ducts; warm air	with the earth
Branch duct
Fan	Disconnect box
INDOOR UNIT
Trunk duct
Damper
	Coils
DAMPERS ADJUST AIRFLOW. In a forced hot-air system, you sometimes can adjust the inline dampers to increase or decrease airflow to a specific part of the house. When the lever is in line with the duct, the damper is fully open. When the lever is perpen­dicular, it’s closed.
Freon lines
Coils
Filter box Blower
OUTDOOR COMPRESSOR

Q: The temperatures upstairs and downstairs are uneven; some rooms are colder or hotter than others. What’s causing this problem? Can it be fixed?

A: You’re likely describing an out-of­balance duct system. If a forced-air system isn’t ducted properly, the flow of supply and return air is unbalanced, resulting, for example, in a ground floor that doesn’t stay warm in heating season or a second floor that’s not sufficiently cooled in AC season. Sometimes it’s due to poor duct design; other times it occurs when air­conditioning is added to a heating system without re-evaluating and possibly resizing the ductwork.

If you have problems with individual rooms and you’ve made sure all the ducts are connected properly (believe me, I’ve seen my share of ducts to nowhere), you might be able to adjust the dampers and guide a little more (or less) air to those areas. Damp­ers are normally located within the first few feet of each branch, or takeoff, and are adjusted by turning an external lever. Gener­ally, when the lever is in line with the duct, the damper is fully open. Airflow also can be regulated somewhat at the register if it’s an adjustable model; however, that can create an objectionable noise as air rushes past the louvers.

While adjusting airflow this way could improve comfort, it doesn’t help the system to perform better. To do that, you need to call in a pro. A good HVAC contractor uses a nationally approved design program to size an entire duct system properly. Ask the contractor to show you how he or she does the design work, and ask ques­tions. The fix can range from a few sim­ple adjustments to installing a mini-split inverter heat pump in the affected areas to ripping out everything and starting over, costing from a couple of hundred dollars to several thousand.

Q: I hear a lot about tuning up furnaces, but how can I boost the efficiency of my heat pump?

A: Like furnaces and boilers, your heat pump should be serviced annually. Cleaning the coils and changing the filter can increase the heat pump’s efficiency by up to 10%. Heat pumps are rated in SEER for cooling efficiency and HSPF or COP for heating efficiency. (See "Say What?" on p. 124.)

The higher the numbers, the higher the efficiency and the lower the operating costs.

If your heat pump operates below 13 SEER and 6.5 HSPF (the current minimum stan­dards set by the federal government), you should plan to replace it. When you do, ask for a 410A refrigerant-based system (Carrier® calls it Puron®). The 410A-based systems are a bit more efficient and a bit more expensive, but the R-22 refrigerant currently in use is being phased out. As a result, it’s unlikely to be available when new equipment wears out.

With today’s fuel costs escalating, you might also want to consider a hybrid heat­ing system, wherein a fossil-fuel furnace is coupled with a high-efficiency heat pump, allowing you to choose whichever system is least expensive to operate at specific times.

These setups often use automatic controls that seamlessly switch from one system to the other based on the internal programming.

Q: I keep hearing about "modulating’ technology in furnaces and boilers. What’s that?

A: Traditionally, heating equipment operates on one speed: Either it’s on, or it’s off. The minute a furnace or boiler fires up, it produces the same amount of Btu whether it’s trying to raise the temperature of a house 2°F or 20°F, and whether the air outside is -5°F or 50°F. But a number of new, high-efficiency stepped-input ("hi-lo fire") furnaces can operate at two levels: low input or high input, with a lower or higher fan speed.

Because the low-input level can be used when outdoor air temperatures are relatively moderate (roughly 70% of the heating sea­son for many of us), modulating equipment promises fuel savings of 30% or more. When the heat-demand load exceeds the "lo-fire" output, the furnace control steps on the gas to meet demand.

Modulation technology has been limited to boilers—until now. York International’s recently released Affinity 33 is the industry’s first truly modulating gas furnace that uses outdoor reset, which adjusts the system based on the air temperature outside, to determine how hard it needs to run to meet a home’s heat loss (from 35% to 100% in 1% increments). Both the burner and the blower modulate as a team to maximize Btu, and the manufacturer claims 98% thermal efficiency.

A furnace first.

The York® Affinity™ 33 is the industry’s first modulating gas furnace and boasts 98% efficiency (www. york. com).

Modulation is an almost universal feature found on high-efficiency condensing boil­ers. Here, too, you’ll find products that can achieve 98% thermal efficiency. Virtually all these high-efficiency products use out­door reset to achieve superior comfort and efficiency.

Q: We’re not ready to replace our heating equipment right now. What can we do to improve our comfort and reduce fuel bills?

A: If you’ ve performed the fixes I already mentioned and you’re still uncomfortable (or breaking open the piggy bank to meet fuel costs), you might consider fine-tuning your system with an auxiliary appliance.

One option is spot-treating one or more rooms with high-efficiency mini-split heat pumps. With efficiencies topping out at 26 SEER and 12 HSPF, these ultraquiet heat pumps give you the option of conditioning just the space you’re occupying while letting the rest of the home’s mechanical systems hibernate. They’re basically self-contained units with supply tubes for refrigerant running through the wall. The best ones use inverter (variable-speed) technology, allowing the units to sip only as much electricity as they need to maintain comfort.

If you have a hot-air system, adding hu­midification can increase comfort while let­ting you reduce the temperature by several degrees. You can plug in a freestanding unit or have a pro connect one to your furnace for $600 or more.

If you have a central system that’s not zoned, a motorized damper system can de­liver heat where you need it most. Multiple dampers can be daisy-chained so that several rooms operate as one zone. One caution: It’s important to have a good professional do this work.

If you have a hydronic system, you can fine-tune the zones with thermostatic ra­diator valves, which can be installed in every room except where the thermostat is located. Once you set the dial, the valves open or close automatically based on the room’s temperature. They’re a good solution in rooms that are chronically overheated or that are seldom used.

In an uncertain economy, investing in energy—that is, the energy you use in your own home—could be your wisest move.

Your ROI (return on investment) begins the second you start using the equipment and can well exceed anything the stock market can yield. You’ll add value to your largest in­vestment (your home), you’ll be more com­fortable, and you’ll get to keep more of your hard-earned money.

A damper with horsepower.

Motorized dampers allow for controlled airflow through ducts from remote locations and can create heating zones in a formerly one-zone house (www. aprilaire .com).

Q: What separates low-efficiency heating systems from high-efficiency models?

A: One difference is the way the unit is vented. A 78%-efficient furnace (or boiler) vents into a chimney and uses the home’s interior air for combustion. New 92%-efficient models are designed for sealed combustion. A direct venting setup draws outdoor combustion air.

Chimney-vented heating equipment con­tinuously drafts heated air out of the house and strips away some of the Btu produced when the furnace is operating. There’s also a hidden energy cost: air infiltration. When­ever its burner fires, the chimney-vented unit draws in warm room air to support combustion—air that must be replaced by cold outside air drawn through cracks and gaps in the home’s shell. Eliminate that draw with a sealed-combustion model, and your fuel bills could fall by 30% or more.

Cost also separates the top performers from the rest. But the difference in price between 78%- and 95%-efficient gas-fired furnaces has narrowed considerably, to about $1,500 for the equipment and in­stallation costs. If your system burns oil, you have fewer choices, and the price gap is wider (about $4,000). But with ever-shifting oil prices, it’s easier to justify the extra expenditure.

A: Given today’s rapidly escalating fuel prices, you really can’t afford not to consider upgrading to a new high-efficiency furnace. Older furnaces were constructed with durability, not efficiency, in mind. Trimming 20% to 70% off your fuel bills is a realistic expectation when you upgrade to high – performance equipment.

Your existing furnace most likely has a 60% to 78% efficiency rating, which was once considered respectable. The current federally mandated minimum efficiency for furnaces is 80%, but there are models— hundreds of them—that operate above 92% and qualify for Energy Star rebates. There are even a few that can achieve 98% efficiency by using a feature called "outdoor reset," which modulates both the blower speed and the burner’s fuel input. As you might expect, the better the efficiency, the higher the up­
front costs. But with the rise in fuel prices and the anticipated 20- to 30-year life span of a furnace, the increased purchase price pales by comparison to the fuel costs saved over time.

Dave Yates owns and operates F. W. Behler Inc., a mechanical-contracting firm in York, Pa.

■ BY DAVE YATES

The economy is down, fuel costs are up, and chances are that your heating budget is already busted. You need to do something—but what? Only a few of us are ready to invest in geothermal or solar. The rest of us need to find the answer in the heating system we already have.

For 70% of U. S. households, that sys­tem consists of a furnace that forces hot air through ducts; for 17%, it’s a heat pump; and for 11%, it’s a boiler that heats with water or steam radiators. The remaining 2% of homes use wood, coal, geothermal, solar, or other heating methods. When it comes to fuel, 58% of us use gas (either nat­ural or propane), about 35% use electricity, and almost 7% use fuel oil.

Your home might not have the most ef­ficient heating system available, but there’s good news: You can tune up your current system so that it performs better, keeps you more comfortable, and doesn’t put as big of a dent in your wallet. The following can help. Although the topics might seem simple, they’re useful in diagnosing deficien­cies. In fact, I usually end up fielding a lot

of these questions from homeowners based on their observations of how their heating system is or isn’t working. Once you know where your system is falling down, it’s pos­sible to boost it (and its efficiency) back up.

Q&A

Q: I hear a whistling noise around the blower compartment of my furnace. What is causing the noise? Should I be concerned?

A: You’ re hearing air leakage. All air handlers (any device with a blower, including furnaces, heat pumps, and central air) have two ducts: one for supply, the other for return. I often find considerable air leakage at both connection points. If the blower is located in an unconditioned location (attic, crawlspace, or basement), it is bleeding out heat, or Btu, on the supply side while pulling in unconditioned air that must be warmed (or cooled and dehumidified) on the return side. This energy loss can add 10% or more to your heating and cooling bills.

You can fix these leaks by sealing the connection with sealant and/or top-grade mastic tape rated to withstand the area’s exposure. While you’re at it, check the air handler’s access door, another frequent

source of air leaks. Because the access door must be opened to service the equipment, you want to use only tape or magnetic strips to seal gaps. Other spots to seal include filter slots and openings for wiring. Last but not least, the accessible ductwork should be examined for leaks. Seal them with high – quality tape, mastic, or sealant that’s com­patible with the duct material and with ex­posure to surrounding air temperatures.

Q: Streaks of dirt are visible around the ceiling registers in our house. What’s causing them?

A: Those streaks are tiny particles of soot blasted across the ceiling by air leaking from around a register that isn’t connected properly. Think of your ceiling as the inner layer of a sandwich. If you had X-ray vision, you’d see the duct boot resting on the attic side of the ceiling with the register below, sandwiching the ceiling between them.

If the boot isn’t firmly attached, you’re heating (or cooling) your attic—typically unconditioned space—which means your energy dollars are being lost to the great outdoors. The same goes for floor registers. In either case, the cure is the same: Remove the register, use a sealant to close the gaps between the boot and the ceiling (or floor), and add foam weatherstripping between the ceiling (or floor) and the register to prevent air leakage.

Furnace Basics

Disconnect

switch

Filter box’

Gas shutoff

Blower’

Q: Our local oil company is offering a $29.95 service special. It seems like a bargain, but does heating equipment need to be serviced every year?

A: Just as people should get an annual physical, all heating equipment should receive an annual checkup to maintain peak performance and to keep the home’s occupants safe. Part of the service is a test for proper combustion using an analyzer that provides CO (carbon monoxide), O2 (excess oxygen), and CO2 (carbon dioxide) levels, as well as net stack (exhaust) temperature. You should ask for a copy of this test, or combustion analysis.

While the internal surfaces of some gas appliances don’t need to be vacuumed (unlike oil units), regular maintenance is particularly important for newer high – efficiency models. Also, in all units, the chimney or venting should be inspected periodically to make sure it’s not obstructed. Dirty heat exchangers in oil burners rob efficiency, which results in increased fuel usage. A layer of soot just Vie in. thick reduces operating efficiency by 10%.

That said, it’s not physically possible to clean and tune up an oil-burning appliance properly for $29.95. Companies offering prices that low often pay technicians a flat rate for each call they make; the more they fit into a day, the more profitable it is for them—at your expense. I often see those fur­naces six to eight years later, when they’re malfunctioning. So accept the fact that if it sounds too good to be true, it probably is, and call in a professional technician you can trust at a believable price.

What Should I Expect from a Service Call?

• Preliminary combustion analysis • Chimney inspection • Top of boiler removed and com­bustion chamber cleaned • Soot vacuumed from all surfaces • Oil filter replaced • Oil-burner nozzle replaced • Reassembly; draft in flue and over burner checked; boiler operation tested

• Final combustion analysis

Q: Our ductwork is located in the attic. There doesn’t seem to be as much warm air blowing from the registers as there used to be. Is that my imagination?

A: Ductwork that travels through unconditioned spaces (basements, crawlspaces, garages, and attics) needs to be well insulated. Uninsulated ducts waste gobs of energy and create drafts as chilled air spills out of ceiling registers; it’s hard to believe how noticeable this is until you’ve felt it firsthand. Newer codes require R-8 minimum insulation on ducts, but on older flex and duct-board systems, it can be as low as R-2.5. Before you consider more insulation, however, remember that insulation can hide the real problem: air

Insulation helps, too. Once all ducts are air – sealed, use insulation to limit heat loss. Owens Corning makes insulated rigid ducts, insulated flexible duct wrap, and foil-faced insulation that can be used to wrap existing ducts (www. owenscorning. com).

Different manufacturers have different details for securing and weather­sealing their windows. However, they all have a sill expander of some type at the top and bottom, and rely on screws to secure the frame to the jamb.

3. Partially driven screws secure the window for centering.

4. Mounting screws in the window frame are used for the final adjustment.

1. Install the bottom sill expander. Use a Speed Square® to make a level reference line so that you can measure how much the sill slopes. Then use a utility knife to cut the bot­tom sill expander to fit snugly against the sill. Tap the expander into the window frame with the butt of a hammer handle.

1. The bottom sill expander is cut to fit against the sloping sill.

2. Install the head expander. If the replace­ment window doesn’t overlap the head stop, you need to add the head expander that fits over the top of the window and fill the airspace with low-expanding foam or fiberglass insulation.

5. The inside sash stop is removed and reused as molding around the new window.

homeowners, but many local fabricators have a retail store on site that will sell you windows at a small premium over whole­sale prices.

You can also buy replacement windows at a home center. If your house is 50 years old or less, you can find fairly good-quality
windows in standard sizes to fit the existing openings.

I advise shopping around, but be sure you’re comparing equal products and ser­vices. Some companies’ standard features are options that cost more from other fabrica­tors. Frame thickness and extrusion designs

3. Insert and center the window. Drive two mounting screws partway through the window frame and into the jambs to keep the window in place. Then use a small pry bar to get the frame centered, level, and plumb.

4.
Secure the window. Insert shims between the window and the jamb as backing for mounting screws. drive mounting screws in all the pilot holes. sometimes these holes are concealed by sash stops or balance guards that can be slid out of the way or removed.

can differ. Bargain windows might have lower-quality frames that require more time to shim and brace adequately for proper operation.

If I have a choice, I use high-quality vinyl windows made locally. Although they might not be a popular name brand, the warranty

is good (20 years) and the price is reason­able. Also, if problems arise, there’s someone local to call.

Get Maximum Value with a Good Weatherseal

If I’ve spent the money, time, and effort to replace a window, I want to get the best performance I possibly can. Proper weathersealing calls for spray foam and caulk.

Foam the gaps. Use low-expanding foam to fill gaps between the old jamb and the new window.

Accurate Measurements Are Critical

I always take measurements myself, and if the sales rep comes out to help, I check that person’s work. The last thing I want is to show up on the morning of a whole-house window replacement and find out that someone else messed up the order.

Most important is checking top, bot­tom, middle, and diagonally for square. The new window has to be sized for the shortest measurement (see the drawing on p. 112).

I use a systematic approach with my own order sheet to note dimensions and location.

Writing measurements on a block of wood just doesn’t cut it. One wrong measurement, and you own a perfectly good window that doesn’t fit.

Know How the Windows Are Sized

Replacement-window fabricators make units on a VWn. basis, a 1/2-in. basis, or a combina­tion of the two. This guideline forces you to order a unit smaller than anticipated when a dimension falls on a 1/8-in. increment, but undersizing a window is better than having it too tight. Window height is more forgiv­ing than width due to the sill and head

Mike Guertin (www. mikeguertin. com) is a builder, remodeling contractor, and writer in East Greenwich, R. I.

indows wear out before a house does. Sometimes the need for replacement windows is obvious, such as when you encounter poorly functioning single-pane sashes with weights. But even windows with insulated glass become difficult to operate, suffer from damaged seals, or show signs of deterioration.

The good news is that replacement win­dows eliminate these problems, offering improved appearance and easier operation, along with greater levels of energy efficiency. Window replacement could save you 5% to 15% off your heating and cooling bills, but how much you’ll save depends on where you live (the potential is much higher in cold climates) and how inefficient your ex­isting windows are.

In some cases, air sealing and better insu­lation elsewhere in your house (see "Home Remedies for Energy Nosebleeds," pp. 12-19) offer more bang for your energy buck. The best way to tell is with a home-energy audit, which will identify the biggest deficiencies in your home’s energy envelope (see "Every House Needs an Energy Audit," pp. 4-11).

If you find that your windows are costing you energy dollars, you can go one of two ways: Hire a full-service installer to measure, order, and install new windows for you; or buy and install them yourself. Replacement windows are easy to order and quick to install, and you can save money if you tackle this project yourself.

Evaluate

Existing Windows

The installation shown here took place in a modest Cape that still had its original single­glazed, sash-weighted windows—a perfect candidate for replacement windows. I chose frame-and-sash replacement windows (also known as pocket windows) because the ex­isting window jambs, sills, and trim were solid, and the siding was in good condition. Had the window frames been rotted or the siding in need of replacement, I would have had to install new-construction windows using the old rough openings. The budget didn’t allow for the extra labor to tackle full

window replacement, which would have required the siding to be stripped back, and the interior and exterior trim to be removed and then reinstalled or replaced.

Finally, I didn’t want to disturb the home­owners. Pocket windows are quick to install and create little mess inside or out. On aver­age, working alone, I can install one in less than 30 minutes.

Choosing the Right Windows

As a contractor, I order windows directly from more than a dozen manufacturers. Some are national, others regional, and a couple make their windows locally near where I work. National and regional manu­facturers generally don’t sell directly to

2. Carefully remove the sashes. swing the inside sash out of the window opening, and cut the counterweight cords to free the sash. Remove the small parting bead between the sashes, and take out the outer sash the same way.

3. Remove the weights. open the counterweight doors to remove the weights and cords; then unscrew the pulleys and remove them. some installation guides suggest hammering the old pulleys into the jamb, but I disagree. The pulley holes make good view spots when installing insulation.

The U-factors reported by European window manufacturers—whether given in European units (W/m2^K°) or North American units (Btu/ft2^F°)—are difficult to compare with U-factors reported by North American man­ufacturers. European and North American laboratories use different protocols to test window U-factors, and most glazing experts agree that European U-factors would look worse if the windows were tested according to NFRC requirements.

U. S. distributors of European windows don’t follow a consistent method for report­ing U-factors. Some use European metric units, while others report North American U-factors or even R-values. Although the NFRC requires U-factors and SHGC to be based on the performance of the whole win­dow, including the frame, many European manufacturers report U-factor and SHGC numbers that measure the performance of the glazing alone.

There is a straightforward conversion fac­tor for converting a European U-factor in W/m2^K° to a North American U-factor in Btu/ft2^F°: Simply divide by 5.678. Unfortunately, while this method converts the units, it doesn’t account for the fact that the European protocol tests windows of a different size from the size used in North American testing, or for the fact that European windows are tested at different temperatures than required for North American tests.

An American Standard

To appreciate the performance of the win­dows featured here, it’s helpful to look close­ly at a typical window made by an American manufacturer. The argon-filled, double – paned window made by Marvin (above) is an example of a unit suitable for houses built to code minimums.

The European Difference

For the most part, the glass in European Pas­sive House windows is quite similar to the glass used in the best Canadian windows: argon – or krypton-filled triple glazing with two low-e coatings and warm-edge spacers. That’s why many energy experts report that the thermal performance of the best Euro­pean windows is about the same as that of fiberglass-framed, triple-glazed Canadian windows. Katrin Klingenberg, founder of the

MARVIN

ULTIMATE

PUSH-OUT

CASEMENT

U-factor: 0.28 SHGC: 0.25 VT: 0.42 Cost: $670

Passive House Institute US, gives a bottom­line analysis: "Our experience has been that the overall performance of the fiberglass­framed Canadian and U. S. windows is al­most as good as the German Passive House windows if you look at the overall systems design [using Passive House Planning Pack­age software]."

However, European window manufac­turers continue to push the performance envelope, and glazing manufacturers are always striving to improve their products. The latest versions of low-U triple glazing from Europe may have a higher SHGC than comparable low-U triple glazing available in North America. According to some window experts, European manufacturers are already selling windows with better insulated frames and glazing with a slightly lower U-factor than any frames or glazing available from North American manufacturers.

Typical European Passive House windows have composite frames, often including a wood lamination on the interior, a core of foam or cork to act as a thermal break, and a weather-resistant exterior cladding of alumi­num or rot-resistant wood.

Although the wide frames on European windows reduce the windows’ thermal performance—especially their potential for solar heat gain—compared to narrow-framed

North American fiberglass windows, the thermal breaks incorporated in European frames are usually more effective than those used by North American manufacturers.

North American Products Rely on Narrow Frames and Synthetic Materials

Although European triple-glazed windows are well built and attractive, they cost far more than North American windows with similar performance specs. (For an operable triple-glazed casement window measuring 8 sq. ft., you can expect to pay between $400 and $520 for an Inline, Fibertec, or Thermotech® window. A Serious window with Heat Mirror™ glazing will have a lower VT rating, but it will cost about the same—$400 to $560, depending on the glazing chosen.) Windows from Europe also have a long lead time—anywhere from 10 to 12 weeks.

Unlike almost all U. S. manufacturers, Ca­nadian manufacturers of fiberglass windows offer full-thickness (13/s in.) triple-glazing. Even when U. S. manufacturers offer triple glazing, it’s usually thin (1 in. or 7/s in.), low-performance glazing. While Canadian window manufacturers offer both low-solar – gain and high-solar-gain triple glazing, it’s difficult to buy high-solar-gain triple glazing from a U. S. manufacturer.

Canadian fiberglass windows have other attributes that make them more attractive than European offerings. Canadian windows have narrower frames than European win­dows. Because frames have a lower R-value than a superinsulated wall, narrower frames mean better thermal performance overall. Also, narrow-framed windows allow more light and more solar heat gain than wide­framed windows.

When looking for high-performance win­dows made domestically, you’ll come across the following materials.

PULTRUDED FIBERGLASS FRAMES

The pultruded fiberglass used for the best Canadian window frames is similar to the fiberglass used to make stepladders, only denser and smoother. Even when left un­painted, pultruded fiberglass is extremely durable and weather resistant. Because it has a coefficient of thermal expansion that closely matches that of glass, it’s a much more suitable material for window frames than vinyl.

HEAT MIRROR GLAZING

Heat Mirror glazing has only two panes of glass; the performance of the glazing is improved by one or more stretched plastic films suspended between the two panes. The plastic films create two or three separate air spaces between the inner and outer panes of glass, mimicking the performance of triple or quadruple glazing but with less weight.

The best-known manufacturer of Heat Mirror windows is Serious Materials. Serious offers windows with lower U-factors than any triple-glazed window. Its best-performing operable window (a 1125 series casement or awning window with three plastic films) has a whole-window U-factor of 0.13. The low-U-factor glazing comes with a down­side, however: a very low SHGC (0.20) and a very low visible transmittance (0.30). In other words, the windows don’t let in much light or heat. European window manufactur­ers (and most Passive House builders in the United States) have been reluctant to use Heat Mirror windows due to lingering skep­ticism about the long-term durability of the plastic films and an unwillingness to accept lower SHGC and VT ratings.

VINYL FRAMES WITH TRIPLE GLAZING

Builders experiencing triple-glazing sticker shock may want to consider a lower-cost option: vinyl windows. Paradigm Windows of Portland, Maine, offers casement win­dows with foam-injected frames. Paradigm’s best performing krypton-filled triple-glazed casement windows have a whole-window U-factor as low as 0.17. Unfortunately, these

almost all U. S. window manufacturers, Para­digm Windows doesn’t yet offer high-solar – gain triple-glazed products.

High-Performance Windows Don’t Make Sense in All Homes

The high cost of triple-glazed windows is hard to justify unless you’re building a su­perinsulated house in a cold climate. But once your wall specs reach the R-40 level, triple-glazed windows start to make sense.

A triple-glazed Optiwin tilt-turn window will cost at least $880, while a window from Bieber® will cost almost twice as much. Fortunately, Canadian windows with com­parable performance specs cost roughly half the price of an Optiwin window.

Because of their positive latching hardware, casement, awning, and tilt-turn windows always outperform single – or double-hung windows.

Martin Holladay is a contributing editor to Fine Homebuilding.