-- Scotts Contracting - StLouis Renewable Energy: Home Weatherization

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Showing posts with label Home Weatherization. Show all posts
Showing posts with label Home Weatherization. Show all posts

4.20.2011

Part 2 on Home Weatherization Series, by Scotts Contracting-St Louis Renewable Energy

Example of How a Box Sill is Constructed using Standard Building Techniques

Box Sill-What is it? And How to Insulate the Area 

In this Article I'm going to explain how to Seal and Insulate the Box Sill of your home and why it is important to add Insulation in this area of your Building. Adding Insulation will: Reduce the Energy Needs of your Property, while Increasing Your Personal Comfort level. 
Its a Win-Win option for any Home-Owner

2.02.2011

Air Sealing Your Home- Weatherization, Tips, Photos, Suggested Sealing Techniques

WHAT  A R E  T H E  B E N E F I T S  O F  A I R
S E A L I N G ?
Air infiltration can account for 30 percent or
more of a home’s heating and cooling costs
and contribute to problems with moisture.

In the previous post: Suggested Reading- How to Design and Build an Energy Efficient Home
I covered many aspects of Designing and Building an Energy Efficient Home. 


This blog posting will cover Air Infiltration-

Seal plumbing behind tub
electrical penetrations
Attic living space
Knee wall
Attic space
Unwanted air leakage
Attic Ventilation
Seal tub penetration
Seal kneewall to create a continuous air barrier.
Seal and insulate exterior wall before installing bath tubs.
Attic ventilation
Rafter Sheet
dropped soffit
Seal chases
 top and bottom plates
Soffit vent
Caulk bottom plate
Caulk
to subfloor
electrical fixtures to drywall
Seal HVAC
Caulk band joist to subfloor and plates
penetrations
Seal electrical penetrations
Seal bottom
Tape or caulk exterior
Seal plumbing penetrations
sill plate-Caulk bottom plate to subfloor
sheathing seams
Sheathing
Seal dropped soffit ceilings, plumbing and electrical penetrations, etc
Seal exterior sheathing joints, and top and bottom plates. chases.

and More.


Download the Free Technology Fact Sheet on Air Sealing / Air Filtration.  Sealing Air Leaks will SAVE YOU MONEY.

Air infiltration control in housing: A guide to international practice (Bulletin no. 139 from Division of Building Technology, Royal Institute of Technology, Stockholm, Sweden)

Wind and trees; air infiltration effects on energy in housing (Report - Center for Environmental Studies, Princeton University)

Applicable Models for Air Infiltration and Ventilation Calculations

Minimising Air Infiltration in Office Buildings: (BR 265) (Building Research Establishment Report)

Infiltration and Air Leakage

Air tightness and air leakages of new lightweight single-family detached houses in Estonia [An article from: Building and Environment]

11.01.2010

Scotts Contracting, Updated Training Certificate-Master Insulation Certificate

Home Repair and Green Building Services-Scotty, Scott's Contracting GREEN BUILDER, St Louis 'Renewable Energy' Missouri- Find Us at: http://stlouisrenewableenergy.blogspot.com/, http://www.stlouisrenewableenergy.com,
scottscontracting.wordpress.com;
contact  scottscontracting@gmail.com for additional information or to Schedule a 'Green Site Evaluation'--


Scotts Contracting Certainteed Insulation Certificate

10.25.2010

Roof and Attic Ventilation

Roof Ventilation Update

The construction industry's leading researcher explains why what we think is true often isn't, and how some of our best hunches, based on observation of field performance, have paid off with problem-free attic assemblies

by William B. Rose

I've gotten many calls over the years about attics and attic ventilation; almost invariably the caller is confused, having heard different things from different people. In this article, I'll discuss the performance of attic assemblies and try to shed light on why there are so many points of view about roof ventilation.

Research Findings
The temperature of a northern-climate roof we monitored throughout the 1990s is shown below (Figure 1). Here is a summary of the study: The roof gets cold at night and is hot during the day. It gets hotter on a sunny day than on a cloudy day. Attic assemblies with openings to the outdoors ("vented" attics) stay a bit cooler during the daytime than unvented assemblies. They also stay slightly warmer at night.


Figure 1. Sheathing temperatures are affected somewhat by roof ventilation, but many other factors play a bigger role.

Many factors influence the temperature on the roof. A prioritized list might include hour of day, outdoor air temperature, cloud cover, color of the roof, roof orientation, where the measurement is taken (sheathing or shingles, top or bottom), latitude, wind speed, rain or snow on the roof, heat conduction across attic insulation, roof framing type (truss or cathedral), and attic ventilation to the outdoors. As you can see, ventilation falls pretty far down the list.

To better understand how wind affects roof ventilation, Canadian researchers T.W. Forest and I.S. Walker measured the air exchange rate in attic assemblies using tracer gases. The graph below (Figure 2) gives us a feel for what they found. That is, air-change rates in the attic tended to increase with wind speed, but the amount of air change at a given wind speed was unpredictable. In fact, even with specific information about climate, construction type, and wind speed and direction, the resulting air-change rates may vary by a factor of 10 or more. Whether air flows out through a roof opening or in through that opening, and whether this airflow induces flow from indoors into the attic or helps dilute and remove moist air from the attic, can never be pinned down very well, except to say that wind is a more powerful factor than buoyancy (the "stack effect").


Figure 2. While higher wind speeds tend to increase attic ventilation, the relationship is a weak one: Ventilation rates at a given wind speed can vary by a factor of 10.

For the most part, roof assemblies behave like any wood structure — they are wetter when cold and drier when warm. Roof assemblies tend to be hot, thanks to the sun, so they tend to be dry. Of course, if the roof leaks, that becomes the biggest source of wetness. High moisture levels indoors or in basements or crawlspaces can also increase moisture levels in the roof. Roof members can become particularly wet or covered with frost near holes in the ceiling or leaks in attic ductwork, where humid air enters the attic. It was the formation of local frost "walnuts" like those shown on the next page (Figure 3) that led researchers in the late 1930s to recommend attic ventilation. (If only they had offered to seal up the ceiling instead!)


Figure 3. Moist interior air leaking through a hole in the ceiling can produce moldy sheathing or frost on a roof truss. This photo by the author shows results from the Attic Performance Project.

Many attic assemblies are built with vents to the outdoors on the presumption that outdoor air will enter the attic and dilute moisture coming from indoors or from the foundation. The further presumption is that indoor air is wet and outdoor air is dry. Both of these assumptions are often false. If there are openings in the ceiling, then air movement in the attic can induce airflow from below, or dilute air from below, or do nothing, in ways that are just plain unpredictable no matter how much research is done. Attic air movement can also induce flow into the living space below, which is a nasty problem when the air conditioning is running.

Observations in the Field
Suppose that the picture of attic ventilation provided by physics, described above, doesn't quite cut it. Too many qualifications; nothing pinned down. Then we can go to our own observations and experiences, subjective and incomplete as they may be. Here's my main finding: Attic assemblies built over the last 15 years or so are pretty good. They may be a crapshoot in building-physics terms, but the crapshoot is heavily biased toward good performance.

Let's look at attic assemblies by component:

Truss construction seems to do quite well. There are disasters that occur during construction. Truss uplift continues to be a problem requiring cosmetic fixes. The industry has, for the most part, discontinued the use of fire-retardant treatment of truss members, thereby avoiding what was a serious concern for several years. The truss heels in many cases still fail to provide the height necessary for good insulation. Attics have become a forest of truss webs, and thus are less usable for attic storage space. But the overall picture is good (at least by my observations).

Gypsum wallboard ceilings have shown improvement. The message seems to have gotten out that ceilings must be airtight — there is no justification, summer or winter, for allowing indoor air or foundation air to pass into attic cavities. The common culprits, such as framed soffits over kitchen cabinets, open oversized plumbing or mechanical chases, and leaky can lights, are going away in most construction where the word has gotten out. Weatherization of existing buildings has kept the focus on closing off any ceiling bypasses. In my experience, most truss-framed attics do fine without special vapor-barrier membranes in the ceiling, but in cold locations, cathedral ceilings may need vapor protection just as walls do.

Insulation. Regarding insulation, most areas of the country have healthy amounts in the attic — R-30 in general and R-38 in northern areas. Cellulose provides good insulation and helps block airflow. Fiberglass, in sufficient density and with good installation, also provides good thermal insulation. Foam insulation is being used more commonly, and has become the material of choice for residential air-sealing. Structural insulated panels (SIPs) work fine, as long as the airflow problem at joints is addressed. Foam insulation has been sprayed on the underside of board and wood-panel sheathing with great success. Insulated panels (often polyisocyanurate) make for good roof-deck assemblies, as we know from commercial low-slope construction, where the foam insulation is often sandwiched between the structural roof deck and the roofing membrane. (All foam needs fire protection, of course.) Open-cell foams such as Icynene may need more vapor protection than closed-cell foams, which have greater resistance to vapor flow.

Vapor barriers still cause squabbling, but most builders know that moisture flow from below comes mostly through holes in the ceiling. Cathedral ceilings require special care in insulation placement and vapor protection. But the new code provisions should encourage insulated sheathing materials or insulated "sandwich" assemblies that resist moisture transport and heat flow as a package. With these roof assemblies (I call them "insulated vapor retarders" or "fat vapor retarders"), the inside surface stays close to indoor conditions, the outside surface stays close to outdoor conditions, and nothing bad happens in the middle. Our laboratory has had such an assembly in place for more than 15 years, with one inch of foil-faced polyisocyanurate insulation directly beneath the OSB decking; the sheathing gets hot during the day, but the OSB above the foam insulation is the driest sheathing of all. Remember: Hot means dry.

Ductwork in unconditioned attic assemblies is not ideal. It's best to place all ductwork in conditioned spaces.

OSB has become the universal sheathing material, by economic and environmental necessity. But we still know too little about the moisture performance of this material, such as under what conditions it will begin to fail. In my laboratory, we have seen the material swell by 50 percent or more under extreme conditions. Will it begin to show signs of sagging between trusses, or will workers be putting their feet through it at the time of reroofing? I don't know, but the absence of signs of product failure in the field — at least to my drive-by observations — is reassuring. Nevertheless, I look forward to the day when the marketplace provides a product with more clearly established performance characteristics. I'll be a strong supporter.

Shingles. I'm reviewing the condition of the shingles installed on our research laboratory in 1989; after 18 years, signs of aging are appearing. We hope to conduct laboratory tests to pin down and better quantify the shingle performance and the factors that influence it. The aging we see shows some temperature effect: The white shingles are in better shape than the dark, and a few of the most aged-looking shingles are found on the hottest bay, the one with foam directly on the underside of the sheathing. Without the numbers to go by, we must rely on observation, and our observations suggest that performance depends on other factors besides the presence or absence of ventilation and whether the assembly is truss-framed or cathedral ceiling.

Of course, natural weathering tests that began 18 years ago say little about shingles that are made today. I sense that the shingle industry is currently producing dimension shingles that seem to lie quite flat, resist wind uplift, and hang on to their UV-protecting granules. I don't know how to reroof over dimension shingles, and it does seem unfriendly to the landfill to have that much more mass in the shingle. Nevertheless, my drive-by observations show a lot of good-performing shingles going on roofs over the last couple of decades, and that is very reassuring.

Roof vents. Many years ago, we measured the "net free area" of about a dozen ridge-vent materials. (We used an apparatus that measures the pressure drop across a vent device with great accuracy.) We found that ridge vents with large openings (minimum opening dimension around 1/4 inch) had an equivalent net free area very close to their rated capacity. Vent devices with small openings — or with filter fabrics, or scrims — performed much worse, as much as 75 percent less than their rated area. (If you want to know how restrictive a vent device is, use your imagination — if it looks like air would have a hard time moving through, it probably does.)

This discrepancy would be a big deal, I suppose, for someone who felt that vent regulations were critical to attic performance. I don't, so for me, having vent devices with less airflow than advertised is not a cause for concern.

Building Codes
You — and your building code inspectors — may be unaware that the 2006 version of the IRC for one- and two-family dwellings permits attic construction with no ventilation of the attic cavity. This new provision, R806.4, is largely due to the efforts of Joseph Lstiburek, Armin Rudd, and their colleagues. In brief, unvented conditioned attic assemblies are permitted when an air-impermeable insulation such as rigid foam is applied in direct contact to the underside/interior of the structural roof deck, with sufficient thickness — given the climate — to prevent condensation on the underside (see "Insulating Unvented Attics With Spray Foam," 3/07).

This new provision is a direct challenge to the rule of thumb that has been in place for 50 years, which says that you have to vent a steep-roof attic so the ratio of net free vent area to the projected roof area is 1-to-300 (or 1-to-150 when using "cross ventilation" rather than soffit and ridge vents). This ratio arose from observations of frost on protruding nail points in Wisconsin homes by researchers at the Forest Products Laboratory in 1937, and frost on aluminum plates in research "doghouses" at the University of Minnesota in 1938, under "outdoor" conditions of -13°F.

The Federal Housing Authority turned these findings into the famous 1-300 ratio in 1942, to be applied as a minimum building requirement for the small homes in its financing program. The requirements were picked up by model codes and others following World War II, and the rest, as they say, is history. Shingle manufacturers did not begin piggybacking their warranties on venting regulations until reports of shingle problems began piling up following the change in asphalt sources in the early 1980s.

To Vent or Not
Every designer and builder should be able to produce good attic and roof assemblies, both with and without ventilation — or anything in between — with just part of a conventional ventilation system. For example, from our studies, roof assemblies that have holes but not necessarily straight airflow paths (one gable end vent, or soffit-only) should also be candidates for good performance. And although unvented roof assemblies can perform well, there are still good reasons to vent: The truss-framed, steep-roof attic with an insulated ceiling has been the workhorse of single-family construction, and ventilation works well with this construction, at least in the northern United States.

In some cases, there are also good reasons not to vent: in wildfire areas, in complex cathedral ceiling assemblies, in existing and historic buildings that have never had ventilation, in shed roofs beneath clerestory windows, with foam insulation (foam and ventilation do not go together — think fire), and in complex roof assemblies that combine steep and low-slope construction. I've also heard persuasive arguments against venting in hurricane-prone regions, but I'm not an expert in that area. In short, since critical performance doesn't hinge on ventilation, then either vent, no-vent, or an in-between "kinda"-vent can be taken as the starting point. Whether the choice works or not depends mostly on other factors.

So you should vent where venting is appropriate and not vent where it is not appropriate. As it turns out, the worst-performing, most mold-ridden attics I have seen were vented — with a flooded crawlspace and a direct path for air movement from the crawlspace to the attic. You can mess up a vented attic by allowing such airflow. You can mess up an unvented attic as well, usually by not providing vapor protection appropriate to the climate and indoor moisture levels. Tight ceilings would be a great first step toward moisture control, summer and winter.

Conclusions
The father of a colleague of mine says that when the word "ventilation" comes out, people stop using their heads. Vented assemblies often perform well, but not always. Sometimes roofs appear to be vented but actually aren't. Still, we can take comfort in the observation, based on years of experience, that our attic assemblies are pretty darn good, and — in my opinion — they're getting better. We need to constantly be on the lookout for new conditions and new problems, as they crop up.

Those of you working in the trenches should continue to build in a way that complies with code and that you know works for your climate. For more information about ice damming, summer cooling load, shingle service life, and moisture issues, visit www.fpl.fs.fed.us/documnts/pdf1999/tenwo99a.pdf (TenWolde and Rose, "Issues Related to Venting of Attics and Cathedral Ceilings"). For all four of these concerns, ventilation makes a contribution that is generally more positive than negative, but it hardly ever makes the difference between success and failure.

For the most part, the focus of codes, researchers, designers, and builders on roof ventilation is misplaced. Instead, the focus should be on building an airtight ceiling, which is far more important than roof ventilation in all climates and all seasons. The major causes of moisture problems in attics and roofs are holes in the ceiling and paths for unwanted airflow from basements and crawlspaces. People should focus first on preventing air and moisture from leaking into the attic. Once this is accomplished, roof ventilation becomes pretty much a nonissue.

William B. Rose is a research architect with the Building Research Council at the University of Illinois at Urbana-Champaign, and the author of Water in Buildings: An Architect's Guide to Moisture and Mold. This article was adapted from The JLC Guide to Moisture Control.

--
Scott's Contracting
scottscontracting@gmail.com
http://stlouisrenewableenergy.blogspot.com
http://greenmeupscotty.wordpress.com

Insulating Roofs, Walls, and Floors

ABOUT INSULATING ROOFS, WALLS, AND FLOORS

Its not unusual for a house to have three or four types of insulation: spray foam, loose fill, rigid foam, and/or batts. Each type has multiple uses, but most also have limitations on where they can be used.

The best insulation for each location depends on a number of factors, including cost, ease of installation, available space, and the material's resistance to moisture.
All insulation types perform best when they're installed well. Some (like batts and blankets) can lose significant R-valuewith even a slightly sloppy installation.


Grading installation quality

The Residential Energy Services Network (RESNET), a national association of home-energy raters, long struggled with the question of how to estimate the R-value of walls that vary widely in performance depending on the skill of the insulation installer. Eventually, RESNET developed a useful rating system for insulation installation quality. The system is described in an article published in the January/February 2005 issue of Home Energy magazine, "Insulation Inspections for Home Energy Ratings," by Bruce Harley. The RESNET rating system recognizes three levels of insulation installation quality: Grade I, Grade II, and Grade III.



Grade I is the best installation


"In order to qualify for a Grade I rating, insulation must … fill each cavity side to side and top to bottom, with no substantial gaps or voids around obstructions (that is, blocking or bridging—as seen in the grade II photo below), and it must be split, or fitted tightly, around wiring and other services in the cavity. In general, no exterior sheathing should be visible through gaps in the material," Harley wrote. "Compression or incomplete fill amounting to 2% or less of the surface area of insulation is acceptable for Grade 1, if the compression or missing fill spaces are less than 30% of the intended fill thickness (that is, 70% or more of the intended insulation thickness is present)."

The standard for a Grade II installation is somewhat lower


"A Grade II rating represents moderate to frequent defects: gaps around wiring, electrical outlets, plumbing, other intrusions; rounded edges or 'shoulders,' larger gaps, or more significant compression. No more than 2% of the surface area of insulation missing is acceptable for Grade II."

Grade III installations are the worst
"A Grade III rating applies to any installation that is worse than Grade II." For further information on the RESNET grading system—including illustrations of good jobs and sloppy jobs—see "Assessing the Quality of Insulation Installed in New York Energy Star Labeled Homes."



ABOUT INSULATING FOUNDATIONS

Basements

Because foundations aren't really exposed to vast temperature swings, less insulation is needed there. Insulation in a basement should be chosen to do more than slow the flow of heat through these relatively stable environments; the best choices of basement insulation stop air and water, too. Basement walls and floors can be insulated on the inside or the outside, inside being the easier method for retrofits and outside being easier (in general) for new construction.

Exterior insulation choices should be moisture tolerant


Below-grade walls and floors should be insulated on the outside with, spray foam, or rigid mineral wool. Because polyisocyanurate can absorb water, it should not be used under a slab or on the outside of a foundation. Polyisocyanurate performs well, however, when used on the inside wall of a basement or crawlspace.

The most common insulation under slabs is XPS, although EPS also works if its density is adequate and if it is rated for ground contact. If the insulated slab must bear heavy loads, XPS is usually a better choice than EPS.

Closed-cell spray polyurethane foam can also be used under a slab.
Basement walls can be insulated on the exterior or interior with EPS, XPS, spray polyurethane foam, or rigid mineral wool (for example, Roxul drainboard).

To insulate a basement wall from the inside, the foam should be applied directly to the concrete, in order to keep moist interior air away from the cool, damp surface and lower the risk of condensation. To allow any accumulated moisture to dry to the inside, a semipermeable foam (EPS or XPS) is the best choice. To meet code requirements for a thermal barrier, the foam will probably need to be protected with a layer of gypsum drywall; fiberglass-faced drywall is more moisture resistant than paper-faced drywall.

Under no circumstances should fiberglass batts be used to insulate basement walls. Because fiberglass batts are air-permeable, they are unable to prevent moist interior air from contacting colder basement walls. That's why fiberglass-insulated basement walls can easily become damp and moldy.

Crawlspaces

Although some builders insulate the floor above a crawlspace (the crawlspace ceiling), most building scientists recommend building a sealed, insulated crawlspace that includes wall insulation. It usually requires less insulation (and involves fewer tricky details) to cover a short wall around the perimeter than the whole floor.

Sealed crawlspaces should be built and insulated exactly like basements.
Of course, a well-detailed insulated crawlspace needs more than just insulation. Among the other critical details are careful air-sealing of the rim-joist area and (if the crawlspace has a dirt floor) installation of a ground cover.

Slabs on grade

Some builders insulate slab perimeters without insulating under the slab. In all but the warmest climates, however, it's better to install a continuous layer of EPS, XPS, or spray polyuyrethane foam under the entire slab. Some builders modify an ICF  for use as a form for the slab that includes insulation.

If the home has in-floor radiant heat, it's especially important to include a thick layer of foam directly under the entire slab. Experts disagree on exactly how much foam to add, but they all agree that at least some is a good idea. Engineer John Straube of Building Science Corp. says that after about 4 in.—perhaps 6 in. if the slab includes radiant heat—the money is better spent elsewhere. However, Passivhaus builders sometimes install up to 14 in. of sub-slab insulation.

Soil has a measurable R-value, so it can insulate the bottom of the slab from the exterior air to some extent. But soil is also a nearly infinite heat sink. The average soil temperature varies depending on the climate and the soil depth; however, if the soil has an average temperature of 55°F and the interior of a house has an average temperature of 72°F, heat will always want to flow from the warm side of the slab toward the soil. That's why it's important to insulate under a slab.

ABOUT INSULATING ABOVE-GRADE WALLS

The strategy adopted for insulating a home's above-grade walls depends on the wall construction used.
  • Walls built from SIPs or ICFs already include insulation.
  • Concrete-block  walls are best insulated from the exterior with rigid foam or spray polyurethane foam.
  • Wood-framed walls can be insulated with cavity insulation (fiberglass batts, sprayed-in-place fiberglass, cellulose, or spray polyurethane foam), on the interior (with rigid foam board), on the exterior (with rigid foam board or spray polyurethane foam), or with a combination of approaches (for example, some cavity insulation and exterior foam sheathing).
Thermal bridging
The effective R-value of a framed wall assembly with cavity insulation is always less than the R-value of the insulation alone, as thermal bridging through the studs degrades the performance of the wall. Thermal bridging can be reduced, and the thickness of the wall increased, by:
  • adding foam sheathing to the exterior of the wall;
  • adding a layer of rigid foam under the interior drywall; or
  • building a double-stud wall with staggered studs.
Foam sheathing


The performance of any wood-framed wall will be improved by installing exterior rigid foam sheathing; the usual choices are XPS or polyisocyanurate. Although EPS can be used, it is more fragile than the other two options.
Adding foam insulation to the outside of a wall affects the wall's ability to dry out when it gets wet. Different types of foam insulation have different permeance ratings, but after a few inches they're all pretty impermeable to moisture. Most foam-sheathed walls are designed to dry to the inside. This means that interior plastic vapor barriers should never be used on foam-sheathed walls.

According to Joseph Lstiburek and Peter Baker of Building Science Corp. (see link below), adding 1 in. of R-5 insulation to a 2x6 wall insulated with fiberglass batts increases the effective R-value of the wall from 14.4 to 19.4, a 35% gain with only a 15% increase in wall thickness.

Adding 2 in. of foam raises the R-value from 14.4 to 23.8, an improvement of 65%. A layer of insulating foam on the outside of walls also reduces the risk of condensation by raising the dew point of the surface where water vapor is likely to collect.

Thick foam sheathing is safer than thin foam sheathing. To learn more about determining a safe thickness for exterior foam, see "Calculating the Minimum Thickness of Rigid Foam Sheathing."

ABOUT INSULATING FLAT CEILINGS

Flat ceilings under unconditioned attics can be insulated with fiberglass batts, blown fiberglass, or blown cellulose, but cellulose works best—especially in very cold temperatures when convective loops can degrade the performance of fiberglass. Regardless of the type of insulation used, more is always better, and it's usually an inexpensive upgrade as space is less of a limiting factor than it would be for walls.

Spray polyurethane foam can also be used to insulate a flat ceiling, although at a much higher cost than cellulose. An advantage of spray foam is that it air-seals as it insulates. With all types of attic insulation, air-sealing before insulating is almost more important than type and depth of insulation.

Attic-floor insulation should extend over the top plates of perimeter walls. To provide enough room for the necessary depth of attic insulation, be sure to specify raised-heel roof trusses.

Locating insulation at the attic floor has several advantages over locating insulation along the slope of the roof:
  • It's cheaper, easier, and faster to install thick insulation at the attic floor.
  • Unconditioned attics are easier to vent than insulated rafter bays.
  • It's easier to detect and pinpoint roof leaks when the attic is unconditioned.

ABOUT INSULATING ROOFS

Sloped ceilings and roofs can be insulated from above (by installing rigid foam on top of the roof sheathing), by installing insulation between the rafters, from below (by installing rigid foam under the rafters), or by a combination of some or all three of these insulation methods. Any of these methods will work. Although installing insulation on top of the roof sheathing is more foolproof, it's also less common.
EPS
,or polyisocyanurate foam can be installed above roof sheathing. Two or more layers of rigid foam with staggered seams can be topped with eave-to-ridge 2x4s to create vent channels, followed by a second layer of roof sheathing. Exterior insulation like this with staggered seams disrupts conductive heat flow through the framing assembly.

Installing insulation in rafter bays is risky, as interior moisture can migrate through the insulation (either by diffusion or by piggybacking with exfiltrating air) and contact the cold roof sheathing, leading to condensation. This problem can be prevented by using closed-cell spray polyurethane foam, with or without a ventilation channel under the roof sheathing.

ABOUT RETROFITTING INSULATION

Although adding insulation to an existing home is always more challenging than insulating a new home, weatherization contractors have developed many cost-effective methods of improving existing insulation levels.

It's important to manage any moisture problems in a home before engaging in air-tightening measures or insulation improvements. Inspect the home to identify any leaks or high-moisture areas, and be sure that the home is equipped with adequate mechanical ventilation.

Among the tried-and-true methods used by experienced weatherization workers:
  • To insulate a basement floor, install a continuous layer of XPS foam on top of the concrete. Top the foam with 2x4 sleepers and a plywood subfloor. If a low ceiling makes every inch critical, the sleepers can be omitted; in that case the plywood subfloor should be mechanically fastened through the foam to the concrete.
  • Basement or crawlspace walls can be insulated with interior XPS, EPS, or closed-cell spray polyurethane foam. The foam should be protected with a thermal barrier (for example, 1/2-in. drywall).
  • Above-grade frame walls can be insulated by blowing dense-packed cellulose into stud cavities through holes drilled through the siding. When insulation is complete, the holes are plugged.
  • If siding is being replaced, rigid foam or spray polyurethane foam can be installed on top of the exterior sheathing. Exterior foam retrofit jobs require considerable trim work around windows and doors, however.
  • Flat ceilings under unconditioned attics are usually easy to insulate with blown-in cellulose.
  • Improving the insulation over a sloped ceiling is often easier from the exterior than the interior. Rigid foam insulation can be added above the roof sheathing in conjunction with new roofing.
After air-sealing and insulation work is complete, the renovated home should be tested for radon. Radon levels often increase after a home has been weatherized.
If a house is undergoing extensive remodeling, it's worth considering a deep energy retrofit.
--
Scott's Contracting
scottscontracting@gmail.com
http://www.stlouisrenewableenergy.com
http://stlouisrenewableenergy.blogspot.com

9.20.2010

Spray Foam-Eco Conscious

Spray foam for the eco-conscious

  June 17th, 2009 in Blogs         
RYagid Rob Yagid , associate editor

Hardworking crops. The oil from soybeans, which is also being considered to create alternative forms of energy, is replacing the petroleum in some spray foams.
Hardworking crops. The oil from soybeans, which is also being considered to create alternative forms of energy, is replacing the petroleum in some spray foams.
Photo: BioBased Insulation


I've gotten a lot of good feedback on an article I wrote for FHB#204 on spray foam. Many folks were concerned about the environmental impact of the foam itself and its toxicity to the resources we're ultimately trying to conserve. Below, I'll share a little bit about the make-up of the foam and also describe what makes some foam "green". For those of you interested in learning more about the various players in the spray-foam market right now, see the source list from my article toward the bottom of my post. And, of course, feel free to comment if you have opinions on the performance of spray-foam or its greater environmental impact.

Spray foam is made of a two-part mixture. The A part is isocyanate, a petroleum-based chemical made by only a handful of companies in the world. The B part contains a catalyst, polyol resin, a surfactant, and a blowing agent.
Consuming fossil fuels to make products intended to conserve fossil fuels makes little sense to a lot of people. All spray foams contain a certain level of petroleum in their A component and in their B component. Manufacturers such as BioBased Insulation, Demilec, and Icynene have created more environmentally benign spray-foam products by reducing the amount of petroleum used in their B component. They replace a portion of the polyol resin, which makes up 20% to 30% of the B component, with a renewable resource such as soybean or castor-bean oil. Apex even has a sucrose-based polyol. Manufacturers say that the transition to bean oil or sucrose doesn't alter the look or the performance of open- or closed-cell foam in any way.
The amount of soybean, castor bean, or sucrose found in foam varies by manufacturer, so identifying the "greenest" foam might not be so easy. 

According to the U.S. Department of Agriculture, only 7% of a spray-foam product needs to be made of a renewable resource to be labeled as a bio-based foam. This, of course, doesn't factor in the petroleum fueling the crop-cultivation process. I wonder how "green" these foams really are? Sure, they may be a bit more healthful than strictly petroleum based foams, but can manufacturers be doing more to produce a better spray foam product?
Although this is not a complete list of spray-foam manufacturers, it is representative of the larger national companies. For assistance in finding a spray-foam insulation contractor, visit the Spray Polyurethane Foam Alliance.
Apex Foam Industries     Fomo Products
BASF
                              Great Stuff
BioBased                        Icynene
CertainTeed                   NCFI
Chemical Design            Tiger Foam
Corbond                         Touch n' Seal
Demilec                          Urethane Soy Systems 
Foametix                        Versi-Foam Systems
Read the complete article...
Spray Foam: What Do You Really Know?
To get the full benefit of this superinsulation, you must understand the difference between open- and closed-cell foams, how they perform, and how they're installed
by Rob Yagid
Get   the PDF



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9.11.2010

Spray Foam- Insulation That Works-Photos Included

Scotts Contracting is available to assist in your Home and Business Insulation Needs.  I even have a Local Supplier / Manufacturer of Spray Foam Insulation- This Insulation is Soy-based Which is Green and Eco Friendly- Many of Our Missouri Farmers Grow Soybeans!!! Support our Missouri Farmers !!!  Click Here to email Scotts Contracting to Schedule a Free Green Site Inspection.

The Following Article is a Follow Up to the Prior Posts about Spray Foam Insulation from these Posts Below




    Spray foam insulation is all the rage because of its
    effectiveness at sealing a building, but builders complain
     that the added cost is significant. Because First Coast
    implemented sealing procedures, the company sticks with fiberglass ...


    Instead, he uses 2 x 6 studs, spray foam
    insulation
    , and metal bracing to make the
    studs rigid. "The studs are energy highways,"
    he says. He then wraps his houses
     in 1.5 inches of foam board, which creates a thermal break. ...


    Seal for Leaks with, caulking and
     spray foam, from anything that is
    sticking out of your Home. This could
    come from the Air Conditioning Unit,
    various wires for Telephone and Cable
    lines. The Power Line or Electric Line. ...

    Certain materials used to seal these
     leaks—such as caulk, spray foam,
    or weatherstripping—can qualify for
    federal tax credits. "It's something that
    homeowners can do easily," Thull says.
     "And there are a lot of different products out ...

    Insulation That Works

    With closed-cell spray foam, the benefits go way beyond R-value

    by Steve Easley

    These days, it's not an exaggeration to say that almost all homeowners expect their homes to be durable, energy efficient, safe, and comfortable. But this is especially true in coastal markets that cater to high-end clients who demand supreme quality and impeccable performance from their homes. Even in today's markets, which are euphemistically described as "relaxing," there seems to be no shortage of wealthy home buyers snapping up second-home properties along the coveted coast. If you build in this market, it's this kind of discriminating home buyer who will most expect you to get things right.

    In more than 25 years of consulting with builders on ways to reduce callbacks, I've spent most of my time solving problems related to heat and moisture transfer through buildings, because this is often where builders — even very good builders who deliver well-appointed homes to the coastal elite — get things wrong. Most of the serious (read "expensive") performance failures are moisture related, and a good number of these are closely tied to the thermal performance of the home. Yet I am surprised how often the insulation is installed without much thought or understanding about how it works. Consequently, very little attention gets paid to the details that really matter. Typically, fiberglass — selected as the least expensive option up front — is jammed in the walls and stuffed around electrical wires, plumbing pipes, and HVAC ducts, then covered up as soon as the municipality allows. The result is gaps, compression, and hollow voids that compromise occupant comfort and increase the building's energy loads. A sloppy insulation job can also lead to moisture problems by creating thermal conditions in walls and ceilings that promote condensation, wetting, mold growth, and rot.


    Batt insulation works best when it is fully lofted, not jammed into the tight spaces (above). Compression of the batt reduces the number of air pockets that provide the material's insulation value. It also leaves a hollow between the insulation and the drywall, creating areas where air can circulate. These voids can siphon off energy and may create conditions for condensation and moisture problems.

    Bright Star
    The updated Energy Star label for homes provides a quality standard that can guide builders away from these problems. New program requirements have raised the level of quality in the program, making it a label that savvy home buyers will more likely be looking for. As of January 1, 2007, a home that qualifies for an Energy Star label must pass a "thermal bypass inspection": a rigorous assessment of a home's air barrier. The bypass inspection requires builders to follow the EPA's Thermal Bypass Inspection Checklist — a 25-point list of details aimed at stopping the movement of heat around or through the insulation. Thermal bypasses — the defects that most commonly reduce the energy performance and comfort of homes — typically result from missing or compressed insulation, missing air barriers, and gaps between the air barrier and the insulation.


    The Energy Star Thermal Bypass Inspection Checklist must be completed by a certified home energy rater. However, in order for a home to qualify for the Energy Star label, up to six items may be verified by the builder to minimize required field trips by the rater.

    In my opinion, this checklist is one of the best guidelines to come out of the EPA's Energy Star program, and I think it substantially raises the bar for thermal and moisture performance of building envelopes. Of particular value to builders, the 86-page Thermal Bypass Checklist Guide (available free online at www.energystar.gov; search "Thermal Bypass Guide") provides a very practical and comprehensive look at reducing air infiltration. It should be required reading for anyone who's serious about building a quality home in any climate, but especially in demanding coastal climes.




    Living Spaces Over Garages
    Living spaces over garages create conditions that demand careful attention to insulating the floor. Yet it is difficult to support the insulation in this cavity, and oftentimes the insulation falls onto the garage ceiling. This separation between the insulation and the living space floor creates a thermal bypass that compromises the value of the insulation. Air easily infiltrates in at the band-joist area over the top of the insulation, which scavenges away heat. This often freezes plumbing pipes, creates cold floors, and can lead to major mold and water damage. Builders often try to solve the problem by supplying forced-air heat near the plumbing, but this only succeeds in pressurizing the space with warm, humid air. As this air exfiltrates through the exterior cracks, it can condense and lead to even worse moisture and mold problems at the band-joist areas.


    The issues are easily solved with ccSPF, which sticks to the bottom of the subfloor so insulation and air barrier are always in contact. The foam also stops air infiltration. It is a good idea to wrap any plumbing with a thin layer of fiberglass insulation before spraying foam over it to make servicing the plumbing easier.

    An Insulation for All Reasons
    I've included in this article a short catalog of some of the problem areas addressed on the Thermal Bypass Inspection Checklist that I find are frequently missed.

    What stands out about all of these problem points is that they can be difficult to get right with inexpensive fiberglass insulation unless a builder is working with an experienced and service-minded insulation crew. However, these problems are easily avoided when using closed-cell spray foam (ccSPF) insulation. This alone provides a strong argument for always using ccSPF, but it's certainly not the only reason.

    There are many reasons why ccSPF makes particularly good sense in a coastal home:

    • It has a high R-value of 6.5 to 7 per inch.
    • It absorbs a negligible amount of water. It can even be used as an effective secondary rain barrier and is the only FEMA-approved insulation for flood-resistant construction.
    • It does a good job of controlling diffusion.
    • It has good air barrier qualities to reduce airflow into and out of wall cavities.
    • It expands to fill voids in hard-to-
    insulate areas.
    • It provides some structural integrity to the frame (see "The Structural Properties of Foam," page 26).

    Steve Easley
    is principal of Steve Easley Associates, a company based in Danville, Calif., that provides building-science training and quality assurance for builders nationwide. All photos by the author.



    Attic Knee Walls
    These are areas where the insulation on the back side of unsheathed walls is exposed to outdoor temperatures and airflow. They are often adjacent to ventilated attic areas. The Energy Star Thermal Bypass Inspection Checklist requires that an air barrier be placed on all sides of the insulation. This means that the back sides of knee walls need to be sheathed and sealed. Thin-profile cardboard sheathing with ccSPF works well here. Since ccSPF is air impermeable, the insulation does not have to fill the entire cavity, and it meets the air barrier requirement. Some codes require R-19 insulation, which is difficult to do in a 3 1/2-inch space with batt insulation, but 2 inches of ccSPF provides about R-19.5.





    Sloping Roof Areas
    The sloping areas in a cathedral ceiling can be the sites for significant thermal bypasses. These areas are not only difficult to insulate but are difficult to ventilate. Yet ccSPF solves both problems. Placing ccSPF directly on the underside of the roof deck also creates a secondary rain barrier, and because of ccSPF's high R-value and low permeability, moisture is not likely to condense on its surface, eliminating the need for cavity ventilation.







    Band-Joist Areas
    The band-joist area is typically a major site for air infiltration. These areas are usually very poorly insulated, causing one of the most significant thermal bypass areas. If the home is under a positive pressure (air pushing out from inside) in a heating climate, the air is likely to be at a high humidity level. This can cause frost, and eventually mold, to build up on the back side of the band joist. In a cooling climate that is under negative pressure (air pulled inward — a condition that's commonly caused by leaky HVAC ducts), this can pull hot, humid air from outside, where it is likely to condense and lead to mold problems. The sealing properties of ccSPF will reduce these air-infiltration and energy-loss problems in this troublesome area.





    Attic and Crawlspace Bypasses
    Attic and crawlspace bypasses are penetrations into the living spaces. Pipes, ducts, flues, and electric wires are the most common reason for these penetrations, and the best way to seal them is often (but not always) with ccSPF. Because ccSPF expands and seals, it does an excellent job of filling voids that allow conditioned air to escape. However, ccSPF should not be used to seal around high-temperature areas such as combustion appliance flues.




    The Structural Properties of Foam

    Recent research conducted at the University of Florida has demonstrated that closed-cell spray foam (ccSPF) applied to the underside of roof decking effectively bonds the sheathing to the framing, significantly increasing uplift resistance. The study, conducted by Dr. David O. Prevatt and funded by Honeywell and Huntsman, two makers of ingredients that go into ccSPF, found that 3 inches of the foam sprayed between framing members provided a threefold increase in uplift resistance as compared with traditionally installed roof sheathing panels. While these results sound impressive, Dr. Prevatt points out that the increase provides the same benefits as increasing the nailing schedule to a 6/6 schedule (every 6 inches along panel edges and every 6 inches in the field) from the usual 6/12 schedule. What was perhaps most impressive is that using only spray foam to glue the sheathing to the framing provided almost as much resistance (178 to 209 psf) to uplift as does 8d common nails (205 psf) installed at the 6/6 schedule. This suggests what may be the biggest structural advantage of a foamed roof assembly — reducing the likelihood of a roof blowoff when the sheathing doesn't get nailed off with enough nails or when too many nails miss their mark.


    A test panel (left) in a study at the University of Florida simulates a roof assembly consisting of 1/2-inch OSB fastened to 2x4 framing at 24-inch centers. The framing bays have been filled with closed-cell spray foam. During the study, the assembly was placed on a pressure chamber and a vacuum pump (above right) drew a vacuum that was increased in 15-psf intervals until the assembly failed and the sheathing popped off the framing. For the fully foamed assemblies, this occurred at around 240 psf. The assemblies that had ccSPF fillets installed failed at 160 psf. The assemblies with sheathing alone nailed only with nails (6/12 schedule) failed at about 75 psf.

    The uplift study also evaluated the benefit of installing a "fillet": a 3x5-inch bead of ccSPF in the corners between the sheathing and the roof framing. The fillet method effectively doubled the uplift resistance of the baseline assembly of 2x4 framing on 24-inch centers sheathed with 1/2-inch OSB nailed on a 6/12 schedule.

    The uplift study is one of several recent studies of the structural properties of ccSPF. Tests conducted by Building Science Corporation (BSC) to evaluate the impact resistance of wall systems showed that conventional wood-framed walls do not have the same impact resistance as impact-resistant windows. (That is, walls consisting of studs, 1/2-inch OSB sheathing, housewrap, and siding cannot sustain the impact required by the ASTM E1886 and E1996 missile test, which hurls a 9-pound 2x4 at 50 feet per second.) The only test panel in the BSC demonstration capable of resisting the required impact load included a layer of 1/2-inch OSB sheathing between 1-inch foam insulating sheathing and 2 inches of ccSPF sprayed between 2x6 studs. Surprisingly, BSC found that a wall with foam sheathing, housewrap, and ccSPF (no OSB) performed better in impact tests than a wall with housewrap and OSB sheathing.


    When a roof is not likely to be replaced anytime soon and the sheathing nailing can't be verified (on a tile roof in good condition, for example), contractors in Florida are beginning to employ the "fillet method." This practice uses closed-cell spray foam to help bond the roof sheathing to existing framing and provide a secondary water barrier.

    The BSC study notes that walls may not have to be built to the same standard as windows, despite these surprising results. When a window fails under impact, the resulting hole in the wall (the entire window) is relatively large, providing a big enough hole to internally pressurize a home, which often leads to catastrophic failure. When a wall fails, the zone of impact is marginally bigger than the impacting face of the projectile. Such an opening may not be large enough to have a catastrophic effect. — Clayton DeKorne


    Scotts Contracting is available to assist in your Home and Business Insulation Needs.  I even have a Local Supplier / Manufacturer of Spray Foam Insulation- This Insulation is Both Closed and Open Cell Soy-based That is Green and Eco Friendly. Click Here to email Scotts Contracting to Schedule a Free Green Site Inspection.

    Build Green Scotty


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    Additional details or schedule a Free Green Site Evaluation at: Scott's Contracting
    scottscontracting@gmail.com

    9.08.2010

    Insulation-If Walls Could Talk Part 1

    If Walls Could Talk

    Insulation: A tougher code necessitates more remodeling training

    Roofing & Insulation
    Credit Available30% of cost (product only, no labor)
    $1,500 maximum for all improvements combined
    TimelineMust be "placed in service" (ready and available for use)
    Jan. 1, 2009 – Dec. 31, 2010
    Requirements
    Metal and Asphalt RoofsEnergy Star–qualified
    InsulationMeets 2009 IECC & Amendments
    Must be expected to last five years or have a two-year warranty
    Primary purpose must be to insulate. As of May 31, 2009, IRS has not ruled on SIPs or insulated siding, but it is believed that SIPs are eligible
    Provided by Scotts Contracting 


    Dollar for dollar, insulation and weatherization deliver more bang for their energy-efficiency buck than almost any home improvement. Happily for manufacturers and installers, the American Recovery and Reinvestment Act's $1,500 tax credit can be applied, in theory, to a broad array of materials and methods — batts, spray foam, loose-fill; wraps, sealants, tapes, and flashing; even structural insulated panels — that are primarily designed to reduce the heat loss or gain of the nation's estimated 80 million underinsulated homes.
    On its surface, the insulation provision is simple: Homeowners can take a tax credit of 30% of the cost of materials only, to a maximum of $1,500, for insulation work performed this year and next. That's triple the credit available since 2005. The sum of the resulting "insulation material used in layers" must meet the R-values prescribed by the 2009 International Energy Conservation Code (IECC).

    "We think the recovery bill is a great opportunity to move forward" toward a more energy-efficient housing stock, says Gary Nieman, vice president of government policy initiatives at Owens Corning, feature one of several insulation manufacturers that were interviewed for this article.

    Guardian Building Products' "customer base has expressed heavy interest in several areas of the ARRA," says Aaron Hock, national sales manager.
    Code of Conduct

    More on the Building Envelope

    Things start to get sticky with the IECC. Published by the International Code Council (ICC) and based on goals set by the U.S. Department of Energy, the 2009 IECC will produce 15% in energy-efficiency gains over the 2006 version, according to the DOE. (To purchase the 2009 IECC, go to www.iccsafe.org.

    Regarding insulation, the 2009 IECC is considerably tougher than the previous version, particularly in colder parts of the country, where R-values (thermal resistance) are now as high as 21 for wood frame walls, 38 for floors, and 49 for ceilings and attics. "The new code requirements make it tough for builders to do things as usual and still meet the code," says Bob Burgess, president of Accurate Insulation, in Upper Marlboro, Md., whose 65 installers work all over the mid-Atlantic region. This is especially true in remodeling, when insulation is sometimes compressed into small cavities, potentially compromising R-value.

    Numerous products meet the specified R-values, including fiberglass and cotton batt insulation with ratings of R-21 or higher that can be installed in a 2x6-framed wall cavity, plus several loose-fill products using fiberglass, cellulose, or other materials that can be installed behind netting in open framing or used to fill cavities in existing walls.

    Such products likely won't be as inexpensive as the old mainstays, however, or necessarily prove as easy to find, at least based on a few calls to building supply retailers.

    In some cases, in fact, meeting the prescribed R-values becomes almost cost-prohibitive. Ironically, it may even deter homeowners from choosing what many green remodeling advocates believe are the best (but most expensive) insulating products: water-based spray foams that expand to fill gaps and holes.

    "They're speaking batt language," says Laura Calfayan of Calfayan Construction and AirTight SprayFoam of Southeastern PA, in Huntingdon Valley. "If I were to spray R-38, I'm literally forcing people to spend more than they need to," she says, to achieve the same comfort effects that can be achieved with 2 inches of AirTight's water-based, closed-cell foam, whose continuous air barrier reduces energy use beyond its stated R-value of 7 per inch.

    Even so, business is up for spray foam companies. An Icynene product, for example, has a 3.7-per-inch R-value, allowing 2x6 walls insulated with it to meet the 2009 IECC in zones that require R-20.
    By mid-April, downloads of the Icynene manufacturer's certification statement (needed for tax documentation purposes) had risen by 68% since January, according to Teresa Crosato, the company's marketing communications supervisor.

    If homeowners must dig a bit deeper at the point of sale, that's the price of progress, says Darren Meyers, technical director of energy programs with the ICC. "[The 2009 IECC] is a paradigm shift because the nation and the home-building community have not understood how far behind our construction practices are. We've never had a call to action [to be very energy efficient]," he says. The DOE's goals, and the resulting code, are the call to action.


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    contact for additional details-->Scott's Contracting
    scottscontracting@gmail.com

    7.25.2010

    Missouri Renewable Energy and Efficiency-Grants and Incentives

    Missouri Residential Incentives

    Financial Incentives for Renewable Energy-Energy Efficiency-PACE Funding-Solar-Wind-Geo Thermal-Grants-Loans-Tax Incentives-Tax Breaks-Rules-Regulations-Local Options-Utility Loan Program-Appliances-Rebate-Net Metering-Photovaltaic


    PACE Financing
    Personal Deduction
    State Rebate Program
    Utility Loan Program
    Utility Rebate Program
    Rules, Regulations & Policies

    Net Metering
    AmerenUE - Photovoltaic Rebate Program

    Last DSIRE Review: 01/08/2010
    Program Overview:
    State: Missouri
    Incentive Type: Utility Rebate Program
    Eligible Renewable/Other Technologies: Photovoltaics
    Applicable Sectors: Commercial, Industrial, Residential, Nonprofit, Schools, Local Government, State Government, Fed. Government, Agricultural, Institutional
    Amount:$2.00/W DC
    Maximum Incentive:$50,000
    Eligible System Size:Maximum capacity of 100 kW (the limit for net metering in Missouri)
    Equipment Requirements:Equipment must be new; modules and inverters must have a minimum warranty of 10 years; lockable external disconnect switch required
    Installation Requirements:System must be grid tied, net metered, and permanently installed on the customer's property
    Ownership of Renewable Energy Credits:Customer-generator
    Web Site: http://www.ameren.com/sites/aue/source/Renewable/Pages/ADC_Ameren...
    Summary:
    AmerenUE offers rebates to its customers for the installation of net metered photovoltaic (PV) systems on their properties. The rebate is set at $2.00 per DC watt with a maximum rebate of $50,000. Although the program guidelines and application do not list a firm maximum system capacity, the requirement that the system be net metered implicitly limits system size to 100 kilowatts (kW), the maximum size allowed under Missouri's net metering rules. Only systems that become operational after the opening date of the program (January 1, 2010) are eligible for incentives. In order to qualify for incentives, a customer must have an electric account in good standing with the utility. Eligible systems must use new equipment; be permanently installed on the customer's property; and have module and inverter manufacturer's warranties of at least 10 years. Installations must comply with all applicable federal, state and local codes and standards, including the state of Missouri's Interconnection Standards. Rebate recipients must certify that the system will remain in operation on their property for its useful life (deemed to be a minimum of 10 years). Notably, the customer retains ownership of all solar renewable energy certificates (SRECs) generated by the system. This program arises from 2008 Proposition C, a ballot initiative that established a state renewable portfolio standard in Missouri and required the state's investor-owned utilities to offer solar rebates of at least $2.00 per watt beginning in 2010. Please see the program web site and look under the heading of "Missouri's Proposition C" for further details and program applications.

    -- For your next Green Building Project-let Scotty supply a Free Green Site Evaluation that will outline the areas for saving Energy + Money in your Home or Business. Scott's Contracting scottscontracting@gmail.com http://stlouisrenewableenergy.blogspot.com http://www.stlouisrenewableenergy.com

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